TECHNICAL USER MANUAL CONARCH OVERBRIDGE STANDARD DESIGNS

Transcription

1 TECHNICAL USER MANUAL for CONARCH OVERBRIDGE STANDARD DESIGNS Standard Detail and Design Drawings 1 of 50

2 Summary This Technical User Manual is applicable to the reconstruction of masonry arch overbridges using precast concrete conarch units. 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 reconstruction of existing structures; however they can be used for new-build applications. 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 A1 First Issue 2 of 50

3 Content Section Description Page 1. Introduction Conarch Suite Documents Technical User Manual Standard Design Inner & Edge Precast Concrete Unit Drawings Standard Design Parapet Beam Precast Concrete Unit Drawings Standard Detail Precast Concrete Unit Drawings Standard Detail In-situ Concrete Drawings Standard Details Drawings Conarch Calculator Use of Network Rail Standard Designs and Details Safety/CDM and Environmental General Possession Plan Design Risk Assessment National Design Codes General Design Requirements: Actions and loadings: Concrete design: Abutment strength: Geotechnical design Bar bending schedule: Network Rail Approval Documents Executive Summary Benefits of using the Standard Designs At Each Bridge Location Scheme Specific Designer Precast Concrete Manufacturer Geometrical Envelope Span Skew Rise Bridge Width Construction Depth Road Profile Vertical Profile Horizontal Profile Gauge Clearances Conarch Calculator Layout Design Reinforcement Scheduling Tool Design Assumptions and Restrictions Structural Analysis modelling & Actions Structural Models Actions Verifications Background of the Conarch Standard Design and Details Conarch Unit Details 18 3 of 50

4 Conarch Unit Widths Edge units Inner units Tie Bars Parapet Beams Parapet panels Construction Depth Capping Slab Rear Vertical Saw Tooth Profile to Backfill Concrete Concrete Specification and Nominal Cover to Reinforcement Couplers Existing Substructure Abutment Thickness Abutment Strength Loading on Abutments Substructure Restrictions Main Railway Related Details Soffit Profile & Clearances Curvature and Clearance Requirements Standard vehicle gauges Analysis Envelope profile Electrical protection, earthing and bonding Protection from stray currents Ancilliary Railway Related Details OHLE Fixings Bridge ID Plates Main Highway Related Details Existing Masonry Bridge Widths Existing Masonry Overbridge Reconstructions Proposed New Overbridges Internal Bridge Width Road Restraint Systems Highway Alignment and Cross Fall Criteria Road Surfacing Material Asphaltic Plug Joints Footpath Construction Road Drainage Details Sub-Surface Drainage Ancilliary Highway Related Details Service Duct Size and Location Lighting Columns Fixings Conarch calculator Input Data Layout Design Reinforcement Scheduling Tool Standard Drawings & Details Standard Design Precast Concrete Unit Drawings Standard Design Parapet Beam Precast Concrete Unit Drawings Standard Detail Precast Concrete Unit Drawings 34 4 of 50

5 Standard Detail In-situ Concrete Drawings Standard Details Drawings Site Construction Methodology Construction Guidance Conarch Unit Weights Temporary Restraint Ties and Beams Temporary Restraint Ties Temporary Restraint Beams Trial erection Site Installation Cill Units & Bearings Inner and Edge Units Shear Key Joints In-situ concrete and waterproofing Existing Wing Walls Abutment Backfill Transition Parapet Slabs & Parapets Kerbs, Road and Pavement Surfacing and Drainage Scheme Specific Design Process Background Data Initial Feasibility Flow Chart Site Surveys Feasibility Study Conarch Calculator Further Site Surveys Detailed Design Re-use of existing sub-structure Criteria Criteria Criteria Scheme Specific Designers Responsibilities Scheme Specific details Standard Designs and Details Conarch Calculator Standard Design Precast Concrete Unit Drawings Standard Detail Precast Concrete Unit Drawings Standard Detail In-situ Concrete Drawings Standard Details Drawings Site Specific Form A Contents Summary 49 ANNEXE 1 Schedule Of Standard Drawings ANNEXE 2 Standard Vehicle Gauges & Profile Envelope Sketches ANNEXE 3 Excel Spread Sheet For Envelope Profiles ANNEXE 4 Conarch Structure Details ANNEXE 5 Conarch Bridge Span Variance Sketch ANNEXE 6 Conarch Bridge Deck Width Variance Sketch ANNEXE 7 Construction Sequence ANNEXE 8 Road Vertical Profile Envelopes ANNEXE 9 Design Risk Assessment ANNEXE 10 Conarch Calculator 5 of 50

6 Definitions Span: Clearance: Carriageway: Conarch calculator: Tunnel: clear distance between inside face of precast units, on elevation clear distance between inside face of parapet panels, perpendicular to the road distance between kerbs, road width active design spreadsheet soffit profile of precast units Conarch Structure 6 of 50

7 1. INTRODUCTION A library of Standard Designs and Details for the reinforced concrete Conarch Units for masonry arch overbridge reconstructions 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. Advice on circumstances when the Standard Designs and Details may not be used. 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 CONARCH SUITE DOCUMENTS The conarch suite of Standard Designs and Details includes the following documents: Technical User Manual This document provides the following information: Details of the design process to be followed. Details of the standard designs and how they are to be incorporated into the Scheme Specific Design. Details of the standard details and how they are to be incorporated into the Scheme Specific Design. Instructions on the use of the Conarch Calculator during the scheme specific design process Standard Design Inner & Edge Precast Concrete Unit Drawings General arrangement and reinforced concrete detailed drawings for the Inner and Edge Units for the following spans and skews: 7.4 metre span o Square span o 15 skew span both left and right skew o 30 skew span both left and right skew o 45 skew span both left and right skew 8.4 metre span o Square span o 15 skew span both left and right skew o 30 skew span both left and right skew o 45 skew span both left and right skew 9.4 metre span o Square span o 15 skew span both left and right skew o 30 skew span both left and right skew o 45 skew span both left and right skew 7 of 50

8 Standard Design Parapet Beam Precast Concrete Unit Drawings General arrangement drawings for the Parapet Beams between a curved and horizontal top profile for the following spans and skews: 7.4 metre span o Square span o 15 skew span both left and right skew o 30 skew span both left and right skew o 45 skew span both left and right skew 8.4 metre span o Square span o 15 skew span both left and right skew o 30 skew span both left and right skew o 45 skew span both left and right skew 9.4 metre span o Square span o 15 skew span both left and right skew o 30 skew span both left and right skew o 45 skew span both left and right skew Reinforcement layout drawings for the Parapet Beams for the following spans and skews: 7.4 metre span o Square span 9.4 metre span o 45 skew span right skew Standard Detail Precast Concrete Unit Drawings Generic general arrangement and reinforced concrete detailed drawings for the Parapets, Transition Parapet Edge Upstand Beams and Cill Units Standard Detail In-situ Concrete Drawings Generic general arrangement and reinforced concrete detailed drawings for the Backfill Reinforced Concrete, Capping Slab Reinforced Concrete and Transition Parapet Slab Reinforced Concrete Standard Details Drawings Generic general arrangement drawings for the following elements: Construction Sequence Concrete Finishing Details Lifting Details Waterproofing details Road Surfacing details Transition Parapet layout details Conarch Calculator The Conarch Calculator is an active spread sheet to assist the Scheme Specific Designer with the detailing of the replacement bridge structure. The spread sheet has two sections as follows: Layout Calculator 8 of 50

9 This section allows the scheme specific designer to input the data of the existing structure and will then provide layout details of the proposed conarch structure components. Precast Reinforced Concrete Scheduling Tool This section will then provide the reinforcement schedules for the Inner Units, Edge Units, Parapet Beams, Parapet Panels and Cill Beams as generated from the layout calculator USE OF NETWORK RAIL STANDARD DESIGNS AND DETAILS The following flowchart demonstrates the use of the Technical User Manual and Standard Design and Standard Detail 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 overbridge solution. Specific Site Requirements Technical User Manual Scheme Specific Designer Input Conarch Calculator Standard Drawings Standard Details Conarch Design Solution 1.3. SAFETY/CDM AND ENVIRONMENTAL General The general (non site specific) risks associated with the bridge design, construction and operation are listed in the Designer Risk Assessment, Appendix 9. 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 but should include looking into the effect the additional land required for the ramp will have on the locality, whether the protective coating needs to be changed to avoid the possibility that its renewal may contaminate watercourses and the aesthetic effect of the bridge s presence, which may have requirements for bridge colouration or other details. 9 of 50

10 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 Possession Plan Availability and lengths of possessions will vary from site to site. The longest single element of the reconstruction works will be the demolition of the existing structure and it is anticipated that a minimum possession length of 26 hours will be required for the demolition of a single span two lane bridge. The reconstruction process can be undertaken with individual or a number of Conarch Units being erected in a series of short Rules of Route Possessions, or all the conarch units erected in a single long possession if available Design Risk Assessment The generic design risk assessment of the Standard Designs and Details is included in Annex 9 of this document. It is for the Scheme Specific Designer to take responsibility for the document and amend the document by adding site specific risks or deleting risks as they designed out NATIONAL DESIGN CODES The design was carried out to Euro Code (EC) and to EC National Annexes (EC NA) using the following documents: General Design Requirements: EC0 and EC NA0 Basis of structural design were used Actions and loadings: EC1 1.1 and EC NA1 1.1 Densities, self-weight, imposed loads for buildings EC1 1.3 and EC NA1 1.3 Snow loads EC1 1.4 and EC NA1 1.4 Wind actions EC1 1.5 and EC NA1 1.5 Thermal actions EC1 1.6 and EC NA1 1.6 Actions during execution EC1 1.7 and EC NA1 1.7 Accidental actions EC1 2 and EC NA1 2 Traffic loads on bridges Concrete design: EC2 1.1 and EC NA2 1.1 General rules and rules for buildings EC2 2 and EC NA2 2 Concrete bridges, Design and detailing rules Abutment strength: EC6 1.1 and EC NA6 1.1 General rules for reinforced and unreinforced masonry structures Geotechnical design EC7 1 and EC NA7 1 General rules Bar bending schedule: BS 4449 Steel for the reinforcement of concrete 10 of 50

