Contractors carrying out roadworks on the A46 in Warwickshire claim they have cut the project's carbon footprint by a quarter by recycling the old road surface. The companies conducting resurfacing work on the A46 Warwick Bypass reused more than 17,000 tonnes of the original material during the project.

The busy road had deteriorated so badly that National Highways, the government-run organisation in charge of motorways and major A-roads, commissioned a “full-depth” reconstruction. That meant digging down almost 15 inches and completely resurfacing the 3.5-mile section of the northbound carriageway between the Sherbourne roundabout and the Leek Wootton roundabout.

At that depth, much of the material is classed as carcinogenic, and must be dealt with as hazardous waste, which is disposed of at a licenced waste processing facility. But tar-bound material can be recycled through processing and re-mixing, reducing the amount of landfill waste.

Workers resurfacing street with fresh asphalt

Contractors Kier and Aggregate Industries (AI) devised a low-carbon design, and AI turned the old road into asphalt using a cold mixing process. That meant the asphalt could be made at a lower and safer temperature, reducing fumes on site.

And the mixing was all done on site, allowing the two companies to reduce vehicle movements. With fewer raw materials required and less need to dispose of waste, the companies estimate that 82,000 road miles were saved over the course of the project.

In total, National Highways says 56 percent of materials were recycled from the old road into the new one, while any remaining material not used in this scheme, was recycled back across the road network through other projects. As a result, the organisation estimates the carbon footprint of the works was 23 percent lower than would normally be expected.

National Highways’ project manager, Ryan Davies, said the new method of carrying out roadworks would help the organisation in its aim to make the UK motorway network carbon-neutral.

“We have committed, through our net zero carbon plan, to rapidly cut carbon from road construction, maintenance and operations, and support the transition to zero emission vehicles,” he said. “A vital part of meeting our ambitious objectives is having the support of our supply chain on schemes such as this. Through close collaboration with partners such as Kier and AI we are taking great strides on our journey to net zero carbon.”