The highway structures assessment, strengthening and maintenance strategy of Highway Authorities ensures the fulfilment of their statutory obligations under the Highways Act – “to provide a free passage for all vehicles up to the Construction and Use limit on the Highway,” taking into account local transportation issues and policies. From the 1st January 1999 this has included vehicles weighing up to 40 tonnes.
Prior to 1989 bridges constructed before 1922 were required to be assessed in accordance with Department of Transport Standard BD21/84 to determine their local carrying capacity.
The assessment of these bridges was designated as Stage 1 after European Community Directive 89/460/EEC was issued requiring the United Kingdom to accept 40 tonne vehicles on roads after 1st January 1999. At the same time a requirement to assess highway bridges designed prior to 1973 (Stage 2) and bridges of loaded length greater than 50 metres (Stage 3) was added.
Most of our bridges have now been assessed although there are still bridges where these assessments have yet to be completed i.e. those owned by Network Rail and Canal & River Trust. The main delay in the completion of these assessments has been due to the delay in implementation of a National Agreement between Local Authorities and Statutory Transport Undertakers.
Following the assessments a strategy has been determined to prioritise strengthening and reconstruction works following consideration of a number of factors such as location, route designation, traffic flows, local conditions, availability of alternative routes, environmental problems and consideration of neighbouring authorities requirements.
The maintenance and upgrading of bridges prevents structural deterioration. This includes concrete testing and repair, waterproofing and other structural works.
This work is prioritised and can be met from the same funds as bridge strengthening. But the funds to do this via the Local Transport Plan has not kept pace with requirements.
Meetings between the bridge authorities in the West Midlands have been taking place on a regular basis. More recently the bridge group merged with other local authorities to form the West Midlands Area Bridge Conference.
Network Rail, Canal & River Trust own and maintain many highway bridges. The vast majority of these were built before the introduction of the first Government loading for highway bridges in 1922.
Strengthening of these bridges where needed means that they have to be included in the priority ranking list. Much of the cost being met by the local highway authority. This is because the Statutory Transport Undertakers have only to meet their load carrying obligations under the Transport Act 1968.
Because of the national concern to improve services such as the maintenance of highway structures, performance indicators are being developed which affect the inspection and maintenance of bridges.
These performance indicators will monitor and compare bridges throughout the Country based on their Condition, Availability and Reliability.
These performance indicators will look into a comparison of the Condition of Bridges, their Availability and their Reliability for bridges throughout the Country.
As well as these performance indicators an Asset Management model is being developed for highway structures. This will assist in factors such as the decision making process, life costing, prioritisation and value management. Although it is early days yet in the development of this model for local authorities it is following on from work already done for the Highway Agency in looking after the Motorway and Trunk Road Network.
There is therefore an extensive amount of work in progress in the management of bridges which requires considerable output at local level.
