Where are the works taking place? These essential works are required on the bridge which carries the eastbound slip road off the M8 over the A899 Livingston Road. This structure was built in 1970. It is a slip road that is used by around 8,000 vehicles per weekday, 500 per hour at peak times.
Why are the works needed now? It is over 50 years since this bridge was constructed and these repair works are essential to ensure the long term integrity of the structure, which is an important transport link into Livingston. Doing the work now will be less disruptive than repairs required in the future if left unresolved.The project will involve structural repairs to address:
– Deterioration of the concrete beams
– Leaking joints in bridge deck
– Deterioration of concrete in abutments and piers
– Bringing the structure up to current standards
Once engineers accessed the bridge for the initial works it was established that the bridge bearings, intended to allow the structure to expand and contract in response to temperature changes, are not functioning as intended. These components have been in place since the bridge was first built over 50 years ago and have reached the end of their serviceable life. Therefore, the project has been extended to include the replacement of the bridge bearings
Is the bridge safe given all of these issues? Yes, the bridge is safe. Road user safety is our top priority and if there were any immediate safety concerns the bridge, and perhaps the A899, would be closed to traffic but that is not the case at present and is not expected to be the case in the near future. That said, it is important we undertake these works before the condition of the concrete deteriorates either to the point of becoming a safety risk to users of the A899, or to the point of reducing the load carrying capacity of the structure and resulting in weight restrictions for users of the slip road.
What do these works involve? – Replacement of defective concrete along the edge of the structure
– Extensive concrete repairs to piers, abutments and the underside of the deck
– Installation of a Cathodic Protection system to the bridge supports
– Installation of a Cathodic Protection system to the underside of the deck adjacent to joints
– Replacement of leaking joints
– Installation of new parapets to current standards
What does ‘cathodic protection’ mean? Cathodic Protection is a method used to control the corrosion of steel reinforcing bars within the concrete. For the structure in question, it will involve the installation of a metallic mesh to the existing concrete surfaces which, when energised by a very small electrical current, attracts the causes of corrosion away from the structural reinforcement and towards the sacrificial mesh instead. This therefore extends the life of the existing reinforcement which is currently corroding. The mesh will be covered by a new layer of sprayed concrete and so won’t be visible following works completion.
How much is this refurbishment costing? The extensive bridge refurbishment project was possible thanks to a £1.3m investment from Transport Scotland. The bearing replacement element that was added to the scope of works sees a further investment.
Who is undertaking the works? BEAR Scotland is leading this project as part of its responsibility for the SE Trunk Road Network on behalf of Transport Scotland. Specialist contractor, Freyssinet, is responsible for the delivery of key elements of the project including the concrete refurbishment, bearing replacement and the cathodic protection.
How are the works being carried out? Much of the initial work is being carried out from a scaffold access system over the bridge. Although this will require the closure of the M8 eastbound slip, it is necessary to allow the works to be undertaken safely and with the minimum disruption to local traffic on the A899 below.The bearing replacement element of the programme does not require the closure of the eastbound slip road off the M8 at Junction 3, except for two very short duration overnight closures during the process of lifting the deck off of its existing bearings and lowering it back down onto the new bearings. The A899 will need to be restricted to a single lane of traffic in both directions between the Dechmont and Livingston East roundabouts to protect the temporary props and jacks that will support the bridge after the existing bearings are removed and until the new bearings are in place.
When are the works taking place? Site activities for advance preparation works start in January 2023 under minor traffic management arrangements.The main works commence in February at which point the M8 Junction 3 Eastbound offslip will close for up to 25 weeks. At the same time the A899 below the structure will be reduced to a single lane in each direction until mid-August.
In addition, closures of the A899 will take place overnight as the scaffold system is installed on the bridge above. For the northbound this is currently planned to be 13 February to 24 February and 20 March to 31 March southbound.
