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Agenda Item No

 

The Vale of Glamorgan Council

 

Cabinet Meeting: 24 March, 2014

 

Report of the Cabinet Member for the Environment and Visible Services

 

Ewenny Bridge Strengthening / Replacement

 

Purpose of the Report

1.         To inform Members of the current position with regard to the management of the Network Rail (NR) owned Ewenny Bridge which carries the B4265 at St. Brides Road, and to seek approval for the amendment of the bridge design and of paragraph 10.2 in the Bridgeguard Agreement with NR for the provision of future maintenance.

Recommendations

1.         That Members note the current position with regard to the management of Ewenny Bridge.

2.         That Members approve that the Council's contribution to the Ewenny Bridge deck replacement is based on option 6 as described within the report, and that this contribution is fixed at £1m.

3.         That Members approve the changes to paragraph 10.2 in the Agreement with NR for the provision of a 32% contribution for future major maintenance of the new structure.

Reasons for the Recommendations

1.         To advise Members of the current position.

2.         To agree the relevant bridge replacement option to enable NR to include the strengthening scheme in their Capital Works Programme for 2014 / 2015, whilst removing any risk in respect to the Council's capital contribution.

3.         To agree the Council's share of any major maintenance of the new structure.

Background

2.         Ewenny Bridge is a NR owned structure and carries the B4265 St. Brides Road over the Vale of Glamorgan railway line. 

3.         The B4265 is an important route of the highway network in the west of the Vale and forms part of the route for abnormal loads to and from the Aberthaw Power Station from the west.  The road is frequently used by the quarrying operations both to the north and south of the bridge and is a strategically important link from the west.

4.         The County Surveyors Society and the rail authorities have agreed a standard form of Agreement ‘Bridgeguard 3’ for the assessment of the load carrying capacity of highway bridges over railways.  This Agreement identifies what action should be taken by the parties to the Agreement should the assessment prove that a bridge is substandard.  The Council entered into an Agreement with NR in March 1998 for the 12 no. railway bridges within its administrative area, including Ewenny Bridge. 

5.         In accordance with the requirements of the Agreement should a structure be found to meet NR’s load carrying obligation in accordance with its liability but not provide the load carrying capacity required by the Highway Authority, then any enhancement to the existing assessed capacity above NR’s obligation would have to be funded by the Highway Authority along with the cost of appropriate highway alterations.

6.         The assessment of the Ewenny Bridge indicated it to be substandard and that the existing traffic signal system installed to give priority to large vehicles leaving the quarry be adapted.  To limit the traffic movements over the bridge to single way working and thereby reduce the live traffic loading on the bridge.  This single lane control is considered to be an "Interim Measure" and should not be seen to be a long term solution.  NR continue to monitor the structure and, should there be any change in its condition, it is possible the structure could be further restricted to a 3T limit or even closed.

7.         The management strategy for the Ewenny Bridge requires that the structure be strengthened or replaced.  It has been agreed that this structure be placed on a high priority list and that action be taken due to its poor condition and its importance on the highway network.

8.         NR commissioned WSP Consultants to prepare a feasibility report identifying the strengthening / replacement options for the structure. 

9.         Two reports, presented to Cabinet on 9/7/2008 (Minute No. C62 refers), and 14/4/2010 (Minute No. C836 refers), together with a Capital Monitoring Report on 23/9/2013 (Minute No. C2027 refers), have confirmed the Councils commitment to the scheme and also identified the Council's £1m financial contribution towards the works.

Relevant Issues and Options

10.      The Cabinet decision was confirmed with NR and a draft agreement sought. NR initially included the scheme in their Capital Works Programme for 2013/14.

11.      The original preferred option was 2a (detailed in the 2008 Cabinet report) which included a widened deck with 2 no 3.65m standard width lanes but with only a 40 tonne load carrying capacity. This attracted a 86%/14% VoG/NR split with a VoG financial contribution at that time calculated at £629,000.

12.      Since the 2008 and 2010 reports to Cabinet there has been a change to the infrastructure plans for rail services in Wales with electrification shortly to be introduced.  This has enabled officers to re-negotiate the cost split and also, at the same time, to arrange for improvements in the design and load carrying capacity of the bridge, due in part to the height of the structure being affected by the electrification works.

13.      The bridge design proposed is now option 6 from the 2008 report, a plan of which is attached at Appendix A.  This option is not limited to 40 tonnes and will allow the bridge alignment to be much improved and for a 1.5m walkway to be introduced to the east.  The Vale's contribution to this structure has been negotiated and is now at 53%/47% VoG/NR as opposed to the previous 86%/14% VoG/NR split reported in 2008.

14.      In addition, to remove any risk to the Council of the new design exceeding the current £1.89m construction estimate it is proposed that the Council's £1m contribution (5.3%) will be fixed at this value.  This offers sufficient benefit to the Council by eliminating the pain / gain contractual relationship and providing protection against any future cost and price rises during the construction phase of this project.

15.      The Modified Bridge will comprise of a widened deck structure of 10.6m to accommodate :

·           2 x 3650mm wide carriageways

·           600mm verge on the west side

·           1500mm walkway on the east side

·           600mm allowance for parapet zones

·           Span of structure to match existing.

·           Abutments widened on the eastern ends to accommodate new deck.

·           Deck to carry loadings as defined in (Eurocode) BS EN1991-2-2003 and National Annex.

·           New structure to be built to a minimum headroom of 4780mm above the rail for electrification compliance.

·           Parapets to be of H4a standard and compliant for electrification requirements.