11 1.5. NETWORK RAIL APPROVAL DOCUMENTS The following Network Rail documents form part of the design approval process: Network Rail Form A document signed by DPE Bridges on 24 th September 2008 Tony Gee Addendum to Form A Document no. L109004/501/Addendum No.1 Alternative Conarch Design dated 26 th May Tony Gee Addendum to Form A Document no. L109004/501/Addendum No.2 Eurocode Requirements dated 18 th November of 50

12 2. EXECUTIVE SUMMARY To improve the efficiency in terms of time scales and driving down the costs of the reconstructions of masonry arch overbridges required as part of gauge enhancement and overhead electrification schemes, the Conarch Unit Standard Design Project has developed in addition to a Suite of Standard Drawings and Details a site specific design procedure that will suit a large range of bridge geometrical layouts. The site specific design procedure includes an active design spread sheet (Conarch calculator) that the Scheme Specific Designer uses to determine the basic structural layout parameters and the reinforcement schedules of the main precast units required for each structure BENEFITS OF USING THE STANDARD DESIGNS At Each Bridge Location The major benefits at each bridge location are as follows: Increased railway gauge clearance beneath the structure for both gauge enhancement and OHLE electrification schemes with minimum road profile changes across the structure. Flexible geometry: Existing bridge spans between 7.4 and 9.4 metres Existing skews between 0 to 45º, both left and right hand Existing internal bridge widths between 4.5 and 12.5 metres High containment parapets (H4a) are provided for each structure with standard details for the approach parapet transitions. Significant reduction in design time associated with the use of the standard designs for the precast units and associated standard details which can be generated utilising the Conarch Calculator Scheme Specific Designer The major benefits to the Scheme Specific Designer are as follows: Initial feasibility of the overbridge reconstruction using the conarch units can be undertaken in a short timescale utilising the Conarch Calculator. All precast conarch units have been designed with available reinforcement schedules available for the Inner Units, Edge Units, Parapet Beams, Parapet Panels and Cill beams which can be generated utilising the Conarch Calculator. Significant reduction in design time associated with the use of the standard designs for the precast units and associated standard details Precast Concrete Manufacturer The major benefits to the precast concrete manufacturer are as follows: Units have a common central curved Soffit Tunnel Profile perpendicular to the tracks with the two support legs formed with straight vertical and sloping sections. The span range is achieved by varying the height of the vertical and the length of the sloping components of the legs. For all spans the common central curved Soffit Tunnel Profile is utilised for a length of 7.4 metres perpendicular to the track. For spans between 7.4 and 9.4 metres extension straight side Soffit Shutters formed of vertical and sloping sections are added to the main soffit tunnel unit to suit the specific site geometry. 12 of 50

13 High degree of standardisation on reinforcement layouts and details GEOMETRICAL ENVELOPE The project allows for the conarch units to be produced within the following parameters: Span Internal face of unit span range is between 7.4 and 9.4 metres Skew Skew range is between 0º (square) and 45º both right and left hand Rise Rise from foot of unit to crown of arch is 2.2 metres Bridge Width The internal width at road level between parapets can extend from a minimum width of metres (14ft 9¼in), up to any required width by varying the width of the Inner Units (900 to 1250mm) except for a small zone between metres (17ft 1½in) and 5.360metres (17ft 7in). If a bridge width is required in this zone then the scheme specific designer will need to consider a small increase in the bridge width with the cill units extending over the end of the abutments by up to 70mm Construction Depth The minimum construction depth at the crown of the arch is 575mm which is formed of the following items: Road surfacing 100mm Waterproofing & Protection 25mm Capping slab concrete 150mm Conarch unit 300mm 2.3. ROAD PROFILE Vertical Profile The minimum road vertical curve radius is metres with the minimum construction depth at the crown for all the square spans. For the skew spans the minimum vertical curve will be dependent on both the internal width of the bridge and the skew. For internal bridge widths between the parapets of metres the minimum vertical curve for varying skews are as follows: 15º metres 30º metres 45º metres To achieve a constant section of road surfacing material across the structure, the difference between the underside of the road material profile and the top of the conarch units is made up by varying the thickness of the capping slab Horizontal Profile It is assumed that at most bridges there will be no requirement for any major changes to the highway horizontal alignment except for minor local changes to suit the run on to and the run off from the bridge. 13 of 50

14 The ideal alignment is expected to be straight across the bridge deck, but any existing curvature can be replicated within the existing width of the bridge GAUGE CLEARANCES The Conarch Soffit Tunnel Profile has been designed to suit a double track railway (standard 1970mm sixfoot) and be clear of the gauge envelopes for both straight and curved track using the following parameters from GE/RT8073: The dynamic vehicle profiles listed in GE/RT8073 have been enlarged to include for the end and centre throw from a 360 metre radius curve. The straight track is set out about the centre line of the structure, with the curved track translated side ways to include for the cant and the curvature through the opening. The versine (offset) for a 360 metre curve through the maximum bridge width of 12.5 metres is 54mm. The dynamic vehicle profiles are shown with 150mm of track cant. The clearance required to the dynamic vehicle envelopes for both the curved and straight track are to have the normal clearance of 100mm plus an additional 50mm to include for future track lifting and or slewing. In addition an OHLE electrification envelope profile with 4640x1435mm pantograph is added. This gives a minimum headroom from the highest rail to the crown of the arch as follows: o Non OHLE electrified track 4455mm o OHLE Electrified track 4790mm The Scheme Specific Designer has the opportunity to change any of the above defined criteria which will have any affect on the highest rail to crown of the conarch dimension as follows: If the tracks pass through the bridge opening offset to the centre line then the vertical distance will increase. If the track curvature is reduced (radius is increased) and the cant reduced then the vertical dimension will reduce. If the track curvature is increased (radius is reduced) and the cant maintained then the vertical dimension will increase. If the sixfoot is reduced then the vertical height will reduce, likewise if the sixfoot dimension is increased the vertical height will increase CONARCH CALCULATOR The Conarch Calculator is an active spread sheet to assist the Scheme Specific Designer with the detailing of the replacement bridge structure Layout Design The Conarch Calculator is used to produce the following layout data which will be used by the Scheme Specific Designer to layout the proposed bridge structure on the detailed design drawings: The number required and widths of the Inner Conarch Units and the size of the gaps between. A section through the bridge perpendicular to the tracks showing the proposed railway gauge relative to the conarch. A plan of the proposed structure. 14 of 50

15 A section through the bridge showing the highway vertical longitudinal profile across the bridge. A cross-section through the bridge showing the layout of the carriageway and verges. An elevation of the parapet beam taking into consideration the bridge skew. Lifting details for the main units including the location of the cast in lifting anchors and unit tie bar requirements. Abutment loading from the new structure Reinforcement Scheduling Tool The Conarch Calculator is used to produce the reinforcement schedules to suit the span and skew of the scheme specific bridge for the following units: Edge Units Inner Units Parapet Beam And Parapet Panels Cill Units Transition Parapet Edge Upstand Beams The Conarch Calculator provides reinforcement details to suit the span and skew of the scheme specific bridge for the following elements: Shear key joints Backfill concrete including the rear vertical saw tooth profile Capping slab Transition Parapet Slab 15 of 50

16 3. DESIGN ASSUMPTIONS AND RESTRICTIONS 3.1. STRUCTURAL ANALYSIS MODELLING & ACTIONS Structural Models LUSAS model LUSAS, a three dimensional structural analysis programme was used to undertake the structural analysis of the conarch models Model Geometry Twelve models were constructed and analysed to cover the following span and skew options as detailed below: 7.4 metre span, with square span, 15º skew, 30º skew and 45º skew. 8.4 metre span, with square span, 15º skew, 30º skew and 45º skew. 9.4 metre span, with square span, 15º skew, 30º skew and 45º skew. Each model was formed of two conarch Edge Units 1725mm wide and four conarch Inner Units 1250mm wide to provide a bridge arrangement that provided a nominal width between the parapets of 7.62 metres (25 feet) Actions Dead Load & Superdead Load The dead load densities of the conarch structure were taken as follows: Reinforced concrete 28kN/m³ Asphalt 24kN/m³ Masonry 25 kn/m³ Wind Load, Thermal Action and Snow Load The following wind loads and thermal loads cover the worst conditions in the UK up to an altitude of 452 metres at the Druimachdar summit on the line between Perth and Inverness and represent one hundred and twenty year return period. The maximum wind map velocity has been taken as 30m/s given in EC1 1.4: Figure NA.1; exposure factor as 4.2 given in EC1 1.4: Figure NA.7 and wind load factor as 4.0 given in EC1 1.4: NA Minimum and maximum air shade temperatures have been taken as -21 C and +35 C given in EC1 1.5: Figure NA.1 & NA.2. Snow load may generally be ignored in the UK as EC0 NA Traffic Load Load Model 1: Tandem System (TS) in Lane 1 300kN, Lane 2 200; UDL System in Lane kn/m 2, other lanes 2.5 kn/m 2 given in EC1 2: Load Model 2: Single Axle (SA) 400kN given in EC1 2: NA Load Model 3: Special Vehicle (SV) as VS196, 1500 kn given in EC1 2: NA Load Model 4: crowd loading as 5.0 kn/m 2 given in EC1 2: LM1, LM2, LM3 and LM4 were applied to the model. Maximum two lanes of traffic. 16 of 50

