How To Increase Vehicle Height Of A Tunnel In Daugherd Port

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1 Height of Dublin Port Tunnel Background Note The Dublin Port Tunnel 1. The Dublin Port Tunnel will run from the existing M1 Motorway at Santry to link with Dublin Port and the local road network. Construction commenced in June The tunnel is expected to open to traffic in Quarter III 2005, subject to satisfactory operational and safety testing. Its total estimated cost is 715m (2004 prices). The overall length of the project is approximately 5.6 km. of which approximately 4.5 km. is in tunnel. When completed it will provide a motorway connection from the existing M1 motorway at Santry to link with Dublin Port and the adjoining public road network at East Wall Road. Currently there are almost two million truck journeys in and out of Dublin Port each year, all of them passing through city centre streets and adjacent residential areas that were never intended to cater for such traffic. In the future these trucks will be able to access the motorway network directly through the tunnel, providing much needed relief to the city streets. Using the tunnel journeys from the M50 to Dublin Port will only take 6 to 7 minutes. 2. On completion of the Port Tunnel, a traffic management plan will be implemented by Dublin City Council to take account of the alternative access to Dublin Port available to trucks and remove them from the city centre. Any such restrictions imposed will be a matter for Dublin City Council. Height of the Tunnel 3. The tunnel, as currently being constructed, will have a height of 4.9m. For operational safety, a vehicle height limit of 4.65m will apply. In developing the Port Tunnel scheme, Dublin City Council and the National Roads Authority were fully cognisant of vehicle height legislation existing at that time in Ireland which provided for a maximum height of heavy goods vehicle of 4.25 metres. Having regard to this legislation, and international practice in tunnel heights, the project was developed on the basis of a 4.9 metre height to accommodate all truck traffic complying with the legislation, as well as the higher double deck bus size (4.57m). It was on this basis that the project was developed, an Environmental Impact Statement published, a public inquiry held, and construction tenders obtained. During the design of the Port Tunnel, the design clearance was adequate for 100% of legally permissible vehicles in this country. 1

2 HGV Heights 4. In July 2000 the Irish legislation governing vehicle heights was revoked because the European Commission had challenged the procedural basis on which the related statutory instrument had been made which left a situation of effectively no Irish legislation governing truck height limits. Given that no road infrastructure can provide for unlimited dimensions, it was decided by the NRA/Dublin Corporation to proceed on the basis of the already developed and approved project. This approach had regard to the following: The tunnel height accorded with, and exceeded, the practice in many other European countries, An EU Directive governing heavy goods vehicles undertaking international journeys requires that only vehicles not exceeding 4.0 metres in height must be accommodated, Any height change to the project would result in substantial time delay and extra cost. Preparation of draft regulations to provide for maximum height of vehicles is at an advanced stage. The Minister for Transport proposes to publish shortly draft regulations proposing a maximum vehicle height of the order of 4.5m and to invite comments from the public. HGVs over 4.65m in Dublin Port Tunnel 5. It was, and continues to be, the view of Dublin City Council and the National Roads Authority that the tunnel will facilitate almost all of the truck traffic currently using Dublin Port. Two Vehicle Height Surveys of HGVs using Dublin Port have been carried out (one by the Dublin Port Company and one by the National Institute of Transport Logistics). Their results are summarized below. Period of study Dublin Port Company Survey Ongoing (data Oct 02 July 03) National Institute of Transport Logistics Survey One week in May 2003 Measurement location Tolka Quay Road Exit All entry and exit points except Tolka Quay Road Exit Number of vehicles surveyed 785,580 Approx 53,000 Number over 4.65m (total) Number over 4.65m (percentage) 0.60% 1.74% Number over 4.65m (average per day)

3 Consultants appointed and scope of works 6. Atkins (consulting engineers) were appointed on August 28 th 2003 to review the feasibility, safety implications and cost of raising the height of the Dublin Port Tunnel. They were requested to review a range of options for increasing the physical height (4.90 metres) and operational height (4.65 metres) of the tunnel, their feasibility, having regard to the state of implementation of the current design and build contract, the additional costs likely to arise and their likely impact on safety in the tunnel and the current project completion date. Results of the Technical Review 7. Atkins assessment of the feasibility of various height options, having regard to the current state of implementation of the design/build contract, the additional costs likely to arise and their impact on the current project completion date is as follows: Option Max Vehicle Height to be accommodated % HGVs* Cost/Programme Implications ( in millions)** Base Mid High m months 52 5 months 78 8 months m months 53 5 months 79 8 months 3*** 4.80m m months 85 8 months months m 100 Not Feasible m 100 Not Feasible * defined as the estimated percentage of HGVs currently unable to use the DPT that would then be able to use the DPT at the maintained headroom shown (refer to Section of the report) ** for definitions of base, mid and high estimates, refer to Section of the report *** Option 3 cost/programme implications are the same as Option 4, refer to Section 7.4 of the report 8. These conclusions were qualified in a number of respects, most significantly: o The costings are qualified given the nature of the design/build contract and the difficulty of assessing the impact of a contract variation (This is reflected in the range of costs proposed by Atkins in respect of each option); o The need for legal advice regarding the possible implications of redesigning the tunnel and a longer construction period for the existing Environmental Impact Assessment. 9. To achieve the height increase identified all the feasible options involve reducing the width of the traffic lanes and lowering the floor of the tunnel. In the case of options 1 and 2, the walkways would be maintained at their current height and only the road carriageway would be lowered, thereby increasing the kerb height. Options 2, 3 and 4 also involve repositioning the ventilation and other mechanical and electrical equipment. Of the options considered, Option 2 with a maintained headroom of 4.75m (at a mid-range 3

