TECHNICAL USER MANUAL for STANDARD HALF THROUGH UNDERBRIDGES Z TYPE

Transcription

1 NR/CIV/TUM/1200 Rev D May 2010 TECHNICAL USER MANUAL for STANDARD HALF THROUGH UNDERBRIDGES Z TYPE Standard Detail and Design Drawings Page 1 of 38

2 NR/CIV/TUM/1200 Rev D May 2010 Summary This technical user manual is applicable to the standard Z type half through underbridges. It provides guidance on the selection and application of Network Rail s suite of standard drawings. The standard designs and details within these drawings will generally be used for new build structures, and part replacement e.g. deck replacement. Issue record This technical user manual will be updated when necessary by distribution of a complete replacement. A vertical black line in the margin will mark amended or additional parts of revised pages. Revision Date Comments A December 2008 Issue for review B April 2009 Network Rail Review C June 2009 First issue D May 2010 Second issue Eurocode Update Page 2 of 38

3 NR/CIV/TUM/1200 Rev D May 2010 CONTENTS GLOSSARY 6 1 INTRODUCTION TO STANDARD DESIGNS AND DETAILS Network Rail s Requirements Delivery Requirements Functional Requirements 8 2 GUIDANCE FOR USE OF NETWORK RAIL STANDARD DESIGNS AND DETAILS Approval of Schemes Using Standard Designs & Details Modifications to Standard Designs & Details Drawing Selection Flowchart 14 3 Z TYPE UNDERBRIDGE APPLICATION DETAILS 16 4 DETAILS OF STRUCTURAL FORM Geometry and Configuration Span Skew Floor Type Floor Width Construction Depth Clearances Structure Gauge Clearances Static Electrical Clearances Clearances Limits Affecting Design Track Arrangement Positioning Cant Ballast Depth Sleeper and Rail Details Site Constraints Direct Fastening Systems 24 5 INSTALLATION GUIDANCE Trial Erection Installation Tolerances Lifting Guidance Check List for Non Standard Arrangements and Non Standard Items Check List for Installation Options 27 Page 3 of 38

4 NR/CIV/TUM/1200 Rev D May GUIDANCE FOR USE OF THE Z TYPE STANDARD DESIGNS AND DETAILS General Arrangement Drawing General Assembly Drawings Details Drawings Span Skew Traffic Main Girder Length and Floor Overhang Past Trimmer Concrete and Reinforcement Drawing Bar Bending Schedules Protective Treatment and Waterproofing Basic Principles and General Comments Protective Treatment Waterproofing Drainage Substructure and Ancillary Items Bonding / Stray Current / Insulation 36 7 FABRICATION AND CONSTRUCTION Fabrication Construction 37 8 SAFETY / CDM AND ENVIRONMENTAL 39 LIST OF APPENDICES APPENDIX A Schedule Of Standard Drawings APPENDIX B History APPENDIX C Design Assumptions APPENDIX D Technical Details APPENDIX E Hidden Parts APPENDIX F Draft 12 of NR/L2/CIV/020 Design of Bridges & Culverts LIST OF FIGURES Figure 2.1: Flowchart to show the use of Network Rail s Standard Details and Designs 10 Figure 2.2: Process using the Standard Drawings and Technical User Manuals 13 Figure 2.3: Process to determine the Standard Details and Designs to use in detailing a Standard Z type Underbridge 15 Figure 4.1: Construction Depth 20 Figure 4.2: Cant Effects 23 Figure 6.1: Definition of Skews 29 Page 4 of 38

5 NR/CIV/TUM/1200 Rev D May 2010 Figure 6.2: Cross Girder / Transverse Rib Setting Out 30 Figure 6.3: Traffic Type and Detail Classification 32 Page 5 of 38

6 NR/CIV/TUM/1200 Rev D May 2010 GLOSSARY Abutment Bearing Bridge Cill Deck Deep Girder Designer Filler Beam Floor Gauging Diagram Impost Main Girder Part of the bridge structure that supports the bearings at the end of a deck and often supports and retains the approach embankment. The elements between the impost / cill and the main girders on which the deck is supported. A deck and its supporting structure (e.g. impost / cill, abutment or piers). Alternative name for impost. The (usually) concrete beam on which the lower part of the bridge bearings are located. A pair of main girders and a floor. A main girder located within the area for fixed infrastructure (platforms) in the lower sector structure gauge. May act as a robust kerb. The person responsible for selecting the relevant standard designs and details to suit the specific requirements for a particular scheme. A steel and concrete floor arrangement comprising transverse spanning steel sections encased within and acting compositely with a concrete slab. The transverse element that supports the ballast and track. May comprise filler beams composite with concrete slab, or steel transverse ribs and steel plate. A diagram showing the clearances between the lower sector structure gauge and the proposed structure. Alternative name for cill. The (usually) concrete beam on which the lower part of the bridge bearings are located. The primary load sustaining element that spans between bearings and supports the floor. Comprises a pair of flanges, possibly flange doubler plates, a web, web stiffeners and bearing stiffeners. The flanges are offset and resemble a Z shape. Page 6 of 38

7 NR/CIV/TUM/1200 Rev D May 2010 Pier Protective Treatment Scheme Shallow Girder Transverse Rib Trimmer Beam TUM SDD Walkway Waterproofing Z Type Part of the bridge structure that supports the bearings at the end of a deck. Generally used where more than one span, in between abutments. A treatment applied to structural elements to protect them from environment. Any planned work that involves the replacement of an existing bridge or deck. A main girder located either below the lower sector structure gauge or within the area reserved for items intended to come in close proximity to trains (up to 110mm above rail and between 730mm and 558mm from the rail horizontally) allowed in GE/GN A steel transverse member formed of a tee rib. The first cross member adjacent to the main girder bearings. May or may not support the trimmed ends at adjacent cross members. Technical User Manual Standard Designs and Details A standard detail comprising brackets attached to web stiffeners and longitudinal spanning members positioned to allow railway personnel traverse the bridge away from the track. Measures applied to handle and remove water off the deck and away from structural elements. A standard underbridge arrangement comprising a pair of Z shaped main girders, a floor and four bearings. Page 7 of 38

8 NR/CIV/TUM/1200 Rev D May INTRODUCTION TO STANDARD DESIGNS AND DETAILS The development of the Standard Designs and Details (SDD) has been undertaken by Network Rail to improve safety, asset reliability and increase efficiency. Their development is linked to Network Rail s overall business objectives, to improve reliability of the railways and reduce the funding requirements for on going management and maintenance of the network. The basis of the SDD focuses on two main areas that derive from these issues: Ensuring that the design meets Network Rail s requirements The design is as successful as the designs of previous railway engineers, who built and maintained bridges that have given good service for approaching 150 years. The use of the SDDs is promoted from the highest level within Network Rail. Alternatives to the SDDs will only be considered where it can be demonstrated that a SDD cannot be used and must be agreed with Network Rail s professional head of civil engineering. Failure to use a SDD may lead to project authority being withheld. 1.1 Network Rail s Requirements Network Rail s requirements are split between two areas, delivery and function: Delivery Requirements The SDDs have been taken to a stage where Form As and Form Bs for each aspect covered (underbridge design, ancillaries etc.) have been submitted and approved. This leads to the following benefits: A reduction in the design development timescales and costs. Minimising contractor and sub contractor costs associated with uncertainties in detailing requirements. Streamlining the technical approval process for commonly used designs and details Functional Requirements The SDD have been designed to ensure satisfactory performance of the asset under both normal operations and abnormal operations (both planned and unplanned). A further consideration has been Network Rail s requirement to reduce the volume of maintenance and management costs through the adoption of good practice. This leads to a number key design drivers including: Failure modes: Critical failure modes should give warning, and alternative load paths should be provided for potential local failures. Page 8 of 38

9 NR/CIV/TUM/1200 Rev D May 2010 No hidden details: All main structural elements should be visible from at least one side. Robustness: It is desirable for elements of the structure to have a degree of robustness so that they are not damaged by unforeseen events disproportionate to the cause. Capability to support load. Acceptable deformations. Structure gauge requirements: The underbridges have been designed to cater for a range of positions of the structure gauge allowing their wide use. Safe working environment: The bridges have been designed to minimise the risk to people on or about the bridge. Resistance to bridge bash : The bridges have been designed minimise the risk of catastrophic failure in the event of a bridge bash. Resistance to derailment: The bridges have been designed to cater for the codified derailment loads, as well as protecting the structure whilst mitigating damage to the surrounding structures. These functional requirements are requirements of draft Network Rail standard NR/L2/CIV/020. Draft 012 of this standard has been used and the requirements therein met in designing the standard Z type details. A library of standard designs and details for a range of half through underbridges forms meeting these requirements has been produced. This document contains guidance on the use of these standard drawings, including advice on the following: The elements and options contained within the suite of standard designs and details. Instruction on configuring a design using the standard designs and details Specific design restrictions and design assumptions Installation guidance Safety / CDM / environmental issues The library will be maintained and distributed by Network Rail to its stakeholders and key external suppliers for adoption across the network at a national level. Page 9 of 38

10 NR/CIV/TUM/1200 Rev D May GUIDANCE FOR USE OF NETWORK RAIL STANDARD DESIGNS AND DETAILS The underlying philosophy of this standard is that a single standard deck design is provided, together with general details of the other components (i.e. main girders, bearings, walkways, protective treatment, waterproofing etc.) which go to make up a standard Z type bridge superstructure. This allows the designer to produce a specific bridge design to suit the particular span, skew, track geometry, cable ducting and walking route requirements of any particular location with the minimum of design and drawing time, so long as they are within the limits of validity of the standard. The flowchart in Figure 2 1 demonstrates the use of the technical user manual and standard drawings. The designer should analyse the constraints and requirements that exist for the specific project site. This information should be used in conjunction with the design advice contained within the technical user manual, to decide which elements can be taken from the suite of standard designs and details and which items, if any, need bespoke design. This designer output, and the series of standard drawings can be combined to produce the final Z type underbridge solution. Figure 2 1: Flowchart to show the use of Network Rail s Standard Details and Designs This manual describes the 2009 standard for rail underbridges using a half through construction arrangement of Z type main girders with either a filler beam floor or a steel floor. It is intended to be read in conjunction with the set of standard drawings listed in Appendix A and aid the designer in producing an individual bridge design using this standard, or in comparing these Page 10 of 38

11 NR/CIV/TUM/1200 Rev D May 2010 standard designs and details with other solutions. The manual discusses issues that will need to be covered in a contract specification for a bridge of this type. The designer is required to determine the bridge steelwork layout and produce a scheme specific deck steelwork general arrangement drawing. The designer will also have to produce survey, proposed general arrangement, substructure detail, track layout and levels and setting out drawings, as necessary, plus detailed reinforced concrete drawings and schedules. A list of the standard drawings used that define the required works shall be included on the general arrangement drawing. The standard drawings shall not be redrawn or modified. Any required changes (e.g. when defining geometry or facilitating construction methodology) shall be shown on a separate drawing that clearly identifies the affected details. The deck and other components have been designed to cater for a wide range of spans, skews and track geometry. For situations outside these parameters, the standard cannot be assumed to be applicable. Equally it will be obvious that the design here, in catering for such a wide range of circumstances, will inevitably involve conservatisms on specific aspects and for specific bridge arrangements. Thus it may be possible to use the existing design in whole or part outside the given limits without modification, or to achieve a less substantial design (e.g. lower weight) within those limits: In both cases they will need approval, full re design, and an appropriate check. These are matters that will need discussion with Network Rail s project sponsor and Network Rail s professional head of civil engineering if such a course of action is favoured. 2.1 Approval of Schemes Using Standard Designs & Details The SDDs for each half through underbridge form have been submitted and approved by Network Rail at both Form A and Form B (including a Category III Check) stages of the Network Rail approvals process in accordance with NR/CIV/SP/003. The flowchart in Figure 2 2 demonstrates the general process of using the SDDs and TUMs. The blue shaded boxes assist the designer to select the appropriate details or confirm the suitable options available. A list of typical site parameters to consider in determining the appropriate details or confirm the suitable options available is included in section Page 11 of 38

12 NR/CIV/TUM/1200 Rev D May 2010 Page 12 of 38

13 Figure 2 2: Process using the Standard Drawings and Technical User Manuals NR/CIV/TUM/1200 Rev D May 2010 The designer will need to produce a scheme specific Form A for the site under consideration. This Form A will detail the site specific parameters, include a gauging diagram and a list of the SDDs that will be used. As discussed previously the SDD Form As have been approved and a site specific Form A is to be produced to gain approval for use of the particular SDDs selected on the scheme. Following Form A approval the designer will need to produce general arrangement drawings and reinforcement schedules only for the scheme. As discussed previously the SDDs have been approved (Form B), and include a Category III Check. Therefore the checking required for each specific scheme will be of the general arrangement and reinforcement details and schedules to ensure they are suitable in meeting the scheme requirements. The level of checking required is: Category I Check of the application of the standard designs and details Category II Check of the general arrangement (including site survey information) and bar bending schedules 2.2 Modifications to Standard Designs & Details Modifying the standard designs and details will only be accepted by Network Rail where the modifications can be justified technically and where it can be demonstrated that the modifications will not incur any significant additional whole life cost to Network Rail. Any modification invalidates the Standard Designs and Details Form As and Form Bs. In the event that modification is proposed the following justification must be provided: Technical justification considering structural capacity, longevity with respect to fatigue and reserves fro future corrosion allowance: o Form A documentation. o Form B documentation. Cost justification o Estimate of the increased cost of maintaining non standard assets. o Estimate of the increased cost of managing non standard assets. o Estimate of the increased cost of additional Network Rail approval and review costs. Page 13 of 38

14 NR/CIV/TUM/1200 Rev D May Drawing Selection Flowchart The following flowchart assists the designer in deciding the options to select and which drawings to use in detailing a standard walkway and approach: Page 14 of 38

15 NR/CIV/TUM/1200 Rev D May 2010 Figure 2 3: Process to determine the Standard Details and Designs to use in detailing a Standard Z type Underbridge Page 15 of 38

16 NR/CIV/TUM/1200 Rev D May Z TYPE UNDERBRIDGE APPLICATION DETAILS The standard Z type design may be used at any suitable location in UK and complies with The Railways (Interoperability)(Amendment) Regulations 2007 (S.I No. 3386) with the following exception: The use of shallow girders (refer to for definition) within the zone up to 110mm above rail and between 730mm and 558mm from the rail horizontally (allowed in GE/GN8573 2) is not permitted on the UK parts of the High Speed Trans European Network (TEN). Note that the use of shallow girders within the zone up to 110mm above rail and between 730mm and 558mm from the rail horizontally is permitted on the UK part of the Conventional Rail Network. The standard drawings provide a complete set of details for the superstructure including the bearings. For a particular bridge, the designer needs to determine the specific layout, choose the appropriate drawings, add the necessary dimensions and exercise specific options on these standard drawings. It is intended that only those standard drawings relevant to the specific contract are issued to the contractor as part of the contract drawings, together with general arrangement drawings particular to the specific bridge. The general arrangement drawings prepared by the designer will specify all principal dimensions and sizes, including material grades. Standard drawings relevant to the particular bridge should be listed on the general arrangement drawing. The standard drawings allow for skew spans between 6m and 17m for three skew related ranges: Square spans. Spans for bridge skews in the range 0 o to 25 o. Spans for bridge skews in the range 25 o to 50 o. Where skew affects the design details (e.g. cross girder / transverse rib details), there are three separate standard drawings, one for each range. For other details which are not skew related (e.g. bearings) there is a single drawing. The designer should therefore choose the relevant drawings for his particular bridge skew range from the full set of standard drawings. Refer to flowchart in Figure 2 3. To simplify details and fabrication, the designer should make low skew decks square where possible. For skew bridges, the drawings are drawn for one (unstated) particular skew and span, which may not match the particular bridge under design. The standard design has considered all skew variations and the details shown can be rotated to suit the required skew. Page 16 of 38

17 NR/CIV/TUM/1200 Rev D May 2010 For the overall layout of the superstructure the key drawings are: The steelwork general assembly (for the relevant skew range). The filler beam floor or steel floor dimensional details (for the relevant skew range). The standard drawings were not developed to be used as fabrication drawings and fabricators may have to produce accurate bridge specific drawings. Most views will therefore need adjustment to the exact dimensions chosen for the particular bridge. Note that the standard drawings shall not be redrawn or modified and the required changes shall be shown on separate drawings. Page 17 of 38

18 NR/CIV/TUM/1200 Rev D May DETAILS OF STRUCTURAL FORM The standard Z type deck comprises a single track half through deck with two z shaped steel main girders and either a filler beam floor or a steel floor. The main girders are simply supported on short rocker bearings. Trimmer girders are supported on the inside edges of the main girder bottom flanges. Refer to the figures in Appendix D for general arrangement details. 4.1 Geometry and Configuration The designer will need to utilise the following Railway Group Standards (or their successors, where appropriate): GE/RT8073 Requirements for the Application of Standard Vehicle Gauges. GC/RT5112 Loading Requirements for the Design of Bridges. GC/RT5203 Infrastructure Requirements for Personal Safety in Respect of Clearance and Access. GC/RT5212 Requirements for Defining and Maintaining Clearances. GE/GN8573 Guidance on Gauging NR/L2/CIV/020 Design of Bridges and Culverts (a copy of draft 12 appended to this TUM) GC/RC5510 Recommendations for the Design of Bridges. 4.2 Span The span range of the standard Z type underbridges considered in the SDD is the span measured between centres of bearings and is 6.0m to 17.0m. Limitations apply to the maximum span when considering shallow girders with a ballast range of 200mm to 300mm. 4.3 Skew The skew range, measured between the bearing centre line and perpendicular to the track centreline, is 0 (square) to 50 (maximum). Page 18 of 38

19 NR/CIV/TUM/1200 Rev D May Floor Type There are two Z type floor arrangements, a filler beam floor option and a steel floor option. The filler beam floor option is suitable for the majority of schemes with the exception where lifting weights or the loads on existing abutments are to be minimised. In this situation, the steel floor option is advantageous at the detriment of the construction depth which is greater than the equivalent filler beam floor. The steel floor standard detail includes a maintenance gap between the transverse rib flange and main girder flange. This gap must not be reduced without the agreement with Network Rail s professional head of civil engineering. There are further advantages of using the filler beam floor, including less long term maintenance and a lower capital cost. As such the filler beam floor is the preferred option. 4.5 Floor Width The upper deck width limit of 3300mm between main girder web centres allows the deck to be wide enough to accommodate DC traction cables without the need for an adjacent cable bridge. This carries a weight penalty for lifting in a new bridge compared to narrower decks. The narrow deck width is that required for straight track with ±25mm tolerance on track lateral positioning. Where shallow girders are specified (refer to section 4.7.3) a 2588mm wide sleeper is considered and a 50mm minimum clearance between the structure and sleeper end required. At the narrower end of the deck width range, shallow depth main girders must be utilised to comply with clearance requirements to the structure gauge. Where narrower deck widths are proposed, due attention must be paid to the electrical clearance requirements where conductor rails are present. Deck widths and the position of any cess walkways will also be affected by the cant, curvature and track alignment of each particular bridge location. Consideration must also be given to existing abutment width and adjacent structures, walkway positions and bridge end access requirements. The minimum track radii that can be accommodated by the standard designs and details are given indicatively in Table 4.1. The designer is responsible for confirming scheme specific details and ensuring the maximum lateral force limits (refer to Appendix C) are not exceeded: Floor width 3.300m 2.900m 3.300m 3.165m 3.300m 2.900m 3.300m 3.165m Span 6m 6m 6m 6m 17m 17m 17m 17m Girder type Shallow Shallow Deep Deep Shallow Shallow Deep Deep Speed 50kph 200kph 60kph 200kph 50kph 200kph 70kph 200kph Radius 200m 250m 250m 350m Page 19 of 38

20 Table 4.1: Indicative Minimum Track Radii on a Standard Z Type Deck NR/CIV/TUM/1200 Rev D May Construction Depth The construction depth for each Z type floor type varies with span ranges and ballast depth, with a minimum of 913mm and a maximum of 1153mm. Refer to drawing NR/CIV/SD/1201 for specific details. The construction depth has been determined assuming the following: depth of track (rail, rail pads and sleeper) of 368mm, the nominal ballast depth, waterproofing (assumed as 15mm thick) and the chosen floor type depth. Figure 4 1: Construction Depth 4.7 Clearances Structure Gauge Clearances The designer should: Ensure that adequate clearance is provided between existing and proposed vehicles and the structure. Consider the maximum offset of the rail centre line and bridge centre line. Ensure that the structure gauge considered (to include cant and end throw allowances) is suitable for the line considered for each specific scheme, in accordance with current Network Rail and Railway Group Standards. Ensure that the required track radius (if any) will not result in encroachment on the structure gauge by any part of the deck or walkway. See earlier comment The limits that the standard designs have been designed within are discussed in section 4.8 noting that the bridge structures are straight and the allowances for track offset small. Equally the effect of cant on maximum girder depths and on ballast top relative to shallow girder top must not be overlooked. The maximum cant of 150mm (super elevation + track) was derived to alleviate this problem. Page 20 of 38

21 NR/CIV/TUM/1200 Rev D May Static Electrical Clearances Where conductor rails are present, the designer should: Ensure that adequate clearance is provided between the conductor rail and the structure Clearances Limits Affecting Design. There are three basic cases to consider: a) Bridges with shallow girders. In case a), the tops of the main girder are low enough to avoid any interference with the kinematic envelope and are placed in the zone up to 110mm above rail level and between 558mm and 730mm from the running edge of the rear rail (allowed in GE/GN8573 2). Therefore the only potential clearance conflict is with the hand railing on any walkways. This aspect is addressed by making the walkway width large enough to meet the clearance requirements (See Section 6.1). The limiting criteria on track position in this case is the need to provide an adequate distance from sleeper end to the main girder top flanges or webs. An absolute minimum distance of 50mm is recommended and, where possible, should be increased to provide tolerance for track positioning. Where a conductor rail is present, the designer must ensure adequate static electrical clearance between the conductor rail and the structure. Note that shallow girders with the top flange above rail level cannot be used on the UK parts of the High Speed Trans European Network (TEN) where the Railways (Interoperability)(Amendment) Regulations apply. Decks with shallow girders only should not generally be used unless protected by adjacent decks (i.e. multiple track situations) or structures that act as or provide robust kerbs. b) Bridges with deep girders. For case b), the deep main girders may act as robust kerbs. This arrangement has the additional limitation of the clearance from the compression flange inside edge to the kinematic envelope. An absolute minimum clearance of 25mm has been assumed. The maximum distance between the rail and flange level considered in the standard designs is 350mm. Note that the designer should assess if this is acceptable for specific bridges, i.e. permanent way clearances and requirement to maintain gauge, or construction and installation tolerances, as a minimum clearance of 50mm is desired for possible future works. On the standard deck (3300mm wide) this leaves an allowance of 92.5mm to cater for the effects of cant, end and centre throw, track curvature and positional tolerance. Cant throw effects can be countered by offsetting the track. If this is done then the minimum radius of curvature that can be achieved at the Page 21 of 38

22 NR/CIV/TUM/1200 Rev D May 2010 maximum span range of 17.0m is in the order of 350m at 70kph. This limiting criterion has been used in arriving at the 3300mm standard deck width. In case b) the sleeper end position will not be critical. Walkway widths however must be determined, as in case a), to be wide enough to clear the upper part of the kinematic envelope with particular attention paid to canted or curved track arrangements. The designer must also confirm the deep girders can be located within the space available in the six foot. Typically there is insufficient space in the six foot for a pair of deep girders and an outer, deep girder acting as a robust kerb and a shallow inner six foot girder is provided. c) Bridges with one deep and one shallow girder. Where appropriate, case c), a deep and a shallow girder may be used on a single deck. In this case the outer deep girders will act as a robust kerb. Note that the deck centreline and the straight track centreline will not be coexistent for the minimum deck width. (Note: deep girders are as defined as girders that act as a robust kerb, i.e. 350mm above rail level (deep) and shallow girders are those below the structure gauge. Refer to drawing NR/CIV/SD/ Track Arrangement A minimum distance of 50mm is assumed between the edge of the top flange and sleeper. A lateral positioning tolerance of 25mm is then provided to ensure the 50mm between the edge of the top flange and sleeper is maintained. Therefore 25mm is the total minimum lateral tolerance for positioning the track and deck where shallow girders are used. A minimum distance of 25mm is assumed between the edge of the top flange and the structure gauge. This distance is the total minimum lateral tolerance for positioning the track and deck where deep girders are used. The total lateral tolerance for track and deck installation assuming straight track, relative to the centre line of the deck, is as follows: Deep girders ± 92.5mm on a 3300mm wide deck reducing linearly to 25mm on a 3165mm wide deck. Shallow girders ± 226mm on a 3300mm wide deck reducing linearly to 26mm on a 2900mm wide deck. For bridges with deep girders a lower maximum offset will apply due to the need to keep the inside edges of the main girder compression flange clear of the kinematic envelope of the design traffic. Page 22 of 38

23 NR/CIV/TUM/1200 Rev D May 2010 The designer should check that the effects of curved track (end and centre throws) does not cause the structure gauge to foul the structure and that sufficient installation tolerances are provided. 4.9 Positioning An absolute minimum lateral positioning tolerance of 25mm has been assumed although it is recommended that where possible, a minimum clearance of 50mm should be provided for possible future track slues. The minimum vertical tolerance for the rail position in relation to a shallow girder is 13mm, noting the assumed track depth in section 4.5. Note that where possible, the vertical tolerance should be maximised as the typical tolerance on vertical track position is + 10mm, 25mm (depending on line speed) and datum plates will be needed to control the position Cant The absolute maximum cant permitted on the standard design is 150mm. This is made up of track cant and deck super elevation. The designer should ensure that the effects of cant, such as cant throw do not cause the structural gauge to foul the structure. The limits of the cant components can be seen in figure 4.2. Figure 4 2: Cant Effects 4.11 Ballast Depth The desired ballast depth is 300mm at mid span under the low rail. Shallower ballast depths may be used, to a minimum of 200mm, however permanent way approval will be required. The absolute maximum ballast depth below the sleeper shall be 400mm averaged over the span. Page 23 of 38

24 NR/CIV/TUM/1200 Rev D May Sleeper and Rail Details The total depth of the rail, chair and sleeper has been taken as 368mm. The designer should check that the chosen rail and sleeper combination will not cause the structural gauge to foul the main girders and sufficient distance is provided between the sleeper ends and the main girders. Where narrow decks with steel floors and a shallow ballast depth are required, in order to avoid the ballast plates within the ballast layer, narrow wooden sleepers at close spacing may be required to ensure adequate clearance (50mm minimum) is provided between the ballast plate and the sleeper Site Constraints The designer will need to consider the site constraints, including but not limited to: OLE, existing abutments, S&T, location of cess etc. Headroom above highways or waterways should be maximised where possible and appropriate signage fixed to the structure (ideally to the bash beam or web stiffener. Refer to ancillary details in NR/CIV/SD/1800 series). Note that the signs will be the responsibility of the Local Authority, Highways Agency or similar authority Direct Fastening Systems The standard Z type design has not been developed specifically to accommodate direct fastening systems but the use of the standard drawings does not limit their use to ballasted track. Where a direct fastening system is required for a specific scheme, the designer shall select the suitable standard design with the required track / structure performance. Additional design checks will be required to ensure suitability of the chosen detail as the intensity of the railway loads will be greater than for ballasted track. Form A and Form B submission and approval will be required. Page 24 of 38

25 NR/CIV/TUM/1200 Rev D May INSTALLATION GUIDANCE The standard Z type has been designed to be lifted by cranes (mobile road cranes and rail cranes, size to be determined by the designer), or rolled or slid in while supported at the bearings or jacking points. Specific calculations will be required of the designer if any other erection method is proposed. The bridges can be installed with up to 300mm of clean ballast in place, though the designer should ensure it s stability and that the ballast is suitably retained. It is suggested that the density of ballast is taken as 18kN/m 3 when calculating the lift weight. 5.1 Trial Erection As stated on drawing NR/CIV/SD/1202 the bridge should be fully trial erected: The trial erection should include all superstructure and ancillary items such as walkways, impost / cill beams, ballast walls and cover plates. This is particularly important for skew bridges. During the trial erection all bolts should be hand tightened. Any HR bolts fully torqued should be marked and discarded. No trial lifts shall be undertaken until the bridge deck is structurally complete in accordance with standard and scheme drawings. 5.2 Installation Tolerances The tolerances assumed in the standard design are for installation of the decks by crane. The standard designs were developed assuming the decks could be positioned within 10mm and the track placed within 15mm of the design position on plan. Vertical positioning tolerance of 10mm has been considered appropriate as it is assumed the track profile could be locally adjusted on site if necessary. Installation by alternative methods will require these tolerances to be reviewed. 5.3 Lifting Guidance Where the decks are installed by lifting them into position by lifting brackets attached to the main girder top flanges, the designer should ensure that lifting points on one girder are located perpendicularly opposite to the lifting points on the opposite girder. Details are given on the standard drawings and assume that the standard 25t or 50t lifting brackets are used (refer to ancillary drawings NR/CIV/SD/1800 for details of the brackets). Page 25 of 38

26 NR/CIV/TUM/1200 Rev D May 2010 Lifting brackets should be located at the web stiffener locations and the web stiffener increased in thickness to 30mm. Where the web stiffener arrangement is such that web stiffeners are not perpendicularly opposite, an additional 30mm thick lifting web stiffener may be inserted in the appropriate location as detailed. Care must be taken when determining the curtailment of any top flange doubler plates to ensure the lifting bracket is in full contact with the flange doubler plate. It is recommended that the decks lifter demonstrated lifting slings to ensure equal loading on each lifting bracket. The lifting points should ideally be located between the quarter and third points of the span and the lift arrangement should ensure no transverse force is applied to the main girder top flange, unless a suitable temporary bracing system has been installed for the lift. In all cases the designer must ensure that during the lift, the stresses (a safety factor of 2.0 is recommended) in the main girder top flange does not exceed the theoretical stresses at the end installation from permanent loads, unless lift specific stress checks are undertaken. Specific calculations will be required of the designer if any other erection method is proposed. 5.4 Check List for Non Standard Arrangements and Non Standard Items The following check list (not exhaustive) lists non standard arrangements and items to be designed or checked by the designer for the particular scheme. Where appropriate, a separate Form C will be required. Capacity and stability of the bearing lifting bracket if the imposts / cill beams are to be attached to the deck during installation. The effect of the proposed lifting / support arrangement on; o the lifting lugs (where applicable), o the load distribution to each lifting / support point, o the effect on the main girder if not lifted in accordance with Section 5.3 or supported in accordance with Section Error! Reference source not found.. The suitability of the substructure: o check the load effects from the new deck including pressure at base and under the impost / cill beam, o check overturning and sliding stability with and without the new deck in place. Undertake suitable geotechnical investigation to determine soil properties. Check that the differential settlement predicted does not exceed the value the standard designs have been designed to accommodate (At SLS, 1 in 1000 along the abutment subject to a maximum 5mm difference between bearings). Check the effects of supporting the deck at any point other than assumed for lifting (refer to section 5.3). Note that alternative methods of installation may be more suited Page 26 of 38

