BRIDGE MAINTENANCE STRATEGY
- Meeting of Performance Scrutiny Committee, Thursday, 26 January 2017 9.30 am (Item 6.)
- View the declarations of interest for item 6.
To consider a report by the Senior Engineer- Highways and Environmental Services (copy enclosed) to aid in understanding the risks that the current condition of the Country’s Highway Structure infrastructure poses, and to enable scrutiny of the Council’s proposed strategy to manage the identified risks.
11am – 11.45am
The Lead Member for Public Realm introduced the report (previously circulated) outlining the method by which the Council managed its highway structure assets and explained how it intended to manage its current backlog of work in relation to those structural assets. Via a PowerPoint presentation a Senior Engineer – from Highways and Environmental Services gave members an overview of the County’s approach to managing its Highway Structures. He outlined the definitions for the different highway structures which made up the Council’s Highways Structures estate along with the number of structures in each category:
· 150 highway bridges (53 of which were listed and a further 6 were scheduled);
· 258 culverts;
· in excess of 300 retaining walls; and
· more than 300 a Public Right (PROW) of Way bridges
If the Council had to replace all of the above it would cost it in the region of £313m. In addition to the Highway Act 1980 the Council also had a duty to maintain all scheduled or listed monuments (including bridges).
The Senior Engineer:
· outlined the Asset Management Process followed by the Council and the myriad of Advice Notes and BSEN safety standards with which it had to comply;
· detailed Denbighshire’s Highway Asset Management Plan (HAMP) which set out local standards and the risk based approach adopted to the frequency of inspection – this approach, also adopted by other County Highway Authorities and the North and Mid Wales Trunk Road Agency, had saved the authority a substantial amount of money compared to complying with National Standards whilst not compromising asset users’ safety;
· outlined the amounts of funding allocated from within the Highway and Environmental Service’s Revenue and Block Capital budget for 2016/17 for highway structure management and advised that this equated to £445K;
· provided data on the number of structures which had been assessed as weak structures, some of which had already been placed under weight restriction orders. Details were given on the various weight restrictions usually applied on structures and the types of vehicles which would be affected by different restrictions. Whilst weight restrictions were applied on safety grounds they could potentially have an adverse effect on residents, business, community life and emergency vehicles’ access to areas and properties;
· displayed photographic evidence of different highway structures and the various types of erosion/material deterioration incurred and repair undertaken or required on the a number of structures across the county;
· advised that the appendix to the report detailed both the revenue and capital costs associated with the structures in the proposed Highway Structures Backlog Works Project. The estimated cost of this project would be circa £6m over a 10 year period and would be jointly funded from the Highway Block Capital Budget, which had been increased by approximately £320K per annum. Undertaking the project over a 10 year period would ensure that other projects funded from within the Highway Block Capital Budget would not be adversely affected too much by having funding diverted from them to the structures project. During the course of this work bridges and retaining walls would be restricted in order to reduce the rate of deterioration and ensure that they did not collapse. It was also proposed to increase the revenue budget to support the backlog programme and to maintain a planned preventative maintenance programme. A number of efficiency measures, including employing specialist staff rather than procuring services from external specialists, were being explored in order to realise value for money during the course of the project. The remainder of the proposed budget requirement would be subject to an additional capital bid in due course;
Responding to members’ questions the Lead Member, Senior Engineer and Highway Service Managers advised that:
· the prioritisation list for maintenance work on structures was flexible and was subject to change on a regular basis due to sudden changes in their material conditions i.e. severe weather/flood damage; structural damage caused by vehicles etc.;
· issues such as third party ownership and access to some structures for maintenance work need to be worked through;
· structural assessments were generally undertaken using mathematical modelling ;
· it was only when assessing structures that the actual extent of damage/erosion could be fully confirmed. It was during such assessments that engineers also could establish whether structures were actually built on much earlier structures across a river etc.;
· very few councils met the National Standards for Highway Structures, the majority undertook a risk based approach towards their asset management;
· scour was a major problem as it was undermining the foundation of a number of structures;
· the loading format for agricultural vehicles was ‘shared’ more evenly compared to Heavy Goods Vehicles (HGVs) and consequently less highway structure damage was attributed to them;
· a regular programme of maintenance was undertaken on the county’s largest bridge, the bridge spanning the river Clwyd on the Rhuddlan bypass. Modern bridges such as this one had been designed to have a 120 year lifespan, nevertheless they would require regular maintenance during their lifetime;
· Cadw had provided a financial contribution towards the work undertaken on the river Elwy Bridge at the bottom of the High Street in St. Asaph;
· the old bridge over the river Clwyd in Rhuddlan, now that it had been restricted to single lane traffic, was not considered to be at immediate risk as it was the external 19th century steel widening which was the cause of concern, not the earlier stone structure which was also listed;
· the benefits of dredging rivers below bridges had to be assessed on a bridge by bridge basis, as in some cases this could potentially cause more problems in the long term;
· a high level of trust existed between the Council’s highways officers, heritage officers and Cadw which assisted repair work etc. to be undertaken swiftly when necessary, as happened when Pont Nantglyn suffered vehicle damage. The level of mutual trust between all parties ensured that the bridge was repaired within a short period of time and reduced the disruption for residents and local users;
· a number of meetings had taken place between Finance and Highways officers with a view to drawing up a deliverable backlog works plan, based on service efficiencies and a long-term spend to save strategy without the need to apply for prudential borrowing;
· officers had considered a 5 year backlog works plan but this would have incurred significantly higher costs;
· officers were in regular contact with neighbouring counties regarding conditions of structures which spanned rivers on the county’s boundaries and which served as access routes to and from the county e.g. Pont y Ddôl, in the Trefnant ward;
· the Council did inform a number of satellite navigation programmes providers once weight restrictions were place on structures or when any legal notifications relating to the highway system were published. It was the provider’s responsibility to update its sat nav programmes;
· third party owners of bridges had the same responsibilities as the Council to maintain their assets. However the Transport Act of 1968 placed some financial liabilities on councils for strengthening some third party owned bridges; and
· the Council erected advisory signage where restrictions etc. were placed.
The Committee’s representative on the Strategic Investment Group (SIG) confirmed that SIG had supported the proposals submitted for the Highways Structure Backlog Works Project and was recommending that County Council should approve them.
Members thanked officers for an extremely informative presentation and acknowledged that a staggering amount of investment would be required to raise all structures to National Standards. They were therefore of the view that the managed approach suggested in the report was a logical way of addressing the backlog and the risks identified. The Committee:
Resolved: - to support the approach being taken by the Service to manage the backlog of works in relation to highway structures assets as per the suggested Highway Structure Backlog Works Project.
- Bridges Report 260117, item 6. PDF 103 KB
- Bridges Report 260117- App 1.docx, item 6. PDF 86 KB
- Bridges Report 260117- App 2, item 6. PDF 424 KB