The pursuit of net zero targets has thrust road building and maintenance into the spotlight, prompting the industry to develop various strategies for reducing carbon emissions. While the challenge of managing road networks, improving conditions, increasing capacity, and achieving net zero carbon emissions may seem daunting, it has become a critical task for the English highways operator, National Highways. Similar challenges are faced by Transport for Wales, Transport Scotland, and local authority highways departments throughout the country. The urgency to meet the 2050 net zero target (2045 for Scotland) has necessitated a comprehensive overhaul of road operation and maintenance systems. This article explores the initiatives and innovations undertaken by these entities to address carbon emissions in road construction and maintenance.
Reducing Corporate Emissions:
Highways authorities, like National Highways and Transport Scotland, have recognised the need to reduce their own operational emissions. National Highways, led by its sustainability division, has committed to achieving net zero corporate emissions by 2030. A significant portion of its electricity consumption is allocated to lighting the road network, and the organisation aims to switch to LED bulbs, targeting a 70% transition by 2027. National Highways plans to replace its traffic officer rapid response fleet with plug-in hybrid electric vehicles and downsize its office estate by one-third. Transport Scotland has already reduced its corporate emissions by over 70% since 2016, primarily by adopting LED lighting on roads. While these efforts mark a positive start, achieving a carbon-neutral road system requires further innovation and substantial changes.
Accurate Carbon Calculation:
Accurate carbon calculation is crucial for effective emissions reduction. In recent years, methods for measuring carbon emissions have rapidly evolved. Transport Scotland employs a bespoke tool developed by Jacobs to calculate carbon emissions from embodied carbon materials in its contractual requirements. To align with changing decarbonization practices, the tool has been updated in-house and incorporates emissions factors from reputable sources such as the Bath Inventory of Carbon and Energy and the Department for Business, Innovation and Skills. Transport Scotland aims to make this tool publicly available for those interested in calculating embodied carbon emissions. National Highways is also developing its own carbon calculation tool, which will be integrated into its cost estimation process by autumn, enabling informed decision-making and design improvements for carbon reduction.
Modified Materials:
Besides lighting, the construction and maintenance of roads themselves contribute significantly to carbon emissions. To address this, National Highways has committed to using only zero-carbon construction equipment on its work sites by 2030. Even more promising are the advancements in materials being utilised. The increased utilisation of warm mix asphalt (WMA), produced at 40°C lower temperatures than traditional hot mix asphalt, can reduce emissions by 15%. National Highways estimates that adopting WMA nationwide could annually cut 61,000 tons of carbon emissions. Collaborating with oil company Total and materials producer Tarmac, National Highways has developed Total Styrelf Long Life, a low-maintenance bitumen that enhances road longevity by resisting fatigue, fretting, and thermal cracking. Trials of graphene-based surfacing are underway, as the use of graphene, a material stronger than steel, has the potential to extend the operational life of roads. Results from the first trial on a 5km stretch of the A1 in Northumberland are expected later this year.
Engaging the Supply Chain:
While having the right tools and materials is essential, collaboration with suppliers is equally vital to achieving the net-zero agenda. Transport Scotland emphasises the importance of engaging with the supply chain, recognising its influence on decision-making processes. Clear expectations regarding the purchase of low-carbon materials and a collaborative approach are crucial to realizing emissions reduction goals. Supplier cooperation and commitment are seen as key challenges but also as exciting opportunities for effective carbon management.
Technological Precision:
Digital tools play a crucial role in planning future roads to minimise congestion and reduce emissions. National Highways' digital roads initiative, launched in February, aims to create a digital twin of the motorway and trunk road network. This digital representation facilitates efficient building, maintenance, and usage planning, without the need for additional lane capacity or road construction. Simulations of work and traffic management can be conducted beforehand, enabling better planning to alleviate congestion and reduce emissions. The digital roads concept will be a significant component of Road Investment Strategy 3 (RIS3), National Highways' investment program from 2025 to 2030.
The transformation of road construction and maintenance to meet net-zero targets is a monumental task, but the industry's numerous initiatives, developments, and innovations, along with a shared commitment, provide reasons for optimism. However, the need for change is not taken for granted, and stakeholders emphasize their determination to overcome barriers. Recognising the existential nature of reducing emissions in road building, the industry aims to foster collaboration, treating carbon reduction as a collective challenge rather than a competitive advantage. Achieving these goals necessitates working hand in hand with suppliers, adopting low-carbon materials, utilizing accurate carbon calculation tools, and embracing digital technologies for precise planning. The ongoing efforts to drive down carbon emissions from roads represent a crucial step towards a sustainable future.