The dates for the removal of the scaffold are the northbound A899 to be closed overnight on Monday 12 and Tuesday 13 June and the southbound A899 to be closed overnight on Wednesday 14 and Thursday 15 June.
M8 Junction 3 Eastbound offslip will reopen to at least one lane of traffic in July 2023.
Works below the structure are extending to February 2024 at the latest to allow for the replacement of bearings which was identified as being needed once the job had started.
How will traffic be affected? Livingston remains open for business. Additional signage to this effect is being put in place ahead of Junction 3A East bound.An agreed diversion route for those who would usually exit the M8 at junction 3 will be signed from Junction 3A. It is the official route that is suitable for all trunk road traffic. However, it is worth noting that there are other local routes available.
Eastbound traffic heading to Livingston will be directed to leave the M8 at Junction 3A, the junction prior to where the works are taking place. The diversion will follow Carnegie Road, Deans Road and the A89 east to join the A899 Livingston Road at Dechmont Roundabout.
This will add less than one mile and typically less than five minutes to journey time – though longer delays can be expected during peak times. Westbound M8 motorway traffic will remain unaffected.
Two-way traffic on the local A899 will be maintained when possible, however overnight closures will be required for the safety of road users during the erection and dismantling of scaffolding on the structure overhead near the start and end of the bridge repair programme.
While the slip road is being reopened in July 2023, restrictions on the A899 below the bridge will remain in place till February 2024 at the latest to allow for the replacement of the bearings.
Why does the slip road need to be closed for such a long time? These are extensive works to a structure that is over 50 years old. The approach being adopted, i.e. the use of the scaffold, actually allows the works to be delivered within a shorter time frame compared to other, more disruptive methods.We are aware of the impact on road users and are doing all we can to minimise the overall duration of the works.
Will this not have a negative impact on local routes? The official diversion route has to be appropriate for trunk road traffic. The diversions have been agreed through consultation with West Lothian Council (WLC) and Police Scotland.BEAR Scotland is undertaking a public engagement campaign to highlight the project to all those who may be potentially affected. This will allow people to plan their journeys. We are aware there are also alternative local routes available, though only the official diversion route will be promoted.
BEAR is working in partnership with WLC to monitor the impact of the works and identify any additional strategies that may help, such as live messaging signs.
Has traffic been analysed to assess the impact of the works? Yes, we have analysed traffic data to understand the average number of vehicles currently using the slip road and how this compares to current traffic volumes on the A89, for example.We have also undertaken extensive consultation with West Lothian Council regarding these proposals in order to agree the diversion route based on their inherent local knowledge of the adjoining routes.
Since the project began traffic analytics indicate the diversion of traffic has not been causing any issues and that there’s been no discernible difference in average travel time for local traffic. A project specific traffic modelling exercise has not been undertaken, primarily because vehicles currently using the Junction 3 eastbound offslip will have a myriad of potential destinations and it would not be possible to collect data recording all journey end points and
whilst an agreed diversion route will be signed, a number of alternative local routes are available, and it is not possible to accurately predict how many vehicles will follow the full agreed diversion route and how many will take an alternative route to their destination.
As a result, any traffic model would be largely based on assumptions. Therefore, the output of any site-specific traffic modelling could not be relied upon to reflect what will happen in reality and would not be of sufficient value.
In addition, through engagement with specialist contractors, we have established that closure of the slip road is the only feasible way to undertake these essential works. The outcome of a traffic model would not change the fact that these essential works need to be undertaken or change the way in which they are undertaken, which will be using the most efficient approach we have developed.
We are therefore proactively engaging with stakeholders well in advance of the works so that they are well informed of the implications and can plan accordingly.
What does the public engagement campaign involve? – Stakeholder engagement with emergency services, local authorities, community councils and businesses
– Media releases to highlight key milestones and changes in traffic management
– Social media including a video
– Posters in prominent community locations
– Project webpage for information and regular updates
– Education outreach programme with local schools already underway
– Radio advertising will be undertaken in lead up to slip road closure