FM Conway has delivered a carbon-neutral highways scheme in Westminster, laying a new road surface containing 92% recycled materials - thought to be the highest ever used on a UK road.
As Westminster City Council's highways partner, FM Conway delivered the upgrade of the road and footways on Elmfield Way using multiple low-carbon techniques to achieve a total embodied and operational carbon saving of 78% – equal to approximately 100 tonnes of CO2 equivalent.
Residual carbon emissions were offset using high-quality Verified Carbon Standard (VCS) units, administered and certified by Verra, the world's largest carbon registry.
Through the scheme, approximately 280 tonnes of warm mix asphalt was laid as a single layer, covering 1,600 square metres of carriageway.
FM Conway designed, manufactured, and laid a proprietary mix using a combination of three specifications of the contractor's 14mm SureLayer E product with the addition of extra recycled aggregate.
The material contained a bespoke polymer modified bitumen to increase durability and resilience, while the asphalt was manufactured at lower temperatures and laid in a thinner layer, saving carbon and cutting resources by 30%.
In addition, the road planings were transported back to the same plant where the asphalt was made.
The full scope of works were also carried out using no fossil fuels on-site. The highways team used Hydrotreated Vegetable Oil (HVO) in the resurfacing element of the scheme, plus electric mini-excavators, disc cutters and compaction plates. A solar-powered welfare unit was also deployed, with HVO as a backup, in the footways element.
FM Conway sustainability director Matt Tallon said: 'This one-of-a-kind scheme illustrates how it is possible to stack together the best low carbon products, methods and techniques that are available today, to deliver massive carbon reductions.
'It is only once these embodied and operational carbon savings are made, should the residual carbon be offset, which in this case was done with high quality, verified ‘VCS' carbon removal and renewable projects, as well as the planting of trees in the UK.'
Alongside the new carriageway, the scheme also involved the enhancement of the footway between the Woodfield Medical Centre and Harrow Road, as well as the installation of 11 new LED lamp columns, 200m of new cabling, and a full drainage review and cleaning.
FM Conway and Westminster City Council have a longstanding history of pioneering recycled content in highway schemes. A trial to lay an 80% recycled content surface in Sutherland Avenue in June 2019 was followed in 2021 by a warm mix surface course containing 85% recycled content on Third Avenue in 2021.
Cllr Paul Dimoldenberg, cabinet member for city management and air quality, said: 'The use of 92% recycled materials is remarkable and a huge step in the right direction as part of the council's commitment to creating a fairer environment. We're not only reducing our carbon footprint but also promoting a cleaner, greener future for Westminster. This is only the start of more carbon saving initiatives we'll be trialling in the city to get us one step closer to hitting our net-zero targets.'
Head of operations (Highways) at Westminster City Council, Phil Robson, said: 'The transition requires the use of offsets at this time but we expect to see lower reliance on them over time. A big thank you to all the excellent engineers that have worked on this project.'