27 NR/CIV/TUM/1200 Rev D May 2010 for installation in short (8 hour) possessions but may require additional installation tolerances (refer to section 5.2). 5.5 Check List for Installation Options The following check list (not exhaustive) lists typical issues to be considered by the designer for the particular scheme when deciding on the available options to install the deck. Access to site o Clearances to street furniture, overhead cables, low headroom or weight restricted bridges etc., o Road profile (horizontal and vertical): Proximity to hump back bridges, tight curves etc. that may restrict access to site or plant movement. o Location for site compound. Services: Highway / waterway. o Services in or alongside the highway or waterway must be protected from bridge installation activities. Services: Railway. o Services may restrict or complicate installation of new bridge decks. Some methods of installation will be more suited for sites with numerous railway services, e.g. if services cannot be raised, this may preclude installation with SPLV. Access around site o Consider size of compound to rig cranes, store plant and materials, store bridge elements, staff accommodation and welfare provision. Site properties o Strength of ground (ground reinforcement or piling for cranes or temporary works), o Access to site (haul roads and access agreements with land owner), o Environmental issues (minimise damage to habitat, restrictions due to the presence of rare or protected fauna and flora, relocation of rare or protected fauna and flora, limitations on time of year to do the work to minimise impact on flora and fauna). o Working over water. Available possessions o Minimise all possession times. o Railway possessions. Strive for an 8 hour railway possession. Installation with SPLV is usually quicker, thus minimising railway possessions, but will need larger installation tolerances (refer to Section 5.2) and will not be suitable for all sites. o Highway and waterway possessions may be limited at certain times of the year, depending on the site location, e.g. a highway possession will be unlikely in December if the site adjacent to a retail outlet, and a waterway possession unlikely in July and August if heavily trafficked with recreational vessels. Page 27 of 38

28 NR/CIV/TUM/1200 Rev D May GUIDANCE FOR USE OF THE Z TYPE STANDARD DESIGNS AND DETAILS 6.1 General Arrangement Drawing General arrangement drawings should be produced in line with Network Rail s requirements for the specific site. However it is expected that these drawings should normally include the following: Plan, bridge elevation and a cross section through the bridge including the elevation of one abutment and the bridge seating arrangement. Geotechnical information, details of services (railway and other), details of land ownership and details of adjacent infrastructure, Principal dimension information such as span, skew, clearances from rail to main girders and walkway parapets, six foot gap (where applicable), bearing, bridge soffit, rail, walkway and parapet levels, clearance to road (or river or rail as applicable). List of drawings forming the complete bridge design. Scheme specific deck steelwork general arrangement drawing. 6.2 General Assembly Drawings The setting out and arrangement of cross girders / transverse ribs, trimmers and main girders will be unique in most instances and dependent upon many variables including, bridge span, abutment skew, clearance requirements, main girder stiffener design and compliance with minimum and maximum spacing requirements of cross girders. Where decks are to be positioned side by side, the designer should ensure web stiffener positions are staggered to enable future access for inspection and maintenance. It should be noted that the trimmer skew will be different to the bridge skew in all instances except that of a square bridge deck as the trimmer is supported inboard, on the main girder bottom flanges. The floor overhangs the trimmer so that the floor skew equals the deck skew. For setting out of the trimmer see drawings NR/CIV/SD/ and Figure 6.1. Page 28 of 38

29 NR/CIV/TUM/1200 Rev D May 2010 Figure 6.1: Definition of Skews Page 29 of 38

30 NR/CIV/TUM/1200 Rev D May 2010 For deck skews up to and including 25 o skew, a fanned cross girder / transverse rib arrangement is required at the deck ends as acute connections into the trimmer are neither desirable nor practical. Fanning of the last few cross girders is usually all that is necessary on low skew bridges. As the skew increases and the required number of fanned cross girders / transverse ribs increase, fabrication details may become excessively complicated. In these instances there is an option to skew all or some of the cross girders / transverse ribs by the same amount through the middle of the bridge to allow duplication of fabrication details. For shorter spans, fanned cross girders/transverse ribs are not practicable: Insufficient length is available to fan the cross girders / transverse ribs perpendicular to the main girder. For these cases cross girders / transverse ribs should remain parallel to the trimmer girder. For details refer to standard drawings NR/CIV/SD/1201. For deck skews between 25 o and 50 o a trimmed cross girder / transverse rib arrangement is shown at the deck end. All cross girders / transverse ribs are square to main girders. Where cross girders / transverse ribs connect into the trimmer, there are alternative details for both filler beam and steel floor types. Setting out of the cross girders / transverse ribs shown on the standard drawings considers the setting out point as the intersection at the main girder web and a line perpendicular to the web at the point the cross girder / transverse rib centre line meets the inside of the web. Where required, the centreline at the web stiffener goes through the setting out point. Refer to figure 6.2. Figure 6 2: Cross Girder / Transverse Rib Setting Out Page 30 of 38

31 NR/CIV/TUM/1200 Rev D May Details Drawings Details are provided for all spans and skews. In a number of cases, to avoid any conservative designs, the details depend also on the traffic type and annual tonnage. This section gives guidance on how the required details should be selected Span The standard details drawings give details for particular span ranges. Where the span required (measured between bearings, parallel to the main girders) is not included on the standard drawings, the details for the next span are to be used. e.g. if span required is 11.7m, the main girder details for the next span, i.e. the 12m, are to be used Skew The standard details and drawings give details for particular skews ranges. Where a skew of 17.4º, the details for deck skews (i.e. between main girder bearings) between 0º and 25º are to be used. Where skews are 0º or 25º, the designer may chose the drawings to be use, but must ensure they are used consistently. For very low skew angles, the designer should, where practicable, make the bridge square as this will simplify many of the details Traffic The standard designs and drawings give details that may vary depending on the railway traffic anticipated at the particular site. Where details vary, e.g. main girder flange, doubler plate and web details and steel floor deck plate thickness, the detail to be used is either classified HEAVY or LIGHT in the table given on the particular drawing and replicated below in figure 6.3. Page 31 of 38

32 NR/CIV/TUM/1200 Rev D May 2010 Figure 6 3: Traffic Type and Detail Classification e.g. for a detail subject to 15 million tonnes of traffic per annum and medium EC mix traffic type, the details to be used are the LIGHT details, as shown above. Where the annual tonnage is stated in two columns, the column to the left shall be used, e.g. if the detail is subject to 18 million tonnes of traffic per annum and EC mix traffic type, the details to be used are the HEAVY details Main Girder Length and Floor Overhang Past Trimmer The length of the main girder will be determined by the designer: To simplify the ancillary details and arrangements (e.g. ballast walls, impost / cill units, refer to series NR/0IV/SP/1800) the deck skew will not equal the trimmer skew except for square decks. The floor skew is kept equal to the deck skew by varying the floor overhang past the trimmer. The allowable overhang is given as the standard drawings and should not be exceeded. The depth of deep main girders should be determined by the designer to suit the required ballast depth. e.g. a filler beam floor, deep main girder for a 12.4m span with 335mm of ballast and track make up of 365mm will have the following details if traffic is 40 million tonnes per annum and EC mix traffic. Main girder span: use 14m span details on NR/CIV/SD/1221 Main girder type: read where million tonnes per annum column crosses the EC mix traffic type row in the table in the notes column. This table requires HEAVY girder details, i.e. use left hand side details on NR/CIV/SD/1221. Girder depth stated is for 300mm ballast and track make up at 368mm. Therefore need to increase girder depth by ( ) = 35mm, i.e. main girder now = 1400mm deep from top of bottom flange to top of top flange doubler to provide a robust kerb 350mm (to top of top flange) above rail assuming rail make up in section 4.6. e.g. a steel floor, shallow main girder for a 10.4m span with 225mm of ballast and track make up of 350mm will have the following details if the traffic is 18 million tonnes per annum and Type 9 MU traffic. Main girder span: use 11m span details as NR/CIV/SD/1227 Main girder type: read where million tonnes per annum column crosses Type 9 MU traffic row in the table in the notes column. This table requires LIGHT girder details, i.e. use right hand side details on NR/CIV/SD/1227. Page 32 of 38

33 NR/CIV/TUM/1200 Rev D May 2010 Girder depth stated is for 200mm and track make up at 368mm. Therefore increase girder depth by ( ) = 25mm for ballast depth. And decrease girder depth by ( ) = 18mm for track make up. Thus the net increase in girder size is = 7mm, i.e. girder now = 1002mm from top of bottom flange to top of top flange doubler. This allows for 13mm tolerance for positioning the deck and the track vertically and ensuring the lower structure gauge is not compromised. If this is insufficient, the girder can be reduced in size but must not be less than the value stated on the drawing, i.e. in this case it must be 995mm from top of bottom flange to the top of the top flange doubler. 6.4 Concrete and Reinforcement Drawing Reinforced concrete is required to act compositely with the steel cross girders in a filler beam floor and cantilever from the trimmer beam to achieve the required deck skew and support for ballast plates in both filler beam floors and steel floors. The standard details provide a floor skew to match the bridge skew. This will generally ensure that the deck end is roughly parallel to the line of the abutment and also enables the possibility of aligning adjacent bridge decks with spans up to 25 o skew. The reinforced concrete standard drawings require tailoring to suit specific skew arrangements. In doing so the designs should maintain the size and spacing of the bars to ensure adequacy of the reinforcement, and to ensure the minimum steel is present in any face to prevent early thermal cracking. Guidance is given on the standard drawings. Floors should be detailed to allow easy placement of reinforcement as well as meeting all relevant design requirements. If it is required to change the dimensions of the floor and cantilever this should be done with care and the following points should be taken into account: Reinforcement and cover to steelwork should be maintained. Adequate room should be provided around the trimmer for location of reinforcement and placing concrete. The floor end cantilever should not be increased above the maximum values stated on the standard drawings as this will increase loadings on the trimmer, trimmer end restraints, floor overhang and inward moments on the bearings. It may also exceed the allowable upward deflection at the end of the deck. 6.5 Bar Bending Schedules Production of deck specific bar bending schedules to accompany the deck drawings are necessary in all instances. Page 33 of 38

34 NR/CIV/TUM/1200 Rev D May Protective Treatment and Waterproofing Basic Principles and General Comments The basic principles are as follows: All buried surfaces beneath or at the sides of the track are protected by a waterproofing arrangement designed to ensure water and other train related pollutants do not come into contact with the bridge superstructure and support / end units. Drainage arrangements, such as providing a longitudinal fall (recommended minimum fall 1 in 250, noting deck camber to be considered), are incorporated in the overall bridge design to minimise maintenance requirements. Other steel surfaces permanently exposed in the final structure are specified as receiving a protective treatment. Refer to standard drawings for details. Both protective treatment and waterproofing should be carried out as far as possible in shop conditions to ensure the maximum integrity and quality. Details are shown on the standard drawings of the residual site joint protection involving hand applied protective treatment and waterproofing system. It is envisaged that some remedial site painting will be required, to be carried out in accordance with the Network Rail Specification Protective Treatment The standard steelwork protective treatment specified is a type N1 system in accordance with NR/SP/CIV/039. The standard drawings show details in accordance with NR/GN/CIV/002. Where no guidance is provided the requirements of NR/GN/CIV/002 shall apply. Points to note are include: Areas encased in concrete (e.g. Filler floor trimmer beams, filler beams) should remain untreated, only loose rust or mill scale removed. Areas partially encased in concrete (e.g. lower part of inner main girder, trimmer end blocks, steel floor trimmer beams, bearing stiffeners within concrete) should be blast cleaned and primed only. Where the concrete finishes the protective treatment for the adjacent area should be extended not less than 25mm into the concreted area and a sealant applied in a rebate in the concrete to minimise the risk of water ingress at the steel / concrete interface. Faying and bearing surfaces (e.g. bolted connections, trimmer support positions) are blast cleaned and metal sprayed only, to maintain optimum friction conditions with minimum protection. Subsequent layers of protective treatment to be stepped back. Joints carried out on site will need completion of protective treatment after bolting up. Page 34 of 38

35 NR/CIV/TUM/1200 Rev D May 2010 Exposed areas inaccessible after erection (e.g. around bearings and the back of bearing stiffeners in the 6 foot where two spans are erected to each other) are painted with the N1 system. Concrete surfaces that may be exposed to chlorides (e.g. filler floors above highways) should receive a hydrophobic pore lining impregnant in accordance with Highways Agency Document BD43/03. The use of weathering steel was not developed as a standard design. Where the use of weathering steel has been assessed favourable, the standard designs and details may be considered as a basis for design but the design will be classed as a modification (refer to Section 2.2). Approval for the use of weathering steel is required from Network Rail s professional head of civil engineering. If weathering steel is to be used, the designer must (list not exhaustive): Follow requirements of Highways Agency standard BD7/01, including increasing the plate thicknesses. The designer must o Check the bridge deflection are within the limits set in BS EN 1990:2002 and NR/CIV/L2/020. o Check the availability of components, in particular nuts and bolts (generally supplied in imperial sizes) and may not be available in the sizes called up on the standard designs Waterproofing The waterproofing system shown is based upon an acrylic spray system protected with a protective layer against local damage. The waterproofing details are shown on drawing NR/CIV/SD/1270, 71 & 72. Deck ends are waterproofed to ensure water drains from the deck to the back of deck drainage. 6.7 Drainage Positive drainage should be considered where possible. Details of drainage provision options are given on the standard drawings and details in the series NR/CIV/SD/1800. Generally, drainage locations and thus the profile of the back of the impost / cill unit may be governed by the abutment thickness. A narrow abutment invites a simple arrangement of deck end and upstand aligned vertically with the rear of the abutment. Ideally the drainage pipe should be located below the final top of the existing abutment. This should ensure that water will not permeate along the underside of the impost and then down the abutment face. Where the existing abutment is much wider and the new deck stops short then providing drains in the impost at the deck end and below impost / cill to the rear of the abutment is often preferred even to the extent of terminating the waterproofing at the impost / cill drain. Page 35 of 38

36 NR/CIV/TUM/1200 Rev D May Substructure and Ancillary Items Within the standard detail suite of drawings, details are provided for underbridge ancillary items (drawing series NR/CIV/SD/1800 and associated technical user manual). The Z type superstructure details refer to these and the details regarding assumptions are contained therein. To ensure a smooth transition from the stiffness of the bridge approach to the stiffness of the deck and then the stiffness of the deck to the stiffness of the approach, the designer should consider the use of a suitable transition detail. Where an existing substructure is being reused the scheme design should ensure that there is no significant change in the loads or points of application, and also the acceptability both the re use of the existing substructure and foundations. The design of the standard deck details covered in this TUM have assumed a maximum abutment differential settlement at SLS of 1 in 1000, but not exceeding 5mm under a single bearing. The load applied shall be in accordance with BS EN 1990:2002 and include railway loads. The designer shall determine the soil parameters and ensure that the maximum design settlement under a single bearing is not exceeded. Refer to the check list in Section 5.4 for guidance and limits on differential settlement allowed for in the standard designs. 6.9 Bonding / Stray Current / Insulation The designer must ensure that suitable details are provided to ensure that the structure is adequately bonded / insulated / protected from stray current effects. Page 36 of 38

37 NR/CIV/TUM/1200 Rev D May FABRICATION AND CONSTRUCTION The standard details have been developed from previous Z type designs (refer to the history of the Z type development in Appendix B). The details are generally straightforward and a competent fabricator or contractor should be able to determine their own procedures for ensuring the required quality is achieved. The areas where the details require particular attention are discussed below. 7.1 Fabrication Along with the continuous shaping and straightening of the Z shapes main girders, the most difficult detail in the fabrication process is the machining and fitting of the cross girders / transverse ribs. It is intended that the end plates to the cross girders / transverse ribs are attached and then machined down to the exact thickness required for fit noting that the plate thicknesses shown on the standard drawings are the minimum thicknesses required at the end of machining. Alternatively the cross girders / transverse ribs could be machined to the correct length. The fabricator must ensure that all faces are in full contact to make the HR bolted connections effective. This is particularly important for the shear key details on the steel floors where two separate faces must be in contact. The fabricator must also pay due attention to the reinforcement location and orientation to ensure holes in trimmer beams and cross girders (filler beam floors) and shear studs (steel and filler beam floors) are suitable to facilitate the accurate fixing of reinforcing bars and concreting. On standard drawing NR/CIV/SD/1210, the camber required for the main girders is that required at the end of steelwork fabrication, with steel ancillary items such as walkways attached. The designer shall consider construction stages and calculate allowable deflections or camber requirements for the scheme specific fabrication and construction sequence. 7.2 Construction When constructing the concreted areas of the standard Z type decks, the contractor must be careful to ensure suitable clearance between reinforcing bars is provided to allow concrete to surround all reinforcing bars. This is particularly relevant where the cross girders in the filler beam floors are fanned and the reinforcement will bunch in the narrow end. The designer should determine which bars can be curtailed in this situation. Page 37 of 38

38 NR/CIV/TUM/1200 Rev D May 2010 The contractor should consider the use of vibrating shutters where the reinforcement is congested and limited access for pokers, such as casting the concrete behind the trimmer beam on steel floors. A suitable concrete slump shall be specified by the contractor to ensure the required quality of concrete is provided and to suit his concrete methodology. Page 38 of 38

39 NR/CIV/TUM/1200 Rev D May SAFETY / CDM AND ENVIRONMENTAL The general (non site specific) risks associated with the bridge design, construction and operation are listed on drawing NR/CIV/SD/1202. In addition there may be others arising from site specific considerations, such as the presence of overhead line equipment (OHLE) or vulnerable services. Environmental issues can only be determined on a site by site basis, bridge aesthetics including its colour, should be considered also. The effect of renewing the protection scheme on the environment, particularly any watercourses, should be taken into consideration during the selection of the elements of the protection scheme. Page 39 of 38

40 NR/CIV/TUM/1200 Rev D May 2010 Appendix A SCHEDULE OF STANDARD DRAWINGS Description Drawing NR/CIV/SD/1200 Index of Drawings NR/CIV/SD/1201 Key to Types NR/CIV/SD/1202 General Notes and H&S Risk Register NR/CIV/SD/1210 Steelwork General Assembly Notes NR/CIV/SD/1211 Steelwork General Assembly Details for Square Filler Beam Floor NR/CIV/SD/1212 Steelwork General Assembly Details for 0 to 25 Skew Filler Beam Floor NR/CIV/SD/1213 Steelwork General Assembly Details for 25 to 50 Skew Filler Beam Floor NR/CIV/SD/1215 Steelwork General Assembly Details for Square Steel Floor NR/CIV/SD/1216 Steelwork General Assembly Details for 0 to 25 Skew Steel Floor 1 of 2 NR/CIV/SD/1217 Steelwork General Assembly Details for 0 to 25 Skew Steel Floor 2 of 2 NR/CIV/SD/1218 Steelwork General Assembly Details for 25 to 50 Skew Steel Floor NR/CIV/SD/1220 Main Girder Details Notes NR/CIV/SD/1221 Main Girder Sizes Filler Beam Floor Deep Girders NR/CIV/SD/1222 Main Girder Sizes Filler Beam Floor Shallow Girders 300mm Ballast NR/CIV/SD/1223 Main Girder Sizes Filler Beam Floor Shallow Girders 200mm Ballast NR/CIV/SD/1224 Main Girder Steelwork Details Filler Beam Floor NR/CIV/SD/1225 Main Girder Sizes Steel Floor Deep Girders NR/CIV/SD/1226 Main Girder Sizes Steel Floor Shallow Girders 300mm Ballast NR/CIV/SD/1227 Main Girder Sizes Steel Floor Shallow Girders 200mm Ballast NR/CIV/SD/1228 Main Girder Steelwork Details Steel Floor NR/CIV/SD/1230 Floor Steelwork and Trimmer Details Notes NR/CIV/SD/1231 Details of Cross Girder and Trimmer Girder 0 to 25 Skew Composite Floor NR/CIV/SD/1232 Details of Cross Girder and Trimmer Girder 25 to 50 Skew Composite Floor NR/CIV/SD/1235 Details of Transverse Ribs and Trimmer Girder Square Steel Floor NR/CIV/SD/1236 Details of Transverse Ribs and Trimmer Girder 0 to 25 Skew Steel Floor NR/CIV/SD/1237 Details of Transverse Ribs and Trimmer Girder 25 to 50 Skew Steel Floor Sheet 1 of 2 NR/CIV/SD/1238 Details of Transverse Ribs and Trimmer Girder 25 to 50 Skew Steel Floor Sheet 2 of 2 NR/CIV/SD/1239 Details of Transverse Ribs to Trimmer Girder Connections. All Skews NR/CIV/SD/1240 Bearings Notes NR/CIV/SD/1241 Standard Bearings Details NR/CIV/SD/1250 Steelwork Protective Treatment Notes NR/CIV/SD/1251 Filler Beam Floor Main Girder and Floor Protective Treatment Details NR/CIV/SD/1252 Bearing Protective Treatment Details

41 NR/CIV/TUM/1200 Rev D May 2010 NR/CIV/SD/1255 NR/CIV/SD/1260 NR/CIV/SD/1261 NR/CIV/SD/1262 NR/CIV/SD/1263 NR/CIV/SD/1264 NR/CIV/SD/1265 NR/CIV/SD/1266 NR/CIV/SD/1267 NR/CIV/SD/1268 NR/CIV/SD/1270 NR/CIV/SD/1271 NR/CIV/SD/1272 NR/CIV/SD/1281 Steel Floor Main Girder and Floor Protective Treatment Details Concrete and Reinforcement Details Notes Concrete Details for Square Filler Beam Floor Concrete Details for 0 to 25 Skew Filler Beam Floor Concrete Details for 25 to 50 Skew Filler Beam Floor Reinforcement Details for Square Filler Beam Floor Reinforcement Details for 0 to 25 Skew Filler Beam Floor Reinforcement Details for 25 to 50 Skew Filler Beam Floor Concrete Details for Steel Floor Reinforcement Details for Steel Floor Waterproofing Details Notes Waterproofing Details for Filler Beam Floor Waterproofing Details for Steel Deck Ballast Plate and Filler Rail Details

42 NR/CIV/TUM/1200 Rev D May 2010 Appendix B HISTORY The Z type girder and filler beam floor has been in use for over 40 years on the former British Rail network. Although its history is not fully documented, it is understood that it derived from the old standard A Type, in use since the 1950s, which consisted of traditional I section main girders, with steel cross girders with a concrete infill between them to provide a floor to support ballasted track and for local distribution purposes. Cross girders soffits in the A Type were exposed. The outside faces of the main girders in the 'six foot' zone were infilled with brickwork. Decks were either not waterproofed, or poorly waterproofed. It then evolved into the Z type during the 1960s as a result of experience and identification of shortcomings with the A Types in use. The introduction of the Z shaped girders allowed the brick infilling to be deleted and proper access to be provided to the outside girder faces in the very constrained situation between adjacent bridges placed in the standard 'six foot' gap between adjacent tracks on two track lines. It also reduced deck widths, and hence weight. Cross girders were fully encased to allow longitudinal cracking reinforcement to be placed above and below cross girders, to get over corrosion and cracking problems at the concrete / steel interface along cross girder soffit edges. Deck waterproofing was incorporated, or improved. Changes from fixed trimmers bolted on to main girder end plates, to the principle of the present arrangement also occurred. Standard Drawings B/18/1 and /2 were issued in The issue of cracking of concrete soffits and other general problems with concrete and floor reinforcement, meant that floor reinforcement was increased on at least two occasions in the early 1970s and late 1970s in response to these issues and to the greater knowledge of reinforced concrete reflected in new and amended design codes. Design continued on the basis of the Z girders being individually designed on each bridge (using various versions of the British Railways Board (BRB) Plate Girder Design Programme (PGDES)) with decks based on the standard arrangement with a limited design / check calculation to the BRB Technical Note 27 (1976). Different regions, whilst working within the above framework, did evolve and vary the designs, with differing regional standards coming into existence in the 1980s. Use of the standard was extended to longer spans also. In 1996 the Z type Bridge Standard drawings were completely redesigned to meet new design codes and other new or revised requirements. The deck was completely redesigned to meet BS 5400 requirements (for the first time), subject to certain departures which were agreed with

43 NR/CIV/TUM/1200 Rev D May 2010 Railtrack. The main girder design arrangements were also re evaluated in the light of BS 5400: Part 3. This has involved some substantial background work and the evolution of appropriate departures from the code. Since the 1996 update, BS :1982 was superseded with BS :2000. The revised standard incorporated the departures. The 2009 Z type Design update (revision A), was completed in accordance with the current standard with no departures as described. The 2009 update (revision B) also included verification of the design to the structural Eurocodes. Summary of Details Updated Since The 1996 Z Type Standard Detail The following items have been modified since the 1996 design. Explanation is given. Steel Floor An alternative floor arrangement has been developed, based upon the Tee Rib floors adopted for the Western Region Boxes. The steel floor has been developed to reduce the weight of the bridge and allow easier installation. It is intended for use only where weight must be kept to a minimum. Bearings and Uplift Detail The modified bearing design has been based upon details used and implemented successfully on a number of projects. The modified design consists of a single machined line rocker bearing block, welded to the bearing set. Uplift restraint is provided by a clevis plate, welded to the bottom flange and separate base plate. The modified design is more robust and requires less fabrication and welding than previous bearings. The modified design allows for easier replacement of components, with allowance for the replacement of the uplift details or bearing set individually. The details and arrangement of the uplift bracket components allow the bearings be lifted in one piece, already attached to the main girders. Bearing Stiffeners The modified bearing stiffener design has been developed following discussion with a number of bridge fabricators, and has been based upon details used and implemented successfully on a number of projects. The modified design consists of three full height fin bearing stiffeners fillet welded to the main girder web and flanges, with three shorter inner load spreading stiffeners. A number of issues with the previous bearing stiffener have been eliminated through the modified design. Fabricators highlighted the issues with the former detail, including distortions due to butt welding of the stiffener, and a number of complex and awkward welds. The modified design has been designed on the basis of the sole use of fillet welds. Fabricators highlighted issues with the use of bent plates which has been eliminated through the use of fins requiring flame cutting and localised machining to fit the bottom flanges. The walkway connection to the bearing stiffener has also been simplified through the use of the fin arrangement. Flange Curtailment Detail

44 NR/CIV/TUM/1200 Rev D May 2010 A modified flange curtailment detail was developed to reduce the effect of welded details on the ductility and fracture classification of the flanges. The modified detail gave a detail type of 2.6 (from BS :1980 Table 17 (b)) allowing the use of thicker plates and negating the necessity to carry the bottom flange doubler through to the bearing, which would complicate the bearing detail unnecessarily. Where the top flange curtailment point is close to the end the main girder, the doubler plate should continue to the end the main girder and the square curtailment detail be used. The Eurocode (BS EN :2005) does not differentiate between the width of attachments (referred to as cover plates) but the detail developed to satisfy the BS rules has been retained. The lowest detail category in accordance with BS EN :2005 Table 8.5, detail 6, was verified. Cross Girder / Transverse Rib Connection with Main Girder Web To simplify the fabrication of the cross girder / transverse rib connection with the main girder web, lap joints were considered but rejected as: It could not be demonstrated that they had sufficient capacity to resist longitudinal shear effects. Network Rail have historically had problems with such details and requested that they are not developed as a standard design.

