Delivering Innovation

The A303 in Wiltshire is one of the best-known roads in the South of England and deals with a heavy usage of traffic, resulting in general wear and tear, which has led Highways England to consider plans to upgrade the road.

In particular, FM Conway were commissioned to resurface the section between Winterbourne Stoke and Amesbury, as in some places the entire depth of the road pavement was damaged and had to be replaced.

FM Conway’s Business Development Director, Nick Burman, said:

“The main treatment was the replacement of 50mm surface course across the whole scheme. But within that, there were areas where there was structural damage to the pavement, and here we had to reconstruct to different depths to provide a stable base for the surface course.”

In total, the team were required to apply 14 different pavement treatments, varying in solution depending on the nature and severity of the structural failure and location. These ranged from planing 50mm off the existing surfacing and replacing it with a new thin surface course, through to complete 180mm reconstruction of base course, binder course and surfacing.

“In an ideal world, we would have planed 50mm off the whole area, then gone deeper where we needed to, before laying all the new material,” explains Nick. “But we had to do all the work during night-time closures between 10pm and 6am. Whatever section we worked on had to be completed in time to reopen it in the morning.”

To deliver a more efficient way of working, FM Conway used innovative materials such as lower temperature asphalt to speed the whole procedure up. This new type of asphalt was used throughout the reconstruction and surfacing, enabling the materials to cool faster and increase the speed of the laying process.

“By using lower temperature asphalt, we reduced the programme by two days,” says Nick. “It enabled us to do larger areas each night, which had a major impact on the availability of the network.”

Challenges and Solutions

The biggest challenge facing the team was the location of the project, largely due to the works being set on one of the busiest roads in the South West of England for holidaymakers, local traffic and heavy goods vehicles.

Not only did the road need to remain operational but works needed to be completed with plenty of time for the asphalt to cool to be ready for traffic. To achieve this, the team worked throughout the night to maximise the time on the project.

Nick added: “This is the biggest challenge on all Highways England schemes – making sure the road is fully operational. We typically aim to finish laying at about 4am, which gives the material time to cool ready for traffic, and also gives the white lining contractor time to do their work, and for the traffic management to be removed.”

Traffic management was also a major part of the programme of works, however due to the team cutting the project time by two nights, the number of times traffic management had to be implemented could be reduced, allowing for greater health and safety benefits to the project.

During the works the team also encountered a large amount of tar during the asphalt resurfacing process. In total, 600t of asphalt waste containing coal tar (AWCCT) was removed and disposed of in a licensed facility.

Since this project, FM Conway have utilised its ability as an industry leader in materials recycling to provide a solution and have installed a foam plant at its Heathrow asphalt plant, which is capable of offering a closed loop recycling solution for AWCCT.

Outcomes

The A303 project was successfully completed in nine full overnight road closures, between 25 June and 9 July 2019.

During that time, FM Conway’s surfacing business partner Toppesfield laid a total of 2,500t of asphalt for the different pavement treatments, all supplied by FM Conway’s asphalt plant at Theale.