17 Accidental Actions Vehicles on footway: 200kN axle load given in EC1 2: Collision force on kerbs: 100kN load given in EC1 2: Collision to vehicle restrain system: 600kN transverse, 100kN longitudinal and 175 vertical force given in EC1 2: NA Load Model 2: Single Axle (SA) 400kN given in EC1 2: NA Load Model 3: Special Vehicle (SV) as VS196, 1500 kn given in EC1 2: NA Differential Settlement Lateral Displacement Each model allowed for long term rearward movement of a total of 15mm at each abutment Verifications Ψ Factor Combinations of actions were defined as given in EC0: NA Ultimate Limit State EQU : Loss of static equilibrium of the structure or any part of it considered as a rigid body given in EC0: STR: Internal failure or excessive deformation of the structure or structural members given in EC0: GEO: Failure or excessive deformation of the ground where the strengths of soil or rock are significant in providing resistance given in EC0: FAT : Fatigue failure of the structure or structural members given in EC0: Serviceability Limit State Fundamental combination was used as 6.15b given in EC0: NA of 50

18 4. BACKGROUND OF THE CONARCH STANDARD DESIGN AND DETAILS 4.1. CONARCH UNIT DETAILS The conarch units have been designed to suit overbridge clear square spans of between 7.4 and 9.4 metres with a skew up to 45, with a rise at the crown of 2.2 metres. Sections through the 7.4, 8.4 and 9.4 metre spans for both the Inner and Edge Units are shown on a sketch in Annexe 6 of this document. The Soffit Profile perpendicular to the tracks has been designed so that the centre section which extends 3.7 metres either side of the centre line is common for the whole span range. This section covers the full width of the smallest span of 7.4 metres and to complete the 7.4 metre span conarches vertical legs are provided on each side. The spans are increased up to 9.4 metres by extending the ends of the central sections tangentially downwards on a slope in conjunction with reducing the height of the vertical leg to provide the constant arch rise. The intermediate span of 8.4 metres has legs which have the upper section inclined and the lower section vertical. The maximum span of 9.4 metres has the majority of the leg inclined with a small vertical section at the bottom. This means that a single soffit shutter, Tunnel Profile, supporting the central common section can be constructed by the precast concrete manufacturer, with varying leg shutters at each end to suit the bridge span being cast. See sketch in Annexe 5 of this document Conarch Unit Widths The width of the Edge and Inner Arch Units have been sized to suit the bridge widths identified in Section 4.4.1, taking into consideration the effect that the unit weight will have on the delivery to site, craneage and erection methodology Edge units The Edge Units are of a constant width of 1745mm and have been developed to accommodate a separate parapet beam which supports either a masonry sandwich or reinforced concrete high containment parapet (H4a). The Edge Units will be manufactured off site and brought to site as a single unit and lifted in to place Inner units The Inner Units have been designed with a maximum width of 1250mm with standard reinforcement schedules to suit this width, but to allow the flexibility of varying bridge widths the site specific designer can specify widths down to 900mm. There is no required change to the reinforcement schedules except that (i) the external links which are formed from two U bars decrease in length and increase in number and (ii) the longitudinal reinforcement will need to be displaced side ways and re spaced to suit the revised width Tie Bars Temporary tie bars are required to be provided to the edge and inner units to maintain their geometry until the units have been erected. 18 of 50

19 Parapet Beams Dependant on the span, the Parapet Beam and Parapets can be transported to site as a single unit and lifted in or for the larger spans the Parapet Beam can be transported to site as a single unit, set up on the ground adjacent to the bridge allowing the Parapets to be constructed before being lifted into place. For either situation the parapet beam needs to be supported for its full length when the parapet panels are constructed. The Parapet Beam is designed to be supported off a return wall directly above the abutments with the spandrel wall set back to the inside face of the Parapet Beam. This alleviates the problem of match casting the Parapet Beam onto the Edge Unit and allows the Parapet Beam to be cast separately from the Edge Unit. A standard shear key joint will be provided between the Parapet Beam and the Edge Unit central section. In addition reinforcement couplers will be provided at close centres along the top of the inside face of the parapet beam. This is to allow site transverse reinforcement to be fixed as part of the in-situ capping slab over the Inner Units to transfer the high transverse loads from the high containment parapets into the main bridge structure. The Parapet Beams have been designed to support a high containment Parapet up to a maximum height of metres above the adjacent verge/footpath level, with the road longitudinal profile varying from the minimum radius up to a horizontal profile. To suit the horizontal road longitudinal profile, the Parapet Beam is increased in depth at the ends Infill concrete top profile The top profile of the lower surface on the parapet beam will be designed to match the top profile of the infill concrete and capping slab, which in turn is determined from the design vertical road alignment and surfacing for each individual site Parapet beam top profile The parapet beam top profile (upper top surface) forms the interface with the parapet panels. For any given bridge, the profile is a constant height above the infill concrete top profile, but the height adopted can vary dependent on the following:: The width and cross fall on the verges/footpaths Increase in depth (maximum 95mm) of verges/footpaths to accommodate service ducts Parapet panels The conarch superstructure is designed to support high containment parapets (H4a) up to a maximum height of 1825mm above the adjacent footpath/verge level Type of parapet The conarch suite provides typical details of masonry sandwich or reinforced concrete parapets Length and Number of panels The length and the number of Panels is dependent on the total length of the Parapet Beam Construction Depth The minimum construction depth at the crown of the arch is 575mm which is formed of the following items: Road surfacing 100mm Waterproofing & Protection 25mm 19 of 50

20 Capping slab concrete Conarch unit 150mm 300mm Capping Slab For the square span structures with the minimum road curvature the capping slab has a constant thickness of 150mm across the conarch units, with a constant section through the road surfacing material. For all the other road profile conditions, to achieve a constant section of road surfacing material across the structure, the difference between the underside of the road material profile and the top of the conarch units is made up by varying the thickness of the capping slab Rear Vertical Saw Tooth Profile to Backfill Concrete To provide adequate horizontal restraint to the ends of the conarch units parallel to centre line of the units from the abutment backfill material a vertical saw tooth profile is required. The rear face of the in-situ concrete saw tooth profile is set perpendicular to the centre line of the conarch units and is the same width as the conarch unit, with the depth of the side surfaces increasing with the skew. At the acute corners of skew bridges the transverse tie bars from the parapet beams are turned down into the back fill concrete to provide the appropriate anchorage Concrete Specification and Nominal Cover to Reinforcement The reinforced concrete grade and cover has been derived as follows: Concrete Specification The concrete specification for all precast concrete units and insitu concrete is to be: Class C40/50 Nominal maximum aggregate size 20mm Maximum water/cement ratio 0.45 Minimum cement content 360kg/m³ Nominal Cover to Reinforcement The nominal cover to the reinforcement is in accordance with BS EN Exposure classes are as follows: XC1 Nominal Cover 30mm XD1 Nominal Cover 40mm XF2 Nominal Cover 60mm The nominal cover includes a fixing tolerance as follows: Precast concrete +/- 5mm Insitu concrete +/- 10mm Couplers Reinforcement couplers are required to be used for the continuity of the main transverse reinforcement in the top of the capping slab from the parapet beams. It is proposed to use full strength parallel threaded screwed couplers such as Ancon Bartec Type A couplers or similar approved in the central area where the connecting bars can be rotated and Ancon Bartec Type B couplers or similar approved at each end where the connecting bars cannot be rotated. 20 of 50

21 4.2. EXISTING SUBSTRUCTURE The following assumptions have been made with regard to the existing abutments: Abutment Thickness It has been assumed that the minimum abutment thickness is 1200mm for a square span increasing proportionally up to 1750mm for a 45º skew span. It is for the site specific designer to verify the thickness of the abutments through coring, see section Abutment Strength It has been assumed that the existing masonry abutments have a minimum strength of clay masonry units with M6 mortar Loading on Abutments The following schedules identify the loading from the twelve analysis models at the underside of the cill units. The Scheme Specific Designer will need to check the interpolated value taken from the table below to suit the site specific span and skew against the calculated capacity of the existing abutments on site including the overall stability. See section 6.8. The following table defines the load required to be transferred into the abutments for the twelve structural models. The table shows the GEO loading, which is failure or excessive deformation of the ground where the strengths of soil or rock are significant in providing resistance (EC0 6.4). In simplistic terms: safety factor of dead load is 1.00; the live load is 1.15; wind 1.45 and thermal actions Skew 7.4m Span 8.4m Span 9.4m Span GEO Vertical load (kn) Horizontal load (kn) Vertical load (kn) Horizontal load (kn) Vertical load (kn) Horizontal load (kn) Square 2,988 3,137 3,145 2,983 3,463 2,932 15º 3,095 3,087 3,255 2,916 3,575 2,624 30º 3,294 2,867 3,495 2,480 3,922 2,976 45º 3,760 2,198 4,141 2,993 4,335 3, Substructure Restrictions Actual substructure restrictions will need to be determined by the Scheme Specific Designer as following: Comparing the existing masonry arch bridge loading on to substructure with that identified in this document for the new structure. Any available ground investigation information. General condition of existing bridge MAIN RAILWAY RELATED DETAILS Soffit Profile & Clearances The soffit profile of the conarch unitss perpendicular to the tracks has been developed in consultation with the Network Rail Gauging Engineer at York to be clear of all the vehicle profiles detailed in Railway Group Standard GE/RT8073 and the minimum headroom 21 of 50