4 cost estimate of 53 million and a mid range estimate of programme delay of five months) and Option 4 with a maintained headroom of 4.90m (at a mid range cost estimate of 85 million and a mid range estimate of programme delay of eight months) were seen by Atkins as the best technical options. Quotation sought from contractor 10. For all of the options considered, the major elements of the cost and programme estimates were allowances for potential delay to project completion caused by a change at this stage of the construction contract, and the contractual implications of imposing a variation on the Contractor. In the light of the uncertainty caused by these contractual implications the Minister for Transport requested that Dublin City Council invite a proposal from the Contractor to deliver a specified increased maintained headroom, that would be on a fixed price basis. 11. The contractors were asked to supply a cost and time quotation for Option 4 of the Atkins Report, i.e. to modify the tunnel to allow HGVs of a maximum height of 4.9m to use it. The contractors, Nishimatsu Mowlem Irishenco (NMI), provided their quotation to Dublin City Council and the NRA on Friday 28 th May, Two alternative proposals were submitted: Quotation 1-65m with a seven months delay to project timescale 12. The contractor imposed a number of conditions on this price. Therefore, the quote would have the potential to increase significantly in respect of cost and delay. Conditions include: a) exclusion of all statutory compliance risk associated with departure from the approved EIS including the risk of legal challenge and consequent delay b) cost of resolution of an identified potential for high vehicles to impact with the inner face of the tunnel at roof level is excluded c) exclusion of design responsibility for safety implications of the increased kerb height d) a detailed risk assessment of the project following amendments and the identification and carrying out of all measures necessary to ensure safety remains to be carried out and all remedial/additional works in excess of those listed in the quotation would have to be carried out at the client s additional cost which could prove substantial. Quotation 2-33m with no delay to project timescale (fundamentally altering existing contract) 13. This quotation is subject to the same conditions as the first quotation. In addition, it requires streamlining the design checking and approval process and involves an undefined refinement to the manner in which the works are undertaken on site. The varied manner of working on which this lower quotation is based is not fully explained in the quotation. It is predicated on fundamental changes to the current contract. 4

5 Views of the National Roads Authority (NRA) and Dublin City Council (DCC) 14. The NRA and DCC have serious concerns about a number of aspects of the options identified particularly regarding the safety implications of: - reducing lane widths which would, in the context of a tunnel carrying a very high percentage of heavy goods vehicles, including fuel tankers and other hazardous cargoes, constitute a reduction in overall tunnel safety. While the magnitude of that reduction may be the subject of debate, it is intuitively apparent that wider traffic lanes offer greater vehicle separation than narrower lanes; - increasing kerb height - it is apparent, on both an engineering and intuitive basis, that a 150mm kerb must represent a safer provision than a 200 mm kerb height. While it is probably the case that the magnitude of difference in level of safety is small, it is the NRA s position that the lower kerb height is preferable from a safety perspective; - Potential Vehicle Impact Issue - NMI state in their quotation that they have identified a potential clash under certain circumstances of vehicles with the intrados of the lining. It would be necessary to examine in detail with the contractor all of the areas where the construction tolerance has been utilised and to formulate solutions in each area; - Overheight HGVs on the existing national road network the implications of facilitating higher vehicles through the tunnel than the national motorway and road network can safely accommodate. Bridges and other structures on the motorways and national roads are not designed to cater for vehicles higher than the current tunnel height and safety concerns would arise over the discharge of any such vehicles from a revised tunnel onto the national road network. Proposed action 15. Increasing the operational height of the tunnel would raise considerable safety concerns relating to, in particular, narrower lane widths and increased kerb heights. Using the lower (qualified) prices submitted by the contractor, the cost of an increase to 4.9m ranges from 33m to 65m and would delay the project by seven months or more. It is difficult to make an argument on economic grounds for changes to the height of the Port Tunnel with costs and delays of this magnitude having regard to the proportion of HGVs that are overheight. The Minister, therefore, proposes that the project be completed as planned and being constructed and that the issue of routing overheight vehicles (greater than 4.65m) through the city be addressed in the context of a HGV Management Strategy being prepared by Dublin City Council. 5