45 NR/CIV/TUM/1200 Rev D May 2010 Appendix C DESIGN ASSUMPTIONS Structural Models The proposed new decks have been analysed using a linear elastic model of a complete deck. One corner of the deck was fixed in position. The bearings in the other corners allow rotation and movement longitudinally, laterally or in both directions. A quasi static approach was used. The trimmer beam was supported on the bottom flanges for all skews and the end of the trimmer free to rotate. The main girder bearings are line rockers and positioned to ensure restraint at the bearings is provided by the bearing stiffeners acting as cantilevers. The simple approach to fatigue assessment (without damage calculation) was used. Loading The following is a summary of the Eurocode design loads and draft Network Rail standard, NR/L2/CIV/020 (draft 12): Permanent Actions Item Density / Load Load Factor (γ G ) Concrete 25 kn/m Steel 77 kn/m Ballast 21 kn/m 3 depth 575mm over full floor area between webs of main girders (appropriate to 300mm depth under sleepers with additional average 100mm allowance for variations in ballast depth due to cant, track gradients, 1.35 deflections etc). The weight of the top 300mm of ballast was factored by ±30% in accordance with NA BS EN Track 6 kn/m (per track, includes sleeper and rail only, no allowance for ballast between sleepers) 1.35 Waterproofing 0.36 kn/m 2 over floor area (equivalent to 15mm thickness at 24 kn/m Trackside Cables 1.0 kn/m (equivalent to 7 no. solid 40mm diameter lead cables) 1.35

46 Variable Actions Load Reference Notes LM71 BS EN :2003 NR/L2/CIV/020 NR/CIV/TUM/1200 Rev D May 2010 An additional a factor of 1.1 has been applied to provide adequacy in accordance with TSIs for high speed lines, or γ det for standard lines. The total alpha factor used where applicable, α = Dynamic Effects BS EN :2003 Factor taken as 2.0 for shorter span bridges, as detailed below. Centrifugal Force* BS EN :2003 Value based upon V = 120kph, r = 654m Maximum line speed 200kph. Fatigue BS EN :2006 Damage equivalence method adopted Maximum traffic 42 MTPA Walkways + NR/L2/CIV/020 Draft 12 Uniformly Distributed load: 5.0 kn/m 2 Single Point Load: 2.0 kn Parapet Lateral Load on top rail: 0.74 kn/m Longitudinal BS EN :2003 The track is assumed not continuous over the bridge for the purpose of distributing longitudinal live loads off the bridge, i.e. all longitudinal load resisted by the bridge. Crane Loading (temporary case) KIROW KRC1 200UK Rail Mounted Crane Refer to NR/L2/CIV/020 for Axle Distribution, and reduced partial load factors apply. Notes: * Maximum Centrifugal Force Factor (defined as the vertical effect of the centrifugal force on a girder expressed as a fraction of the static LM71 load): 0.2Q vk. Note that the designer must determine the minimum track radius a deck can accommodate, considering clearances, tolerances etc. + These loads are used for the walkway, parapet, walkway bracket and main girder intermediate stiffener design. Design of Main Girders The Girders have been designed in two main forms, shallow and deep: Shallow: Standard shallow girders are those whose tops are at a level no greater that 110 mm above rail level and are intended to fit below the structure gauge. Note that shallow girders above rail level cannot be used on the UK parts of the High Speed Trans European Network (TEN) where the Railways (Interoperability) regulations apply. Deep: Standard deep girders are those whose top flange (not doubler) tops are at a maximum 350 mm above rail level, to provide a robust kerb on bridges where the main girders are outside the structure gauge (as apposed to below for shallow girders). They cannot be used in standard 'six foots' or on narrow (<3165 mm) decks as they would otherwise infringe clearance

47 NR/CIV/TUM/1200 Rev D May 2010 requirements. The requirements for the robust kerb and maintainable flange thicknesses have limited the minimum thicknesses to 30mm for flange plates, to sustain light vehicular impact. Main girder geometry has been designed to allow for the minimum construction depth whilst maintaining adequate maintenance spaces. Refer to Annex 2 for details. The flange plate thickness ranges are from 30mm to 80mm. The doubler plate thickness ranges are from 20mm to 75mm. The absolute maximum flange thickness is 155mm including the doubler plate. Web thickness ranges are 20mm to 25mm. Based on these thickness and the requirements for ductility the following grades of steel have been specified for thicknesses: J2, max thicknesses permitted are 45mm (tension) and 80mm (compression). K2, max thicknesses permitted are 55mm (tension) and 95mm (compression). NL, max thicknesses permitted are 80mm (tension) and 140mm (compression). These thicknesses are appropriate for a design minimum bridge effective temperature at 24ºC and are not adjusted for the detail category. Where the detail category is significant (refer to NA BS EN ) the allowable thicknesses are reduced. Where flange and doubler thicknesses allow for differing grades, the thinner plate has been specified as per the thicker plate to avoid confusion. For the short span decks, the decks are too stiff to satisfy upper bound frequency requirements, i.e. their natural frequency too high and exceed the upper bound values in figure 6.10 in BS EN :2003. A dynamic factor of 2.0 was therefore applied. A dynamic analysis was not undertaken as studies have shown that for half through structures the high frequency dynamic effects are not significant. The main girders have been designed in accordance with BS EN :2006, with no departures (although some aspects not covered as noted below). The following assumptions have been made during the design: The girders have been design as I Girders, with an additional F H force applied at the shear centre to account for the eccentricity of the top flanges. When calculating the properties and strength of the main girder no benefit from the longitudinal floor reinforcement (and concrete) or floor plate has been taken. Fatigue on shallower girders, especially for 25t axle traffic, was found to be the governing criteria, in cases where the maximum readily available plate sizes were used and fatigue criteria were not met, limits have been indicated on the drawings. U Frame spacing has been taken as 1800mm. The designer will need to determine the U Frame spacing, based upon the overall geometry of the specific structure, using the limits specified on the drawings of 1200mm minimum to 1800mm maximum.

48 NR/CIV/TUM/1200 Rev D May 2010 For the purposes of calculating U Frame restraint the rotational capacity of the U Frame six bolt connections was taken as follow: Filler beam 0.2x10 10 rad/nmm, transverse rib floor 0.5x10 10 rad/nmm. The main girders have been assumed to be restrained by cantilevered bearing stiffeners at their ends. Design of U Frames Neither the Eurocodes nor the NCCI give explicit rules for the design of half through structures where the compression flange is restrained by U frames. Therefore the rules in BS EN :2005 were complied with and the restraint forces from the U frames calculated from first principles, replicating the rules in BS5400 3:2000 Clause 9.12, and specifically Clause and Clause The only aspect not covered in the code is the inclusion of the F H as detailed below. The connections have been designed to take the worst fatigue loading of 25t axles Traffic in the range 42 MTPA. In addition to the F R and F C forces for intermediate stiffeners, U Frame connections have been designed to carry an additional F H force as detailed in the 1996 Z type User manual. The F H force has been determined based upon the following formula, taken from Network Rail Assessment code discussion (taken from ongoing work, not yet published, by Cass Hayward and Partners): Af σ f e Δ y F H = Wu M x Δ y + δ R where: A f is the area of the top or bottom flange of the beam. s f is the average stress in the flange arising from the bending moment M x. e is the horizontal eccentricity of the top or bottom flange of the beam with respect to the centre line of the web. M x is the maximum bending moment in the beam about the x axis. W u is the load carried by or transmitted to the beam including its self weight over a length equal to the spacing of U Frames l u at the location of M x. D y is the free lateral deflection of the top flange of the beam at the location of M x assuming that it is disconnected within the span under a loading equivalent to a unit lateral force applied at the location of each U Frame. For a uniform spacing of U Frames D y may be taken as: 5L 4 Δ y = 384EI l L is the span of the beam c R

49 NR/CIV/TUM/1200 Rev D May 2010 I c is the second moment of area about the y y axis of the flange remote from cross members, plus one third of the height of the web. d R is the deflection of the U Frame under a unit horizontal load. l R is the spacing of the U Frame. The F H force is assumed to act outwards only. The connections have been designed to take the combination of F R, F C, F H and walkway loads, combined with associated local moments generated. Design of Bearing Stiffeners The bearing stiffener has been modified as described previously. The bearing stiffener has been designed in accordance with BS EN :2006 with no departures from the standards. The bearing stiffener loads have been conservatively assumed to be transferred through the welds only, with sections locally machined as shown on the drawings. Revised bearing centre lines have been considered due to the modified bearing detail as discussed below. No effect of the trimmer cross girder on the bearing stiffener was considered. The Trimmer is assumed to be supported separately, bearing directly onto the main girder bottom flange. Design of Bearings The bearing design has been modified to that of a short line rocker bearing in order to improve robustness and simplify fabrication by reducing the weld requirements. The bearings have been designed to be used in all fatigue and skew situations. Effects of the trimmer end blocks on the bearing have also been considered. In order to avoid confusion and simplify the drawings, only one bearing size has been specified. The designer, in determining the setting out, should determine the design installation levels to minimize the potential for twisting the decks and generate significantly uneven bearing loads. The bearings have been designed in accordance with BS EN :2006 and BS EN :2000. The bearings have been designed to accommodate movement of the structure from thermal expansion / contraction. This has been achieved via keep strips allowing guided movements longitudinally / transversely as required. Maximum longitudinal expansion/contraction allowed is 12mm, maximum transverse expansion / contraction allowed for is 2mm. Longitudinal (braking/traction) and transverse (nosing/centrifugal) loads have been assumed to be taken by the keep strips and welds. The load effects are assumed to be applied to the bridge at least 0.5 m away from any particular bearing centre line.

50 NR/CIV/TUM/1200 Rev D May 2010 The trimmer is kept in position by a pair of steel blocks welded to the main girder bottom flange. These blocks also resist the horizontal couple force from the trimmer concrete overhanging the deck end and subject to axle loads. The bearing has been designed as a short rocker, required to ensure the bearing stiffeners act as a cantilever in restraining the main girder. To do this the bearing is set in board of the main girder web so that the vertical force through the web, acting eccentrically to the bearing, offsets the moment due to the bearing stiffener actions. The bearing reaction is retained within the middle third of the bearing block at all times to ensure stability. Jacking points for the standard designs are located at the position of the uplift restraint. Uplift restraint lower plates will require removing and the exposed base plate then used as a jacking platform. Jacks used should be at least 100mm in diameter and should be positioned under the main girder flanges in line with the main girder web. An offset of 50mm from the centre of the pack to the centre of the web can be accommodated. Spreader plates are required if the jack is less than 100mm diameter. Jacking can take place with the full permanent load on the deck. The designer must check the jacking arrangement. Grade S460 NL Bearing Plates The bearing plates attached to the main girder ends and in contact with the bearing block are specified in a higher grade material to avoid problems of local yield and grooving (to ensure the bridge does not lock up and start to carry loads from expansion and contraction effects). The choice of grade is dictated by the need to avoid any overlap of the yield stress range of the two parts. The upper side of the bearing plate is shown machined on the drawings to ensure the underside of the bearing plate is level (under dead loads only) on top of the bearing upstand so significant gradient, deck tilt and camber effects are taken out, and any tendency for a tilted deck to creep against the side stops (and seize up longitudinally) is minimised. The designer should ensure that the client s attention is drawn to the need for pre ordering these plates which are generally less readily available. Collision Loads. The Z type bridges and bearing arrangements shown have been designed in accordance with the requirements of NA BS EN Following discussion between Network Rail and the standard designs designer, a qualitative assessment was made for the minimum flange thickness, taken as 30mm, to provide suitable robustness against light impact. The weld between the main girder bottom flange and the web

51 NR/CIV/TUM/1200 Rev D May 2010 was designed to distribute the codified collision load, considered as a point load applied to the outer edge of the bottom flange, without overstress of the weld. The arrangement for dealing with the design collision loads in the new standard is to provide attachments to the main girder bearing stiffeners which are loosely pinned to matching attachments on the bearing assemblies. These will limit uplift to not more than 5 mm. For longer span decks and high ballast depths, the designer may justify not providing the uplift bracket. However, the uplift bracket has been detailed to enable the bearing to be connected and lifted into place in one piece, as opposed to positioning the lower bracket assembly and lowering the deck and upper assembly to meet the lower. Welds Limits on the location and extent of fabrication welds in the main girder web and flanges have been shown on the standard drawings. Note that a number of welds with limited access have been drawn as butt welds although fillet welds will be appropriate. These welds are clearly marked on the standard drawings and the fabricator may decide on the most appropriate option. Where such butt welds are used, testing is as required for a fillet weld. One further detailing change with the 2009 standard drawings is the removal of cope holes in favour of sniped details that facilitate complete sealing at joint. The 2009 detail improves greatly the quality of the protective treatment application. Design of Deck The 2009 Z type Standard Details provide two alternative options for the floor type; the previous filler beam floor and a new steel floor. Details for the filler beam floor were maintained as those from the previous design. Steel floor details were based upon the previous Western Box Standard Types. The choice of floor is based upon the required weight for lifting during construction or to minimise the load on abutments. The filler beam floor provides a shallower construction depth but is heavier than the steel floor. The steel floor provides a lighter option but the construction depth is deeper than that of the filler beam floor. The steel floor detail includes a maintenance gap between 46mm to 51mm (depending on the floor plate thickness). This gap must not be reduced without the approval from Network Rail s professional head of civil engineering. The filler beam floor is Network Rail s preferred option. The standard Z type underbridge can be used up to a width between main girder centre lines of 3300 mm, and down to a minimum 2900mm. The standard drawings show 3300mm wide decks. The floor is designed for main girder web centres at 3300mm to allow for both the use of deep main girders and to provide room for laying cables on the ballast off the sleeper ends.

52 NR/CIV/TUM/1200 Rev D May 2010 The filler beam floor is assumed to act compositely in the transverse direction. The surface area acting to provide bond strength between the concrete and steel section is considered as only that acting in compression (locally, ignoring global tension effects). The effect of the composite concrete action at connections (notably U Frame) has been ignored. Composite action has also been considered for the trimmer section. End connections for the steel floor type transverse ribs are bolted connections with shear plates. Network Rail requested this detail to provide a failsafe in the event of bolt failure. The concrete encasement of the steel floor trimmer has been ignored during the design stage. The concrete has been designed to resist early thermal cracking in accordance with Highways Agency Standards BD28/87 and BA24/92 and checks have been undertaken to ensure cracking is within the limits of BS EN :2005. However the concrete has been included to reduce maintenance in and around the back of the trimmer section. Longitudinally, due to global tensile effects, only the steel reinforcement, enhanced by the tension stiffening effect of the surrounding concrete, is considered in calculating section properties, strains and crack widths for filler beam floors. Longitudinal shear effects acting on steel floors, through the transverse rib connections and floor plate have been considered. As a result the first cross girder (adjacent to the bearing stiffener) is shown as a six bolt M27 connection on the drawings. The first transverse rib must not be at a U frame. Similarly for the filler beam floors, the first cross girder connection should be a six bolt connection (M20). The longitudinal shear is resisted through the cross girder connections but also by the friction between the concrete in compression and the main girder web. The filler beam floor (and concrete specification) has been designed to reduce early thermal cracking effects, to reduce the deck's susceptibility to chloride ingress, to limit the risk of spalling and to improve its durability generally. The concrete class at the soffit location has been taken as XD3 for chloride induced (corrosion, cyclic wet and dry) as the soffit is likely to be exposed to spray from potential highways below. The top surface is protected by waterproofing, and would be a lower classification. In determining nominal cover the value of Dc has been taken as 10mm. The designer should consider applying a hydrophobic pore lining impregnant in accordance with Highways Agency document BD43/03 where the deck may be exposed to chlorides. For the higher skews the main girder and deck end cantilevers have been limited to avoid rotation under loading that would result in the vertical movement at track level exceeding the allowable limits. The reinforcement around the trimmers has been increased to cater for the deck end cantilever and torsional effects.

53 NR/CIV/TUM/1200 Rev D May 2010 Appendix D Basis of Geometry: TECHNICAL DETAILS STEEL FLOOR FILLER BEAM FLOOR maintenance gap (not to be reduced) maintenance gap (not to be reduced)

54 NR/CIV/TUM/1200 Rev D May 2010 Appendix E Hidden Parts The standard designs and details have, where possible, practicable and in accordance with NR/L2/CIV/020 (draft 12), minimised the number of structural elements that are considered, i.e. that cannot be inspected from at least one side. The areas considered as hidden parts on the standard Z types are listed below with a description of how the details are protected and access is provided for inspection. Z type Description of hidden part Protection provided Access provided Filler beam floor. Transverse filler beam section and trimmer beam. Encased in concrete that provides protection and a secondary load path in the event of failure. None. Filler beam floor. Transverse filler beam section and trimmer beam connection to main girder. Encased in concrete that provides protection and a secondary load path in the event of failure. One side of the connection is visible. Filler beam floor. Outer bearing stiffeners. Access difficult when decks side by side so the stiffeners encased and protected in concrete. Bearing stiffener outer edges visible but site constraints will require lighting and possible video equipment to inspect them. Filler beam floor. Inner bearing stiffeners. Encased in floor concrete None.

55 NR/CIV/TUM/1200 Rev D May 2010 Appendix F Draft 12 of NR/L2/CIV/020 Design of Bridges & Culverts

56 Ref NR/L2/CIV/020 Issue 1 (Draft 12) Date 2008 Level 2 Design of Bridges & Culverts Endorsement & Authorisation Endorsed by:... K. Brady, Standards and Assurance Engineer (Civil Engineering) Authorised by:... A. Dray, Head of Structures Engineering Accepted for issue by:... M. McManus, National Standards Manager This document is the property of Network Rail. It shall not be reproduced in whole or part nor disclosed to a third party without the written permission of the Standard Owner. Copyright 2008 Network Rail Uncontrolled copy once printed from its electronic source. Published & Issued by: Network Rail 40 Melton Street, London NW1 2EE

57 Issue Record Issue Date Comments New standard. Incorporates and supersedes RT/CE/S/007: Design loading for accommodation and occupation overbridges. Compliance This Network Rail standard specifies mandatory requirements and must be complied with by Network Rail and its contractors from.. It is permissible for projects that have formally completed GRIP Level 4 at the compliance date (i.e. acceptance of Form A in accordance with NR/L2/CIV/003: Technical approval of design, construction and maintenance of civil engineering infrastructure) to continue to comply with the Network Rail standards and other standards and requirements as identified in the Form A and not to comply with the requirements contained herein, unless otherwise stipulated in the accompanying Briefing Note or Network Rail s specific requirements for the project. Reference documentation Railway Group Standards GC/RT5021 Track System Requirements GC/RT5112 Loading Requirements for Design of Bridges GC/RT5203 Infrastructure Requirements for Personal Safety in Respect of Clearances and Access GC/RT5212 Requirements for Defining and Maintaining Clearances GE/RT8073 Requirements for the application of standard vehicle gauges GE/RT8025 Electrical Protective Provisions for Electrified Lines GL/RT1253 Mitigation of DC Stray Current effects GM/RT2149 Requirements for Defining and Maintaining the Size of Railway Vehicles Railway Approved Code of Practice / Guidance GC/RC5510 Recommendations for the Design of Bridges GE/GN8573 Guidance on gauging. Page 2 of 109

58 Network Rail Standards At the time of publication a new reference system for Network Rail standards was being introduced; the references given to the following standards are those anticipated to be adopted in their next issue. NR/L1/CIV/044 Managing structures works NR/L2/CIV/003 Technical approval of design, construction and maintenance of civil engineering infrastructure NR/L2/CIV/017 Examination of Bridges and Culverts NR/L2/CIV/035 Assessment of structures NR/L2/CIV/037 Managing the risk arising from mineral extraction and landfill NR/L2/CIV/039 Specification RT98 protective treatments for Railtrack infrastructure NR/L2/CIV/041 Waterproofing systems for underline bridges NR/L2/CIV/067 Design of equipment support structures NR/L2/CIV/071 Design of earthworks, earthwork remediations and geotechnical aspects of foundations for structures NR/L2/CIV/076 Management of bridge strikes from road vehicles & waterborne vessels NR/L2/CIV/140 Control and use of model clauses NR/L3/CIV/001 Waterproofing for underline bridge decks NR/L3/CIV/002 Application and reapplication of protective treatments to Railtrack infrastructure NR/L3/CIV/008 Model clauses for specifying civil engineering works NR/L3/CIV/025 The structural assessment of underbridges NR/L3/CIV/202 Management of the risk of bridge strikes NR/L3/TRK/030 Lineside security NR/SP/ELP/21085 Design of earthing and bonding systems for 25 kv A.C. electrified lines NR/SP/OHS/069 Lineside facilities for personal safety NR/SP/TRK/038 Longitudinal timbers design, installation and maintenance NR/SP/TRK/102 Track construction standards NR/SP/TRK/9006 Design, installation and maintenance of lineside drainage RT/CE/S/007 Loads for occupation/accommodation bridges (Superseded by this standard) Page 3 of 109

59 Network Rail Structures Engineers Technical Advice Notes SE/TAN/0038 Helical screwed pile foundations for equipment support structures British Standards BS 5268 Structural use of timber: Part 2: 2002: Code of practice for permissible stress design, materials and workmanship BS 5395 Stairs, ladders and walkways: Part 3: 1985: Code of practice for the design of industrial type stairs, permanent ladders and walkways BS 5400 Steel, concrete and composite bridges: Part 1: 1988: General statement Part 2: 2006: Specification for loads Part 3: 2000: Code of practice for design of steel bridges Part 4: 1990: Code of practice for design of concrete bridges Part 5: 2005: Code of practice for design of composite bridges Part 9: 1983: Bridge bearings Part 10: 1980: Code of practice for fatigue BS 5628 Code of practice for use of masonry: Part 1: 2005: Structural use of unreinforced masonry Part 2: 2005: Structural use of reinforced and prestressed masonry Part 3: 2001: Materials, components, design and workmanship BS 6799 Highway parapets for bridges and other structures Part 4: 1999: Specification for parapets of reinforced and unreinforced masonry construction BS 7818: Specification for pedestrian restraint systems in metal 1995 BS 8004: Code of practice for foundations 1986 BS Structural use of concrete. Part 1: 1985Code of practice for design and construction BS 8300: 2001 BS EN BS EN 1990: 2002 Annex A2 Code of Practice - Design of buildings and their approaches to meet the needs of disabled people Road restraint systems Part 2: 1998: Performance classes, impact test acceptance criteria and test methods for safety barriers Eurocode Basis of structures design, Annex A2: Application for bridges Page 4 of 109

60 BS EN BS EN BS EN BS EN ISO N.A.D. for ENV : 1995 Eurocode 1: Actions on structures Part 1-7: 2006: General actions Accidental actions Eurocode 1: Actions on structures Part 2: 2003: Traffic loads on bridges Railway Applications Fixed Installations: Part 1: 1998: Protective provisions relating to electrical safety and earthing Part 2: 1999: Protective provisions against the effects of stray currents caused by d.c. traction systems Paints and varnishes Part 3: 1998: Design considerations. UK National Application Document for ENV : 1995 Eurocode 1 Basis of design and actions on structures Part 3: Traffic loads on bridges Highways Agency standards BA 9/81 The Use of BS 5400: Part 10: 1980 Code of practice for fatigue BD 9/81 Implementation of BS 5400: Part 10: 1980 Code of practice for fatigue BD 20/92 Bridge Bearings. Use of BS5400: Part 9: 1983 BD 21/01 The Assessment of Highway Bridges and Structures BD 29/04 Design Criteria for Footbridges BD 30/87 Backfilled Retaining Walls and Bridge Abutments BD 42/00 Design of Embedded Retaining Walls and Bridge Abutments BD 60/04 The Design of Highway Bridges for Vehicle Collision Loads BD 65/97 Design Criteria for Collision Protection Beams BD 74/00 Foundations TD 19/06 Requirement for Road Restraint Systems Her Majesty s Railway Inspectorate Railway Safety Section A: Guidance on the Infrastructure Principles and Section B: Guidance on Stations Guidance: Part 2 Section C: Guidance on Electric Traction Systems Department for Transport Managing the accidental obstruction of the railway by road vehicles Strategic Rail Authority Code of Practice: Train and Station Services for Disabled Passengers International Union of Railways Page 5 of 109

61 UIC Leaflet 719-R UIC Leaflet 774-3R UIC Leaflet 776-3R Earthworks and track bed construction for railways Track-bridge interaction. Recommendations for calculations ( 1st Edition 1989): Deformation of bridges American Association of State Highway & Transportation Officials (AASHTO) Load and resistance factor design (LRFD) Bridge Design Specifications Institution of Civil Engineers Burland and Kalra: Queen Elizabeth II Conference Centre: geotechnical aspects, Proc. Instn Civ. Engrs, Part 1, 1986, 80, Dec., Disclaimer In issuing this document for its stated purpose, Network Rail makes no warranties, express or implied, that compliance with all or any documents it issues is sufficient on its own to ensure safe systems of work or operation. Users are reminded of their own duties under health and safety legislation. Supply Copies of documents are available electronically, within Network Rail s organisation. Hard copies of this document will be available to Network Rail employees on request to the Document Controller and to other organisations from IHS (Technical Indexes Ltd) ( ). Comments The applicability and content of this standard will be reviewed on a regular basis. Written comments on the accuracy and utility of this standard will be taken into account when assessing the need for a new issue of the standard; such comments should be sent to the Standards and Assurance Engineer (Civil Engineering) at 40 Melton Street, London NW1 2EE. Page 6 of 109

62 Contents 1 Purpose 12 2 Scope 12 3 Roles, responsibilities and competencies 15 4 Definitions 15 5 Principles 17 6 General Design requirements Structural adequacy, general location and dimensions Purpose, intended use and Remit Operational safety Construction, maintenance and decommissioning Compatibility with other infrastructure Health and safety, and environmental considerations Legal obligation and commercial liability issues Bridges not owned or controlled by Network Rail Interface with the railway Railway tracks Structure gauge and clearances to the railway Railway equipment Electrical protection, earthing and bonding Protection from stray currents Technical Specifications for Interoperability (TSI) General requirements for interfacing with external authorities, Outside Parties and third parties Interface with Planning Authorities Interface with services, Statutory Undertakers and public utilities Interface with highways Highway Authority acceptance of the Design Clearances to highways and other roads Highway widths and construction 32 Page 7 of 109

63 Highway sight lines Highway lighting and road traffic signs Road traffic signs for restricted headroom Bridges Prevention of vehicle incursion Interface with waterways Clearances over waterways Lighting and signs over waterways Interface with mineral extraction and landfill 33 7 Particular Design requirements Technical Approval Design life New Bridges and reconstructed superstructures Strengthening, alterations, repairs and temporary Bridges Durability and corrosion protection Water management and drainage Waterproofing Structural form and articulation Protection against derailment Security, fencing and protection from vandalism Parapets, safety barriers, walkways, handrailing, etc Vehicle parapets and safety barriers for Overline Bridges Spans over electrified railways Prevention of accidental vehicle incursion Replacement of parapets or safety barriers Walkways, positions of safety and handrailing for Underline Bridges Protection on wing walls, abutments and Culvert head walls Trackside walkways and personal safety beneath Overline Bridges Parapets for a Bridge remote from the railway Footbridges Particular requirements for footbridges Pedestrian hand-rails for stairs, ramps and spans Pedestrian subways Pipe Bridges 47 Page 8 of 109

64 7.13 Bearings Fasteners Hydraulic Design for Culverts Temporary Bridges 49 8 Deformation and fatigue for Underline Bridges General requirements Natural frequency check for applicability of dynamic factors Deformations due to railway loading Vertical deformation of the deck Track twist (for traffic safety) Uplift at bearings Combined response of structure and track Track-Bridge interaction Longitudinal displacement of the end of the deck Stresses in rails Uplift at the end of the deck Rotations and uplift forces on directly fastened rails Transverse deformation and vibration of the deck Vertical deflection at midspan (for passenger comfort) Fatigue requirements for Underline Bridges 55 9 Loading General requirements for loading Loading for new and replacement Underline Bridges Railway loads for Underline Bridges Dynamic effects for Underline Bridges Fatigue loads for Underline Bridges Additional loads for direct fastening and embedded rails Additional loading for continuous beams in Underline Bridges Walkway loading for Underline Bridges Parapet and handrailing loads for Underline Bridges Accidental (derailment) loads for Underline Bridges Accidental loads for Underline Bridges over highways Accidental loads for Underline Bridges over waterways Loading for strengthening, alteration or repair of Underline Bridges 60 Page 9 of 109

65 9.4 Loading for new and replacement Overline Bridges and footbridges Highway vehicle loads for new and replacement Overline Bridges Pedestrian, cycle and equestrian loads Parapets, safety barriers and handrailing for Overline Bridges Accidental (derailment) loading on Overline Bridge supports Loading for strengthening, alteration or repair of Overline Bridges Other loads and effects for Underline, Overline and other Bridges Loads to be considered Aerodynamic effects Bridges over watercourses Loading for substructures Design standards General Steel, concrete, composite and masonry Bridges Timber Bridges Bridges constructed from other materials Foundations for new Bridges Earth retaining elements Existing substructures affected by new construction Site investigation and geotechnical Design Specifications for materials and workmanship Strengthening, alterations and repairs Identification of Bridges Records 76 Appendix A: Application of Structure Category to individual structures 77 Appendix B: Amendments to BS5400: Steel, concrete and composite Bridges 80 Page 10 of 109

66 Appendix C: Railway loads, application, dynamic factors, and amendments to BS : Appendix D: Collision loads from railway traffic 89 Appendix E: Additional requirements for lineside handrailing on Underline Bridges 92 Appendix F: Existing substructures affected by new construction 93 Appendix G: High Speed TSI requirements 96 Appendix H: Modification to Appendix 1 of GC/RT Appendix I: Railway infrastructure / other issues interfaces 103 Appendix J: External authority, Outside Party etc. interfaces 104 Appendix K: Information to be included in the AIP Submission 106 Appendix L: Non-mandatory recommendations 108 Page 11 of 109

67 1 Purpose This Network Rail standard defines the requirements for the Design of Bridges and Culverts, and other structures within the scope of this standard. This standard contains requirements supplementary to Network Rail standard NR/L1/CIV/044: Managing Structures Works. Compliance with this standard and with the standards referenced herein will, in respect of the Design of structures within the scope of this standard, ensure compliance with NR/L1/CIV/044 and Railway Group Standard GC/RT/5112 (Issue 1: Loading requirements for the design of bridges. At the time of drafting this standard, GC/RT/5112 was being revised for Issue 2. This standard complies with Draft 3b dated May 2008 of Issue 2 of GC/RT/ Scope This standard applies to the Design of the following types of structure, to those involved with the Design, and to those appointed by Network Rail to be responsible for the management of such structures: Bridges, Culverts, avalanche shelters (loads for Design shall be agreed with Network Rail), cut and cover structures, pipe bridges (except as identified below in this Clause), structures that support buildings over operational railway lines (but not the buildings), subways, elevated vehicle forecourts and ramps, any other structure required by Network Rail to be designed as a Bridge or a Culvert. Examples of structures that are within the scope of this standard are included in Structure Category A as shown in Appendix A. The scope includes all Bridge substructures, and earth retaining or wing walls that are integral with the Bridge substructure, and other earth retaining walls adjacent to the Bridge. Intersection Bridges, which carry a railway over a railway, shall be designed for the applicable requirements of both an Underline and Overline Bridge. Bridges which neither carry the railway nor span over the railway, shall be designed for the most onerous applicable effects according to what the Bridge carries and what the Bridge spans over. Page 12 of 109

68 For the purposes of this standard, the use of the terms Bridge or structure shall be deemed to include Culverts and any other structure within the scope of this standard where applicable. This standard applies to the Design of: all Bridges that are, or will be, owned or managed by Network Rail, all Bridges that are Shared with Outside Parties, so far as is reasonably practicable, all Bridges that are owned by Outside Parties, where failure of the structure has a potential to affect the safety of train operations. This standard also applies to: all stages where permanent works are Taken Into Use in stages before final completion, all temporary works, as defined in NR/L2/CIV/003: Technical Approval of design, construction and maintenance of civil engineering infrastructure, that are provided for the execution of such Bridges. The scope of this document covers the Design of the following categories of work: repairs, strengthening, replacement of parts, renewal / replacement of superstructures or substructures; new Bridges, temporary Bridges. Where existing Bridges are to have parts repaired, strengthened or replaced (including the renewal / replacement of superstructures or substructures), the requirements of this standard shall apply to the Design of such parts and the consequential effects on other retained existing parts. Retained existing parts do not need to comply with the requirements of this standard providing (a) the loads and effects on such parts will not be made more onerous by the alterations or the addition of other parts, (b) the retained parts are not showing any signs of distress, and (c) the load-bearing capability of the retained parts meets Network Rail s requirements. However, consideration shall be given to bringing retained existing parts into compliance with this standard where it is reasonably practicable and economic to achieve compliance. Where structural works are to be carried out, identifies requirements to strengthen or replace weak existing parts. Page 13 of 109