22 required for future electrification of 4640mm as defined in section A.8.1a Notes on Standard Structure Gauge of the Track Design Handbook NR/L2/TRK/2049 issue 11. All eleven standard vehicle gauges have been reviewed and an envelope produced for both straight and curved track Curvature and Clearance Requirements Gauge envelopes have been developed for both straight and curved track using the following parameters: The dynamic vehicle profiles listed for straight track have been generated from the railway standard. The dynamic vehicle profiles for the curved track are based on the straight track profiles enlarged to include for the end and centre throw from a 360 metre radius curve. The clearance required to the dynamic vehicle envelopes for both the curved and straight track are to have the normal clearance of 100mm plus an additional 50mm to include for future track lifting and or slewing. The above envelopes were then plotted on bridge openings with the following parameters: Two tracks 3405mm apart (1970 sixfoot), for both straight and curved track. The minimum curve radius of 360m was plotted with the maximum cant of 150mm. The straight track is set out about the centre line of the structure, with the curved track translated side ways to include for the cant and the curvature through the opening. The versine (offset) for a 360 metre curve through the maximum bridge width of 12.5 metres is 54mm. Electrification envelope profile with 4640x1435mm pantograph. Range of span from 7.4m to 9.4m. Height of concrete conarch unit 2.2m. This gives a minimum headroom from the highest rail to the crown of the arch as follows: Non OHLE electrified track 4455mm OHLE electrified track 4790mm Standard vehicle gauges The eleven available vehicle gauges are given in GE/RT8073 s Appendices. The coordinates are given for static and dynamic cases, incorporating with 35m/s side wind load, and the overthrows formulas on curved track are given for each different profile. W6a W7 W8 Upper gauge: Table A.2 Lower gauge: Table A.3 Overthrow: Upper gauge: Table B.2 Lower gauge: Table B.3 Overthrow: Upper gauge: Table C.2 Lower gauge: Table C.3 22 of 50

23 W9 W9+ W10 W11 W12 WC1 WC1-Appendix A Locomotive Overthrow: Upper gauge: Table D2 Lower gauge: Table D.3 Overthrow: Upper gauge: Table E.2 Lower gauge: Table E.3 Overthrow: Gauge: Table F.3 Overthrow: Gauge: Table G.3 Overthrow: Gauge: Table H.3 Overthrow: Upper gauge: Table I.6 & I.7 Lower gauge: Table I.4 Overthrow: Upper gauge: Table J.2 Lower gauge: Table J.3 & J.4 Overthrow: Gauge: Table L.2 Overthrow: Analysis A calculating Excel spread sheet has been made to determine the envelope of the profiles for both straight and 360m radius curved track including dynamic effect and overthrow where appropriate. The spread sheet is included in Annexe 3 of this document Envelope profile Sketches in Annexe 2 of this document show the available clearances from the design envelopes for both straight and curved track, with and without the requirement for clearances to provide OHLE equipment through the bridge opening. Please note the clearance between the two vehicles with a standard sixfoot of 1970mm on curved track, is very tight but there is still enough space for the 100mm passing clearance Electrical protection, earthing and bonding A draft copy of NR/L2/CIV/020 Design of Bridges & Culverts identifies the following issues with regards to electrical protection, earthing and bonding that need to be considered. 23 of 50

24 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 non-conducting fencing. Trays or ladders which support electrical cables and are attached to a Bridge shall be earthed to the Bridge. In D.C. electrified areas, Bridges shall not be bonded to the negative return rail unless otherwise agreed with Network Rail. 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. 24 of 50

25 Protection from stray currents A draft copy of NR/L2/CIV/020 Design of Bridges & Culverts identifies the following issues with regards to protection from stray currents that need to be considered. Where third rail D.C. electrification, or dual overhead A.C. and third 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 Rail as to the 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 ANCILLIARY RAILWAY RELATED DETAILS OHLE Fixings If there is a requirement to fix OHLE equipment to the underside of the Soffit of the bridge, the fixing should be located within the joints between the conarch units. No drilling into the actual soffit of the conarch units will be permitted. It will be the responsibility of the Scheme Specific Designer to check the capacity of the fixings of OHLE equipment Bridge ID Plates Bridge ID plates are to be provided at track level on both sides of the bridge MAIN HIGHWAY RELATED DETAILS Existing Masonry Bridge Widths Historically, the Acts of Parliament that the original railway routes were built under required the majority of the road over rail bridges to be constructed with either 15 feet (4.57m) between the parapets for small country public roads and accommodation access routes or 25 feet (7.62m) for main roads. Typically the parapets on these bridges were 18 inches thick (457mm) Existing Masonry Overbridge Reconstructions As the 4.57 metres (15ft) and 7.62 metres (25ft) width between parapet masonry arch bridges are the most common widths that will require to be reconstructed, the conarch units have been sized so that common Edge Units can be used with varying numbers of Internal Units which also can vary in width from 900 to 1250mm to make up the bridge widths. A sketch showing the proposed units layouts for the 4.57 metres (15ft) and 7.62 metres (25ft) width between parapet bridges are included in Annexe 6 of this document Proposed New Overbridges The most likely use of the arch units in new bridge constructions is for a new bridge to carry a road diversion allowing an existing level crossing to be closed. It would be expected that the bridge would need to carry a new two lane highway with a footpath on one side 25 of 50

26 and a verge on the other. A sketch showing the proposed units layout for these bridge width is included in Annexe 6 of this document Internal Bridge Width The internal width at road level between Parapets can extend from a minimum width of 4.5 metres (14ft 9¼in), up to 12.5 metres by varying the width of the Inner Units (900 to 1250mm) except for a small zone between metres (17ft 1½in) and metres (17ft 7in). If a bridge width is required in this zone then the Scheme Specific Designer will need to consider a small increase in the bridge width with the cill units extending over the end the abutments by up to 70mm. The Conarch Standard Details provide a bridge cross section that is formed from two Edge Conarch Units and multiple numbers of varying width Inner Conarch Units to provide the required road width. The Edge Units and Parapet Beam with high containment parapets are 1745mm wide and are common for all bridge widths, with the overall width made up of Inner Units which can each be provided with a width between 900 and 1250mm. A schedule of the unit numbers and widths for varying bridge widths is shown in the table below: Overall Bridge Width (m) Width between Parapets (m) Width between Parapets (ft) Edge unit Width (mm) Inner unit Width (mm) Joint Width (mm) ft 9¼in 2 x x x ft 2 x x x ft 2 x x x ft 0¾in 2 x x x 30 No available combination of Units in range of 5220mm mm (17 ft 1½in - 17 ft 7in) ft 7½in 2 x x x ft 8½in 2 x x x ft 2in 2 x x x ft 2¼in 2 x x x ft 2 x x x ft 4in 2 x x x ft 7¾in 2 x x x 20 Any width available beyond 5.4m between parapets by adjusting number and width of Inner units 26 of 50

27 Road Restraint Systems TD19/06 Requirement for Road Restraint Systems TD19/06 describes the requirements for road restraint systems in the area of bridges covering both the approach and departure areas and the bridge parapets. Figure 1.2 defines the vehicle restraint system at bridges as follows: Safety fence road vehicle restraint system either side of the structure Transition Interface between two restraint systems Vehicle Parapet safety barrier installed on the edge of a bridge The main requirement of TD19/06 is that the Road Restraint Risk Assessment Process is undertaken at each bridge to determine the containment level of the bridge parapet and safety fences. It is the responsibility of the Scheme Specific Designer to undertake this risk assessment Very High Containment Parapets (H4a) For new structures over railways TD19/06 requires very high containment parapets (H4a) to be provided, but where parapets on existing structures are to be replaced it requires the highest possible containment to be provided, but not less than normal (N2). It is a Network Rail Policy to provide high containment parapets (H4a) to all public highway bridges with normal containment parapets for accommodation bridges. To reduce the number of structural options the standard conarch designs only provide details of the very high containment parapets which will be used at all locations Parapet Types The Conarch Standard Drawings provide details for both very high containment reinforced Concrete Parapets in accordance with BS :1991 and very high containment Reinforced Masonry Parapet in accordance with BS :1999. The Scheme Specific Designer has the opportunity where the site specific requirements allow, to use other forms of very high containment parapets such as a steel (H4a) parapet or subject to any site specific risk assessments a normal containment (N2) parapet Parapet Heights The standard design includes for the high containment parapets up to a maximum height of metres above the adjacent verge/pavement level. The Scheme Specific Designer is to set the top level of the parapets on both sides of the road either 1525mm (normal conditions) or 1825mm (bridle paths) above the design footpath/verge profile. The height of the Parapet Beam is adjusted so that there is a constant parapet height above the design road vertical profile Parapet Ends The very high containment parapet ends will be provided square to the road alignment with cast in anchorages for the connections from the adjacent transition parapets section of the approach and departure safety fences. The following Highway Construction Detail drawings are used for this connection: SB/151 Connection Bracket SB/152 Cast in anchor unit 27 of 50

28 Safety Fences and Transitions Standard details for the approach and departure safety fences and the transitions on to the very high containment parapets of the conarch structure are based on the Highway Construction Details Double Rail Open Box Beam Safety Fence Connection to Structure (Verge) as follows: GA/84 Connection to structure GA/85 Connection to HVCB or concrete structure at approach end (Sht 1of 5) GA/86 Connection to HVCB or concrete structure at approach end (Sht 2of 5) GA/87 Connection to HVCB or concrete structure at approach end (Sht 3of 5) GA/88 Connection to HVCB or concrete structure at approach end (Sht 4of 5) GA/89 Connection to HVCB or concrete structure at approach end (Sht 5of 5) GA/90 Connection to HVCB or concrete structure at departure end (Sht 1of 3) GA/91 Connection to HVCB or concrete structure at departure end (Sht 2of 3) GA/92 Connection to HVCB or concrete structure at departure end (Sht 3of 3) These construction details have been developed for the conarch structure to take into consideration the need to provide an adequate restraint to the transition length of the safety fence directly behind the abutments above the existing masonry wing walls. It is proposed that a reinforced parapet transition slab is provided over the wing walls to support the transition length of the safety fence on either side. This will extend away from the bridge for a length of 13.8 metres to provide support to all seven 150x150 RHS fence posts. Beyond this point the zed section posts will concreted into the ground as per the construction detail drawings Transition Parapet Support Slab The transition support slab is formed of precast concrete Edge Upstand Beams that sit on top of the wing walls, nominally 1500mm wide that support the posts of the Transition Parapet. An in-situ concrete slab is provided between the Edge Upstand Beams to tie them together. The Scheme Specific Designer will be responsible for determining the dimensions and alignment of these units to suit the site conditions Transition Parapet Infill For bridges over OHLE electrified lines, the Steel Transition Parapets are to be enclosed on the front face with a solid steel panel and provided with a solid steeple capping to the same height and profile as the bridge parapets for a distance back from the face of the abutment of 3 metres Highway Alignment and Cross Fall Criteria Highway Horizontal Alignment It is assumed that at most bridges there will be no requirement for any major changes to the highway horizontal alignment except for minor local changes to suit the run on to and the run off from the bridge. The ideal alignment is expected to be straight across the bridge deck, but any existing curvature can be replicated within the existing width of the bridge. 28 of 50

