Through a combination of materials, manufacturing and machinery, Tarmac and its supply chain reduced carbon emissions on the A64 for National Highways by 75% per cent compared to a traditional maintenance project of a similar scale – without resorting to offsetting to massage the numbers.
The trial was on the repair of a 1.5 mile section of the A64 eastbound carriageway at junction 44 near Bramham in North Yorkshire.
Over a seven-day period the team, including HW Martin, Premier Roadmarkings, Kier and Mway Comms, combined several low carbon materials, eco paving technology and plant equipment to deliver 260 tonnes of carbon savings.
Overall, 41.3% of the project’s carbon reduction total was delivered using low carbon raw materials, 14.7% from the transport of materials and the paving process, including the use of electric plant equipment, and 44% from exploiting sustainable manufacturing techniques.
A warm mix asphalt was used together with a ‘carbon sink’ bio-component binder from Shell, which locks carbon into the road to prevent it being released into the atmosphere. The lower layer of the pavement used 40% recycled asphalt planings (RAP) with a further 20% in the surface course to help reduce the need for primary materials.
A number of zero emissions plant vehicles and prototypes were used including electric and hybrid road rollers and an electric bond coat sprayer, minimising noise and further reducing tailpipe emissions as well as CO2. Tarmac’s Cross Green asphalt plant in Leeds, which manufactured many of the materials used on the project, was powered by a combination of biofuel and clean electricity.
Other construction methods adopted on the scheme delivered other benefits, including enhanced pavement life and smooth pavement. This was achieved through continuous paving using an ‘echelon’ paving method, where asphalt is laid across the entire road surface, rather than in lanes.
Eliminating joins reduces water infiltration into the road surface. This results in a more durable road that is expected to last more than 20% longer than those constructed with conventional surfacing methods. It should also require less maintenance, reducing operational carbon in the longer term. In addition, the increased smoothness of the surface improves ride quality, which reduces fuel consumption, therefore lowering associated emissions and particulates from vehicles.
In addition, to assist with ultimate drive to net zero pavements a small 150-metre section using all of the above technologies but with a standard penetration grade binder and a small percentage of a negative carbon aggregate combined to create the UK’s first net zero pavement.
Tarmac technical director Brian Kent said: “This trial sets a blueprint for low carbon delivery on the strategic road network and the exacting requirements of decarbonising every element of highways maintenance. It demonstrates how shorter, more focused use of road networks can improve efficiency, boost productivity and minimise nighttime closures, reducing disruption for road users.
“The ambitions of this scheme reflect our commitment to delivering not only low carbon pavements but also the significant benefits of new delivery models which will be essential as part of the transition to net zero.”
Angela Halliwell, head of carbon and environmental sustainability strategy and planning at National Highways, said: “We’re taking positive steps towards a more sustainable, decarbonised future. We hope this project will pave the way for industry-wide changes, resulting in significant carbon savings and improved road surfaces for drivers.
“National Highways has ambitious plans, backed by science, to decarbonise the road network. We aim to achieve net zero for our corporate emissions by 2030, for our maintenance and construction activities by 2040, and for our whole network by 2050.
“A net zero Britain will still travel by road, and finding low carbon ways to maintain our road network is vital. National Highways’ carbon management system and low carbon opportunities register capture innovations like those used on this project, with the intention to make them standard procedure across the road network in future.”
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