69 This standard is applicable to Designs for conventional railway traffic at associated conventional speeds including: passenger rail traffic with maximum permitted speed not exceeding 125 mph (200 km/h), freight traffic with maximum axle weight of 25 tonnes and maximum permitted speed not exceeding 60 mph ( 100 km/h), freight traffic with maximum axle weight of 22.5 tonnes and maximum permitted speed not exceeding 75 mph (120 km/h). For rail vehicles travelling in excess of the above speeds, guidance shall be obtained from Network Rail s Professional Head of Structures. This standard does not apply to the Design of the following: longitudinal timbers, which shall be designed in accordance with NR/SP/TRK/038: Longitudinal Timbers Design, Installation and Maintenance, gantries for signals or overhead line electrification (OLE), cable bridges, pipe bridges for which the Design basis stated in the AIP Submission is NR/L2/CIV/067: Design of Equipment Support Structures, Outside Party pipelines and other undertrack crossings, buildings or other structures that are supported by a Bridge. Earthworks associated with a Bridge shall be designed in accordance with NR/L2/CIV/071: Design of earthworks, earthwork remediations and geotechnical aspects of foundations for structures. Equipment support structures that are attached to a Bridge shall be designed in accordance with the requirements of NR/L2/CIV/067: Design of Equipment Support Structures as applicable. This standard covers structural aspects of Design and those aspects of Design relating to the safe movement of users (including clearances) and the provision of adequate protection to users. However, it does not cover other health and safety aspects of Design, such as choice of materials (e.g. exclusion of lead based paints), ventilation, means of escape, access platforms and ladders. This standard incorporates those parts of Railway Approved Code of Practice GC/RC5510: Recommendations for the Design of Bridges which Network Rail requires to be mandatory. The requirements of this standard shall take priority over GC/RC5510, which at the time of drafting this standard was due to be withdrawn. However, the additional information and guidance for the Design of Bridges available in GC/RC5510 should be used where not in conflict with this standard. Page 14 of 109

70 In order to address potential effects of climate change regarding temperatures, an additional 10 o C has been added to effective Bridge temperatures see Appendix B. The principal standards for managing structures works are shown in NR/L1/CIV/044: Managing structures works. 3 Roles, responsibilities and competencies Ref: NR/L2/CIV/020 Those appointing persons to positions with responsibilities to deliver the requirements of this standard shall ensure that appointees are competent and that they understand their responsibilities. Appointments, responsibilities and duties shall be documented. The skill, expertise, training and experience of those employed on a Design shall be appropriate to the nature and complexity of the structure being designed. This competency shall be assessed by the person making the appointment. The Construction (Design and Management) Regulations 2007 set out requirements for those managing construction / Design work with respect to competency. Roles, responsibilities and competencies of those involved in the production and checking of a Design, and its construction, shall be in accordance with NR/L2/CIV/003: Technical Approval of design, construction and maintenance of civil engineering infrastructure. The responsibilities of Network Rail s Infrastructure Liability Manager as regards this standard are identified in 6.7 and Definitions Accommodation Bridge A Bridge provided to maintain access to lands that were severed by the construction of the railway and which can only legally be used by the successor to the original landowner whose land was severed; however, subsequent public footpath and bridle rights may have been acquired by other users. AIP Submission The submission for approval in principle as required by NR/L2/CIV/003: Technical Approval of design, construction and maintenance of civil engineering infrastructure. Authorised Walking Route A designated route providing pedestrian access to and egress from places of work (including booking-on points and stabling points) and which is suitable for use by persons not certificated in Personal Track Safety. Page 15 of 109

71 Bridge A structure of one or more spans greater than or equal to 1800 mm, whose primary purpose is usually to carry traffic or services over an obstruction or gap, but excluding Culverts. Cess Walkway A designated walkway along the cess where persons certificated as competent in Personal Track Safety may walk safely while trains pass. (Note: a Cess Walkway does not constitute a Position of Safety unless it can be accessed from the side of the track.) Containment Level The capacity of parapets and vehicle safety barriers to restrain road vehicles. (See Highways Agency standard TD 19/06: Requirements for Road Restraint Systems). Culvert A structure with a span or diameter greater than 450mm but less than 1800mm whose primary purpose is usually to permit water or services to pass under or adjacent to a railway, road or other Network Rail infrastructure. The term excludes Outside Party pipelines. Design Information in the form of drawings, diagrams, calculations and/or specifications (performance, materials and workmanship) which together describe in detail what is to be constructed and, where applicable, how it is to be constructed. The term is also used to describe the process by which such information is produced, including the undertaking of structural calculations where necessary. Designer The person responsible for the Design who is authorised to sign the Approval in Principle Submission and/or the Design certificate on behalf of the Design organisation. Interworking The ability of the structure to carry current and foreseeable rail traffic including at the published capability of the route, traffic permitted in excess of the capability of the route, traffic diverted from other routes, the cascade of rail vehicles from one route to another and interoperability requirements. Occupation Bridge A Bridge carrying a private road which generally pre-existed the railway and which can only be used by authorised users - typically the successors of the original users of the road and their invitees, although subsequent public footpath and bridleway rights may have been acquired by other users. Page 16 of 109

72 Overline Bridge A Bridge which passes over the railway and includes public highway, Accommodation, Occupation and bridleway Bridges, and footbridges. Ref: NR/L2/CIV/020 Outside Party A person or organisation, other than Network Rail, that is an infrastructure owner or developer, or is a user or occupier of Network Rail s infrastructure. The term includes Highway Authorities, Roads Authorities, Passenger Transport Executives, public or private developers, and Train Operating Companies. Real Trains The axle loads and axle spacings for particular trains and/or railway vehicles, and the combinations of such trains/vehicles, defined by Network Rail. Remit The formal document issued by Network Rail describing the purpose, scope and objectives for a project, an outline of the service required, key responsibilities, and outputs to be delivered at completion of the project phases. Shared Bridge A Bridge of which the ownership and/or management is shared between Network Rail and an Outside Party. Structure Category The category (A, B, C, D, E, F or G) to which a structure is assigned, in accordance with NR/L1/CIV/044: Managing Structures Works, that defines the processes to be used to manage the structure works. Taken Into Use The state of new, altered or renewed civil engineering infrastructure provided under a scheme or maintenance works or temporary works, whether complete or not, when fit for the safe passage of trains, occupying by users, use of or passage by members of the public, or installation of plant or equipment as applicable. Underline Bridge A Bridge carrying one or more operational railway tracks. 5 Principles This document supports the philosophy of the HMRI Safety Principles by requiring that Bridges and associated earthworks are designed so that: they permit the safe operation of, and protection to, the railway, they are capable of carrying and transferring loads and forces applied to them, Page 17 of 109

73 there are adequate clearances between trains on adjacent tracks and between trains and Bridges, they provide for the free and safe movement of people, they can be executed, examined, maintained and decommissioned safely, reasonably foreseeable future developments are considered. In addition, structures are to be identifiable on site. 6 General Design requirements 6.1 Structural adequacy, general location and dimensions Bridges shall be designed with reasonable professional care such that, for the duration of their intended life, and assuming appropriate standards of construction and maintenance: they provide adequate resistance to the intended applied loads (including self weight), they provide adequate resistance to the likely effects of external influences, they have sufficient robustness not to suffer damage, due to accidental events (e.g. train derailment) or vandalism, to an extent that would be disproportionate to the severity of the cause, their deformation under load is satisfactory, they are safe for people on or in the vicinity of the structure, they can be maintained economically. Consideration shall be given to incorporating structural redundancy within the Design, so that alternative load paths are available in the event of unforeseen failure of part of the structure. Generally, the mode of failure shall not be catastrophic, the structure shall be designed so that the critical failure modes are those that give advanced warning of failure (e.g. bending rather than shear), and the structural form shall incorporate adequate ductility and/or redundancy. A summary of the approach adopted shall be identified and recorded in the AIP Submission, in accordance with NR/L2/CIV/003: Technical Approval of design, construction and maintenance of civil engineering infrastructure. The locations and dimensions of the Bridge (including any intended equipment that it is designed to support) shall provide, where appropriate: for the safe movement of vehicles, persons (including those whose mobility is impaired) and / or equipment, Page 18 of 109

74 adequate protection from, and or deterrence to, unauthorised access (e.g. trespass or vandalism), adequate protection to vehicles or persons using or affected by the Bridge. 6.2 Purpose, intended use and Remit Bridges shall be designed in accordance with the appropriate principles and requirements identified in this standard so that, as far as is reasonably practicable, they are suitable for the purpose for which they are intended and do not have an unacceptable influence on the safe operation of the railway, Outside Parties and third parties. Network Rail, or other relevant Authority as agreed with Network Rail, shall specify the purpose and intended use of the Bridge, outline the operational and safety requirements for the intended and future use of the Bridge, and provide relevant Design information, in the Remit or other documentation. Relevant existing information shall be made available to the Designer. The Remit shall specify the following project specific requirements, as applicable and where not as specified in this standard: legal and commercial liability issues (6.7), positions of tracks to be supported (6.9.1), gauge and clearance requirements (6.9.2), whether the Bridge is on a High Speed TSI route, and particular requirements for assessment of conformity and verification(6.9.6 and Appendix G), particular clearance requirements (6.9, 6.13), Design life for strengthening, alteration, repairs of temporary Bridges (7.2.2), Requirements for parapets on a Bridge that is remote from the railway (7.9.8), whether the Bridge in on a primary route, and any particular requirements for passenger comfort (8.6), loads to be supported, including traffic (railway or highway), equipment and services (including Statutory Undertaker s), and numbers of persons (where relevant), with consideration given to the likely or reasonably foreseeable future loading or other requirements (9, Appendices C and D), accidental loading requirements (9, Appendices C and D), speed, tonnage and traffic mix for fatigue (9.2.3), Page 19 of 109

75 loading for an Accommodation or Occupation Bridge, where is excess of HA and 30 units of HB (9.4.1), planned abnormal use, particular security requirements, other project specific requirements. To ensure that any specified restrictions on loads or limitations on use are observed, methods of control shall be identified and recorded in the AIP Submission, and provisions shall be incorporated into the Design (e.g. requirements for the erection of notices, weight restriction plates or physical barriers, etc). 6.3 Operational safety Influences or requirements which may affect the safety of railway operations, the general public, or persons whose duties take them on or near the line, shall be taken into account, including: safety of train operations of other railway infrastructure owners that are likely to be affected by the structure, sighting of train control equipment or other lineside signs, safety of staff and the general public on platforms, provisions for staff on or about the track, including positions of safety and walkways (on or under Bridges), and sighting distances to trains, aerodynamic effects of passing trains, potential arcing of electric power equipment, induced voltages, ground water, where this has the potential to affect train control or other safety critical equipment, or the track, seasonal fluctuations in ground water levels, avoidance of any projections or sharp edges that have potential to cause harm to staff or the general public, protection against falls from heights in excess of 2 metres, protection from or deterrence to unauthorised access e.g. trespass or vandalism. Appendix I contains a non-exhaustive list of railway infrastructure interfaces. 6.4 Construction, maintenance and decommissioning The Bridge shall be designed so that: Page 20 of 109

76 there is at least one safe and feasible method by which it can be constructed, and subsequently demolished or removed (decommissioned), taking into consideration the safety of the operational railway; examination in accordance with NR/L2/CIV/017: Examination of Bridges and Culverts may be carried out safely, examination in accordance with NR/L2/CIV/017: Examination of Bridges and Culverts will be sufficient for the future management of the structure, foreseeable maintenance requirements, including the replacement of limited-life components such as bearings and the reapplication of protective coatings, can be carried out safely so that the Bridge can achieve its Design life, the Bridge meets the requirements of Network Rail, and those of Outside Parties as agreed by Network Rail. The Design shall consider the construction methodology and shall minimise the impact on the operational railway. The method of construction, and any principal construction stages envisaged by the Designer that need to be taken into account in the Design, shall be stated in the AIP Submission and the Design documents. In applicable cases a detailed description, drawings, etc. shall be included. The envisaged method of decommissioning the Bridge, and any hazards associated with demolition that would not be apparent from an examination of the Bridge or from its anticipated Design or construction records, shall be stated in the AIP Submission. Consideration shall be given to provisions for examining and maintaining hidden elements, those with difficult access, hollow sections, buried parts and connections to foundations. Hidden details shall be avoided where reasonably practicable to do so. Where hidden details are unavoidable, they shall be described in the AIP Submission with recommendations for future examination. Consideration shall be given in the Design process to the interfaces between the Bridge and the object that is crossed, e.g. railway, road or river, and the effects and operations of each on the other during the construction, maintenance and future de-commissioning. The Design and envisaged construction shall avoid unnecessary disruption to interfacing operations. In order to avoid delays or rejection of the AIP Submission, materials, components or construction methods that have not previously been Page 21 of 109

77 generally accepted by Network Rail, or new methods of using the same, shall be referred to Network Rail s Professional Head of Structures prior to submission of the AIP. 6.5 Compatibility with other infrastructure The Bridge shall be designed so that: the Bridge itself and any equipment it supports will not adversely affect the safe functioning of adjacent, existing or proposed structures or equipment, adjacent existing or proposed structures or equipment will not adversely affect the safe functioning of the structure or the equipment it supports, existing or foreseeable requirements for services or plant can be accommodated on or within the structure. 6.6 Health and safety, and environmental considerations The Design shall as applicable take into account the following, without limitation, as regards their effect on health and safety, and the environment: use by disabled persons, safe means of access and egress, including in emergencies, fire safety, suitable materials and standards of workmanship for the construction and planned maintenance/ examination, use of new materials, components or methods, environmental issues, including the impact on sensitive species, management and discharge of track drainage and surface water, contaminated run-off and the need for separators;, discharge into rivers and watercourses. Where appropriate for a particular Bridge, its location or its potential impact on the environment, the relevant environmental agency (e.g. Environment Agency, Environment Agency Wales, Scottish Environmental Protection Agency) shall be consulted before submission of the AIP, subject to the restrictions and requirements of 6.10 and Where applicable, the agency s agreement to the Design and/or the specifications for work and materials, shall be obtained and documented. Other authorities and Outside Parties that may need to be consulted are identified in Appendix J. Page 22 of 109

78 6.7 Legal obligation and commercial liability issues The Design shall take into account Network Rail s liabilities applicable to the Bridge as established by Network Rail s Infrastructure Liability Manager (ILM) and included in the Remit or as otherwise notified to the Designer. All legal obligation and commercial liability issues and queries, including the following, shall be addressed by Network Rail s ILM or equivalent authority (unless responsibility has been delegated to the Designer): liabilities, easements, and wayleaves, load carrying obligations (both statutory and safety requirements), establishing requirements for headroom and carriageway widths (see ), navigation envelopes (see ), etc, confirming existing agreements regarding repairs, replacements and renewals of infrastructure and affected services. The Designer shall notify the ILM at an early stage in the Design about any such issues that are relevant and which were not identified in the Remit, and shall ascertain Network Rail s requirements. 6.8 Bridges not owned or controlled by Network Rail Where a Bridge is within the scope of this standard but is not owned or controlled by Network Rail, Network Rail shall use its best endeavours to ensure that the Bridge is designed to comply with the requirements of this standard. Where this is not the case, the relevant details shall be recorded and the appropriate authorities notified. Where the safety of train operations or Interworking is likely to be affected, the matter shall be brought to the attention of the Network Rail s Professional Head of Structures. 6.9 Interface with the railway Railway tracks The positions and number of tracks to be carried or crossed by the Bridge shall be specified in the Remit, or other Design documentation. Maintenance tolerances on the designed position of the track are identified in NR/SP/TRK/102: Track construction standards. Page 23 of 109

79 For an Underline Bridge, a minimum of 200 mm of ballast shall be provided, or such greater depth as required by NR/SP/TRK/102. A transition zone shall be provided between the end of a new Underline Bridge and the approach embankment to minimise track maintenance requirements arising from a sudden change in track deflection under train loads. The provision of a transition zone shall also be considered where a Bridge is reconstructed. Examples of good practice are given in UIC 719-R: Earthworks and track bed construction for railway lines. Prior to submission of the AIP for an Underline Bridge, the requirements for track (including space for point motors etc.), track support, the transition on/off the Bridge and track drainage shall be agreed with the relevant Network Rail Track Engineer. Provisions shall be made to retain ballast on the approaches to an Underline Bridge, to provide adequate lateral support and to prevent ballast being washed away during floods. The form of the Bridge and its ability to carry the intended loads shall not be unreasonably sensitive to the precise position of the tracks. Where reasonably practicable, the Bridge shall be designed to allow tolerance in the permitted positions of the tracks. The allowable number and tolerable positions of the tracks relative to the Bridge structure shall be identified in the AIP Submission. Where the use or replacement of rail-bearers is not reasonably avoidable, the tolerance in the position of the track shall be identified relative to each rail-bearer. The positions and numbers of tracks on an Underline Bridge shall not be moved or increased respectively, unless both the Bridge superstructure and substructure have been designed (or subsequently assessed) for the change in load effects, and any necessary strengthening or modification has been implemented. For an Overline Bridge, any change to the position of tracks shall not compromise the required clearances Structure gauge and clearances to the railway The structure gauge and clearances shall either be established by the appropriate Network Rail Gauging Engineer or equivalent authority and identified in the Remit, or shall be agreed with the Gauging Engineer during the Design process. The structure gauge and clearances shall comply with the requirements for the route and, where applicable, shall also allow for Network Rail s intentions regarding changes to the railway traffic Page 24 of 109

80 permitted on the route as identified in the Remit. Additional requirements regarding Technical Specifications for Interoperability are referenced in and Appendix G. Clearances shall comply with HMRI Railway Safety Principles and Guidance Part 2 Section A: Guidance on the Infrastructure, Chapter 6, and Part 2 Section C: Guidance on Electric Traction Systems, Chapter 3. Clearance requirements for the safe movement of rail vehicles shall comply with Railway Group Standard GC/RT5212: Requirements for Defining and Maintaining Clearances, subject to a modification to the diagram in Appendix 1 of GC/RT5212 (Issue 1) as identified in Appendix H of this standard. The clearances provided shall take into account relevant operational safety aspects identified in 6.3 and electrical clearance requirements in accordance with GE/RT8025: Electrical Protective Provisions for Electrified Lines where applicable. Requirements for the safety of railway personnel and access shall be in accordance with GC/RT5203: Infrastructure Requirements for Personal Safety in Respect of Clearances and Access and NR/SP/OHS/069: Lineside facilities for personal safety. In determining clearances, allowance shall be made for the track cant and the permitted tolerance in track position, and also any anticipated track lifting, slewing or realignment schemes. Once the most onerous position(s) of the track has been established in relation to each critical aspect of clearance for an Overline Bridge, the Design shall allow for a further 50mm of unplanned future track uplift, unless otherwise agreed with Network Rail. In complying with clearance requirements, the Design shall take into account the deflection or movement of the structure and its foundations under permanent, imposed and transient loads, and tolerances in the construction of the Bridge. If a proposal to reconstruct a Bridge would result in clearances less than those required above, the clearances shall be justified and recorded in the AIP Submission Railway equipment Where required by Network Rail, a Bridge shall be designed to accommodate service cables and ducts, signals, location cabinets, point motors, rail lubricators, overhead line electrification, and other Page 25 of 109

81 equipment or equipment support structures. The loads applied by such items shall be identified in the AIP Submission Electrical protection, earthing and bonding A Bridge carrying or passing over electrified lines shall comply with the electrical protection and bonding requirements of Railway Group Standard GE/RT8025: Electrical Protective Provisions for Electrified Lines. Earthing and bonding systems for a Bridge, its metal parts and supported metal services shall comply with NR/SP/ELP/21085: Design of Earthing and Bonding Systems for 25kV A.C. Electrified Lines. As required by NR/SP/ELP/21085, the Design of such systems shall be in accordance with BS EN : Railway Applications Fixed Installations Part 1: Protective Provisions Relating to Electrical Safety and Earthing and with all other relevant standards. The electrical protection of the Bridge shall take into account the structure itself, any supported/attached equipment, any dual purpose issues, the surroundings and adjacent buildings or structures. Where electrical protection is achieved by physical separation or isolation, the Design of any earthing or bonding systems shall not compromise this protection. Bonding/earthing studs shall be fitted to the Bridge as required by Network Rail. Bonding that is required exclusively for signalling purposes is outside the scope of this standard. Consideration shall be given to maximising the use of metalwork or reinforcement in substructures for earthing, taking into account requirements for low resistance and low impedence. Where required, remote earth test-points shall be provided for in the Design. Where metal fences are attached to a Bridge, the electrical protection of the Bridge and fences, including gates, shall be considered as a whole. Consideration shall be given to using nonconducting fencing. Trays or ladders which support electrical cables and are attached to a Bridge shall be earthed to the Bridge. Page 26 of 109

82 In D.C. electrified areas, Bridges shall not be bonded to the negative return rail unless otherwise agreed with Network Rail. Ref: NR/L2/CIV/020 Where a Bridge carries or passes over an overhead line electrified railway, consideration shall be given to providing effective electrical bonding as follows: uniformly spread over a width of 2.6 m as above bonding a metal Underline or Overline Bridge to the traction return rail or earth wire, connecting the components of a metal Bridge by welding or by substantial, clean metal-to-metal bolted or riveted joints, connecting together and bonding as above any exposed metal parts of an Underline or Overline Bridge (e.g. parapets, handrails and bearings of a concrete Bridge), bonding as above concrete reinforcement (including prestressing anchorages) if it is accessible or if it is electrically connected to accessible metalwork, attaching a bonded metal plate to the underside of a concrete, timber and masonry Overline Bridge, in certain cases where required by Network Rail, using non-metallic embedded service ducts in the Bridge. Where a railway signal structure or any other railway equipment or equipment support structure that is required to be bonded to the traction return rail are attached to a Bridge, the interface between the Bridge and the attached equipment or support structure shall be designed so that all metal parts form a continuous electrical whole. Where a Bridge crosses over an overhead electrified railway, consideration shall be given to waterproofing the Bridge and to managing any run-off to avoid potential damage through dripping water causing flash over. The electrical protection Design shall be subject to acceptance by Network Rail Protection from stray currents Where third rail D.C. electrification, or dual overhead A.C and thirdrail D.C. electrification is present, consideration shall be given to the risk of stray current corrosion arising due to high current flows through the earth. Railway Group Standard GL/RT1253: Mitigation of DC Stray Current effects identifies the process requirements concerning stray currents. Where applicable, details shall be agreed with Network Page 27 of 109

83 Rail as to which requirements of GL/RT1253 are to be included in the Design of the Bridge. Consideration shall be given to special protection, or measures to mitigate the rate of corrosion, such as electrical isolation of substructure reinforcement cages, electrical screening, sacrificial zinc electrodes, or cathodic/anodic protection. Where applicable, protective provisions shall be in accordance with BS EN : Railway Applications Fixed Installations Part 2: Protective provisions against the effects of stray currents caused by D.C. traction systems Technical Specifications for Interoperability (TSI) An introduction to the requirements for complying with the Technical Specification for Interoperability relating to the Infrastructure Subsystem for Bridges that carry or cross high speed rail lines ( High Speed TSI ) of the trans-european network (TENS lines) is given in Appendix G. The TSI for Conventional Rail traffic is under development at the time of drafting this standard and is currently anticipated to come into force in Bridges on or over lines subject to the Conventional Rail TSI will have to comply with the requirements of the TSI once in force. The applicability of TSIs and the particular requirements for each Bridge must be established by reference to the High Speed and Conventional TSIs and the applicable Regulations. The AIP Submission shall identify in a specific appendix the TSI requirements which apply to the Design and demonstrate how the Design complies with these requirements General requirements for interfacing with external authorities, Outside Parties and third parties Potential Design interfaces with external authorities, Outside Parties and third parties are listed in Appendix J. Before making any initial consultations, the arrangements for liaising with all external authorities, Outside Parties and other potentially affected third parties during the Design process, and for subsequently agreeing any requirements, shall be agreed with Network Rail. Liaison with HMRI, TSI authorities (see Appendix G), Notified Bodies, train/freight/station operating companies, and other leaseholders/tenants (of Network rail) shall be carried out by Network Rail, unless specifically delegated to the Designer or others. Page 28 of 109

84 Provision of access to Network Rail property shall be co-ordinated through the Operational Property Service of Network Rail s Property Estates division, or equivalent authority. Ref: NR/L2/CIV/020 In order to ensure that the Design is compatible, so far as is reasonably practicable, with the requirements of authorities and other interested parties external to Network Rail, liaison with external authorities, Outside Parties and third parties shall commence prior to the start of the Design, and shall continue throughout the Design process, as applicable Interface with Planning Authorities Contact with the relevant Planning Authority shall be co-ordinated through Network Rail, and in appropriate cases Network Rail will undertake the consultations directly. No communication is to be made outside Network Rail concerning permitted development status, planning approval, or listed building status, without the prior approval of Network Rail, and the Town Planning Team of the Network Rail s Property Estates division (or equivalent authority). Consultation with the Planning Authority shall commence as early in the overall Design process as practicable, to avoid abortive Design effort. The following planning aspects shall be considered in the Design, where applicable and without limitation: permitted development status, planning permission, including listed building status, materials and finishes, aesthetics and external colour schemes, landscaping, effects of the intended methods of construction Interface with services, Statutory Undertakers and public utilities Requirements for carrying services, Statutory Undertaker s or public utilities equipment, and for alterations to services affected by the Bridge, shall be agreed by Network Rail in consultation with the relevant authorities, unless delegated to the Designer. The Design shall make due allowance for any such services or equipment that are to be supported by the Bridge, and the provisions, loads and alterations shall be identified in the AIP Submission. Where reasonably practicable, equipment for different types of services shall be segregated. Appropriate facilities shall be provided for the maintenance of the services and equipment. Consideration shall also be Page 29 of 109

85 given to the means of future replacement, renewal and upgrading of services and equipment. Ref: NR/L2/CIV/020 Consideration shall be given to providing space or incorporating ducts for future service requirements, and facilitating access in the future with minimal disruption to the railway and other operations. The risk to the Bridge superstructure, substructure and associated earthworks, arising from the consequential effects of the failure of pipes or services carried by or passing under the Bridge, shall be considered in the Design Interface with highways Highway Authority acceptance of the Design Where a Design will affect existing or proposed highways, the acceptance of the relevant parts of the Design shall be sought (subject to the restrictions and requirements of 6.10) from the Highway Authority, including any mitigation of effects that may be required. Relevant details and references to acceptance by the Highways Authority shall be included in the AIP Submission Clearances to highways and other roads Lateral and vertical clearances to highways and other non-public roads shall be determined by Network Rail (see 6.7) in consultation with the Highway Authority, private owner or user as applicable, and shall take into account Network Rail s existing legal obligations or agreements. For a new Bridge over a public highway, the headroom from the soffit shall not be less than 5.3 m, and shall be at least 5.7 m where this can be achieved with reasonable economy. The Bridge shall comply with HMRI Railway Safety Principles and Guidance Part 2: Section A, Chapter 4. Where it is not reasonably practicable to provide a headroom of 5.7 m, details shall be justified and recorded in the AIP Submission. Where the headroom is less than 5.7 m, the superstructure shall be designed for vehicle collision loads in accordance with Highways Agency Standard BD 60/04: The Design of Highway Bridges for Vehicle Collision Loads or suitable protection shall be provided in accordance with BD 65/97: Design Criteria for Collision Protection Beams as applicable. References in BD 60/04 to the Overseeing Organisation shall be deemed to refer to Network Rail. Protection beams shall not be used to carry critical functions, such as signalling cables. Page 30 of 109

86 Columns which support a Bridge that spans over a highway, whether within or further than 4.5 m from the edge of the carriageway, shall be designed and where applicable have mitigation measures provided, in accordance with BD 60/04. Ref: NR/L2/CIV/020 The Design of a Bridge over a highway shall prevent collapse as required by BD 60/04. Associated railway loading for an Underline Bridge is given in Consideration shall be given to the following mitigation in relation to potential impact from highway vehicles, as applicable: provide restraint to prevent the Bridge being moved sideways or upwards, add mass to the structure, provide a flat soffit or ensure the deck can adequately carry the loads if one member is removed, provide stocky flanges, stiffen girder webs, provide additional main girder flange thickness to compensate for damage and facilitate repair options (e.g. dressing of gouges in the steel). Consideration shall be given to the relative gradients of the Bridge soffit and the highway, and the potential for vehicles/loads to bounce after striking the structure, which can make internal parts of the soffit vulnerable to impact, as well as outer girders. Where an existing Bridge superstructure is to be strengthened or reconstructed, so far as is reasonably practicable the resulting structure shall be able to continue to carry rail traffic in the event of a Bridge strike. Network Rail's headroom and legal obligations shall be established in accordance with 6.7. The minimum headroom over a highway shall not generally be reduced where it is already below 5.7 m without Network Rail s approval. Where reasonably practicable the headroom shall be increased to provide the maximum up to 5.7 m. If clearances less than existing are proposed, these shall be determined in consultation with the appropriate authorities and recorded in the AIP Submission. For a strengthened or reconstructed Bridge for which a headroom of less than 5.7 m is proposed, a risk assessment for vehicle impact shall be carried out, and consideration shall be given to designing the Bridge to resist vehicle collision loads in accordance with BD 60/04 or providing other suitable protection designed in accordance Page 31 of 109