29 Highway Vertical Alignment The largest variable associated with the design of the conarch structures is the longitudinal vertical road profile which has an effect on the construction depth at the crown of the arch and the overall dead load of the structure. The conarch units have been designed to accommodate the loading from the vertical road profile from the minimum radius hog curve tight to the top of the conarch units up to a horizontal profile over the bridge with at least 5 metre horizontal sections before and after the structure (5 metre measured from outside face of 200mm backfill within the following ranges See also sketches in Annexe 8 of this document: Square Spans For square spans the longitudinal profile of the road always crosses over the structure perpendicular to the centre line of the conarch tunnel profile. Therefore the minimum radius of the road profile is equivalent to the radius of the top of the conarch units plus the minimum depth of the capping slab and road surfacing. Range 1 Symmetrical Profile The vertical road profile is assumed to be symmetrical about the centre line of the bridge varying from a minimum radius of metres up to a horizontal profile for the full length of the bridge. The minimum construction depth at the crown of the arch is maintained for all profiles. Range 2 Square Spans Asymmetrical Profile It is also acceptable to provide an asymmetrical vertical road profile about the centre line of the bridge varying from a minimum radius of metres up to a horizontal profile. The minimum construction depth at the crown of the arch is maintained for all profiles Skew Spans For any skew span, the longitudinal profile of the road will not cross over the structure perpendicular to the centre line of the conarch profiles. Therefore the minimum road profile vertical curve across the structure will be dependent on both the internal width of the bridge and the skew, the greater the skew and internal bridge width the greater the minimum radius. The minimum vertical curve radius will now be determined from the extreme positions of the upper haunches of the conarch units on the longest diagonal of the structure. The vertical curve through these two points parallel with the centre line of the road maintaining the minimum capping slab and road construction depth at the haunches will require the construction depth at the centre point of the bridge to be increased. See sketch in Annexe 8 of this document. Range 3 Symmetrical Profile The vertical road profile is assumed to be symmetrical about the centre point of the bridge varying from a minimum radius achieved by increasing the construction depth at the crown of the arch by up to a maximum of 200mm, up to a horizontal road profile with the minimum construction depth at the crown of the arch across the bridge. As the profile radius increases towards the horizontal the increase in construction depth at the arch crown reduces. With an internal bridge width between the parapets of metres the table below shows the minimum vertical curve for varying skews: Skew 7.4m Span 8.4m Span 9.4m Span Hog curve radius (m) Hog curve radius (m) Hog curve radius (m) 29 of 50

30 Square 20,667 20,667 20,667 15º 32,042 30,987 30,127 30º 51,257 48,717 46,637 45º 91,467 86,052 81,627 Range 4 Skew Spans Asymmetrical Profile It is also acceptable to provide an asymmetrical vertical road profile about the centre point of the bridge varying from a minimum radius on one side up to a horizontal profile on the other. For this range the increase in construction depth at the crown of the arch must be limited to a maximum of 100mm Camber and Crossfall The standard deck detail assumes that on a two lane highway there is a crown along the centre of the road with crossfalls of 1 in 40 to the kerb line. Any variance in the level of the bottom of the Parapet on each side of the bridge will be dependant on the width and the crossfall of the verge/footways. The Parapet Beam s upstand can be raised by maximum of 95mm in order to increase the diameter of service dusts under the verge/footways. The standard Parapet Beam detail assumes that the two beams are identical Road Surfacing Material The road surfacing will have a minimum construction depth of 125mm formed of a regulating road base course 60mm minimum thickness laid on 20mm thick red sand asphalt over the 5mm thick sprayed waterproofing membrane with a 40mm thick wearing course on top Asphaltic Plug Joints Asphaltic plug joints in the road surfacing at the rear of the abutment where the bridge deck meets the Transition Parapet Slab are to be provided for the full width of the road surfacing Footpath Construction The footpath will be formed from compacted Type 6N material behind a precast kerb with 25mm nominal thickness dense macadam wearing course with 6mm aggregate Road Drainage Details Curved Vertical Road Profiles On bridges which have a curved vertical road profile then it is not proposed to provide any surface water drainage across the bridge structure, but the Scheme Specific Designer will need to consider the requirement for drainage gullies on the bridge approaches Level or near Level Road Profiles On bridges with level or near level road profiles the Scheme Specific Designer will need to consider the requirement to provide kerb channel drains across the structure to manage the surface water on the deck. 30 of 50

31 Sub-Surface Drainage Sub-surface drainage is to be provided across the deck located on either side of each of the kerb lines. The drainage paths will be formed of 50x50 square perforated aluminium ducts wrapped in a geotextile fixed to the top of the conarch capping slab with a bitumen bedding ANCILLIARY HIGHWAY RELATED DETAILS Service Duct Size and Location If service ducts are required across the structure, they will be located within the verge or footpath construction above the main conarch units. The actual alignment and size of duct will be for the Scheme Specific Designer to determine. By increasing the upstand on the parapet beam will allow the maximum size of the service ducts to be increased. This uplift of the upstand must be less than 95mm Lighting Columns Fixings If lamp posts or other signs are required to be positioned on the bridge deck, a plinth with the appropriate holding down bolts will need to be cast above and connected into the Capping Slab above the conarch units. No connection is to be made into the Conarch Units. The Scheme Specific Designer is responsible for the design of the plinths and holding down bolt arrangement to suit the type of lamp post or sign post CONARCH CALCULATOR The Conarch Calculator is an active spread sheet to assist the scheme specific designer with the detailing of the replacement bridge structure. An example of the input and output of the calculator is included in Annexe 10 of this document Input Data The following data from the site survey and the layout of the proposed structure is to be input into the Conarch Calculator: Bridge location details (ELR, mileage etc) Railway data o Proposed railway vehicle gauge o Whether line is to be OHLE electrified o Track details: Cant Radius Sixfoot o Height from top of highest rail to soffit of proposed conarch units Structure data o Clear perpendicular distance (span) between the inside faces of abutments o Any sitback of units from face of abutments o Skew of bridge o Any uplift of parapet beams upstand Highway data: o Carriageway width and crossfalls o Verge/footpath widths and crossfalls o Highway construction thicknesses o Proposed highway longitudinal vertical curvature Parapet data: 31 of 50

32 o Type of parapet panel o Height of parapet panel o Number of parapet panels required Abutment data: o Size and number of dowels o Width of abutment o Existing loading on the abutment Layout Design From the input data the Conarch Calculator produces the following layout data which will be used by the Scheme Specific Designer to layout the proposed bridge structure on the detailed design drawings: The number required and widths of the Inner Conarch Units and the size of the gaps between. A section through the bridge perpendicular to the tracks showing the proposed railway gauge relative to the conarch. A plan of the proposed structure. A section through the bridge showing the highway vertical longitudinal profile across the bridge. A cross-section through the bridge showing the layout of the carriageway and verges. An elevation of the Parapet Beam taking into consideration of the bridge skew. Lifting details for the main units including the location of the cast in lifting anchors and unit tie bar requirements. Abutment loading from new structure Reinforcement Scheduling Tool The Conarch Calculator produces the reinforcement schedules to suit the span and skew of the scheme specific bridge for the following units: Edge Units Inner Units Parapet Beam and Parapet Panels Cill Units The Conarch Calculator provides reinforcement details to suit the span and skew of the scheme specific bridge for the following elements: Shear key joints Backfill concrete including the rear vertical saw tooth profile Capping slab 4.8. STANDARD DRAWINGS & DETAILS The following drawings have been produced and are detailed in Annex 1 of this document: Standard Design Precast Concrete Unit Drawings General arrangement and reinforced concrete detailed drawings for the Inner and Edge Units for the following spans and skews: 7.4 metre span o Square span o 15 skew span both left and right skew o 30 skew span both left and right skew 32 of 50

33 o 45 skew span both left and right skew 8.4 metre span o Square span o 15 skew span both left and right skew o 30 skew span both left and right skew o 45 skew span both left and right skew 9.4 metre span o Square span o 15 skew span both left and right skew o 30 skew span both left and right skew o 45 skew span both left and right skew These drawings are to be used as typical detail drawings for the intermediate spans and skews as follows: Geometry o Intermediate spans and skew Interpolate between lower span with lower skew drawing, lower span and higher skew drawing, higher span and lower skew drawing and higher span and higher skew drawing, i.e. if 7.9 metre span with 18º skew then interpolate between 7.4m span with 0º skew drawing, 7.4m span with 30º skew drawing, 8.4m span with 0º skew drawing, 8.4m span with 30º drawing. Reinforcement o Reinforcement schedules will be generated by the Conarch Calculator, for the layout of the reinforcement. Use the lower span and the upper span reinforcement drawings with appropriate skew as follows: Skew range 0º 15º, use 15º skew drawings Skew range 15º < 30º, use 30º skew drawings Skew range 30º 45º, use 45º skew drawings Standard Design Parapet Beam Precast Concrete Unit Drawings General arrangement drawings for the Parapet Beams between a curved and horizontal top profile for the following spans and skews: 7.4 metre span o Square span o 15 skew span both left and right skew o 30 skew span both left and right skew o 45 skew span both left and right skew 8.4 metre span o Square span o 15 skew span both left and right skew o 30 skew span both left and right skew o 45 skew span both left and right skew 9.4 metre span o Square span o 15 skew span both left and right skew o 30 skew span both left and right skew o 45 skew span both left and right skew Reinforcement layout drawings for the Parapet Beams for the following spans and skews: 7.4 metre span o Square span 33 of 50

