FM Conway’s Sustainable Answer to Low-Carbon Motorways

UK-focused infrastructure and engineering firm FM Conway has showcased sustainable road construction on the M4, one of the UK’s busiest motorways.

In a first-of-its-kind project, FM Conway reduced emissions from the project by 630 tonnes of CO2e - equal to around half of the standard design. FM Conway used low-emission machinery, innovative paving techniques and low-carbon materials to achieve the result.

Andy Weymouth, framework delivery manager at FM Conway, emphasises how collaboration with its partners was central to the project’s success. 

“Delivering this scheme on time and to such a high standard was only possible through genuine collaboration with our partners – we all played a vital role. It took belief in a shared goal and a healthy dose of commitment to integrate the use of these new technologies effectively,” says Andy.

“By working together, we overcame challenges and set a new benchmark for how sustainable road construction can be achieved on the national strategic network. This scheme is proof that when we unite expertise and resources, we can accelerate the transition to greener infrastructure and deliver real impact.”

Power in multiple supply chain partnerships

FM Conway collaborated with construction equipment manufacturer JCB, which supplied its hydrogen 3CX backhoe loader.

Meanwhile, major Chinese equipment manufacturer Sany and Swedish manufacturer Volvo also joined the project by providing an electric planer and 4.5 tonne roller, and a fully electric 42 tonne lorry, respectively.

The National Highways, England’s motorway maintenance company, supported the project through its Low Carbon Demonstrator Fund, which helped with electric charging and hydrogen refuelling infrastructure.

The Fund has been developed for 2025 to 2026 to identify schemes demonstrating low carbon asphalt materials and maintenance methods.

Hydrogen and electric-powered equipment fuel the way

JCB says its 3CX backhoe loader is the only machine of its kind powered by a hydrogen internal combustion engine. 

The loader is meant to be the lowest carbon option available for this type of equipment, but deliver the same performance as diesel alternatives. Ryze Power provided the hydrogen fuel for the machine.

Elsewhere, Sany’s roller and planer were powered by electric, while a Volvo electric low loader powered by a Volvo electric 42 tonne lorry transported equipment to and from the site.

Optimising sustainable techniques and materials

To further reduce emissions, FM Conway used a technique called echelon paving, which involves laying two lanes of a carriageway simultaneously.

The process is designed to remove weak joints between lanes while also being a faster method of road construction.

The longevity of the M4 was boosted through laser profiling to detect irregularities that can be fixed during the asphalt laying process, reducing the potential for future road repairs.

As for materials used, the asphalt included recycled asphalt product (RAP) from other National Highways-operated roads.

FM Conway laid mixes consisting of 60% RAP in the base and binder courses, while mixes comprising 30% RAP were laid in the surface course.

Additional emissions reduction efforts included the use of biogas derived from anaerobic digestion to power manufacturing processes. 

The company says the use of RAP and biogas for manufacturing alone saved over 400 tonnes of CO₂e.