Following the completion of planing on the South cantilever yesterday, planing began on the North cantilever this morning. The work is going well and we expect it to be completed by tomorrow evening. Whilst planing will continue on the north cantilever tomorrow, VolkerLaser will also begin preparing the deck of the south cantilever for the next stage of the resurfacing process. A range of mechanical and hand tools will be used to remove remaining material at the kerb interfaces. This will be followed by the specialist hydro-blasting contractor beginning to remove the last 8-10mm of deck material with a high pressure water jetting system.
As previously explained both cantilevers were closed to traffic at the same time to allow VolkerLaser to work on them simultaneously, reducing the overall project duration by up to eight weeks. With the weather inevitably becoming colder and wetter later in the year, saving this time now becomes increasingly important in avoiding future delays.
Once work on the cantilevers has been completed at the end of July, they will both be opened to traffic. VolkerLaser will then begin work on the main deck.
The main bridge deck works have to be completed in two phases – firstly work will take place on the north half, followed by work on the south half, with a surfacing construction joint running along the centre line of the bridge. This is the same technique we used successfully when the Plymouth side span was fully resurfaced in September 2011.
In order to resurface each half of the main deck, VolkerLaser need to have two full traffic lanes – the eastbound lane and the centre lane, and the westbound lane and the centre lane. This is vital to ensure that there is sufficient segregation of the works from the traffic using the bridge – making the site safer for both bridge users and the workforce, plant and equipment.
Achieving this safe distance between the people using the bridge and the staff working on the resurfacing means it is only possible to provide a maximum of three traffic lanes during the next two phases of the project.
We recognise the impact that this has on traffic flows, particularly at busy times, of the day, and are working with Highways England to ensure that we manage both the lanes and the Saltash tunnel efficiently to keep disruption to a minimum.
Together the bridge and Saltash tunnel form a Tidal Flow Corridor which uses a sophisticated lane control system to change lane priorities to reflect changes in traffic demand or respond to incidents. These include accidents, vehicle breakdowns and fires, and debris on the deck from vehicles shedding their loads.
A team of Control Room Supervisors and Control Room Assistants monitor the CCTV cameras at both the bridge and tunnel and at the roundabouts at Carkeel and St Budeaux 24 hours a day, seven days a week, 365 days a year, as well as liaising with staff at the Toll Plaza and, where necessary, with Highways England and the police.
The sheer volume of traffic using the bridge (an average of 45,000 vehicles every day) means that a relatively minor incident can quickly cause congestion, with a more serious incident which requires lanes to be closed creating additional challenges for bridge staff as well as travellers.
Each change in lane priorities takes up to seven minutes to implement. In addition to the time it takes to implement the directional changes, the Control room staff also have to ensure that the lane to be opened is free of traffic. On occasions waiting for traffic to clear the closed lane can add a further five or six minutes. This means it can take a little time for the lane change to help clear any congestion.
As well as actually changing lane priorities, the control room staff have to make sure the advance warning signs at the two roundabouts and the gantries at the entrance to the tunnel and either side of the bridge have been changed to let drivers know which lanes they can use.
Although the resurfacing works have reduced the number of lanes on the bridge, the commitment to keep three lanes open during peak periods means that the team can still change the lanes to manage traffic flows.
As explained above we recognise the importance of the crossing. We are doing everything we can to resolve any issues and keep traffic flowing across the bridge to minimise disruption to bridge users and local residents and businesses during these essential resurfacing works.