34 9.4 metre span o 45 skew span right skew As the top profile of the parapet beam will be generated by the site specific designer to suit the proposed road profile, the typical drawings are to be used as reference drawings for the site specific parapet drawings as follows: Geometry o Intermediate spans and skew Interpolate between lower span with lower skew drawing, lower span and higher skew drawing, higher span and lower skew drawing and higher span and higher skew drawing, i.e. if 7.9 metre span with 18º skew then interpolate between 7.4m span with 0º skew drawing, 7.4m span with 30º skew drawing, 8.4m span with 0º skew drawing, 8.4m span with 30º drawing. Reinforcement o Reinforcement schedules will be generated by the Conarch Calculator, for the layout of the reinforcement. Use the 7.4m span and zero skew and the 9.4m span and 45º skew reinforcement drawings as reference drawings Standard Detail Precast Concrete Unit Drawings Generic general arrangement and reinforced concrete detailed drawings for the Parapets, Transition Parapet Edge Upstand Beams and Cill Units Standard Detail In-situ Concrete Drawings Generic general arrangement and reinforced concrete detailed drawings for the Backfill Reinforced Concrete, Capping Slab Reinforced Concrete and Transition Parapet Slab Reinforced Concrete Standard Details Drawings Generic general arrangement drawings for the following elements: Construction Sequence Concrete Finishing Details Lifting Details Waterproofing details Road Surfacing details Transition Parapet layout details 34 of 50

35 5. SITE CONSTRUCTION METHODOLOGY It is anticipated that both types of parapets will be constructed on to the Parapet Beam in the precast concrete factory and delivered to site as a single unit. If there are delivery and craneage issue that preclude this then the Parapets could be constructed on site CONSTRUCTION GUIDANCE The typical construction sequence of reconstruction of the masonry overbridge should be as follows (see Annexe 7 for precast unit installation): (a) Prepare site for construction work: clear vegetation, remove obstacles etc. (b) Install temporary road closure. (c) Undertake any service diversions or cap off services either side of bridge. (d) During normal hours remove fill off top of existing arch ensuring that the level difference of the excavation on either side of the bridge is not greater than 500mm. (e) During abnormal possession demolish existing parapets and arch down to springing level. Cut back wing walls to give clear working area. (f) During normal possessions, prepare abutment tops for new cill units. (g) During normal possessions lift in cill units, drill dowel holes and grout dowels in place. Allow grout to reach strength of 50N/mm² before installation of conarch units. (h) During normal possessions, lift in the inner conarch units, starting from the centre and working outwards. The vertical bearings behind the inner units must be packed solid before the temporary ties can be removed. Seal shear key joints and install longitudinal rebar as work progresses. (i) During normal possessions, lift in edge conarch units. The vertical bearings behind the inner units must be packed solid before the temporary ties can be removed. Seal shear key joints and install longitudinal rebar as work progresses. (j) During normal possessions lift in parapet beams and parapets and stabilise in place using temporary struts to top of parapet. Temporary struts to remain in place until the capping slab has been reached its designed strength. Seal shear key joints and install longitudinal rebar as work progresses. (k) Complete concreting of shear key joints. (l) Install rebar to rear of units and erected saw tooth vertical formwork. (m) Connect transverse reinforcement to parapet beam and complete rebar for capping slab. concrete capping slab. (n) Waterproofing bridge deck and install back of abutment drainage. (o) Backfill behind abutments with compacted material. (p) Install transition parapet upstand units and cast slab between. (q) Install transition parapet and approach twin box beam barriers. (r) Reinstate services. (s) Lay kerbs across the bridge deck. (t) Lay new road and footpath surfacing across the bridge deck. (u) Tie in road and footpath surfacing on both approaches to bridge. (v) Install asphaltic plug in road surfacing in line with the rear of the bridge deck (w) Clear site and reopen road. 35 of 50

36 5.2. CONARCH UNIT WEIGHTS With current construction methods and the reduced availability and length of possessions, it is unlikely that delivery to site by rail and erection using rail cranes will be considered by the Contractors. It is anticipate that a road mobile crane would be used to lift in the units, either positioned on the road behind the abutments or at ground/track level adjacent to one corner of the bridge. The dead weight of the individual units are shown in the tables below. These weights exclude the weight of any lifting shackles, beams and chains and additional weight from construction tolerances. Skew 7.4m Span 8.4m Span 9.4m Span Unit Inner (1250mm) Edge Parapet beam & panels Inner (1250mm) Edge Parapet beam & panels Inner (1250mm) Edge Parapet beam & panels Square º º º Skew 7.4m Span 8.4m Span 9.4m Span Parapet beam Horizontal Curved Horizontal Curved Horizontal Curved Square º º º Parapet panel 1525mm 1825mm 1525mm 1825mm 1525mm 1825mm Square º º º TEMPORARY RESTRAINT TIES AND BEAMS Temporary Restraint Ties Temporary restraint ties will be required to be provided to the edge and inner conarch units to ensure the correct geometry of the legs during transportation and erection on site. cast-in DEHA lifting connectors or similar approved are provided in the legs of all the units to allow the restraint ties to be attached to the units. The restraint ties are to be installed immediately the units have been lifted off the tunnel shutter and before they are set down on the ground. The ties are to be adjusted to provide the correct internal dimension at the base of the two legs. The ties are to remain in place 36 of 50

37 during transportation to site and erection and can only be removed following the packing solid of the vertical bearings behind the units Temporary Restraint Beams A steel temporary restraint beam will be required to be fitted to the edge conarch units fixed to the end walls on the alignment of the Parapet Beam to allow the unit to be demoulded, transported to site and erected TRIAL ERECTION A trial erection of the conarch units is required to be undertaken in the manufacturer s yard to ensure that the units align with each other and that there are no clashes between the shear link bars SITE INSTALLATION Cill Units & Bearings Cill Units The cill units will have a standard L shape cross-section profile for all bridge spans and skews with a nominal width of 1200mm. It is desirable that the cill units are provided in a single unit for each abutment. Holes through the units are provided to enable holes to be drilled into the abutment following the cill unit erection for the installation of stainless steel dowels subsequently grouted in place Dowels The dowels are required to transfer the horizontal loads into the abutments. A minimum of 4no. dowels are required, one in each corner for each cill unit. The actual number of dowels required will be obtained from the conarch calculator Vertical Support Bearings A continuous elastomeric rubber bearing nominally 300mm wide is to provided, fixed to the top face of the cill unit to support the vertical loads from the conarch Units Horizontal Restraint Bearings A vertical elastomeric bearing nominally 200mm high will be provided between the rear upstand of the cill units and the bottom of both rear faces of the conarch unit legs. It will be fitted tight to the conarch unit and dry packed off the cill unit upstand Inner and Edge Units Following the landing of each conarch unit on to the cill units in the correct position and prior to the removal of the restraint ties, hardwood wedges are to be inserted to the edges of the rear of the conarch unit and the vertical upstand. The vertical bearing pad is then inserted tight to the rear of the conarch unit and the void up to the vertical upstand of the cill unit is then dry packed or grouted up to ensure full contact between the rear of the bearing and the cill unit upstand. On completion of curing of the packing the wedges can be removed. 37 of 50

38 Shear Key Joints A standard shear key joint is to be provided between all the conarch units. The shear key links in each conarch unit are aligned parallel with the track centerline and are spaced at 300mm nominal centres with the overlapping links of the adjacent unit located at the midspacing. The links are so positioned on either side of the units so that they can be installed on site in either orientation. As the units are erected on site it is advisable to follow on by installing the longitudinal steel through the shear key links. A nominal gap between the parapet beam and the edge conarch unit, the edge unit and inner units and inner to inner units will need to be sealed at the bottom with a flexible filler strip prior to concreting of the joints. The joints should be concreted and allowed to reach a minimum strength of 10N/mm² before any rebar is placed for the in-situ capping slabs In-situ concrete and waterproofing Backfill Concrete with Vertical Saw Tooth Profile The backfill to the conarch units will have a minimum thickness of 200mm across the full width of the bridge between the extension wings on the edge units. Beyond this the vertical saw tooth profile is provided, each profile having the width of each conarch unit with the depth on one side increasing with the skew of the bridge. A 20mm thick compressible board is provided to the top of the cill unit before any reinforcement is fixed. The vertical and horizontal reinforcement is fixed first in the main backfill zone, including the wedge shaped area above the longer span inner units, followed by the reinforcement in each of the saw tooth sections. In addition at the acute corners of the skew decks the main transverse reinforcement from the parapet beam will be fed down into the backfill reinforcement cages. The rear saw tooth formwork is then erected allowing the backfill concrete to be cast up to the underside of the capping slab. This area will need to be completed before installation of the capping slab reinforcement Capping Slab The capping slab will have a minimum depth of 150mm over the top of the inner conarch units when the minimum radius road profile follows that of the top of the units. When the road profile radius over the bridge becomes greater over the bridge up to the horizontal alignment the thickness at the ends of the bridge will become deeper, while the depth at mid-span remains at 150mm. The slab can increase in depth by up to 200mm at midspan to suit the vertical road profile, see section The site specific designer will need to detail the road profile and the depth of the slab at the ends. The top surface of the Slab needs to be of the correct standard to accept the sprayed waterproofing membrane. To enable the high transverse design loads of the H4a parapets to transfer into the main bridge structure, closely spaced transverse reinforcement located within the minimum thickness of 150mm in-situ concrete capping slab across the top of the inner conarch units is required in all cases Waterproofing & Water Management Both the top of the deck and the rear vertical faces are to be provided with a spray acrylic waterproofing membrane with a red asphalt protection membrane beneath the road surfacing and the backfill. At the base of the rear walls a sheet waterproofing membrane sealed on to the sprayed membrane should be dressed down over the back of the cill units and wrap around a transverse perforated pipe surrounded in no-fines concrete forming the back of abutment drain. 38 of 50