87 with BD65/97. Details shall be justified and recorded in the AIP Submission. Ref: NR/L2/CIV/020 The requirements of NR/L2/CIV/076: Management of bridge strikes from road vehicles & waterborne vessels shall be complied with as applicable. Consideration shall be given to the guidance in NR/L3/CIV/202: Management of the risk of bridge strikes. A Bridge over a non-public road shall comply where reasonably practicable with the requirements for a Bridge over a highway, and any different criteria shall be identified and justified in the AIP submission Highway widths and construction Where the Design includes the provision of a highway, the widths, details and construction of the highway shall comply with the requirements of the relevant Highway Authority and details shall be included in the AIP Submission Highway sight lines The Design shall comply where reasonably practicable with the requirements of the Highway Authority to provide, or maintain, sight lines on the highway. Where the Design will unavoidably and unacceptably affect existing sightlines, requirements for appropriate mitigation measures shall be sought (subject to 6.7) from the Highway Authority (e.g. imposing a highway speed restriction) and shall be identified in the AIP Submission Highway lighting and road traffic signs Facilities for providing/attaching lights, lighting columns, road traffic signs etc., and for the provision of power, shall be considered, and shall be included in the Design where such provision has been agreed by Network Rail. The relevant requirements and loading shall be identified in the AIP Submission Road traffic signs for restricted headroom Bridges Where a new, strengthened or reconstructed Bridge has a headroom less than 5.03 m (16' 6''), advance warning signs, and warning chevrons and headroom signs on each face of the Bridge, shall be provided as identified in NR/L2/CIV/076: Management of bridge strikes from road vehicles & waterborne vessels Prevention of vehicle incursion Requirements for preventing the accidental incursion of vehicles onto the railway are given in Page 32 of 109

88 6.14 Interface with waterways Clearances over waterways Lateral and vertical clearances over waterways shall be determined by Network Rail in consultation with the relevant authorities, private owner or user, as applicable and shall take into account any existing legal obligations or agreements. The clearances shall be recorded in the AIP submission. The risk of ship impact shall be considered as identified in and Lighting and signs over waterways Facilities for providing/attaching lights, signs etc., and for the provision of power, shall be considered and included in the Design where such provision has been agreed by Network Rail. The relevant requirements and loading shall be identified in the AIP Submission Interface with mineral extraction and landfill Issues regarding the interaction of a Design with mineral extractions and landfill shall be managed in accordance with Network Rail Standard NR/L2/CIV/037: Managing the risk arising from Mineral Extraction and landfill. Arrangements for liaison shall be agreed with Network Rail before making any initial consultations. 7 Particular Design requirements 7.1 Technical Approval Technical Approval for the Design shall be obtained in accordance with NR/L2/CIV/003: Technical Approval of design, construction and maintenance of civil engineering infrastructure. Like for like replacement of components of an existing Bridge may not require Technical Approval for the components. However, consideration shall be given to the dismantling and installation process, any temporary effect on the integrity of the Bridge, any associated temporary works, and the need to obtain Technical Approval of any of these aspects in accordance with NR/L2/CIV/ Design life New Bridges and reconstructed superstructures The Design life of a new Bridge, or a reconstructed superstructure, shall be explicitly stated in the Design documentation and recorded in the AIP Submission. A Design life of 120 years shall normally be adopted; however, in exceptional circumstances a shorter life may Page 33 of 109

89 be accepted, provided justification for this is recorded in the AIP Submission. Ref: NR/L2/CIV/020 The design life of the substructure of a new Bridge shall not be less than that for the superstructure. Where existing elements are to be retained, their future Design life, and the Design life of any new elements, shall be taken into account Strengthening, alterations, repairs and temporary Bridges The Design life for strengthening, alterations, repairs and temporary Bridges shall be as specified in the Remit or as otherwise agreed with Network Rail, and shall be recorded in the AIP Submission. 7.3 Durability and corrosion protection The durability and corrosion protection of a Bridge shall be commensurate with the Design life of the Bridge. Where it cannot be reasonably avoided for components of the structure to be less durable than the structure as a whole, such as bearings, expansion joints, waterproofing, etc., which are likely to need replacing during the Design life of the structure, consideration shall be given in the Design to the means of replacing such elements, which shall be recorded with the AIP Submission. Where durable steel is used, the additional thickness required to provide a minimum patina shall be identified in the AIP Submission. Paints, sealants and other materials used for the protection of a Bridge shall comply with the requirements of NR/L2/CIV/039: Specification RT98 Protective Treatments for Railtrack Infrastructure. The recommendations of NR/L3/CIV/002: Application and reapplication of protective treatments to Railtrack infrastructure shall be considered. Consideration shall be given to protection below ground level, taking into account the difficulties of examination and maintenance, and the possibility of future changes in ground level adjacent to the structure. 7.4 Water management and drainage The management of water on or under a Bridge, including approaches, shall prevent ponding on the trafficked surfaces or within infill material, ballast, etc., where reasonably practicable. Consideration shall be given to providing falls, pre-camber and drainage facilities. Due account shall be taken of water on the approaches to a Bridge, particularly where parts Page 34 of 109

90 of the structure or associated works are at a low point relative to the approaches. Ref: NR/L2/CIV/020 An Overline Bridge which carries a highway or road shall be provided with carriageway drainage in accordance with the relevant Highways Agency standards, unless otherwise agreed by Network Rail. Footways and parapet upstands and joints shall be designed to prevent surface water flowing over the edge of the Bridge or exiting through gaps onto the railway, overhead line equipment (OLE), or other infrastructure below. Consideration shall be given to providing drainage facilities for an Underline Bridge. Drainage shall not direct water onto the highway, or the railway/ole below an intersection Bridge, or other infrastructure. Drainage shall be provided behind earth retaining abutments and walls to prevent the build-up of water pressure in retained fill material. The suitability of providing weep holes or direct drainage pipework shall be considered, taking into account the means of dissipating the water in front of the abutment, into drainage systems or watercourses, and the need to prevent pollution. Consideration shall be given to the requirements of Highways Agency standard BD 30/87: Backfilled retaining walls and bridge abutments. Drainage systems shall be designed to facilitate maintenance with the provision of suitable manholes and rodding eyes, etc. The Design of drainage adjacent to the track shall comply with NR/SP/TRK/9006: Design, installation and maintenance of lineside drainage unless otherwise justified in the AIP Submission. Where abutments or walls are clad with brickwork or stonework, the gap behind the cladding shall be filled with mortar. For other cladding material, consideration shall be given to providing drainage to the void between the wall structure and facing. 7.5 Waterproofing A Bridge that carries a highway and other road, etc. shall be waterproofed in accordance with the relevant Highways Agency standards, unless otherwise agreed by Network Rail. Other bridges, including Underline Bridges, shall have waterproofing that complies with the requirements of NR/L2/CIV/041: Waterproofing systems for underline bridges. Guidance on waterproofing is provided in NR/L3/CIV/001: Waterproofing for underline bridges. The design life of the waterproofing system shall be stated in the AIP Submission. Page 35 of 109

91 7.6 Structural form and articulation The structural form and articulation of the Bridge shall take into account relevant factors and interactions, including the following as applicable: the safety and ease of construction, the effect on the vertical and torsional stiffness of the bridge, the effects of rotations at the bearings, including uplift at the end of the deck behind bearings, avoiding uplift at bearings, the support provided to the track, constraints on construction depth, geometrical constraints arising from structure gauge requirements, etc., longitudinal and transverse movement, or the effects where such movement is restrained, joint details, waterproofing, and the management of track drainage and surface water, implications for the examination and maintenance of the Bridge, limitations identified in Appendix L. Details that may lead to debris and water becoming trapped, with consequential risks of corrosion, shall be avoided. Consideration shall be given in the detailing to facilitate future repainting of metalwork, including the recommendations of BS EN ISO :1998: Paints and varnishes Part 3: Design considerations. 7.7 Protection against derailment An Underline Bridge shall be provided with a solid deck and shall have robust kerbs to contain the wheels of derailed vehicles, or girders which perform this function, to comply with the requirements of HMRI: Safety Principles and Guidance Part 2: Section A: Guidance on the Infrastructure, Chapter 4. Guidance may be obtained from Clause in Railway Approved Code of Practice GC/RC5510: Recommendations for the Design of Bridges. The following shall be considered in the Design, as applicable. Protect: the ends of main structural girders, Page 36 of 109

92 intermediate stiffeners by placing them on the outer side of main girders (if provided to a centre girder the Bridge should be adequate without the stiffeners on one side of the girder), provide robustness in the main girders, provide internal robust kerbs to protect discrete elements such as truss members above track level. Mitigate: provide robust kerbs to retain the train on the Bridge, the Bridge should not overturn or make the consequences of the derailment disproportionate to the incident, avoid placing single bearing stiffeners in the vicinity of the tracks, so that in the event of one stiffener being damaged then alternative stiffener(s) are available to provide alternative load carrying capacity.. Loading requirements are given in and Appendix C. These loading requirements generally preclude open mesh infill to grillage floors. 7.8 Security, fencing and protection from vandalism The layout of fencing in the vicinity of a Bridge shall be such that the fences, together with the adjacent structure, form a continuous barrier against trespass onto the railway. NR/L3/TRK/030: Lineside security sets out the minimum requirements. Guidance is also given in HMRI: Railway Safety Principles and Guidance Part 2: Section B, Chapter 5. Consideration shall be given to protecting the railway from vandalism and to deterring people from climbing the parapets on an Overline Bridge (e.g. by increasing the height of parapets, attaching mesh screens, installing vandalism cages or anti-trespass spikes, etc.) and by preventing access to the outer faces of an Overline Bridge. The protection arrangements shall be identified in the AIP Submission. Consideration shall be given to providing access gates in fences and to providing steps on embankments/cuttings near a Bridge to facilitate access for examining and maintaining the structure. 7.9 Parapets, safety barriers, walkways, handrailing, etc. Parapets, safety barriers, walkways and handrailing, etc. shall comply with the applicable requirements identified in to Parapets shall comply with HMRI: Railway Safety Principles and Guidance Part 2: Section A, Chapter 4. Page 37 of 109

93 The level of containment and the positions and extent of vehicle or pedestrian parapets, safety barriers, handrails and walkways shall be identified in the AIP Submission Vehicle parapets and safety barriers for Overline Bridges Vehicle parapets and vehicle safety barriers shall be provided, as applicable, on an Overline Bridge that carries a highway (including Accommodation and Occupation Bridges) and on the approaches to the Bridge, and shall comply with the principles of Highways Agency standard TD 19/06: Requirements for Road Restraint Systems, subject to the requirements of this standard. References in TD 19/06 to the Overseeing Organisation shall be deemed to be Network Rail. For an Overline Bridge which carries a public highway over the railway, the following shall apply: A new or fully reconstructed Bridge (i.e. deck and substructures) shall have Very High Containment Level (H4a) parapets in accordance with BS EN : Road restraint systems Performance classes, impact test acceptance criteria and test methods for safety barriers. Where the existing deck is to be replaced (but not the substructures), Very High Containment Level (H4a) parapets shall be provided. In exceptional circumstances, where it is not reasonably practicable to achieve H4a Containment Level, (for example where it would become necessary to reconstruct or significantly strengthen the substructures in order to withstand the containment forces), a suitable assessment of the risks at the particular Bridge shall be undertaken and the highest Containment Level that can reasonably be achieved shall be proposed in the AIP Submission. Where the Bridge is to be strengthened or altered, including where a footway is strengthened or replaced to carry accidental wheel loads, the parapet Containment Level shall be H4a provided that it is reasonably practicable to achieve this and it does not materially alter the scope of the works that was intended. Provision of a Containment Level of less than H4a shall be justified by an assessment of the risk and practicability, and the highest Containment Level that can be achieved shall be provided, which shall not be less than the existing. For an Overline Bridge that is significantly longer than the width of the railway crossed, consideration may be given to providing parapets with a Containment Level less than H4a on parts of the Page 38 of 109

94 Bridge that are remote from the railway, where justified in accordance with the requirements of TD 19/06: Requirements for Road Restraint Systems, provided that the risk of accidental penetration of the parapet and obstruction of the railway is acceptable to Network Rail. The location of the transition between a Very High Containment Level (H4a) parapet and a lower Containment Level parapet shall be set far enough from the tracks and adjacent slopes to protect the railway from errant vehicles that have penetrated the lower Containment Level parapet. Consideration shall be given to the potential trajectory of a vehicle which has penetrated the non-h4a parapet, the height of the bridge above the railway and to other relevant factors (see 7.9.3). The locations of the transitions on the approach to and departure from the H4a parapet shall not be closer to the railway than permitted by TD 19/06 and the Road Restraint Risk Assessment Process (RRRAP) which forms part of TD 19/06. Typically this will mean the transition will not be closer than 25 m in advance of the point of no recovery, and 25 m beyond the opposite point (reduces to 10 m if on a dual carriageway). Parapets are not required to extend beyond the length of the abutment or retaining walls. Consideration, in consultation with Network Rail, shall be given to the possibilities of a railway line being moved, reinstated or constructed, including passing under spans not currently over the railway, in which case parapets of Containment Level H4a shall be provided on such spans. When proposing parapets of different Containment Levels, consideration shall be given to achieving an acceptable transition between the parapet types and to the overall appearance. The provision of parapets with less than Very High Containment Level (H4a) shall be justified by a risk assessment and details shall be provided in the AIP Submission, including any other measures that are to be provided to prevent errant vehicles from striking the parapet or terminating on the railway. Vehicle safety barriers shall normally be provided on the approach and departure to all parapets in accordance with TD 19/06, including the determination of the required Containment Level of the barrier. Where it is not reasonably practicable to achieve compliance with TD 19/06 requirements, for example where the approaches to the Bridge are constrained by existing road junctions, layouts or adjacent properties, alternative proposals shall be justified in the AIP Submission. The highest standard of protection that is reasonably practicable shall be provided. Page 39 of 109

95 Appropriate transitions and connections shall be provided between parapets and safety barriers in accordance with TD 19/06. The Containment Level, and the Impact Severity Level and maximum Working Width Class as identified in BS EN : Road restraint systems Performance classes, impact test acceptance criteria and test methods for safety barriers, for parapets and vehicle safety barriers shall be agreed with the highway authority and Network Rail. Parapets over the railway shall: not be less than 1500 mm high (1800 mm where the Bridge is frequently used by equestrian traffic, or is over an automatic/driverless railway), have an inner face which is smooth and non-perforated over its full height without hand or footholds, be provided with steeple copings or equivalent. Consideration may be given to incorporating parapet profile details given in Appendix G of Railway Group Code of Practice GC/RC/5510: Recommendations for the Design of Bridges. Where the railway face of a parapet is inset from the edge of a Bridge, appropriate anti-trespass and anti-climbing measures shall be incorporated to prevent people gaining access to or along the area of the Bridge outside the parapet. This is additional to provisions for preventing access along the railway face of metal parapets. An Accommodation or Occupation Overline Bridge shall be provided with parapets of Normal Containment Level N2 in accordance with BS EN : Road restraint systems Performance classes, impact test acceptance criteria and test methods for safety barriers, provided a risk assessment is undertaken which justifies not providing a higher Containment Level, which shall be included in the AIP Submission. Vehicle safety barriers shall be provided on the approach and departure to the parapet, subject to the provisions of Spans over electrified railways The following additional requirements shall apply to parapets on a span over a railway electrified on the 25 kv overhead system and where pedestrians, animals, pedal cycles and vehicles drawn by animals are not excluded by Order: Page 40 of 109

96 parapets shall extend at least 3000 mm beyond any uninsulated overhead equipment, subject to greater lengths as required by 7.9.1, metal parapets shall be bonded to earth to counter induction currents (see 6.9.4), consideration shall be given to providing additional protective measures on footbridges where vandalism is known to be a problem in the area, such as providing enclosures or increasing the parapet height to 1800 mm Prevention of accidental vehicle incursion Where a highway approaches an Overline Bridge (at a location where the highway is not supported by the Bridge or other structure), consideration shall be given to the risk of errant vehicles falling onto the railway and, where appropriate, a vehicle parapet, vehicle safety barrier, raised earthwork mound, or other protection shall be provided. This requirement applies to new and reconstructed Bridges, and where a parapet on an existing Bridge is being replaced. Relevant factors at the site shall be taken into account, including the distance and elevation between the highway and the railway, the permitted speed of highway and rail traffic, the curvature and angle of the approach of the highway to the railway. Guidance may be obtained from the Department for Transport document Managing the accidental obstruction of the railway by road vehicles. Consideration of the risk, and any protection provided, shall comply with Highways Agency standard TD 19/06: Requirements for Road Restraint Systems and the Road Restraint Risk Assessment Process (RRRAP) which forms part of TD 19/06. The position and provision of protection arrangements shall be as agreed by Network Rail and the highway authority Replacement of parapets or safety barriers Where existing vehicle or pedestrian parapets or safety barriers on an Overline Bridge are to be replaced or reconstructed (but the Bridge is not to be reconstructed or significantly strengthened), the parapets and safety barriers shall provide the highest Containment Level (i.e. to meet the requirements for a new Bridge as in 7.9.1) that can be achieved without unreasonable additional cost or need for major works to the Bridge. Services in the Bridge, and the effect on them caused by providing a parapet with increased Containment Page 41 of 109

97 Level, shall be investigated and taken into consideration. Local repairs to parapets or barriers shall generally match the existing provisions. In all cases, the existing Containment Level shall not be reduced. Where parapets on an arch Bridge are to be reconstructed, consideration may be given to the use of high level of containment reinforced masonry parapets in accordance with BS : 1999: Highway parapets for bridges and other structures Part 4: Specification for parapets of reinforced and unreinforced masonry construction. The use of such parapets and the level of containment shall be justified in the AIP Submission Walkways, positions of safety and handrailing for Underline Bridges Walkways and handrailing shall comply with the requirements of the Workplace Regulations and with HMRI Railway Safety Principles and Guidance Part 2: Section A. Walkways, Positions of Safety, warning signs and other lineside facilities for personal safety shall be provided in accordance with the requirements of GC/RT5203: Infrastructure Requirements for Personal Safety in Respect of Clearances and Access and NR/SP/OHS/069: Lineside facilities for personal safety, subject to the requirements of where more onerous. Where reasonably practicable a Cess Walkway complying with NR/SP/OHS/069 shall be provided on both sides of a new Underline Bridge, a reconstructed superstructure, and an altered 1 Bridge. Continuous handrailing or equivalent barriers/parapets shall be provided on the outer face where the form of the structure does not provide adequate protection against falling. The walkways shall generally be formed at cess ballast level, although they may be raised or otherwise separated from the track (e.g. passing on the outside of main girders). Where it is reasonably practical to achieve on a new Underline Bridge, a reconstructed superstructure, and an altered Bridge, a Continuous 2 Position of Safety with Immediate Access from the running line (terms as defined in and complying with Railway Group Standard GC/RT5203: Infrastructure Requirements for Personal Safety in Respect of Clearances and Access) shall be provided on both sides of the Bridge. A Cess Walkway may be used as a 1 For example, alterations to an existing walkway or to edge parts of a Bridge, as opposed to un-associated strengthening/repairs, etc. to other parts of the superstructure or substructure. 2 Where reasonably practicable the Position of Safety shall be continuous and uninterrupted throughout the length of the Bridge (obstructions not exceeding 2 m are permitted), and shall not comprise a series of separated Continuous Positions of Safety with or without refuges. Page 42 of 109

98 Continuous Position of Safety where is meets the requirements for a Continuous Position of Safety with Immediate Access. Where a Continuous Position of Safety cannot reasonably be provided, prohibition notices shall be erected in accordance with NR/SP/OHS/069: Lineside facilities for personal safety. Where the Bridge is required to carry an Authorised Walking Route, one such walkway complying with NR/SP/OHS/069 shall be provided on at least one side of the Bridge, and on both sides where required by Network Rail. The height of handrailing on an Underline Bridge shall be at least 1250 mm above the adjacent walkway or cess. Handrailing shall also be infilled, and designed for loads as identified in Appendix E. Where an Underline Bridge crosses a railway (i.e. it is an intersection Bridge) which has 25 kv overhead line electrification (OLE), the handrailing shall be increased to 1.5 m height and shall be solid infilled for at least 3 m either side of the OLE, and shall comply with the requirements of Where handrailing abuts the railway boundary fencing, the layout and interface shall comply with the requirements identified in 7.8. Walkways shall be provided with a non-slip surface and shall be free from tripping hazards. An Authorised Walking Route (which by definition may be used by persons not certificated in Personal Track Safety) which is attached to or is integral with an Underline Bridge, shall be separated from the railway by a barrier to segregate users from the railway in accordance with NR/SP/OHS/069: Lineside facilities for personal safety, with a minimum height of 1500 mm. Where the barrier is attached to the top of a bridge girder which does not provide footholds for climbing, the barrier height may include the depth of the girder above the walkway. A walkway that is attached to or integral with an Underline Bridge, and which intended for use by the public, shall also comply with the applicable requirements for a footbridge (see 7.10). Small gaps between adjacent Bridges, where the tops of outer girders are close to track level, shall be covered to prevent accidents to personnel, or small items or ballast falling through. For Bridges with higher adjacent edges, consideration shall be given to covering the gap. Handrailing shall be provided where there are Page 43 of 109

99 larger uncovered and unprotected openings between adjacent underline Bridge decks. Ref: NR/L2/CIV/020 Where an Underline Bridge is located near to a station or near Stop signals on the approach to a station, where passengers might inadvertantly alight from a train onto a girder, handrail or parapet, consideration shall be given to providing additional protection, unless the structure itself affords adequate protection. Such protection shall be achieved by providing a fence on top of the parapet (provided the parapet is at least 1250 mm high), providing a raised parapet, or providing a high main structural member on the edge of the Bridge, all of which shall be to a height of 1500 mm above platform height (which shall be taken as 915 mm above the plane of the rails). Where appropriate, the Design shall incorporate signs to warn passengers not to alight from the train at such locations Protection on wing walls, abutments and Culvert head walls Suitable fences, handrails or barriers shall be provided along the tops of wingwalls, abutments, and head walls of Culverts, as applicable, to give reasonable protection against falling, where such protection is not provided by the structure or lineside security fencing as required by 7.8. Consideration may be given to the details contained in Highways Agency standard TD 19/06: Requirements for Road Restraint Systems. Provisions for protection shall not compromise the lineside security requirements of 7.8. Where there are openings between adjacent Underline Bridge decks, protection against falling shall be provided along the tops of the abutments between the decks (see Appendices E and L) Trackside walkways and personal safety beneath Overline Bridges Trackside walkways and facilities for personal safety shall be provided beneath an Overline Bridge. For a new Bridge, and where reasonably practicable for a reconstructed Bridge (i.e. where the abutments are also reconstructed), a Continuous 3 Position of Safety with Immediate Access from the running line (terms as defined in and complying with Railway Group Standard GC/RT5203: Infrastructure Requirements for Personal Safety in 3 Note that the GC/RT5203 requirements for a Position of Safety to be Continuous are more onerous than those in NR/SP/OHS/069: Lineside facilities for personal safety. Obstructions shall not exceed 2m in length. Page 44 of 109

100 Respect of Clearances and Access) shall be provided on both sides of the track under the Bridge. Where this is not practicable for a reconstructed Bridge, the walkways and safety facilities shall comply with the requirements of NR/SP/OHS/069: Lineside Facilities for Personal Safety Parapets for a Bridge remote from the railway A Bridge which does not cross a railway, is not adjacent to a railway and does not carry a railway, shall be provided with vehicle parapets, safety barriers and pedestrian parapets as applicable in accordance with Highways Agency standard TD 19/06: Requirements for Road Restraint Systems, or as otherwise specified by Network Rail in the Remit Footbridges Particular requirements for footbridges A footbridge at a station or that gives access to a station shall as a minimum comply requirements given in HMRI: Railway Safety Principles and Guidance Part 2: Section B, Chapter 5. Consideration shall also be given to the requirements of the Strategic Rail Authority Code of Practice: Train Station Services for Disabled Passengers, in which references to the Overseeing Organisation shall be deemed to be Network Rail. Subject to the overriding requirements of 7.10 and elsewhere in this standard, consideration shall be given to the applicable requirements of Highways Agency standard BD 29/04: Design Criteria for Footbridges. Details that do not comply with BD29/04 (subject to this standard) shall be identified in the AIP Submission. The width of footbridge walkways shall be suitable for current and anticipated pedestrian flows. The width of a footbridge at a station shall be determined following consultation with the Head of Station Design and Head of Fire Safety Policy. The minimum width of the footway shall be 1.4 m, with a minimum of 1.2 m between handrails. When reconstructing a footbridge on a public footpath the width shall not be reduced where the existing width is less than 1.8m. For an enclosed footbridge not located at a station and not giving access to a station, internal headroom dimensions shall be in accordance with BS 5395: Stairs, Ladders and Walkways. Consideration shall be given to providing lighting within an enclosed footbridge Page 45 of 109

101 The agreed walkway dimensions shall be identified in the AIP Submission. Ref: NR/L2/CIV/020 Subject to the requirements of 7.9, pedestrian parapets shall be provided in accordance with Highways Agency standard TD 19/06: Requirements for Road Restraint Systems, except for spans where cladding or enclosure provides equivalent protection. A footbridge which is attached to or is integral with an Underline Bridge shall be separated from the railway by a barrier which shall prevent trespass onto the railway and shall comply with NR/L3/TRK/030: Lineside security Pedestrian hand-rails for stairs, ramps and spans In addition to requirements to provide pedestrian parapets on a footbridge, pedestrian hand-rails shall be provided on both sides of stairs, ramps and approaches to ramps. Hand-rails shall either be fixed to the parapet, barrier or structural members, or shall be self-supporting. Hand-rails shall only be attached to cladding or glazing where the cladding/glazing has been designed to accommodate the attachment and applied loads. Hand-rails shall be designed in accordance with BS 8300 Code of Practice: Design of buildings and their approaches to meet the needs of disabled people, and shall comply with the requirements identified in the Strategic Rail Authority Code of Practice: Train Station Services for Disabled Passengers. The height of the hand-rail shall be not less than 900mm or more than 1000mm measured vertically above the surface of the ramp or nosing of the stairs. Consideration shall be given to providing an additional lower handrail at 450 to 550 mm above the stair nosing or ramp surface, to facilitate disabled people and children. An additional central hand-rail need only be provided where the width of stairs or ramps exceeds 3m. Hand-rails and fixings shall be designed to resist the more severe effects of a loading of 700N/m applied separately in the horizontal and vertical directions. This loading is not additional to the loading on parapets. Hand-rails are not normally required along parapets on spans across the railway, and may only be provided where the Bridge is enclosed or the parapet height is increased to maintain the required minimum parapet height above the hand-rail. Where the walkway Page 46 of 109

102 has adequate width, a barrier with hand-rails may be provided along the middle of the walkway Pedestrian subways A pedestrian subway passing under the railway shall comply with the applicable requirements for an Underline Bridge, and those for the stairs and ramps of a footbridge Pipe Bridges Self-supporting pipes, i.e. free-standing pipes, shall not normally be permitted to span over railway tracks. Agreement to free-standing self supporting pipes that carry low pressure water or non-hazardous materials will only be considered where there is no practicable alternative. Pipelines that carry liquids or gases over the railway, where the pipes are not supported by or incorporated in a Bridge structure that was primarily designed for other purposes, shall be supported on a purposedesigned beam or pipe Bridge. Unless not reasonably practicable, such beams or pipe Bridges shall span over the railway without intermediate supports. Supports, including intermediate supports where these are not reasonably avoidable, shall comply with either the clearance or impact requirements of Consideration shall be given to providing: side enclosures to facilitate maintenance of the pipe, solid flooring with edge panels to direct leaks/spillages away from the railway. Adequate measures shall be provided to contain and limit the extent of any spillage of hazardous substances from pipe Bridges, such as shut off valves outside the railway boundary, and to direct spillages away from the railway Bearings Standards for the Design of bearings are identified in 10.2, which shall be applied subject to the following requirements. Provisions applicable to the particular Bridge shall be identified in the AIP Submission. Limitations on the effects at bearings and from Bridge/track interaction, including those arising from rotations or movements at bearings, are identified in 8. Provision shall be made to prevent the effect of rotation at the end of the deck from being transmitted into the top of abutments. Page 47 of 109

103 For Bridges up to 15m thermal expansion length, bearings may be designed as fixed for horizontal movement at both ends, unless in particular cases there are reasons why it is inappropriate to do so. Ref: NR/L2/CIV/020 For Bridges up to 20m thermal expansion length, bearing sliding surfaces may be plain steel-on-steel, unless in particular cases there are reasons why these would be inappropriate, e.g. slender piers. Bearings at halving joints warrant particular consideration. Such joints shall only be used in exceptional circumstances and only where adequate access is provided for inspection and maintenance. As required by 8.3.3, unrestrained uplift at bearings shall not be permitted. Where bearings are permitted to resist uplift forces, their design shall take into account the effects of repeated load cycles. Where the headroom beneath an Underline Bridge is less than 5.7m, the bearings shall be designed for impact forces as identified in Knife edge bearings shall not be used (this is to prevent the Bridge deck dropping off its bearings). Long-stop lateral restraints shall also be provided, including where the Design allows for lateral expansion movement. For a superstructure reconstruction where the ability of the existing abutments to withstand horizontal pressures cannot reasonably be demonstrated, restraints (e.g. bearing keep-strips) shall be provided to allow sufficient movement of the superstructure due to temperature change but so that, should movement of the abutment top occur in the future, such movement is limited. In such cases the superstructures shall be designed to resist any anticipated propping forces. Requirements for existing substructures affected by new construction are given in Appendix F. Where steel roller bearings are proposed, consideration shall be given to the effects of fatigue and the need for any Design checks additional to the requirements prescribed in the standards in In all cases, provision shall be made for jacking the structure to replace discrete bearings Fasteners Where fasteners are used, at least one end of each fastener shall remain accessible after assembly. Where it is not reasonably practicable to permit access to both ends, consideration shall be given to the detailing at the hidden end, to permit the fastener to be removed, examined and reinstated. Page 48 of 109

104 7.15 Hydraulic Design for Culverts Consideration shall be given to the hydraulic Design of a Culvert through which a watercourse or floodwater flows, for determining the internal dimensions, gradient, entry and exit details, aprons and wing walls, etc. as applicable. Particular requirements for hydraulic Design are outside the scope of this standard. Hydraulic Design criteria shall be agreed with Network Rail and the Environment Agency or other relevant authority, and shall be identified in the AIP Submission Temporary Bridges A temporary Bridge shall be designed in accordance with the requirements of this standard, i.e. as for a permanent Bridge, subject to the following. A Bridge that forms temporary works and will be in place for less than 6 months may be subject to a different approval process as identified in NR/L2/CIV/003: Technical approval of design, construction and maintenance of civil engineering infrastructure. Where safety and Interworking are not adversely affected, some relaxation in aspects of the Design requirements may be permitted. In all such cases, the traffic that will be permitted to use the temporary Bridge, the Design life of the temporary Bridge, any site specific hazards and any control measures required to prevent overloading of the temporary Bridge shall be taken into account. For any temporary Bridge, whether intended for less than 6 months use or longer, justification for the adoption of such relaxations shall be recorded using the AIP Submission and shall be subject to acceptance by Network Rail s Professional Head of Structures. 8 Deformation and fatigue for Underline Bridges 8.1 General requirements The deformation of an Underline Bridge shall be determined using the loading specified in BS 5400 Part 2: 2006: Specification for loads as modified by Appendix C. The deformation of an Underline Bridge shall comply with the requirements in: BS EN 1990: 2002: Eurocode Basis of structural design Annex A2: Application for bridges, and BS EN : 2003: Eurocode 1: Actions on structures Part 2 Traffic loads on bridges. as modified by 8.1 to 8.8. Page 49 of 109