 

16.      In December 2013 NR provided the ‘Bridgeguard 3’ Agreement, with an amendment in their requirement in the funding of future maintenance. The proposed future maintenance responsibilities are as follows: 

Inspection & Maintenance responsibilities for which NR are responsible for are :

 

Detailed and Visual Examinations (equivalent to Principal and General Inspections) in line with NR's own inspection procedures.

 

Minor maintenance activities, including vegetation control, minor mortar repairs to the concrete superstructure, minor mortar repairs to the substructures.

 

Significant maintenance interventions for which the Council agree to contribute 32% of the total scheme cost towards would comprise:

 

Deck waterproofing, bearing replacement and expansion joint replacement (if present), including associated re-surfacing costs as a result of these activities.

 

Significant deck repairs as may be deemed reasonable over and above the minor repairs, provided the minor repairs have been routinely undertaken.

 

Substructure repairs over and above the minor repairs that can be directly attributed to the widening of the superstructure.

 

17.      In respect to any future reconstruction costs of the Modified Bridge, a notice period of 2 years shall be given by NR prior to the implementation of significant interventions and reconstruction.

Resource Implications (Financial and Employment)

18.      Officers from the Council's Highway Structures and Engineering Projects Group within the Engineering Design and Procurement Division (Visible Services) manage the Council's stock of highway structures and are dealing with NR on this matter.

19.      From the detailed designs carried out, the estimate for the deck replacement scheme is £1,886,508.03. The Council's liability would be £1m and NR would fund the balance.

20.      The Council has a number of agreements with NR where fees are charged every year to cover our element of maintenance as highway authority.  These include two railway bridges on the Llantwit Major by-pass for which we currently pay NR £7.5k and £10.5k per annum.

21.      In this case, NR wish the Council to enter into an agreement to pay for the increase in bridge deck width and load capacity, with the calculation based on proportioning the increased width (3.886m) against the width of the new bridge deck (10.6m) giving a figure of 32%.

22.      Hence the draft agreement between the Council and NR for the replacement of this bridge, now specifies a 32% major maintenance contribution from this Council.  It should be noted that no fees are required up front as part of this agreement in contrast to the other two agreements previously mentioned.

23.      The whole life cost of the bridge is estimated to be in the region of £2.2m.  This includes the replacement of bearings and re-waterproofing at 30, 60 and 90 year intervals at £300k to £350k each time and the full reconstruction of the bridge deck of £1m to £1.2m once during the 120 years.  32% of this total cost is £700k to £720k over the 120 year life (at today’s prices) which equates to a maintenance liability of up to £6k per annum over the life of the bridge.

Sustainability and Climate Change Implications

24.      The improved bridge design, in particular the increased load capacity, will permit use of the structure by abnormal vehicle loads and two way traffic (the bridge is currently restricted to a single lane) which will provide an improved highway connection at this point.  The height of the new bridge will permit NR to electrify the section of rail below which will assist in the more economic movement of passengers and freight by rail.  In addition, the provision of a footpath will allow pedestrians to cross the structure safely and is likely to encourage walking in and around this location.

Legal Implications (to Include Human Rights Implications)

25.      NR has an obligation to maintain the load carrying capacity of their structures in accordance with BE4, Railway Bridges (Load-Bearing standards), (England and Wales) Order 1972.

26.      The Agreement between NR and the Council for the assessment of NR structures is the ‘Bridgeguard 3:  General Conditions Agreement of Bridges in the Vale of Glamorgan March 1998’. 

27.      Under this Agreement the Council and NR have the following responsibilities:

·           The Council will pay to NR all reasonable costs incurred associated with the assessment to the Highway Agency Standard BD21/97 and Advice Note BA16/97 for the bridges within the County.

·           If any bridge fails to meet the 40 tonne assessment live load requirement NR shall at its own cost arrange for a further assessment of the structural element to determine whether it meets their Load Bearing Obligations.

·           The Council shall, at its own cost, arrange for those highway alterations or other measures which are considered necessary in order to restrict the use of the bridge to vehicles within its assessed load bearing capacity.

·           Should an assessment confirm that the structure does not meet the NR Load Bearing Obligation, the cost of such strengthening or reconstruction works to bring the structure to the full highway load carrying capacity will be divided in proportion to the load bearing obligations of NR and the Council's requirements.

Crime and Disorder Implications

28.      There are no Crime and Disorder implications to this report.

Equal Opportunities Implications (to include Welsh Language issues)

29.      All sections of the community benefit from an unrestricted highway network.

30.      There are no Welsh Language issues in relation to this report.

Corporate/Service Objectives

31.      To provide and maintain a safe highway infrastructure.

32.      Environment – Current and future generations of Vale residents and visitors enjoy the built and natural environments of the Vale of Glamorgan and actively protect and maintain them.

Policy Framework and Budget

33.      This report is a matter for Executive decision by Cabinet.

Consultation (including Ward Member Consultation)

34.      Ward Members were advised previously of issues presented in this report.

Relevant Scrutiny Committee

35.      Economy and Environment.

Background Papers

Cabinet Report dated: 9th July 2008 (C62)

Cabinet Report dated: 14th April 2010 (C836)

Cabinet Report dated: 25th September 2013 (C1425)

 

Contact Officer

Tamsin Robbins-Hill - Senior Technician

Tel No:  02920 673 129

 

Officers Consulted

Operational Manager, Legal Services

Operational Manager, Highways Maintenance

Accountant, Building and Visible Services

 

Responsible Officer:

Miles Punter - Director of Visible Services and Housing