39 The transverse perforated pipe should pass through the wing walls on both sides, one end being provided with a removable end cap to allow future maintenance, the other with a access bend connected into a down pipe, that needs to have a connection into the track drainage system or any other suitable outfall Existing Wing Walls The existing wing walls and pilasters that were cut back to allow the bridge reconstruction are next to be rebuilt using reclaimed bricks or new bricks to match the existing up to the level of the underside of the transition parapet slab. Beyond the reinstated wing walls the remaining parapets will need to be cut down to the level of the underside of the transition parapet slab Abutment Backfill The rear slope of the excavation behind the abutments and between the wing walls will now need to be benched out with 1metre horizontal by 0.5 metre high steps. The void will then be filled with well compacted 6N fill material up to a level of 50mm below the underside of the transition parapet slab. Blinding concrete is then laid up to the underside of the transition parapet slab Transition Parapet Slabs & Parapets The precast concrete transition parapet edge beams are laid out along the top of the masonry wing walls, with the slab reinforcement then being fixed between them. An end shutter is erected and the slab concrete cast. On completion of the concrete the steel parapets can be erected Kerbs, Road and Pavement Surfacing and Drainage The bridge deck is completed as follows: Following curing of the transition parapet slab the sprayed waterproofing membrane is applied. The two kerb lines are then laid out across the bridge deck and transition parapet slabs followed by the sub-surface drainage ducts either side of the two kerb lines. The red sand asphalt is then applied to the top of the waterproofing membrane. Any service ducts are then laid out behind the kerb lines and the remaining voids filled with compact 6N fill up to the underside of the footpath surfacing. The road and footpath/verge surfacing is then applied. The asphaltic plug joint is then constructed with all the construction sealants applied. 39 of 50

40 6. SCHEME SPECIFIC DESIGN PROCESS 6.1. BACKGROUND DATA Obtain background data on overbridge (bridge assessments and inspections) Obtain proposed railway route enhancements (gauge and/or electrification) 6.2. INITIAL FEASIBILITY FLOW CHART The following flow chart details the decision process of the site specific designer to confirm the suitability of the conarch Standard Designs and Details suite to be used for the specific overbridge reconstruction NO Single span masonry arch overbridge? YES NO Span between 7.4 & 9.4 metres? YES NO Skew between 0º & 45º? YES NO Clearance between inside face of parapets: 4.5m to 12.5m? YES NO Track radius greater than 360 metres? YES NO Cant less than 150mm? YES NO Review effect of modified radius, cant and gauge requirements on proposed conarch profile/bridge opening. Can this be accommodated? YES NO Gauge, W6a, W7, W8, W9, W9+, W10, W11, W12, C1, C1 APP(A) + LOCO YES NO Vertical road alignment hog curve up to level? YES NO Parapet height less than 1825mm YES NO Parapet - H4A concrete or masonry YES NO Review alternative requirement. Can this be accommodated? YES Use alternative design process Use CONARCH design process If no, find alternative bridge design process, if yes proceed as follows: 40 of 50

41 6.3. SITE SURVEYS Undertake site surveys to obtain following data: Topographic survey to include: o Track vertical and horizontal alignment survey of both tracks up to 200 metres either side of the bridge. o Gauging survey of existing arch bridge to determine the existing clearances to both tracks taken on both faces and on the centre line of the arch. o Road vertical and horizontal alignment across the bridge up to 200 metres either side of the bridge. o Width between parapets including road and verge/footpath configuration across bridge deck. Buried Services Survey o Buried services information to determine any services that may be crossing over the bridge 6.4. FEASIBILITY STUDY The feasibility study is to determine the suitability of the conarch units to be used to reconstruct the overbridge and will include the following:: Survey Drawings o Plan drawing of the bridge showing road alignment relative to the railway alignment o Drawing of existing section though bridge perpendicular to the abutments at three locations, one on each face and one on the centre of the bridge to show: Soffit and abutment profile of the bridge Position of the tracks including the cant through the bridge opening Local road profile across bridge o Drawing of the existing section through the centre line of the roadway across the bridge (parallel to road alignment) showing the existing road vertical profile on approaches to and across the bridge Initial check o Check height from top of highest rail to the top of the road level at the crown of arch and check as follows: For gauge enhancements without a road lift the dimension should be greater than 4435mm + 570mm = 5005mm For minimum electrification clearance without a road lift the dimension should be greater than 4790mm + 570mm = 5360mm o If existing heights are not satisfactory, then the following need to be considered before continuing: The practicality of a road lift. A reduction in the clearances required for the OHLE equipment. if satisfactory continue with feasibility Feasibility Drawings o Onto the critical clearance bridge section identified above perpendicular to the abutments drawing add the following: Kinemetic envelope of the enhanced stock that is proposed to use the route. Insert conarch unit profile on the centre line of the existing arch and adjust up and down to give a minimum clearance of 150mm to the 41 of 50

42 extremes of the proposed kinematic envelopes. Then adjust legs on each side to suit existing span. Check the available construction depth at the crown of arch above the unit to existing road profile as follows: If less than 280mm, vertical road profile needs to be lifted. If between 280 & 370mm, no changes required If greater than 370mm, consideration needs to be given to raise the conarch unit to ensure construction depth does not exceed 370mm o Onto the road profile long section drawing add the following: Conarch unit profile at both sides of the bridge (the greater the skew the wider apart the profiles are). Check the available construction depth at the haunches of the arch units to the existing road level as follows: If less than 280mm, vertical road profile needs to be lifted. If between 280 & 660mm (road profile level across the bridge), no changes required. If greater than 660mm, consideration needs to be given to raise the conarch unit to ensure construction depth does not exceed 660mm 6.5. CONARCH CALCULATOR The Conarch Calculator is now used to confirm the geometrical details of the proposed Conarch Units that will be required for the reconstruction of the overbridge. From the feasibility drawings and background information the following data is required to be input into calculator: Bridge location details (ELR, mileage etc) Railway data o Proposed railway vehicle gauge o Whether line is to be OHLE electrified o Track details: Cant Radius Sixfoot o Height from top of highest rail to soffit of proposed conarch units Structure data o Clear span between abutments o Any sitback of units from face of abutments o Skew of bridge o Clear distance between inside faces of abutments at road level The Conarch Calculator will then ouput: The number required and widths of the Inner Conarch units and the size of the gaps between. A section through the bridge perpendicular to the tracks showing the proposed railway gauge relative to the conarch A plan of the proposed structure Further data is then input as follows: Highway data: o Carriageway width and crossfalls 42 of 50

43 o Verge/footpath widths and crossfalls o Highway construction thicknesses o Proposed highway longitudinal vertical curvature o Any uplift of parapet beams upstand The Conarch Calculator will then ouput: A section through the bridge showing the highway vertical longitudinal profile across the bridge A cross-section through the bridge showing the layout of the carriageway and verges. Further data is then input as follows: Parapet data: o Number of Parapet Panels required The Conarch Calculator will then output: o An elevation of the Parapet Beam and Parapet taking into consideration of the bridge skew. Further data is then input as follows: Abutment data: o Width of exiting abutment o Size and number of dowels o Existing loading on the abutment The Conarch Calculator will then output: o Abutment loading. The Conarch Calculator output should then be reviewed to confirm that it is feasible to reconstruct the exiting overbridge using the conarch Suite of Drawings and Standard Details FURTHER SITE SURVEYS Undertake the following additional site surveys: Coring o Coring of the abutments to determine their thickness and depth. Mini boreholes o Mini boreholes behind each abutment from road level to determine existing ground characteristics o Mini boreholes in each cess at rail level to determine ground characteristics beneath abutments Trial Trenches o Trial trenches at road level to determine location and details of buried services 6.7. DETAILED DESIGN The detailed design of the complete structure is now undertaken which includes the following elements: Conarch Structure Final Level Confirmation of the vertical position of the conarch structure relative to the tracks to ensure the correct clearances to the proposed gauge or electrification envelopes Road Vertical and Horizontal Alignment Confirmation of the horizontal and vertical road alignment across the bridge, identifying the need for any road lifts Conarch Units 43 of 50

44 User Conarch Calculator to generate conarch unit sizes and superstructure layout Prepare general arrangement drawings for conarch units. Issue Bending schedules with standard drawings to unit manufacturer General Arrangement & Layout Drawings Generation of general arrangement and layout drawings from Conarch Calculator data Abutment stability Check the stability and suitability of the existing abutments to support the new structure. See section 6.8 Determine number of dowels between cill unit and abutment Backfill & Capping Slab Concrete Using standard detail drawings and generic reinforcement schedules, prepare site specific detailed drawings and reinforcement schedules Back of Abutment Drainage and Backfill Using standard detail drawings, prepare site specific detailed drawings. Masonry Wing Walls Prepare detailed drawings for reinstatement of masonry wing walls Transition Parapets Using standard detail drawings and generic reinforcement schedules, prepare site specific detailed drawings and reinforcement schedules. Carriageway, footpath & verge layout across bridge Using standard detail drawings, prepare site specific detailed drawings Service locations Prepare service drawing showing existing and proposed duct layout to accommodate them in new structurere Arrange design check and issue Form B 6.8. RE-USE OF EXISTING SUB-STRUCTURE To aid the understanding of the Site Specific Designer of the conditions for the re-use of the existing sub-structure to support the new super-structure. Where the construction details of the existing substructure and relevant geotechnical information are known, the capability of the substructure to withstand the loads and effects shall be determined unless otherwise agreed by Network Rail and identified in the AIP submission Criteria 1 If existing sub-structures to be re-used for Conarch Units satisfy the following: (i) an existing substructure is in a 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; 44 of 50