105 All deformations due to permanent loading shall be calculated allowing for all permanent loads; deformations due to live loads shall be calculated for the specified loading for the Design, including dynamic effects. Deformations shall be calculated using partial load factors for all loads of 1.0. The permanent load shall include an allowance for future increase in ballast depth. This allowance shall normally not be less than 100mm; confirmation shall be sought from Network Rail whether a greater allowance may be applicable in particular local circumstances. All horizontal deformations (lateral and longitudinal) shall be calculated including wind loading, lateral and centrifugal forces, the effects of global temperature range, and temperature differentials (including those between the two sides of the Bridge), using partial load factors for all loads of 1.0. Unless otherwise stated, the limiting values for deformation are for the total deformation of the Bridge calculated along each track. For vertical deformation, this comprises deformations of the main girders, bearings, cross-girders, rail bearers or deck slabs. For horizontal (longitudinal and transverse) deformations, this comprises deformation of the Bridge and the substructure. All Bridges shall be designed so that the deformations under load do not encroach on the required vertical and horizontal clearances, and do not compromise the safety of the Bridge or railway. Clearance checks shall include, for example, the situation where an Underline Bridge is adjacent to an independently supported platform. Requirements for the application of railway loads are given in Appendix C. The numbers of tracks to be loaded for the calculation of deformations and vibration, and the reduction in loading where more than two tracks are loaded, are identified in Table 1 in Appendix C. Bridge spans greater than 12 m shall preferably be cambered to improve their appearance. Camber shall generally be equal to the dead load deflection plus half the serviceability live load deflection. For a multi-span or skew Bridge with constant-depth main girders, the levels of the bearings shall generally be such that all parts of the main girder soffits lie in a continuous circular curve when viewed in elevation, square to the girders. Page 50 of 109

106 8.2 Natural frequency check for applicability of dynamic factors The natural frequency of the Bridge under dead and superimposed dead loads shall be checked to ensure it is within limits for which the dynamic factors given in BS : 2006 are valid. The frequency limits shall be as identified in Appendix C item (vii); the Appendix also identifies requirements for carrying out a dynamic analysis and additional fatigue checks in cases where the frequency is permitted by Network Rail to be outside these limits. 8.3 Deformations due to railway loading The live loading to be taken into account for calculating deformations shall include vertical loading enhanced by dynamic factors, centrifugal loads, nosing loads, and longitudinal loads due to traction and braking. For ballasted decks, effects such as creep and settlement of foundations may be assumed to be addressed by track maintenance Vertical deformation of the deck For all Bridges, the maximum midspan deflection due to railway loading shall not exceed span/600. Additional vertical deformation requirements for passenger comfort are given in Track twist (for traffic safety) The twist of the Bridge shall be calculated taking into account RU loading, and SW/0 where applicable, multiplied by the dynamic factor, including centrifugal effects. Track twist shall be checked on the approach to, across, and on the departure from the Bridge. Limits on track twist shall be as identified in BS EN 1990: 2002 Eurocode Basis of structural design Annex A2: Application for bridges Clauses A (3) for track twist due to permanent loads and track geometry, plus the twist due to live loads, where the value of t T shall be 7.5 mm over 3 m. The requirements of A (2) shall not apply. In cases of Bridge superstructure reconstruction, where it is not reasonably practicable to comply with the twist criteria identified above, Network Rail s Professional Head of Structures shall be advised early during the Design process, and subsequently any non-compliance shall be identified and justified in the AIP Submission. Page 51 of 109

107 In all cases, the twist (cant gradient) along a 3 m length of the track due to the loading on the Bridge in conjunction with the designed track geometry including any intended rate of change of cant, shall not exceed 1 in 400 (i.e. 7.5 mm) under the intended and foreseeable Real Train vehicles that will cross the Bridge, which shall be represented by the equivalent number of British Standard Units (BSUs) and enhanced by the dynamic factors for Real Trains (1+ φ I + φ II ) identified in NR/L3/CIV/025: The structural Assessment of underbridges Uplift at bearings Unrestrained uplift at bearings shall not be permitted. Restraints to prevent uplift at bearings will only be permitted in exceptional circumstances and shall require advance approval from Network Rail s Professional Head of Structures prior to AIP Submission, and the Design of the bearings and restraint shall be subject to Category III checking. Additional requirements for bearings are given in Limits on the rotational uplift at the ends of decks (beyond the line of the bearings) are given in Combined response of structure and track Track-Bridge interaction The Design shall take into account the interaction effects of the Bridge on the track, and vice versa, in response to variable loads including vertical loading from trains, and traction, braking and temperature effects. Consideration shall be given to the effects on the Bridge caused by longitudinal forces arising from train traction and braking, and from temperature variations, taking into account deformations of the Bridge superstructure, bearings and substructure. Consideration shall be given to the effects of Bridge deformation and temperature, traction and braking effects, on the track (whether approaching, on, or departing from the Bridge) including track welds, switch blades and expansion switch blades. Subject to satisfying the requirements of and 8.4.5, in the following cases other track-bridge interaction effects may be deemed to be covered by the loading specified in 9: Bridge with a total length up to 75 m, but subject to single span lengths not exceeding 50 m, and carrying ballasted or Page 52 of 109

108 non-ballasted continuous welded rail (CWR) track with adjustment switches provided where required by NR/SP/TRK/102: Track construction standards, Bridge comprising a single simply supported span up to 30 m expansion length, carrying ballasted CWR track without adjustment switches, two-span simply-supported or continuous Bridge with each span up to 30 m expansion length, carrying ballasted CWR track without adjustment switches, provided that the fixed point for expansion is at the intermediate support, single-span Bridge up to 15 m expansion length, carrying non-ballasted CWR track without expansion switches, two-span simply-supported or continuous Bridge with each span up to 15 m expansion length, carrying non-ballasted CWR track without adjustment switches, provided that the fixed point for expansion is at the intermediate support, all Bridges carrying jointed track; however, the rail joints shall be kept clear of the Bridge as set out in NR/SP/TRK/102. In other cases, track-bridge interaction effects shall be checked in accordance with BS EN : 2003: Eurocode 1: Actions on structures Part 2: Traffic loads on bridges Clause 6.5.4, wherein the limiting values and requirements in Clauses (1), (2) and (3) shall apply subject to the requirements of and References to alternatives and to the National Annex shall require the agreement of Network Rail s Professional Head of Structures Longitudinal displacement of the end of the deck Where required by the effects of the longitudinal displacement of the end of the deck on the track shall be checked. The longitudinal relative displacement at the end of a deck due to traction and braking (δb) shall not exceed the values given in BS EN Clause (1). The longitudinal relative displacement at the end of a deck due to deformation of the deck (δh) shall not exceed the values given in BS EN Clause (2) Stresses in rails Where required to be checked by 8.4.1, the stresses in the rails on the Bridge and abutment due to track-bridge interaction shall comply with the requirements of BS EN : 2003: Eurocode 1: Actions on structures Part 2 Traffic loads on bridges Clauses Page 53 of 109

109 (1) and (2), within which the relevant authority or specifier for individual projects shall be deemed to be Network Rail s Professional Head of Structures Uplift at the end of the deck The vertical relative displacement (δv) of the upper surface at the end of a deck beyond the bearings, caused by deflection in the span due to variable actions, relative to the adjacent construction (i.e. abutment or another deck), shall not exceed the values given in BS EN Clause (3) subject to the value not exceeding 2mm for any line speed Rotations and uplift forces on directly fastened rails For directly fastened rails, the stresses in rails, supports and fastening systems due to rotations and uplift forces at the ends of the deck (under vertical traffic loads) shall be checked against the relevant limit state (including fatigue) performance characteristics of the rails, supports and fastening systems. 8.5 Transverse deformation and vibration of the deck Transverse deformation and vibration of the deck shall comply with the requirements identified in BS EN 1990: 2002 Eurocode Basis of structural design Annex A2: Application for bridges Clause A and the following, unless other requirements are specified by Network Rail for the individual project. The recommended values given in the Notes to A (2) and (3) shall apply. 8.6 Vertical deflection at midspan (for passenger comfort) Subject to the span/600 limit identified for all Bridges in 8.3.1, vertical deflections due to railway loading shall comply with the requirements of BS EN 1990: 2002 Clauses A and A ; and with A where applicable. The required levels of comfort, and associated vertical accelerations, given in Table A2.9 of BS EN 1990: 2002 shall be as follows, unless other requirements are specified by Network Rail for the individual project: Very good shall be applied to Bridges on a primary route or with a line speed of 90mph (145 kph) or more, Good shall be applied to all other Bridges. For a temporary Bridge, the above requirements may be relaxed to Good and Acceptable respectively. Where a vehicle/bridge dynamic interaction analysis is required for checking passenger comfort in accordance with A , proposals for Page 54 of 109

110 taking track roughness into account shall be submitted to Network Rail s Professional Head of Structures for acceptance. 8.7 Fatigue requirements for Underline Bridges The Design for fatigue shall comply with the standards identified in Loading requirements for fatigue are identified in Loading 9.1 General requirements for loading Adequate provision for all likely and reasonably foreseeable permanent, transient and accidental loads and load effects shall be taken into account in the Design of a Bridge. The Design shall also consider the partial or complete removal of loads that are not permanent, where this produces a more severe effect; for example the removal of tracks and their ballast on a multi-track structure. Unless otherwise stated, the loads identified in this standard are the characteristic or nominal loads. For both the ultimate and serviceability limit states these loads shall be factored (for beneficial or adverse effects) using the load factors and load combinations referred to in the relevant Design standards in 10, with the most severe effect on each element of the structure being considered. In all cases, the loads used in the Design shall be identified in the AIP Submission, and justified where the relevant values are not prescribed by this standard or referenced standards. Where partial load factors and relevant load combinations are not prescribed in the Design standards, details shall be identified in the AIP Submission. Where a Bridge is to be brought into use in stages, relevant loads shall be considered as applicable at each stage. Loads that arise during intermediate stages, but which do not necessarily apply to the finally completed structure, shall be identified in the AIP Submission. 9.2 Loading for new and replacement Underline Bridges Railway loads for Underline Bridges Bridges carrying railway traffic of standard gauge shall be designed for full Type RU Loading in accordance with BS 5400: Steel, concrete and composite bridges Part 2: 2006: Specification for Loads, as added to and amended by the requirements of this standard, and by Appendix C which identifies additional requirements including those for the application of loading. Page 55 of 109

111 Continuous beams shall also be checked for Type SW/0 Loading as identified in In exceptional cases, provided that safety and Interworking are not adversely affected, a loading lighter than full Type RU may be permitted, which shall be defined by multiplying the Type RU Loading by a load classification factor α. The load classification factor α to be applied to the full Type RU Loading shall not be less than In such cases, the loading shall take into account the traffic that will be permitted to use the Bridge, any foreseeable changes in the permitted loading (e.g. prospective different types of trains), any site specific hazards and any control measures required to prevent overloading of the Bridge. The loading adopted must satisfy Network Rail s statutory and contractual obligations and not preclude future interworking. The provision also exists for adopting a heavier loading than full Type RU on particular sections of the railway, which shall be identified by Network Rail in the Remit, by applying a load classification factor α greater than 1.0. Justification for the use of a load classification factor α which is less than 1.0, for loading other than full Type RU Loading, shall be subject to approval from Network Rail s Professional Head of Structures at an early stage and shall be recorded in the AIP Submission. Where a load classification factor α is applied to RU loading, the same value of α shall be applied to the following (also see Appendix C): SW/0 loading, concentrated loads on deck plates and similar elements (except α shall not less than 1.0), centrifugal loads, nosing forces, longitudinal loads (traction and braking) and derailment loads. Where 3 or more tracks on a Bridge are loaded, the loads from trains shall be multiplied by Note that this is not the load classification factor α. The Design shall be able to accommodate the loading from the latest generation of railway mounted cranes, as identified in Appendix C. Page 56 of 109

112 Where the Bridge is to carry a single line track, the Designer shall consult with Network Rail on the requirements for accommodating track renewal plant (e.g. single line track relaying gantries). Requirements for complying with the Trans European Technical Specifications for Interoperability (TSI) relating to infrastructure (High Speed and Conventional Rail), where applicable, are given in and Appendix G. It is anticipated that the future Trans European Conventional Rail Technical Specification for Interoperability (CR TSI) for infrastructure will specify minimum requirements for applying a load classification factor α and these shall be applied when the CR TSI has been published. Other loads are identified in sub-clauses of 9.2 and in 9.3 to Dynamic effects for Underline Bridges Appropriate dynamic factors shall be applied to the equivalent static loading to allow for impact, oscillation and other dynamic effects including those caused by track and wheel irregularities. Requirements, and modifications for the application of dynamic effects from BS 5400: Steel, concrete and composite bridges Part 2: 2006: Specification for Loads, are identified in Appendix C Fatigue loads for Underline Bridges Loads for fatigue shall be as required by the relevant standards identified in The fatigue life shall be 120 years unless otherwise approved via the AIP Submission. In all cases an appropriate traffic mix for fatigue shall be established taking account of the design life of the structure, the proposed rail traffic, and any reasonably foreseeable changes to the rail traffic using the structure. The design speed, total annual tonnage per track and design traffic mix shall be as specified by Network Rail in the Remit for the particular Bridge Additional loads for direct fastening and embedded rails The following additional requirements shall apply to unballasted decks where the rails are directly fastened or embedded, other than rails attached to longitudinal timbers. A single static vertical Design load of 600 kn shall be applied directly to the parts of the structure that support the rail. This load shall be considered at the Ultimate Limit State only. The load includes the partial load factor γfl, dynamic and lurching effects, and is not to be considered in fatigue checks. Page 57 of 109

113 The single 600 kn load shall be applied as follows. To members to which the rail is directly fastened or embedded. Welds inside troughs which are covered by the embedding material shall be ignored at the ultimate limit state and the outer welds shall be designed to carry the 600 kn load. To members which directly support the trough, e.g. rail bearers, slab, etc. In all cases, stresses in the rail shall not exceed the limits referenced in The 600 kn load shall not be applied to other parts of the Bridge. As an alternative to the above loading, a special dynamic analysis may be undertaken, in accordance with the requirements of Network Rail s Professional Head of Structures, to investigate the particular wheel / rail / bridge dynamic interaction effects and establish a Bridge specific design load. The dynamic analysis and Bridge specific design load shall be subject to acceptance by Network Rail Additional loading for continuous beams in Underline Bridges Continuous beams in Underline Bridges shall be designed for Type RU Loading and shall also be checked for Type SW/0 Loading defined in BS 5400: Steel, concrete and composite bridges Part 2: 2006: Specification for Loads. SW/0 loading shall be applied in accordance with Appendix C and this Clause. Type SW/0 Loading need only be applied to continuous members, and shall not be applied in conjunction with Type RU Loading on the same track. Type SW/0 or RU Loading shall also be applied to other tracks where this produces a worse effect. The SW/0 Loading does not have to be considered in any fatigue check. Deformation limits are identified in Walkway loading for Underline Bridges Where an Underline Bridge supports a footway and / or cycle track open to the public, the footway/cycle track loading shall be in accordance with BS 5400: Steel, concrete and composite bridges Part 2: 2006: Specification for Loads. Page 58 of 109

114 Where an Underline Bridge supports a service walkway which is not open to the public, the walkway loading shall be 5 kn/m 2. For local elements a concentrated load of 2 kn acting alone shall be taken into account and applied on a square with a 200 mm side (not the 100 mm diameter circle from Clause 20 of GC/RC5510: Recommendations for the Design of Bridges), or a point load of 100 kn if more onerous Parapet and handrailing loads for Underline Bridges Loads from parapets and handrailing shall be in accordance with the applicable standards and requirements identified in and Appendix E Accidental (derailment) loads for Underline Bridges An Underline Bridge shall be designed for derailment loads in accordance with BS 5400: Steel, concrete and composite bridges Part 2: 2006: Specification for Loads, to be modified and applied as identified in Appendix C item (iii), so that it does not suffer excessive damage, or become unstable in the event of derailment. Robust kerbs provided in accordance with 7.7 to contain derailed vehicles, or girders which perform this function, shall be designed for horizontal derailment loads, which shall be identified in the AIP Submission. Guidance may be obtained from Clause 19.1 in Railway Approved Code of Practice GC/RC5510: Recommendations for the Design of Bridges Accidental loads for Underline Bridges over highways Supports to a Bridge over a highway (whether less or greater than 4.5 m clearance from the edge of the carriageway), and a Bridge with a headroom clearance of less than 5.7 m, shall be designed and protected for the effects of impact from road traffic in accordance with Highways Agency Standard BD 60/04: The Design of Highway Bridges for Vehicle Collision Loads, and as identified in Accidental loads for Underline Bridges over waterways Consideration shall be given to the risk of a waterborne vessel impacting on the spans or supports of a Bridge spanning over navigable water. The Bridge shall be designed for appropriate effects. This may require a specialist study. Consideration may be given to guidance in BS EN : Eurocode 1: Actions on structures - Part 1-7: 2006: General actions Accidental actions and in the AASHTO: Bridge Design Specifications. Page 59 of 109

115 The provision of fenders or other protection shall be considered. The risks of a ship using spans other than designated navigation spans, together with any physical protection that is to be provided, shall be taken into account. Impact loads shall be determined as appropriate to the navigation under the particular Bridge, and shall be related to the clearance and justified in the AIP Submission. 9.3 Loading for strengthening, alteration or repair of Underline Bridges Loading for the strengthening, alteration or repair of an Underline Bridge shall be in accordance with 9.1, 9.2 (excluding 9.2.1, and 9.2.5), 9.3, 9.6 and 9.7 as applicable in conjunction with the following modifications. Where safety and Interworking are not adversely affected, strengthening, alteration or repairs may be designed to carry a lesser loading than that identified in and In such cases the load capacity of the Bridge shall meet the published RA at the linespeed for the Bridge and the RA of traffic permitted to use the bridge. In such cases, the loading shall take into account the traffic that will be permitted to use the Bridge, any foreseeable changes in the permitted loading (e.g. prospective different types of trains including RA7 for loco hauled traffic), any site specific hazards and any control measures required to prevent overloading of the Bridge. The loading adopted must satisfy Network Rail s statutory and contractual obligations. The intended loading shall be justified in the AIP Submission. Generally the strengthening shall also be designed to meet RA 10 at 60mph (or at linespeed where the linespeed is less than 60mph) Any lesser loading shall be subject to the approval of Network Rail s Professional Head of Structures. The loading may be derived from Network Rail Code of Practice NR/L3/CIV/025: The Structural Assessment of Underbridges. The loading shall not be less than the number of British Standard Units (BSUs) equivalent to the published Route Availability (RA) number, increased by 10% and at the permissible speed at the Bridge, subject to 20 BSU (equivalent to RA 10) being limited to 60 mph maximum. For example, the loading shall be the more onerous of 1.1 x (18 BSU at 90mph) or 1.1 x (20 BSU at 60mph), as applicable to the Bridge. Allowance for dynamic effects shall be in accordance with NR/L3/CIV/025. The design fatigue life of strengthened parts shall be 30 years. Page 60 of 109

116 In cases where it is not reasonably practicable to achieve the 10% increase identified above on the loading from NR/L3/CIV/025, justification for not providing the 10% increase shall be included in the AIP Submission. Where NR/L3/CIV/025 would otherwise permit a 75% factor to be applied to the loading on the second and subsequent tracks as identified in Clause 4.3.8, no such reduction shall be permitted in the Design and this shall clearly be stated in the AIP Submission. Where NR/L3/CIV/025 would otherwise permit γ fl load factors to be reduced no such reduction shall be permitted in the Design; where a range of values is provided for any γ fl load factor the maximum value shall be used; and γ f3 shall not be reduced. Justification for the use of NR/L3/CIV/025, and relevant details of the loading and associated γ fl load factors, shall be recorded in the AIP Submission. Consideration shall be given to using a greater loading for the Design to comply with any planned enhancement of the route to meet the route strategy. 9.4 Loading for new and replacement Overline Bridges and footbridges Highway vehicle loads for new and replacement Overline Bridges A Bridge that carries highway traffic shall be designed for full HA type loading in accordance with BS 5400: Steel, concrete and composite bridges Part 2: 2006: Specification for Loads. In addition, for a public highway Bridge, the number of units of HB loading required to be carried and any requirements for abnormal indivisible loads shall be determined in conjunction with the appropriate Highway Authority. Fatigue checks shall comply with BS 5400: Steel, concrete and composite bridges Part 10: Code of practice for fatigue, as implemented by An Occupation or Accommodation Bridge shall normally be designed for not less than HA and 30 Units of HB loading in accordance with BS :2006. Network Rail shall identify requirements in the Remit where more than HA and 30 Units of HB is required. Where the capacity of a new or replacement Bridge exceeds Network Rail s legal obligation, the Designer shall check with Network Rail s Infrastructure Liability Manager whether load restriction plates are to be provided on the Bridge. Page 61 of 109

117 In exceptional cases, a lesser load than that specified in BS :2006 may be permitted by Network Rail for an Occupation or Accommodation Bridge as long as safety is not adversely affected and all other legal obligations are met. In such cases, the loading shall take into account the traffic that will be permitted to use the Bridge, any site specific hazards and any control measures required to prevent overloading of the Bridge. The loading for Design shall be as great as reasonably practicable, but not less than 7.5 tonne Gross Vehicle Weight, and shall correspond to one of the levels of loading given in Chapter 5 of Highways Agency Standard BD 21/01: The Assessment of Highway Bridges and Structures. Any loading for Design less than full HA loading shall be justified in the AIP Submission and shall be subject to approval of Network Rail s Professional Head of Structures. The justification shall take into account the following: the implications of providing for full HA loading (such as, for example, if a Bridge superstructure is to be reconstructed but to provide for full HA loading would also require the substructure to be renewed), the likelihood of the Bridge being used by heavy vehicles during its service life (taking into account both existing and anticipated future traffic). Any consequential requirements (arising from adopting loading less than HA) that are to be incorporated into the Design shall be identified in the AIP Submission, e.g. the requirement for the erection of weight restriction plates or barriers, etc. Other loads are identified in to and Pedestrian, cycle and equestrian loads For footbridges and other Bridges that support a footway and/or a cycle track open to the public, the loading shall be in accordance with the requirements of BS 5400: Steel, concrete and composite bridges Part 2: 2006: Specification for Loads. For a Bridge subject to equestrian use, local elements shall be subject to a vertical live load of 20 kn, acting alone without other uniformly distributed live loading, applied on a square of 200 mm side. This loading includes dynamic factors. For loaded lengths in excess of 36 m where crowd loading is likely to occur, e.g. on Bridges near major public venues, the pedestrian loading given in BS :2006 shall be increased to a value to be agreed with Network Rail s Professional Head of Structures and shall be identified in the AIP Submission. Page 62 of 109

118 Where a Bridge is designed to carry pedestrian or cycle traffic only, suitable physical means shall be provided to prevent the Bridge being used by vehicular traffic which could affect the safety of the Bridge or the railway, e.g. the installation of bollards, barriers, etc., which shall be identified in the AIP Submission Parapets, safety barriers and handrailing for Overline Bridges Loads on, and the effects from, parapets, safety barriers and handrailing shall be in accordance with the requirements in 7.9 and 7.9.1, Highways Agency standard TD 19/06: Requirements for Road Restraint Systems, BS 5400: Steel, concrete and composite bridges Part 2: 2006: Specification for Loads, and the following, as applicable. Metal pedestrian parapets shall not be less than Class 3 in accordance with BS 7818: Specification for pedestrian restraint systems in metal. In situations where more severe loading may be applicable, requirements shall be agreed with Network Rail s Professional Head of Structures. The Class of the parapet, and the loading if more severe than Class 3, shall be identified in the AIP Submission. For a Bridge subject to equestrian use, parapets shall also be subject to a load of 10 kn applied over a 300 mm length at the top of the parapet, in addition to other live load effects Accidental (derailment) loading on Overline Bridge supports Supports to an Overline Bridge shall be positioned at least 4.5m from the nearest running rail. Where this is not reasonably practicable, the supports shall be designed so that: they can withstand the effects of light impacts from derailed coaches or freight wagons, without sustaining irreparable damage, a progressive collapse of the superstructure will not occur as a result of a loss of a single support. Recommendations for dealing with collision loads from railway traffic are given in Appendix D. 9.5 Loading for strengthening, alteration or repair of Overline Bridges Loading for strengthening, alteration or repair of an Overline Bridge shall be in accordance with 9.1, 9.4 and 9.6, as applicable. Page 63 of 109

119 However, in exceptional cases subject to the approval of Network Rail s Professional Head of Structures and where safety is not adversely affected, strengthening, alteration or repairs may be designed to carry a lesser loading than that identified in the preceding paragraph, provided that the existing load capacity of the Bridge is not reduced. In such cases, the loading shall take into account the traffic that will be permitted to use the Bridge, any site specific hazards and any control measures required to prevent overloading of the Bridge. Justification for the use of a lesser loading shall be recorded in the AIP Submission and shall be subject to approval from Network Rail s Professional Head of Structures. 9.6 Other loads and effects for Underline, Overline and other Bridges Loads to be considered Except where modified by this standard, a Bridge shall generally be designed for all other applicable loads and load effects in accordance with BS 5400: Steel, concrete and composite bridges Part 2: 2006: Specification for Loads and this standard, or as otherwise specified by Network Rail, including superimposed dead load, wind, temperature, differential settlement, earth pressure, erection, and secondary live loads. The loads and load effects of the following shall also be considered: dynamic effects (9.2.2), effects of repeated loading (fatigue, 9.2.3, and 10.2), concentrated loading on deck plates and local elements (Appendix C), application of loading to multi-track Bridges (Appendix C), traction and braking forces, lurching forces (deemed in BS : 2006 to be taken into account by the specified dynamic factors), nosing forces (Appendix C), centrifugal forces (Appendix C), skidding forces (road traffic only), deformations, including track twist (8), aerodynamic and slipstream effects from passing trains (9.6.2), effects of track / Bridge interaction (8), deck acceleration and resonance effects (8), Page 64 of 109

120 hydrodynamic effects (9.6.3), load effects from overhead line electrification equipment attached to the Bridge, including accidental loads arising from breakage of catenaries, and load effects from other railway infrastructure and equipment, load effects from noise barriers which are attached to the Bridge. In addition to the self weight and permanent loads, consideration shall be given to superimposed dead loads, equipment loads, variations in ballast depth where appropriate), and the effects of internal forces (e.g. pre-stressing and creep). Other site specific loads shall be considered, including: live load surcharge and soil pressures (9.7), settlement, including the effects of mining subsidence and differential settlement (10.5), water pressures, including those from exceptional flows, storm and flooding, scour, and waterborne debris (10.5), erection, construction and maintenance activities, environmental influences (e.g. wind, temperature variations and temperature gradients), bearing friction, effects due to inclined decks or inclined bearing surfaces, longitudinal anchorage forces from stressing or destressing rails, which shall be taken as 600 kn nominal load per rail, applied to one track only (i.e. 2 rails, 1200 kn total) and at minimum Bridge temperature, longitudinal forces due to breakage of rails, which shall be taken as 600 kn nominal load applied to one rail only. Accidental loads and load effects shall be considered, including: impact from train derailments, both on and beneath a Bridge (9.2.8 and 9.4.4), impact from errant road vehicles, both on and beneath a Bridge (9.2.9), impact from vessels beneath a Bridge over a navigable waterway (9.2.10), Page 65 of 109

121 other accidental loads and load effects, such as those due to soil settlement (10.5), may need to be considered at particular sites. Where a Bridge is required to carry types of road, vehicular traffic or other traffic loads other than as identified in this standard, the loading shall be agreed with the relevant authority and Network Rail, and shall meet the Principles of this standard (5), and shall be justified in the AIP Submission. The Design shall take into account the effects of temperature variations, and shall ensure that the possibility of brittle fractures is avoided. Due allowance shall be made for the forces generated by, or movements required for, thermal expansion, thermal contraction, and differential temperatures, in individual elements and the structure as a whole, including the substructure. The Bridge shall be able to withstand the required wind loading, including the effects on bearings and substructures. The Design of structures that are susceptible to wind induced vibration shall take into account the consequential effects including fatigue in accordance with BS 5400: Steel, concrete and composite bridges Part 10: Code of practice for fatigue as identified in The Design of an Underline Bridge shall assume that unrestricted rail traffic may be present during any high wind conditions. This requirement shall also override any less onerous requirements for wind loading in combinations of live load and wind that may be provided for in Eurocodes or any other Design standards Aerodynamic effects Aerodynamic effects due to passing rail traffic shall be considered where this is likely to have a significant effect on a Bridge or its secondary components, such as: a footbridge, a Bridge supporting a station canopy or similar structure, parapets of an Underline Bridge, cladding panels attached to the Bridge, noise barriers attached to the Bridge. Structures susceptible to the aerodynamic effects of passing trains shall be designed to resist the resultant aerodynamic forces. Structures that are particularly sensitive to transient pressure fluctuations may required a special study to consider their dynamic Page 66 of 109

