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Resurfacing A40 Trunk Road

Close collaboration between FM Conway and Transport for London (TfL), to resurface the A40 trunk road in London by making of an asphalt concrete (AC) surface course containing 50 percent recycled aggregates.

Description of Works

FM Conway worked with TfL to deliver an innovative project on the strategic road network in west London.   We laid an asphalt surface course containing 50 percent high Polished Stone Value (PSV) recycled aggregate on the A40, resurfacing over 20,000 metres.  The project marks a pivotal shift in the way that roads are built and maintained in the UK.  It is the first time that a surface course mix – used for the top layer of a road – containing such a high proportion of recycled material has been laid on a strategic route outside of trial conditions.   

Standard practice has been to limit the recycled content of surface courses for motorways and A-roads to around 10 percent.  The A40 project followed a successful trial carried out by FM Conway and TfL to lay a high-recycled asphalt mix on the A1.  

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“Aggregate and bitumen are finite resources.  We need to look to more sustainable alternatives if we’re going to continue providing a high-quality surface network for London’s road users now and in the future.”   

Herbert Micallef - Highways Technical Manager at TfL
Challenges and Solutions

TfL’s Highways Technical Manager, Herbert Micallef, said that making asphalt recycling standard practice would bring benefits for the public and highways operators: “Asphalt recycling does happen but so far the highways sector has been slow to accept it as best practice for work on both the strategic and local networks.  FM Conway and TfL are changing this, bringing benefits for both road users and network operators.

 
Delivering Innovation 

As well as supporting more sustainable use of materials, the A40 works saw FM Conway introduce an innovative laying technique to speed up delivery and cut costs for TfL.  In contrast to traditional methods of laying surfacing materials in two layers at a depth of 100mm, the new material was laid in one layer at a depth of 70mm, expediting the resurfacing process and allowing road users faster access to return to the A40.     

The material also incorporated FM Conway’s own designed and manufactured Polymer Modified Bitumen (PMB). The use of PMB can significantly improve the durability of highways assets by improving their resistance to rutting and cracking.  

Tim Metcalf, Executive Aggregates and Asphalt Director at FM Conway, commented on the importance of the project:
“Our trial with TfL proved that high-recycled surface course materials are able to perform and be environmentally sustainable.  The project on the A40 takes this work to the next level, using insights from the trial to make recycling standard practice on the strategic network.

“Using the roads as our quarry cuts costs, reduces carbon footprint and transport movements.  It’s a resource and time-efficient approach and we’ll be working with customers and partners to help embed it across the industry.”