45 THEN the existing substructures may normally be considered adequate for retention without modification and without the need for structural or geotechnical analysis Criteria 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: (a) 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 abutment s stability and reducing the maximum soil pressures beneath it: (b) the benefits of new cill beams may be analysed and taken into account. 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 is 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 the entire 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 the 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 , 80, Dec., ) Criteria 3 IF conditions (ii), (iii), (iv) and (v) above are satisfied but the existing substructures are showing signs of significant distress, THEN the following shall apply: The cause of distress should be determined ( e.g., high local forces especially at abutment corners, effects of existing arch integrity failure, failure of waterproofing / drainage, vegetation, settlement, effects of mining, reduction in passive pressure due to track lowering or local trenching). 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 stabilized 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. An existing arch is expected to act as a prop to the abutments (whether designed to or not). Consideration should be 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 45 of 50

46 use of construction plant or by reducing the height of fill behind the abutments during reconstruction). 46 of 50

47 7. SCHEME SPECIFIC DESIGNERS RESPONSIBILITIES The Site Specific Designer will be responsible for undertaking and managing the design and approvals process of the conarch bridge reconstructions as identified in the flow chart below: Gather background record data on masonry arch overbridge geometrical parameters, e.g. skew, span, arch rise Guidance from Technical User Manual Use initial feasibility flow chart to determine suitability of Standard Conarch Suite Confirm that the general parameters fall within the Standard Designs NO YES Undertake site surveys to determine design parameters, e.g. skew, span, arch rise, road alignment, railway clearances, rail to road level difference etc Guidance from Technical User Manual Undertake feasibility study using Conarch Calculator to determine layout & details of standard conarch units Confirm that the bridge parameters fall within the Standard Designs NO Justify decision not to use Standard Conarch Suite to Network Rail s Professional Head of Civil Engineering YES Use Conarch Calculator to confirm conarch unit layout for Site Specific structure Use of nonstandard design accepted NO Select standard precast unit drawings to be used YES Guidance from TUM on Standard Details Prepare General Arrangement Drawings Complete Technical Approval Process in Accordance with NR/SP/CIV/003 Select suitable Standard Details Prepare site specific detailed design drawings incorporating standard details Use Conarch Calculator to generate reinforcement schedules for the various precat units and insitu works Issue drawings, specifications, Health & Safety Risk Assessment and other information and documents to Contractor Prepare site specific specifications. Refer to Network Rail model clauses for specifying Civil Engineering Works NR/L3/CIV140 Prepare site specific drawings. To include general arrangements and layout drawings Prepare site specific Health & Safety environmental and other relevant information Complete Technical Approval Process in Accordance with NR/SP/CIV/003 Reference Standard Drawings & Details Form B. SDD do not require checking except for suitability for use 47 of 50

48 The actual responsibilities are detailed below: 7.1. SCHEME SPECIFIC DETAILS The Site Specific Designer will be responsible for all the site specific details including: Existing permanent way alignment details and any proposed changes. Existing highway alignment details across the bridge and any proposed changes. Existing abutment capacity. In-situ concrete schedule, and road alignment design if it doesn t follow the Conarch Calculator STANDARD DESIGNS AND DETAILS Conarch Calculator The scheme specific designer is to use the Conarch Calculator and is responsible for: Generating the basic layout geometrical details of the proposed bridge reconstruction and taking this information to produce the bridge layout drawings. Generating the reinforcement schedules for the precast Conarch Units and issue to the unit manufacturer Generating the reinforcement schedules for the in situ concrete Standard Design Precast Concrete Unit Drawings The following precast concrete elements of the conarch suite have been designed and design checked and a Form B issued: Conarch Inner Units General Arrangement and Reinforcement Detail drawings Conarch Edge Units General Arrangement and Reinforcement Detail drawings Parapet Beam and Parapet Panels General Arrangement and Reinforcement Detail drawings It is for the Scheme Specific Designer to: Use the details shown on the above drawings plus the layout information from the Conarch Calculator to produce the layout drawings for Conarch Units. Provide the appropriate general arrangement and reinforcement detail drawings with the bending schedules generated from the Conarch Calculator to the precast concrete unit manufacturer Standard Detail Precast Concrete Unit Drawings The following precast concrete elements of the conarch suite have been designed and design checked and a Form B issued: Generic general arrangement and reinforcement detail drawings for: o Parapets. o Transition Parapet Edge Support Beams. o Cill Units. It is the responsibility of the Scheme Specific Designer to: Use the standard details to produce the site specific drawings as follows; o Parapets The Parapet profile and panel lengths will be determined from the proposed highway longitudinal vertical profile. o Transition Parapet Edge Support Beams The layout and shape of the precast units will be determined to suit both the vertical and horizontal highway alignments. 48 of 50

49 o Cill Units The Cill Unit width and length will be determined to suit the skew and width of the bridge. o Develop the generic reinforcement schedules to suit the site specific dimensions of the above elements Standard Detail In-situ Concrete Drawings Generic general arrangement and reinforced concrete detailed drawings for the following in-situ concrete elements of the conarch suite have been designed and design checked and a Form B issued: Generic general arrangement and reinforcement detail drawings for: o Backfill Reinforced Concrete. o Capping Slab Reinforced Concrete. o Transition Parapet Slab Reinforced Concrete. It is the responsibility of the Scheme Specific Designer to: Use the standard details to produce the site specific drawings as follows; o Backfill Reinforced Concrete The shape both vertically and horizontally will be determined from the proposed highway vertical profile and skew of the bridge. o Capping Slab Reinforced Concrete The shape both vertically and horizontally will be determined from the proposed highway vertical profile and skew of the bridge. o Transition Parapet Slab Reinforced Concrete The shape both vertically and horizontally will be determined from the proposed highway vertical profile and skew of the bridge. Develop the generic reinforcement schedules to suit the site specific dimensions of the above elements Standard Details Drawings Generic general arrangement detailed drawings for the following standard details of the conarch suite have been designed and design checked and a Form B issued: Generic general arrangement drawings for the following elements: Transition Parapet layout details. Waterproofing details. Road Surfacing details. Lifting Details. Construction Sequence. It is the responsibility of the Scheme Specific Designer to: Use the standard details to produce the site specific drawings for each of the above elements 7.3. SITE SPECIFIC DESIGN CERTIFICATE SUBMISSION A full site-specific Form A submission will be required for each Conarch bridge, followed by Form B excepting the design of the components and the construction details to be given in the standard Conarch drawings and supporting documents Contents Summary Issues pertinent to the proposed use of Conarch Units are listed below and should be set out and justified in the normal way: 49 of 50

50 ANNEXE 1 ANNEXE 2 ANNEXE 3 ANNEXE 4 ANNEXE 5 ANNEXE 6 ANNEXE 7 ANNEXE 8 ANNEXE 9 ANNEXE 10 Schedul e Of Standard Dr awings Standar d Vehicle Gauges & Profil e Envel ope Sketches Excel Spread Sheet F or Envelope Pr ofiles Conarch Structur e D etails Conarch Bri dge Span Variance Sketch Conarch Bri dge D eck Wi dth Vari ance Sketch Construction Seq uence Road Ver tical Profile Envel opes Design Risk Assessment Conarch Calcul ator NR/CIV/TUM/2000 The existing arch profile showing springer and crown levels with superimposed vehicle kinematic envelopes or gauge envelope to demonstrate lack of existing clearances for the enhanced gauge. The proposed arch profile, showing arch springer and crown levels with superimposed vehicle kinematic envelopes or gauge envelope to demonstrate that proposed clearance and clearance tolerance. (Note that the tolerances of the Lasersweep surveying system, Clear-route modelling software, and the normal tolerances on site setting out and construction, call for provision of 80mm clearance in addition to modelled clearance.) This shall be demonstrated by the site specific Form A submission. Note that the design will not conform to the structure gauges given in the Track Design Manual NR/L2/TRK/2049, and will therefore require derogation by the Track Geometry and Gauging Engineer. Surveyed abutment geometry. Existing highway vertical and horizontal alignments. Existing highway cross-section including any footpaths and verges. Proposed vertical and transverse highway alignment and crossfall in the construction area. Effects on or proposals for sight lines. Proposed highway cross-section and road pavement thickness including footpath and / or verge widths. Selected bridge parapet containment. Safety barrier and transition arrangements on the approaches. Selected parapet height and height extension where adopted. Selection of parapet construction, concrete or reinforced masonry. Number of precast units to provide required bridge width between parapets. Details of services, duct sizes and locations. Locations of any lighting columns and street furniture (must not facilitate parapet climbing). Any requirements for fixing OLE to the structure. Vandalism profile of the site and appropriate provisions. The condition of the existing abutments, wing walls etc, any signs of distress or undue settlement and their causes, and any requirement for repair or strengthening. Any historic evidence of settlement of the sub-structure. Any new differential settlement anticipated in the sub-structure. Whether the effects of dead and / or live loading on the existing substructures or their tendency to sliding / overturning will be significantly greater than existing. Appropriate structural and / or geotechnical analysis carried out. Any underpinning, remedial work or strengthening proposed. Anticipated stability of existing abutments when superstructure is removed. Supporting drawing or drawings. To be white before issue 50 of 50