122 performance when subject to the aerodynamic effects of passing trains. Guidance may be obtained from BS EN : 2003: Eurocode 1: Actions on structures Part 2: Traffic loads on bridges (which replaced ENV : 1995), and pending publication of the National Annex to BS EN : 2003 further guidance may be obtained from the UK National Application Document for ENV : It is anticipated that the National Annex to BS EN will permit the loading to be determined for the individual project and in this case the requirements of UK National Application Document for ENV : 1995 shall apply Bridges over watercourses For a Bridge over a watercourse, hydrodynamic effects and the effects of water scour shall be considered where the structure may be affected. Where scour may occur, the foundations shall be designed to resist the scour or shall be adequately protected. The Design shall be based on a 1 in 200 year return period. The sensitivity of the Bridge shall be checked for a 20% increase in the flow to allow for climate change; the structure shall not suffer catastrophic damage or total loss, but local damage is acceptable. Consideration shall be given to the effects from waterborne debris striking the Bridge. For a Bridge over a navigable waterway, also see Loading for substructures The Design shall take into account all static and transient loads that will be applied, including any long-term increases in lateral earth pressures which are imposed on the substructure. The minimum traffic surcharge loading to be applied to a substructure shall be as follows. For highway traffic, surcharge loads taken in accordance with BS 5400: Steel, concrete and composite bridges Part 2: 2006: Specification for Loads. For railway traffic, a surcharge loading for each track taken as a nominal uniformly distributed load of 50 kn/m 2, uniformly spread over a width of 2.6 m applied symmetrically about the track centreline acting at the level of the underside of the sleepers (subject to particular increases identified below). This Page 67 of 109

123 may be deemed to include for dynamic effects and for centrifugal and other secondary loading effects. Ref: NR/L2/CIV/020 For the design of a ballast wall at the top of an abutment, the above railway traffic surcharge loading shall be increased to 60 kn/m 2, uniformly spread over a width of 2.6 m as above. The resulting strength requirements shall be provided across the full width of the ballast wall so as not to restrict future re-positioning of the tracks. For the upper part of a side wall where the face parallel to the track is within 0.5 m from the ends of sleepers and within 1.0 m below the underside of the sleepers, the above railway traffic surcharge loading shall be increased to 60 kn/m 2 uniformly spread over a width of 2.6 m as above. Where applicable, allowance shall be made for likely future developments such as significant track lift, significant track realignment or the laying of additional tracks. For the Design of a local element close to the track (e.g. ballast wall), account shall be taken of the maximum vertical, longitudinal and transverse loading due to rail traffic. A nominal 10 kn/m 2 surcharge loading (to be regarded as a superimposed dead load) shall be applied to part or all of the plan projected area of a substructure, other than plan areas occupied by railway or highway surcharge loading specified above. This shall be applied to give the most unfavourable effect to the element under consideration, and shall not be applied where its absence is more onerous. If, in exceptional cases, it is considered that values for the design traffic / surcharge loading lower than those given above are applicable, the proposed values shall be identified and justified in the AIP Submission. For piers, columns and similar substructure elements, the dynamic factor for railway loading may be taken as 1.0 where the slenderness ratio L/r of the element is less than or equal to 30 (where L is the element s effective length and r is its radius of gyration). The full dynamic factor shall be applied to crossheads and similar structural forms. 10 Design standards 10.1 General A Bridge shall be designed in accordance with statutory requirements, Railway Group Standards, Network Rail Standards, European and British Standards, relevant industry standards and industry good practice. Page 68 of 109

124 Where a Design standard is mandated in this standard, that Design standard shall be used and shall take precedence over others, unless otherwise justified in the AIP Submission and subject to the approval of Network Rail s Professional Head of Structures. Eurocodes may be used in place of British Standards mandated in this standard, providing the Design requirements are equivalent to the mandated standards and the use of the substitute Eurocodes is justified in the AIP Submission. Designs shall be undertaken using limit state principles, unless there are no applicable standards using these principles, in which case alternative standards and Design principles shall be identified and justified in the AIP Submission. So far as is reasonably practicable, a set of consistent and compatible standards shall be used, covering loading, Design, execution (construction) and material / workmanship specifications. Where it is unavoidable to use standards which are not necessarily compatible, such as a mix of British Standards and European Standards (other than as required by this standard), any incompatibilities arising between the standards shall be identified in the AIP Submission, with proposals for resolving the incompatibilities. Where European Standards are used, EN versions shall only be used in conjunction with the UK National Annexes, unless otherwise specified in this standard, or otherwise justified in the AIP Submission. Standards to be used for the Design shall be identified in the AIP Submission Steel, concrete, composite and masonry Bridges Steel, concrete, and steel / concrete composite Bridges (and parts of Bridges) shall be designed in accordance with the applicable parts of BS 5400: Steel, Concrete and Composite Bridges, unless indicated to the contrary by this standard. The following modifications shall be adopted: Part 1: 1988: General statement (without modification). Part 2: 2006: Specification for loads. This shall be subject to the requirements of 8, 9 and amended by Appendix C of this standard. Part 3: 2000: Code of practice for design of steel bridges (without modification). Part 4: 1990: Code of practice for design of concrete bridges. This shall be as amended by Appendix B of this standard. Page 69 of 109

125 Part 5: 2005: Code of practice for design of composite bridges. This shall be as amended by Appendix B of this standard. Part 9: 1983: Bridge bearings. This shall be as implemented by Highways Agency Standard BD 20/92: Bridge Bearings, use of BS 5400: Part 9: 1983, subject to the requirements and provisions of Part 10: 1980: Code of practice for fatigue. This shall be as implemented by Highways Agency Standard BD 9/81: Implementation of BS 5400: Part 10: 1980 Code of practice for fatigue, subject to the following requirements. Highways Agency Standard BD 9/81 refers to advice on the use of BS 5400 Part 10 given in the complementary Highways Agency Advice Note BA 9/81: The Use of BS 5400: Part 10: 1980 Code of Practice for Fatigue. The reduction in fatigue life recommended in Clause 4.2 of BA 9/81 shall not apply to the Design of a Bridge which is not subject to acceptance by the Highways Agency or highway authority. A masonry Bridge (or part of a Bridge), shall be designed in accordance with BS 5628: Code of practice for use of masonry Timber Bridges A timber Bridge (or part of a Bridge) shall be designed in accordance with the applicable Parts of BS 5268: Structural Use of Timber. Provision shall be made for the following, which shall be recorded in the AIP Submission: the methods for using loads, that are based on limit state terms, in design methods that are based on permissible stress, the effects of repeated application of live loading, the weather exposure conditions of the Bridge and the anticipated examination and assessment regimes Bridges constructed from other materials A Bridge (or part of a Bridge), constructed from a material other than those listed in 10.2 and 10.3, shall be designed in accordance with recognised national, industry or other standards, which shall be identified in the AIP Submission. Where no such standards currently exist, the Design methodology shall be justified and recorded in the AIP Submission. The use of such other materials in the Design of Bridges shall be subject to the approval of Network Rail s Professional Head of Structures prior to submission of the AIP (see 6.4). Page 70 of 109

126 10.5 Foundations for new Bridges Foundations for a new Bridge shall be designed in accordance with BS 8004: Code of practice for foundations, and the applicable requirements of NR/L2/CIV/071: Design of earthworks, earthwork remediations and geotechnical aspects of foundations for structures. Global factors of safety, for use with Moderately Conservative soil parameters as identified in NR/L2/CIV/071, shall not be less than the following unless otherwise justified in the AIP Submission: Bearing capacity: > 3 Sliding: > 2 (ignoring passive pressure in front of walls) Overturning: > 2 (ignoring passive pressure in front of walls) Overall stability: as identified in Clause in NR/L2/CIV/071. The factors of safety to be used in the Design, and the allowable ground bearing pressures and associated factors of safety used to determine the pressures, shall be identified in the AIP Submission. Additional guidance may be obtained from Highways Agency Standard BD 74/00: Foundations. Restrictions on the use of certain types of foundations or structural forms are given in Appendix L. Consideration shall be given to the effects on the Bridge and the track due to settlement or other movement of the foundations, including differential settlement between supports and along a support or foundation tilt, and the effects of subsidence arising from mineral extraction (see 10.8). The effects on the track adjacent to the ends of the Bridge shall also be considered. Movement of the foundations or deflection of the structure shall not cause any part of the Bridge to encroach on the required clearances or compromise safety or performance of the Bridge, railway or supported equipment. Consideration shall be given to the risk of flooding and scour, and their consequences on substructures, foundations and earthworks associated with the Bridge, including where the Bridge is located in the flood plain of a watercourse. Additional requirements for Bridges over watercourses are given in Page 71 of 109

127 10.6 Earth retaining elements Earth retaining abutments, retaining or wing walls that are integral with the abutment, and retaining walls adjacent to the Bridge, shall be designed in accordance with this standard and BS 8002: Code of practice for earth retaining structures. Additional guidance may be obtained from Highways Agency Standard BD 30/87: Backfilled Retaining Walls and Bridge Abutments. For the Design of embedded retaining walls and Bridge abutments, additional guidance may be obtained from Highways Agency Standard BD 42/00: Design of Embedded Retaining Walls and Bridge Abutments. The basis of Design for earth retaining elements including whether global or partial factors of safety are to be used, and their values, shall be identified in the AIP Submission. Where global factors of safety are used these shall comply with Where partial factors are used, any other associated partial factors (e.g. for loading) shall be identified in the AIP Submission. Where applicable, the standards adopted for the design of the Bridge shall be used for the Design of earth retaining elements that are integral with the Bridge Existing substructures affected by new construction Where only the superstructure of an existing Bridge is to be reconstructed, or in other cases where new construction is associated with the total or partial retention of an existing substructure, the following shall apply: the remaining part of an existing substructure need not be deemed unacceptable for continuing service solely because it does not comply with the criteria applicable to a new structure, the soil supporting an existing substructure need not be deemed unacceptably loaded solely because the Design loading will be higher than the loading considered acceptable for the same soil supporting a new structure. Further guidance on the treatment of existing substructures affected by new construction is given in Appendix F. In all cases, due consideration shall be given to the condition and anticipated future deterioration of any existing substructure before it is considered acceptable to be retained. 4 For example, concrete elements shall be designed using BS 5400 Part 4, and not BS 8110 Part 1. Page 72 of 109

128 10.8 Site investigation and geotechnical Design The Design shall take into account the ground conditions in the locality of the Bridge and its foundations, and shall comply with the applicable requirements of BS 8004: Code of practice for foundations. Where there is insufficient existing site investigation or geotechnical data information available to carry out the geotechnical Design, a site investigation appropriate to the size, depth, structural configuration and loading of foundations, geotechnical complexity, likely level of soil and ground water contamination and location of the Bridge shall be carried out. The Design shall take into account the requirements of NR/L2/CIV/071: Design of earthworks, earthwork remediations and geotechnical aspects of foundations for structures applicable to the Bridge, including: site investigation, contaminated land investigation, derivation of geotechnical parameters, interaction of the Bridge and adjacent ground, slope stability. Where the Bridge may be affected by mineral extraction or landfill, Network Rail s Mining Engineer shall be consulted in accordance with NR/L2/CIV/037: Managing the risk arising from mineral extraction and Landfill Specifications for materials and workmanship Specifications for materials and workmanship shall be considered to be part of the Design and shall be prepared in accordance with the requirements of NR/L2/CIV/140: Control and use of model clauses. Requirements for materials and workmanship are given in NR/L3/CIV/008: Model clauses for specifying civil engineering work. The specifications for materials and workmanship shall be compatible with the Design assumptions adopted and shall be in accordance with the applicable Design standards. The specifications shall be suitable for the local environment of the Bridge, and shall comply with environmental, Health and Safety requirements. Page 73 of 109

129 10.10 Strengthening, alterations and repairs Where structural works are to be carried out, as a minimum all existing parts that have been assessed as worse than Assessed Category A2 in accordance with NR/L2/CIV/035: Assessment of structures shall be strengthened or replaced to comply with the requirements of this standard. Where there is a justification for not complying with this requirement the justification shall be subject to the approval of the Network Rail s Professional Head of Structures and provided in the AIP Submission for the works. New elements shall be designed in accordance with the requirements of this standard as for a new Bridge. Where it is not reasonably practicable for strengthening, alteration or repairs on a Underline Bridge to comply with the requirements for a new Bridge, and where safety and Interworking are not adversely affected, the strengthening, alteration or repairs may, subject to the approval of Network Rail be designed to satisfy the requirements of NR/L3/CIV/025: The structural assessment of underbridges, subject to the loading requirements identified in 9.3. The approach to be adopted shall be described in the AIP Submission. (Note: it is not acceptable to use NR/L3/CIV/015 for the design of strengthening. The design of strengthening to a bridge previously assessed to NR/L3/CIV/015 shall include the provision of an assessment to NR/L3/CIV/025 for the remainder of the structure). Consideration shall be given to the interface between the new and existing parts. The Design shall ensure that there are no detrimental effects on the existing parts resulting from the installation of the new parts, particularly with regard to compatibility of the different stiffness the of parts, and the distribution of load effects. The acceptability of changing the patterns of load, as well as the magnitude of loads, shall also be checked. Consideration shall be given to improving retained existing parts to comply with the requirements of this standard, where it is reasonably economic and practicable to do so. Any retained existing parts that do not comply with this standard shall be identified in the AIP Submission. Repairs that are not like for like replacements shall be considered as alterations and shall be subject to Technical Approval in accordance with NR/L2/CIV/003:Technical approval of design, construction and maintenance of civil engineering infrastructure. The Design of alterations to existing metal Bridges shall avoid the introduction of poor fatigue details, including those shown in NR/L3/CIV/025: The structural assessment of underbridges. Page 74 of 109

130 11 Identification of Bridges Each Bridge shall be identifiable on site in such a way that there is no ambiguity between Network Rail s records of the structure and its location on site. Identification plates shall be installed on the following types of new Bridge, and on existing Bridges when works (other than those of a disproportionately minor nature) are undertaken: Underline Bridge with a headroom over the road of 5.7m or less with allowances for sag curve compensation, Underline Bridge supported on columns, Bridge over a navigable waterway, Overline Bridge, Bridges where required by NR/L2/CIV/076: Management of Bridge Strikes from road vehicles & waterborne vessels. Identification plates shall include the following information: The unique identity of the Bridge, for example its name or number, location, road name, mileage, the emergency phone number of the relevant Operations Control office. New Bridges, other than those identified above, shall have identification plates, but which shall only show the emergency phone number where specifically required by Network Rail. For complex structures, consideration shall be given to identification marking of individual elements of the structure in accordance with NR/GN/CIV/041 Structures Condition Marking Index Handbook for Bridges. Guidance on the identification of infrastructure is given in HMRI Railway Safety Principles and Guidance Part 2, Section A, Chapter 8. For new and modified existing Bridges as identified above, Bridge identification signs or plates shall be provided at the track side or attached to the Bridge. The signs or plates shall, so far as is reasonably practicable, be visible to train drivers. Further guidance on the form, size and positioning, etc., of identification plates and trackside identification signs/plates is given in NR/L3/CIV/202: Management of the risk of Bridge strikes. Page 75 of 109

131 12 Records The Design information shall be fully documented in order that as much information about the Bridge as is reasonably practicable remains available. Health and Safety files shall be provided as required by the CDM Regulations. Records of new and altered Bridges shall be created and retained as described in NR/L2/CIV/003: Technical approval of design, construction and maintenance of civil engineering infrastructure. The records shall clearly identify the Design load capacity for the Bridge and any limits on use. Records shall include: calculations, Technical Approval design certification, as-built drawings, material certificates, records of Network Rail s and others services at the site, information on any changes made to the structure, or particular difficulties encountered, during the construction which may affect the performance or maintenance of the Bridge, details of any proprietary products incorporated in the construction, information on items that are anticipated to require maintenance or replacement during the Design Life of the Bridge, the type of maintenance and when it is anticipated, and any unusual access or methods required. Where a Bridge has been strengthened, or altered to an extent which affects the assessed capacity of elements of a Bridge, the Designer shall on completion of the Design provide an update of the existing assessed capacity of the Bridge (e.g. relevant Design calculations or a back-analysis of the existing assessment) which shall identify the changes in the assessed capacity of affected elements and the Bridge as a whole. In addition to providing a Form B for the Design in accordance with NR/L2/CIV/003: Technical approval of design, construction and maintenance of civil engineering infrastructure, the designer shall also provide a signed Form BA in accordance with NR/L2/CIV/035: Assessment of structures. Page 76 of 109

132 Appendix A: Application of Structure Category to individual structures The list of structures in the following Table is not exhaustive. The Table identifies examples of structures that are within the scope of this standard. Structure The structures listed below shall be managed in accordance with the standards applicable to the appropriate Structure Category (see note at end of table). Structure Category (A) (B) (C) (D) (E) (F) (G) Bridges & Culverts Retaining Walls Tunnels Earthworks Buildings & Station Structures Advertising hoardings Avalanche shelters Bridges Buildings, including their basements and undercrofts Boundary or free standing walls Cable Bridges carrying signal or power cables Canopies and supporting elements, other than Canopies on footbridges Close circuit television camera or screen supports (CCTV) Coastal, Estuarine or River Defences Concourses at stations Culverts Customer information screen (CIS) supports including suspension hangers Cut and cover structures, unless required to be designed as a Tunnel Cut and cover structures required to be designed as a Tunnel Driver only operation (DOO) equipment supports Earthworks Electrical control rooms (Building) Electrification structures (OLE), including straight masts, solid or lattice web cantilevers or portals Electrification structures raft type substations Elevated or suspended platforms within stations Elevated vehicle forecourts or ramps * Elevated trackside water tank support structures Equipment box support structures Equipment Support Structures (ESS), other than those more particularly identified in this Table Feeder station support structures Footbridges, including Canopies Coastal, Estuarine & River Defences Ancillary Structures Page 77 of 109

133 Structure The structures listed below shall be managed in accordance with the standards applicable to the appropriate Structure Category (see note at end of table). Gate boxes / houses (Building) Hoist or drive support structures Inspection pits set into the track Integrated electrical control centres (IECCs) (Building) Lighting support structures, including single tube masts or columns, cantilevers or portals, other than metallic lattice towers Location box support structures Metallic lattice tower Equipment Support Structures Minor Retaining Walls Multi-storey car parks Operational control rooms (Building) Platforms at stations or depots, including front and rear walls, cross walls, suspended spans and supporting structures Platforms for uncoupling trains at stations and depots Platforms constructed on embankments or in cuttings to support location cases or other equipment Pipe Bridges and pipelines that form self supporting Bridges Radio telecommunications masts (not metallic lattice) Raised walkways, including train access in berthing sidings Relay rooms (Building) Relocatable equipment buildings (REBs) Retaining Walls (other than Minor Retaining Walls) Sand towers Signal gantries, cantilevers, portals and other signal structures, that span or cantilever over operational railway lines Signal structures (other than those identified above) including straight posts and signal equipment platforms Signal boxes (Building) Signal boxes: support beams to locking frames in mechanical signal boxes Shafts Station accommodation and facility Buildings Structure Category (A) (B) (C) (D) (E) (F) (G) Bridges & Culverts Retaining Walls Tunnels Earthworks Buildings & Station Structures Coastal, Estuarine & River Defences Ancillary Structures Page 78 of 109

134 Structure The structures listed below shall be managed in accordance with the standards applicable to the appropriate Structure Category (see note at end of table). Structures supporting Buildings over operational lines Substations (Building) Subways Supports to raised track in inspection areas Telecommunication equipment supports (other than metallic lattice towers) Timber signal posts, doll and guy posts, telegraph poles Train Sheds and structural elements of adjacent Buildings which provide support Trolley wire supports (OLE) Tunnels, including adits, portals, inverts and drainage within or attached to Tunnel structure, but excluding Shafts Undertrack Crossings Water retaining structures Wheel lathe pits Structure Category (A) (B) (C) (D) (E) (F) (G) Bridges & Culverts Retaining Walls Tunnels Earthworks Buildings & Station Structures Coastal, Estuarine & River Defences Ancillary Structures * Note some structures may need to satisfy requirements of more than one Structure Category; for example an elevated vehicle forecourt or ramp which is primarily a Bridge but is also part of a Building. In such cases appropriate additional Design requirements from the other applicable Structure Category shall be identified in the AIP Submission. Page 79 of 109

135 Appendix B: Amendments to BS5400: Steel, concrete and composite Bridges Applicable parts of BS 5400 shall be used as identified in 10.2 and subject to the following amendments and additional requirements. Clause numbers in the headings below refer to those in BS 5400 except where stated. PART 2: 2006: Specification for Loads Particular amendments and additional information are included in Appendices C and D (in this standard). In addition, the following amendments shall apply: i) Table 11 In order to address potential effects of climate change, for the Design of a new Bridge the values of the maximum effective Bridge temperature given in Table 11 shall be increased by 10 o C to allow for the effects of future climate change. ii) Live load surcharge from railway loading shall be as identified in 9.7 in this standard. PART 4: 1990: Code of practice for design of concrete bridges BS 5400 Part 4: 1990 shall be used with the following amendments: i) (b) Prestressed concrete beams shall be designed as Class 2 members but with no tensile stresses under permanent loads (serviceability limit state). ii) In sub-paragraph (a), all live loading shall be ignored. iii) 4.7 The last paragraph shall be deleted and replaced by the following: For unwelded reinforcing bars the limiting stress ranges for fatigue shall be as follows: (i) for a Bridge carrying a railway - in accordance with Part 10, where in Table 8: m = 9, K 2 = 0.75 x 10 27, σ 0 = 160 N/mm 2 for bars < 16mm dia; Page 80 of 109

136 m = 9, K 2 = 0.07 x 10 27, σ 0 = 125 N/mm 2 for bars > 16mm dia; (the simplified procedure given in Clause 9.2 of Part 10 may be used where the loading is the standard railway bridge loading); (ii) for a Bridge carrying a highway - in accordance with current practice of the Highways Agency. PART 5: 2005: Code of practice for design of composite bridges i) For a Bridge subject to railway loading, the value of γ m shall be taken as 2.05, not 1.85 as stated. ii) Add the following: The effect of axial tension on the static or fatigue shear strength of a connector should be taken into account as follows, unless the reduction in P u or the increase in Q max is less than 10%. For stud connectors the nominal static ultimate shear strength P u in the presence of tension T u may be taken as P u = P u T u / 3 where P u is the nominal static ultimate shear strength as defined in iii) For a Bridge subject to railway loading, the value of γ m shall be taken as 1.5, not 1.4 as stated. iv) Spacing and location of shear connectors Where deck planks or permanent formwork are used, consideration shall be given to preventing the planks/formwork from being accidentally dislodged sideways and falling between the supporting girders. Where shear connectors on the girder flanges are used to provide such fail-safe restraint, their edge distances and spacing along the girder shall take into account the width of the plank/formwork, the overlap provided on the girder flange and construction tolerances. Page 81 of 109

137 Appendix C: Railway loads, application, dynamic factors, and amendments to BS : 2006 This Appendix identifies additional railway loads, requirements for the application of railway loads, dynamic effects, amendments and supplementary requirements to BS 5400: Steel, concrete and composite bridges Part 2: 2006: Specification for Loads, and other additional requirements. Note that RU loading identified in BS : 2006 is equivalent to Load Model 71 in BS EN : 2003: Eurocode 1: Actions on structures Part 2: 2003: Traffic loads on bridges. Where requirements of BS EN : 2003 are applied, the load classification factor α (for loading heavier or lighter than normal rail traffic) shall be taken as the value in accordance with in this standard, or shall be taken as 1.0 where a load classification factor is not required by i) Distribution of axle and wheel loads for RU and SW/0 loading When designing members for which the local effects of wheel loads is critical, an allowance shall be made for eccentricity of loading inside vehicles by distributing axle loads to the wheels in the proportions identified in BS EN : 2003 Clause Eccentricity of vertical loads may be neglected when considering fatigue. For the purpose of determining the patch loading under a sleeper, for ballasted track the wheel load may be distributed over three adjacent sleepers in the proportions identified in BS EN : 2003 Clause provided that the ballast depth is at least 200mm below the underside of the sleepers at the low rail. Alternatively, for ballasted or unballasted track, the longitudinal distribution of vertical wheel loads along the rail onto the bridge deck may be determined by an analysis which takes into account the vertical stiffness of the rails, track components, ballast and track support. The patch loading at the underside of the sleeper shall be applied as identified in BS EN : 2003 Clause (2). Below the underside of the sleeper, each patch load shall be taken as distributed through the ballast at an angle of 1 horizontal to 4 vertical, as identified in BS EN : 2003 Clause (2). Page 82 of 109

138 ii) Application of loading a) All railway loads All railway loads shall be applied as identified in BS EN : 2003 Clauses (1) and (3). b) Type RU loading Type RU loading shall be applied as identified in BS EN : 2003 Clause (4). c) Type SW/0 loading Type SW/0 loading shall be applied as identified in BS EN : 2003 Clause (5). Note that Type SW/0 loading shall be curtailed where this produces a more severe effect on the part being considered. d) Nosing Loads The nominal nosing load set out in BS : 2006 Clause may be distributed over three adjacent sleepers in the proportions: 1 : 1 : 1 4 : 2 : 4 e) Centrifugal Loads Where a Bridge carries curved track, the centrifugal force shall be taken into account in the Design, and for determining the proportion of vertical load carried by each rail. The Design shall take into account: the amount of track cant, the different speeds of heavy and light trains, possible future changes in cant and speed. Reasonably conservative assumptions shall be made in determining the most onerous likely effects. Such effects may be significant for types of construction in which individual elements are predominantly loaded by one rail (for example rail bearers, and narrow unconnected longitudinal beams or girders). Type RU or SW/0 Loading shall be considered as relevant to the part being considered. Centrifugal effects shall be determined in accordance with BS : 2006 Clause and the following: the centrifugal force shall always be combined with the vertical traffic effect. The centrifugal force shall not be multiplied by the dynamic Page 83 of 109

139 factor. When considering the vertical effects of centrifugal loading, the vertical load effects of centrifugal loading less any reduction due to cant shall be enhanced by the relevant dynamic factor; for a Bridge located on a curve, types RU and SW/0 loading shall also be considered without the centrifugal force; where the line speed exceeds 120 km/h (75 mph), an additional check shall be undertaken using RU (and SW/0 loading where applicable) with its dynamic factor and nominal centrifugal force F c calculated with v t = 120 km/hr, and taking the reduction factor f = 1.0, according to the following formula: F c = P (v t ) 2 / 127 r using the notation in BS : 2006 Clause f) Number of tracks to be loaded for checking deformations and vibration Limit state and associated acceptance criteria Track Safety Checks: SLS Checks: ULS Checks: Number of tracks on the Bridge Vertical acceleration of the Bridge (9.2) Vertical deformation of the Bridge (9.3.1) 1 1 or 2 a 1 or 2 or 3 or more b a 1 or 2 or Track twist (9.3.2) 1 1 or 2 3 or more b Combined response of the Bridge and track due to live loads including limits on vertical and longitudinal displacement of the deck (9.4) Transverse deformation of the Bridge (9.5) a 1 or 2 or 1 1 or 2 3 or more b a 1 1 or 2 1 or 2 or 3 or more b Passenger comfort (9.6) Uplift at bearings (9.3.3) 1 1 or 2 a 1 or 2 or 3 or more b Notes: a Whichever produces the more severe effect. b Where 3 or more tracks are loaded, the load from trains shall be multiplied by Table 1: Number of tracks to be loaded for checking deformations and vibration Page 84 of 109

140 iii) Derailment loads (BS : 2006 Clause 8.5) For the ultimate limit state check against collapse, but accepting local damage, the requirements of BS : 2006 Clause (b) shall be replaced by those of BS EN : 2003 Clause Design Situation I, noting that the formula for the loads produces the design loads (i.e. includes γ fl ). For the ultimate limit state check against overturning or instability, but accepting local damage, the requirements of BS : 2006 Clause (c) shall be replaced by those of BS EN : 2003 Clause Design Situation II, noting that: the formula for the loads produces the design loads (i.e. includes γfl), a maximum of 20 m of the udl of LM 71 loading is to be applied, the 250 kn point loads of LM 71 are not applicable. The Bridge deck shall be designed to resist a nominal vertical point load from re-railing jacking equipment equal to α x 250 kn (where α is the applicable load classification factor in accordance with 9.2.1, which in this case shall not be less than 1.0), applied on a 150 mm x 150 mm area anywhere on the deck between the robust kerbs, considering only the ultimate limit state and applying a γ fl of 1.4. The serviceability limit state requirements of BS : 2006 Clause (a) (1) and (2) shall not apply, since they are less onerous than the preceding requirements, and need not be checked. On multi-track bridges, the derailment loading shall be considered on one track in combination with RU (or LM 71) loading on the other tracks as applicable, where this produces a more severe effect. Walkways and similar secondary structural elements which are outside the robust kerb need not be designed to carry derailment loading. If, however, such an element is designed to carry derailment loading, the design of the Bridge as a whole shall be such that it will not overturn when the derailment loading for overturning and instability is applied along the outer edge of the element. iv) Wind Loading (BS : 2006 Clause (a)) The limitation on maximum wind speed coexistent with live loading for highway and foot/cycle Bridges (35 m/s) is not applicable to rail Bridges. v) Permanent loading for Underline Bridges a) Design dead load (BS : 2006 Clause ) Page 85 of 109

141 γ fl values for dead loads at ULS of 1.1 for steel and 1.2 for concrete shall be used in place of the values given in BS : 2006 Table 1. b) Nominal superimposed dead load (BS : 2006 Clause 5.2.1) Where the actual depth of ballast from the underside of sleepers at the lowest rail to the top of the bridge deck is less than 300 mm, the depth of ballast shall be taken as 300 mm for calculating the nominal superimposed dead load. Where the depth exceeds 300 mm, the actual depth of ballast shall be used. Ballast density shall be taken as 21 kn/m3. (This allows for dirty waterlogged ballast). c) Design superimposed dead load (BS : 2006 Clause 5.2.2) For superimposed dead load, γ fl shall be taken as 1.75 at ULS and 1.2 at SLS for track ballast for a depth measured from top of sleeper to 300mm below the underside of the sleeper; the same values shall be taken for slab track. For additional ballast depth or fill γ fl shall be taken as 1.20 at ULS and 1.00 at SLS. For track, γ fl shall be taken as 1.20 at ULS and 1.00 at SLS based on the heaviest likely future track type. This shall generally be assumed to be UIC 60 rail with full-depth concrete sleepers at 600mm spacing. d) Removal of superimposed dead load (BS : 2006 Clause 4.5.2) These requirements do not apply when determining the natural frequency of a Bridge deck for checking dynamic effects. See (vi) and (vii) in this Appendix. Due regard shall be taken of the case where either reballasting or resurfacing work is being undertaken and for the temporary case during erection. Each bridge shall be considered individually and a realistic assessment made. Particular care is needed when continuous elements are being considered. For guidance it may be assumed that: where live load is present, the superimposed dead load (ballast) can be reduced by up to half over the full length of the bridge; where live load is not present, the superimposed dead load (ballast and track) can be removed partially or completely over the full length or part length of the bridge; Page 86 of 109

142 whether or not live load is present, for a multi-track bridge the superimposed dead load (ballast and track) can be removed partially or completely over the full length or part length of the bridge for one or more tracks. Where live load is present, full live load shall be applied to the other tracks so as to produce the most severe effect on the part of the Bridge being designed. vi) Dynamic effects (BS : 2006 Clause and Table 1) The reference in BS : 2006 Clause to the deflection limits in UIC Leaflet 776-3R shall be replaced by the natural frequency requirements identified in 8.2 and item (vii) in this Appendix. The definitions for dimension (L) in Table 1 in BS : 2006 shall be supplemented by the following: Structural Element Battle deck type floor with closely spaced cross girders or ribs and without longitudinal ribs: Cross girders or ribs Deck plate Concrete slab decks Dimension L (m) Twice the cross girder spacing plus 3 m Cross girder spacing plus 3 m The lesser of: 1. the span of the main girders, or 2. twice the main girder spacing Note that details given in Table 6.2 of BS EN shall not be applied. vii) Dynamic factors checks of natural frequency The dynamic factors provided in BS : 2006 shall be applied subject to the following. a) Linespeeds not greater than 90mph (145 km/h): The Bridge shall have a natural frequency within the limits given in Figure 6.10 of BS EN : 2003, unless otherwise permitted by Network Rail s Professional Head of Structures. For a Bridge with a frequency within the above limits, the dynamic factors in BS : 2006 shall be applied and a Bridge-specific dynamic analysis is not required; Where a Bridge is permitted with a natural frequency outside the specified limits, a Bridge-specific dynamic analysis shall be undertaken and additional requirements identified below shall apply. Page 87 of 109

143 b) Linespeeds above 90 mph (145 km/h) but not greater than 125 mph (200km/h): The Bridge shall have a natural frequency within the limits given in Figure 6.10 of BS EN : 2003, unless otherwise permitted by Network Rail s Professional Head of Structures, and no reduction in Type RU Loading and Type SW/0 Loading shall be permitted. For a Bridge satisfying the above frequency limits and full unreduced loading requirements (and other than those Bridges identified in the following bullet point), the dynamic factors in BS : 2006 shall be applied and a Bridge-specific dynamic analysis is not required. For through or half-through Bridges with lightweight all-metal floors, and for any Bridge permitted to be designed outside the specified frequency limits, but excluding the standard Network Rail Western Region box-girder style decks with inverted-t ribs at not more than 650mm centres, a Bridge-specific dynamic analysis shall be undertaken, and additional requirements identified below shall apply. The additional requirements referred to in a) and b) above are: The Bridge-specific dynamic analysis shall use Real Trains to be specified by Network Rail, and load models HSLM-A and HSLM-B as identified in BS EN : 2003; Deck accelerations shall be checked against limits to be specified by Network Rail; Load effects from the Bridge-specific dynamic analysis shall be compared with those from the normal loading for the Design (i.e. normal Type RU and SW/0 Loading), and the more severe effects shall be used in the Design; Supplementary fatigue checks shall be undertaken. viii) Loading for rail mounted crane The following nominal loading for a KIROW KRC1200UK rail mounted crane shall be taken into account in the Design: Loads: 8 number point loads each of 250kN on each of 2 rails Spacings: mm The 16 No point loads (8 axles) shall be applied with a dynamic factor of 1.0 (i.e. there is no increase in the loads for dynamic effects) and the loading is not to be considered for fatigue checks. The crane loading shall be applied as an alternative to RU loading on one track, with normal railway loading (RU, SW/0 etc. as identified in 9.2) applied on the adjacent track(s). The crane loading shall be applied as part of Load Combination 1 in Table 1 of BS : Page 88 of 109

144 Appendix D: Collision loads from railway traffic The following requirements are applicable to permissible line speeds up to 125mph (200km/h). i) General With reference to Clause 8.6 of BS 5400: Steel, concrete and composite bridges Part 2: 2006: Specification for Loads, this Appendix identifies recommendations for Bridge supports near railway lines and accidental loading from railway traffic. These recommendations apply to the supporting structures for new Overline highway Bridges and similar structures, and to structures carrying hazardous materials (e.g. gas), constructed over or alongside railway tracks. They do not apply to lineside railway infrastructure such as overhead line electrification masts or signal gantries. The recommendations shall be applied to new and reconstructed footbridges where reasonably practicable, taking into account the nature of the rail traffic and the track layout adjacent to the Bridge. The recommendations take account of: the definition of a hazard zone where the risk of impact is greatest, the need for columns and piers to withstand the effect of light impacts that might occur from derailed coaches or freight wagons without sustaining irreparable damage, the prevention of a progressive collapse of the superstructure in the event of a major accident which results in the loss of a support. The strategy for the Design should be to help minimise the likelihood an impact occurring, and to mitigate the consequences if an impact does occur. Wherever reasonably practicable, the supports of a Bridge that spans over or alongside railway tracks shall be placed outside the hazard zone (identified in (ii) below). ii) Structures within the hazard zone Where there is no reasonably practicable alternative to placing supports inside the hazard zone they shall preferably be monolithic piers rather than individual columns. The hazard zone shall be assumed to extend for a width of 4.5 m from the running edge of the nearest rail. All supports located between railway tracks shall be considered to be inside the hazard zone. Where individual columns are used within the hazard zone, the Design of the Bridge above them shall Page 89 of 109

145 incorporate a degree of continuity and alternative load paths such that the removal of any one column will not lead to the collapse of the remainder of the structure under the permanent loads and primary and secondary live loads in accordance with Combination 1 in Table 1 of BS 5400: Steel, concrete and composite bridges Part 2: 2006: Specification for Loads. The ultimate limit state partial factors shall be as specified in Table 1 but limited to 1.0 on live loads. To provide robustness against the effect of light impacts, all piers or columns within the hazard zone shall be designed to withstand without collapse a single horizontal Design force of 2000 kn acting at a height of 1.2 m above the adjacent ground level and a single horizontal Design force of 500 kn acting at a height of 3 m. The two forces may act in any direction but need not be considered to act simultaneously. These forces are Design ultimate limit state forces (i.e. include γ fl ) and shall be combined with the permanent loads and the applicable primary and secondary live loads as identified in the paragraph above. The connections between a column and its base shall be such that the connection can resist a horizontal Design force of 2000 kn at the ultimate limit state without being dislocated. Pin jointed connections shall be avoided. Consideration shall be given to the Design and detailing of the connection between a column and the structure it supports so that in the event of the column being struck the load effects generated by the failure of the connection will not cause failure of the supported structure. A check of the unsupported girder shall be made using the ultimate capacity of the connection at failure as a nominal/characteristic load on the supported member in conjunction with the permanent loads and primary and secondary live loads identified above. The supports for a footbridge in a country/non-station location should be set back at least 4.5 m from the running edge of the nearest rail. The position of the supports for a footbridge in a station may be governed by the width of the platform. Where supports are unavoidably within the 4.5 m hazard zone the platform shall be designed to provide protection to the supports (see (iv) below). Consideration shall be given to avoiding the use of single column supports within the hazard zone. iii) Bridge supports in the vicinity of buffer stops Supports to a Bridge which could be endangered by a rail vehicle running past a buffer stop shall be avoided wherever reasonably practicable. Where this is not reasonably practicable, an additional end impact wall shall be provided which, together with the buffer stop, protects the supported Bridge. When designing such an end impact wall, suitable allowance may be made for the restraint provided by the track where this is securely connected to the wall (e.g. by means of a concrete slab to which the rails are fastened directly). Page 90 of 109

146 For a track serving passenger traffic, the end impact wall shall be designed for a horizontal ultimate limit state Design force of 5,000 kn at a height of 1.0 m above the top of the rail, provided that the buffer stop has a minimum braking capacity of 2500 knm. In a shunting and marshalling area, the end impact wall shall be designed for a horizontal ultimate limit state Design force of 10,000 kn at a height of 1.0 m above the top of the rail, provided that the buffer stop has a minimum braking capacity of 2500 knm. iv) Plinths and platforms Where individual columns are used, a solid plinth shall be provided to a height of 915 mm +0/-25 mm above rail level or 1200 mm minimum above ground level where lateral clearance permits. The height of the plinth shall be constant and the ends of the plinth shall be suitably shaped in plan to deflect derailed vehicles away from the column. A solid platform construction shall be used to provide similar protection from derailed vehicles for individual columns within station areas. The column shall be structurally separated from the protecting plinth or platform by means of a covered air gap or compressible material around the column, so that if the plinth or platform is deflected or displaced in an accidental situation the risk of an impact being transferred to the column is minimised. v) Structures in embankments Columns and piers located within embankments, or at the bottom of embankments, may require special consideration even if outside the hazard zone, because of the possibility of derailed vehicles rolling down the embankment. If it is not reasonably practicable to arrange the Design to avoid this situation, appropriate measures shall be taken to safeguard such columns and piers. Consideration shall be given to: the use of guard rails, providing a retaining structure to widen the top of the embankment, the use of massive piers. Page 91 of 109

147 Appendix E: Additional requirements for lineside handrailing on Underline Bridges Open handrailing adjacent to a walkway not open to the public on an Underline Bridge, shall have in addition to a continuous top rail and a 150 mm raised kerb or kicker plate, one of the following: (a) at least one intermediate rail or wire parallel to the top rail such that the clear distance between any two rails / wires or between a rail / wire and the kerb / kicker plate does not exceed 500 mm; (b) vertical or near-vertical infill bars or wires such that the clear distance between bars / wires does not exceed 150 mm; (c) other arrangements (including ornamental arrangements) of rails or bars or wires or similar elements such that a 600 mm x 200 mm rectangle with its long sides vertical will not pass through; (d) mesh infill. Intermediate or infill elements of handrailing shall be able to withstand, without permanent deformation, a horizontal loading of 1.0 kn/m 2 or a horizontal force of 0.5 kn applied at any point, whichever has the more severe effect. Handrailing shall also be designed for horizontal loading of 0.74 kn/m or a horizontal force of 0.5 kn applied at any point to the top rail, whichever has the more severe effect. Page 92 of 109

148 Appendix F: Existing substructures affected by new construction Where the superstructure of an existing Bridge is to be reconstructed on existing abutments, or in other cases where new construction is associated with total or partial retention of existing substructures, the nature and extent of the existing substructures to remain shall be subject to the approval of Network Rail and identified in the AIP Submission. The following guidelines may be applied. (1) IF ALL of the following conditions are satisfied: (i) an existing substructure is in satisfactory condition and shows no significant signs of distress or undue settlement, (ii) the effects of dead loading on the existing substructures or subsoil will not be significantly increased as a result of the new construction (having regard to masonry stresses and to maximum and average soil pressures), (iii) the effects of live loading on the existing substructures or subsoil will not be significantly increased following the new construction (having regard to masonry stresses and to maximum and average soil pressures), (iv) the stability of the existing substructures against overturning and sliding will not be significantly reduced as a result of or following the new construction, (v) there are no particular geotechnical considerations which give cause for concern, THEN the existing substructures may normally be considered adequate for retention without modification and without the need for structural or geotechnical analysis. In this Appendix, the interpretation of the term significant requires engineering judgement to be used in relation to the particular circumstances prevailing at the structure. Significance should be considered in terms of effects on the safety of the structure and the ability of the structure to carry loads. (2) IF conditions (i) and (v) above are satisfied, but the effects of dead and/or live loading on the existing substructures or their tendency to sliding / overturning will be significantly greater than existing, THEN the following shall apply: Appropriate structural and/or geotechnical analysis should be carried out. Account should be taken of any more or less favourable distribution of loading as a result of the new construction. For example: Page 93 of 109

149 (a) A freely-supported span may be replaced by a portal structure which, although heavier, effectively struts the abutment tops, preventing rotation about their bases. (b) A superstructure which bears near the front face of an abutment may be replaced by a new superstructure which bears further back, thus improving the stability of the abutment and reducing the maximum soil pressures beneath it. (c) Beam type construction will generally distribute loads more evenly throughout the abutment than a half through type structure. (d) The effects of a half through type structure can be improved by providing cill beams with sufficient strength to distribute loads. When considering the acceptability of additional soil loading, due distinction should be made between soil types which may fail completely and those whose response is likely to be no more severe than increased settlement. In some cases, increased settlement might be acceptable if the safety, clearances and performance of the Bridge and any supported equipment are not affected. However, in such cases, the new superstructure should be designed to accommodate the effects of any likely increased total or differential settlement. Underpinning and/or strengthening should be considered as applicable. Such underpinning does not necessarily have to carry all of the foundation loading. It may be sufficient to design underpinning to carry the incremental loading only, or in some other way to share the load between new and old parts. However, such load sharing should not be relied upon unless it can be verified that the underpinning structure / soil system will settle under increased loading in an essentially ductile manner and will be able to withstand any tension which may result from the application and removal of live loading. (Useful information may be found in Burland and Kalra s paper Queen Elizabeth II Conference Centre: geotechnical aspects, Proc. Instn Civ. Engrs, Part 1, 1986, 80, Dec., ) (3) IF conditions (ii), (iii), (iv) and (v) above are satisfied but the existing substructures are showing significant signs of distress, THEN the following shall apply: The cause of distress should be determined (e.g. earlier existence of rail joints, high local forces especially at abutment corners, malfunctioning or no bearings, failure of waterproofing / drainage, vegetation, increase in ballast depth, settlement, effects of mining, Page 94 of 109

150 reduction in passive pressure due to road lowering, trenching or scour, etc.). Appropriate structural and / or geotechnical analysis should be carried out. Distinction should be made between movement / damage which has occurred in the past but has since stabilised and movement / damage which is ongoing. In the case of the former, remedial work may not be required. Remedial work should generally be considered as a first choice rather than complete replacement of the existing substructures, allowing where applicable for sharing of load between new and old parts. (4) An existing Bridge superstructure may act as a prop to the abutments (whether designed to or not). Consideration should therefore be given to the stability of existing abutments when the superstructure is removed. Where necessary, temporary props should be provided and / or limitations placed on soil surcharge loading behind the abutment (e.g. by restricting the use of construction plant or by reducing the height of fill behind abutments during reconstruction). (5) When considering ground bearing capacity, consideration should be given to the fact that the ground beneath existing foundations will be consolidated and may have a higher bearing capacity that that determined from ground investigations adjacent to the structure. Page 95 of 109

151 Appendix G: High Speed TSI requirements This Appendix provides an introduction to the requirements of the High Speed Technical Specification for Interoperability relating to the Infrastructure Subsystem (the High Speed TSI, which is published in the Official Journal) as implemented by (subject to any subsequent Regulations or amendment): The Railways (Interoperability) Regulations 2006 (Statutory Instrument 2006 No. 397) (see as amended by: The Railways (Interoperability) (Amendment) Regulations 2007 (Statutory Instrument 2007 No. 3386) (see The 2006 regulations cover both High Speed and Conventional Rail. This Appendix outlines the applicability of the High Speed TSI (Issue II Commission Decision 20 December Reference 2008/217/EC ) and the main aspects that affect Bridge Design. See regarding the Conventional Rail TSI. In addition to the requirements given elsewhere in this standard, it is a statutory requirement that Bridges which carry or cross routes of the trans- European high speed rail system (identified in Schedule 11 of the Interoperability Regulations) shall be designed in accordance with the High Speed TSI. Compliance with details identified in this Appendix shall not be taken to ensure compliance with the High Speed TSI or the Interoperability Regulations. The Remit from Network Rail shall normally identify whether TSI applies to the Design of a Bridge. Where this has not been identified and the Bridge is on a TSI route, confirmation shall be sought from Network Rail s Professional Head of Structures concerning the particular requirements for compliance with the High Speed TSI and Interoperability Regulations, prior to AIP Submission. In all cases, liaison with TSI Authorities shall only be carried out by Network Rail unless specifically delegated to others. a) Application of TSI requirements It is essential that the applicability of the TSI is established for the individual Bridge and works to be undertaken. Advice is available on the Department for Transport web site ( Page 96 of 109

152 Notwithstanding whether or not formal conformity and verification with the High Speed TSI is required, it is Network Rail s policy to apply the High Speed TSI requirements where reasonably practicable to the following structures on High Speed TSI applicable routes (this list includes the TSI requirements): new Underline Bridges, Culverts, Overline Bridges and footbridges (including Outside Party Bridges), Underline Bridge superstructure reconstructions to accept faster and/or heavier rail traffic than that which is currently accepted, where reasonably practicable, Underline Bridge superstructure reconstructions undertaken because of poor condition and/or assessment failure of the existing structure, significant structural work to improve railway clearances across Underline Bridges, under Overline Bridges and through tunnels, significant structural work to accommodate new and/or lengthened station platforms. The High Speed TSI requirements do not apply to minor works ( substitution in the framework of maintenance ), which may be considered to include replacement of components, assemblies or sub-assemblies in accordance with current technology, and also like for like replacement. As a guide, the High Speed TSI requirements do not generally apply to the following types of work: any work which could reasonably be described as maintenance (including repairs or restoration of capability, and remedial strengthening of Bridges resulting from assessment failures), any work which could reasonably be considered as not major upgrade works (including strengthening of bridges to accommodate faster or heavier bridges), alterations to structures which improve safety and/or accessibility but which do not provide for any improvement in the speed, weight or gauge of railway traffic, for example: provision of Underline Bridge impact protection beams, provision of improved walkways on Underline Bridges, provision of new ramped access to existing footbridges, improvements to Overline Bridge parapet containment levels. Where the High Speed TSI requirements are applicable, the Design shall comply with the more onerous requirements of those identified in this standard and those in the High Speed TSI. Page 97 of 109

153 Additional approval and verification procedures apply to work which is within the scope of the High Speed TSI, as identified in the TSI and Interoperability Regulations. b) Main requirements of High Speed TSI The Designer shall check the version of the High Speed TSI current at the time of the Design and shall identify the version in the AIP Submission. UK1 gauge has been revised for Issue II of the High Speed TSI. Application rules are given in Railway Group Standard GE/RT8073 Issue 1: Requirements for the application of standard vehicle gauges, with guidance in GE/GN8573 Issue 2: Guidance on gauging. Where the application of the High Speed TSI requires a load classification factor α (for loading heavier or lighter than normal rail traffic) to be applied, the value of α to be used shall be the greater of the value required by the TSI and the value required elsewhere by this standard, and details shall be identified in the AIP Submission. The Sections of the High Speed TSI (Issue II) likely to be relevant are as follows, without limitation: TSI requirements particularly relevant to Bridge Design (Listing is not exhaustive) Minimum infrastructure gauge TSI Section Number Traffic loads on structures Vertical loads Dynamic analysis Centrifugal forces Nosing forces Actions due to traction and braking (longitudinal loads) Longitudinal forces due to interaction between structures and track Aerodynamic actions from passing trains on line side structures Application of the requirements of EN1991-2: Lateral space for passengers and onboard staff in the event of detrainment outside of a station Lateral space alongside tracks Register of infrastructure 4.8 Assessment of conformity with TSI and/or verification Page 98 of 109

154 Particular features of the British network c) Other TSI aspects to be considered The following TSI (Infrastructure) aspects, relevant to other structure related issues, shall also be considered in the Design: TSI aspect (Listing is not exhaustive) Essential (general and specific) requirements, and meeting those requirements, including: Reliability and availability (including monitoring and maintenance) Safety Health (including materials hazardous to health) Environmental protection Technical compatibility TSI Section Number 3.2 & 3.3 Operational noise Ground vibration Prevention of unauthorised access d) Additional factor for deterioration γ det In addition to the TSI infrastructure requirements, Network Rail also require an additional partial factor γ det to be used in the Design of all Bridge elements that form part of the trans-european high-speed rail network. γ det shall provide an additional 10% allowance on the effects from live loads (at ultimate limit state) for future (normal) structural deterioration, to enable the various TSI structure-related requirements to be met in the longer term and to provide Network Rail with flexibility in asset stewardship in meeting in-service TSI obligations. The application of γ det shall be identified in the AIP Submission. γ det shall not be applied to fatigue checks and shall not be applied to deformation checks. The additional partial factor γ det shall be applied when determining the Design loads for live loads only, such that using the notation in BS 5400: Steel, concrete and composite bridges: Q* =. γ det. γ fl. Q k and is subject to application of γ f3 where: Q* is the design load. γ det is an additional partial factor for structural deterioration, but applied to live loads only. γ det shall be taken as: 1.1 for the ultimate limit state, Page 99 of 109

155 1.0 for the serviceability limit state. γ fl Q k γ f3 is the partial factor for loads defined in the BS 5400: Steel, concrete and composite bridges Part 2: 2006: Specification for Loads, as modified by this standard. is the nominal live load. is an additional partial factor to be applied to the load effects or to the capacity/stiffness in accordance with the applicable Part of BS 5400: Steel, concrete and composite bridges. Page 100 of 109

156 Appendix H: Modification to Appendix 1 of GC/RT5212 Note that this modification to GC/RT5212 shall not be implemented for a Bridge that is subject to High Speed TSI requirements (see and Appendix G). (Note: on these routes there is a statutory requirement to comply with GC/RT5212 via the High Speed TSI). Issue 1 of GC/RT5212: Requirements for Defining and Maintaining Clearances supersedes all of GE/RT8029: Management of Clearances and Gauging (except for Section 14), which has been withdrawn. Appendix B of GE/RT8029 (Issue 1) gave a Structure gauge for areas close to the plane of the rail. This included an area defined as being an area for dwarf signals, bridge girders, and other lineside equipment (conductor rail equipment, such as hook switches, is also permitted to utilise this area). The area extended outwards from a point 240 mm mm = 558 mm from the nearest running edge, to a height of 110 mm above the plane of the rails. In Appendix 1 in Issue 1 of GC/RT5212, the various areas included in the Structure gauge for areas close to the plane of the rail were consolidated into an area designated as an Area reserved for items intended to come in close proximity to trains (for example, conductor rails and AWS magnets). Bridge girders were therefore excluded from the area permitted by GE/RT8029 (as bridge girders are not intended to come in close proximity to trains in the same way as conductor rails and AWS magnets). It has been established that it was not the intention to exclude bridge girders from the area permitted by GE/RT8029 when Issue 1 of GC/RT5212 was drafted. The exclusion was inadvertent - there are no safety grounds for such an exclusion. The Design of Bridges in accordance with NR/L2/CIV/020 shall therefore permit fixed infrastructure to be located in the area for dwarf signals, bridge girders, and other lineside equipment previously identified in GE/RT8029. Until GC/RT5212 is revised, where a Bridge Design includes girders within the area identified above, the girders and the relevant dimensions shall be identified in the AIP Submission, with a cross reference to this Appendix. Note: GM/RT2149: Requirements for Defining and Maintaining the Size of Railway Vehicles permits train builders to design a swept envelope that comes within 50 mm of the area subject to this application, reducing to 25 mm under worst case conditions, such as suspension failure. Section G2 of GC/RT5212 therefore requires: When designing new infrastructure, allowance shall be made for construction tolerances to ensure these requirements [structures do not intrude inside the structure gauge set out in Appendix 1] are met once the infrastructure has been built. Infrastructure is defined as track and structures in combination. Allowance has therefore to be made for construction tolerances of both the structure and the adjacent track. Page 101 of 109

157 Bridge girders occupying the area subject to this modification must continue to meet this requirement. Page 102 of 109

158 Appendix I: Railway infrastructure / other issues interfaces The following is a list of railway infrastructure and other issues for which Network Rail is responsible which should be considered as appropriate in the planning, Design and execution of structures works. The list is not exhaustive. Interoperability Permanent way and track Drainage Signalling OHLE and third rail electrical power Power supply Telecommunications (including radio networks) Passenger flow at stations Clearance and gauging Operational safety Fire safety Environmental requirements Security Emergency evacuation Anti-terrorist requirements Page 103 of 109

159 Appendix J: External authority, Outside Party etc. interfaces Arrangements for consulting external authorities, Outside Parties, etc., shall be agreed with Network Rail in accordance with 6.10 before any consultation takes place. The following is a list of external authorities, Outside Parties and third parties which may need to be considered and consulted with in the planning, Design and execution of structures works. The list is not exhaustive. * Her Majesty s Railway Inspectorate (HMRI) * Technical Specification for Interoperability (TSI) Authorities * Notified Bodies * Train operating companies, freight operating companies and station operating companies * Other Network Rail leaseholders and tenants * Government authorities in England, Scotland and Wales established under the Planning (Listed Buildings and Conservation Areas) Act 1990 * Bodies responsible for structures of historical importance, such as English Heritage, Historic Scotland and Cadw: Welsh Historic Monuments Executive Agency * Local authority planning bodies and environmental authorities * Highway authorities such as the Highways Agency, Scottish Executive, Transport Directorate of the National Assembly of Wales and local authorities Other railway infrastructure owners such as London Underground and light rail and metro operators * Drainage, river and port authorities British Waterways Board and other canal owners * Environmental authorities, such as Environment Agency, English Nature, Scottish Natural Heritage and the Countryside Council for Wales * Utility owners and statutory undertakers Other infrastructure owners Other land owners Other neighbours Emergency services Page 104 of 109

160 * Liaison with these bodies shall be carried out by Network Rail unless specifically delegated to others. Ref: NR/L2/CIV/020 Page 105 of 109

161 Appendix K: Information to be included in the AIP Submission This Appendix lists the clauses in this standard which require information to be included in the AIP Submission. These requirements shall be considered in conjunction with the requirements identified in NR/L2/CIV/003: Technical approval of design, construction and maintenance of civil engineering infrastructure. Clause Title 2 Purpose 6.1 Structural adequacy, general location and dimensions 6.2 Purpose, intended use 6.4 Construction, maintenance and decommission 6.6 Health and safety, and environmental considerations Railway tracks Structure gauge and clearances to the railway Railway equipment Technical Specifications for Interoperability (TSI) 6.12 Interface with services, Statutory Undertakers and public utilities Highway Authority acceptance of the Design Clearances to highways Highway widths and construction Highway sight lines Highway lighting and road traffic sign Clearances over water Lighting and signs over waterways New Bridges and reconstructed superstructures Strengthening, alterations, repairs and temporary Bridges 7.3 Durability and corrosion protection 7.4 Water management and drainage 7.5 Waterproofing 7.8 Security, fencing and protection from vandalism 7.9 Parapets, safety barriers, walkways, handrailing, etc Vehicle parapets and safety barriers for Overline Bridges Replacement of parapets or safety barriers Particular requirements for footbridges 7.13 Bearings 7.15 Hydraulic Design for Culverts 7.16 Temporary Bridges Page 106 of 109

162 Clause Title Track twist Uplift at bearings 9.1 General requirements for loading Railway loads for Underline Bridges Fatigue loads for Underline Bridges Accidental (derailment) loads for Underline Bridges Accidental loads for Underline Bridges over waterways 9.3 Loading for strengthening, alteration or repair of Underline Bridges Highway vehicle loads for new and replacement Overline Bridges Pedestrian, cycle and equestrian loads Parapets, safety barriers and handrailing for Overline Bridges 9.5 Loading for strengthening, alteration or repair of Overline Bridges Loads to be considered 9.7 Loading for substructures 10.1 General 10.3 Timber Bridges 10.4 Bridges constructed from other materials 10.5 Foundations for new Bridges 10.6 Earth retaining elements Strengthening, alterations and repairs Appendices: A Application of Structure Category to individual structures (reference in Footnote) F Existing substructures affected by new construction G High Speed TSI Requirements H Modification to Appendix 1 of GC/RT5212 L Non-mandatory recommendations Page 107 of 109

163 Appendix L: Non-mandatory recommendations This Appendix contains additional non-mandatory good practice recommendations. 1. Railway Approved Code of Practice GC/RC5510: Recommendations for the Design of Bridges At the time of drafting this standard, Railway Approved Code of Practice GC/RC5510 was due to be withdrawn. However, the Design of a Bridge should generally comply with the recommendations and guidance in GC/RC5510 where these do not conflict with the requirements of this standard. 2. Economy Structures should be designed with appropriate economy, with costed alternatives included within the AIP Submission to justify the adopted design. Consideration should be given to the whole life costs prior to submission of the AIP. 3. Clearances Where reasonably practicable, the Design should provide larger clearances than the minimum requirements specified. 4. Clearance for ballast cleaning machines Consideration should be given to the clearance requirements for ballast cleaning machines to pass beside foundations and structural supports. Where applicable, details should be identified in the AIP Submission. 5. Track maintenance plant An Underline Bridge should be designed so that it will not be damaged by track maintenance plant. Where a Bridge deck is ballasted, the Design should, so far as is reasonably practicable, allow for sufficient depth of covering fill material and/or ballast over foundations so as to avoid damage to waterproofing or the structure by the tynes on ballast tampers. A ballasted deck, and the details at the ends of such a deck, should be designed to prevent the loss of ballast. 6. Limitations on structural form The following techniques should not be used in permanent works for abutments or other substructures of Underline Bridges, without obtaining the Page 108 of 109

164 approval of Network Rail s Professional Head of Structures prior to AIP Submission: Ref: NR/L2/CIV/020 reinforced soil abutments, anchored earth, including percussion driven mechanical anchors, ground anchors, steel sheet piles, crib walls, gabion walls, soil nailing. Helical screwed piles should not be used for Underline or Overline Bridge foundations without the approval of Network Rail s Professional Head of Structures prior to AIP Submission. Where such use is permitted, guidance on requirements is given in Network Rail Structures Engineers Technical Advice Note SE/TAN/0038: Helical screwed pile foundations for equipment support structures. 7. Protection on abutments or walls between adjacent Bridge decks Personnel protection is required along the top of abutment walls or transverse infill walls located between adjacent separated Bridge decks. Consideration shall be given to the risk arising from derailed trains striking or dislodging the protection, and the parts to which it is attached. Generally the protection should take the form of lightweight handrailing which complies with the requirements of 7.9 and Appendix E. In addition, the handrailing should be infilled with 3mm minimum diameter galvanised mesh with a maximum hole size of 25mm. Solid construction e.g. brickwork, blockwork or concrete walls, or upstanding extensions of abutment or transverse infill walls, should not be used. Where strengthening, alteration or repairs are to be carried out to existing Bridges which have solid protection walls etc., consideration should be given to altering such protection to comply with the above. Page 109 of 109