Although 90% of local authorities in England and Wales have set net zero carbon target dates - with over half aiming for 2030 – only 11% have updated their highway asset management plan accordingly and just 6% have a carbon reduction target for road surfacing materials, according to the Asphalt Industry Alliance (AIA).
These figures came from research done by AIA for its Annual Local Authority Road Maintenance (ALARM) survey. AIA chair David Giles highlighted these findings at the Local Council Roads Innovation Group’s (LCRIG’s) Strictly Highways conference earlier this month, telling delegates that there is a disconnect between policy ambitions and the reality of managing highways on a limited budget.
In addition to funding constraints, highways authorities also lack the data and guidance they need to work out how to get to net zero. Giles said that, when asked what net zero training they needed, local authorities asked for courses on materials innovation and how to select materials based on carbon impact.
There is some limited information on the carbon footprint of materials. For instance, the Mineral Product Association has just published generic Environmental Product Declarations (EPDs) for the four most commonly used asphalt mixes. However, EPDs only provide information on carbon emissions from cradle to factory gate. Road owners need to account for whole life carbon, which also depends on the longevity of road surfaces and the cost of maintenance and repairs over its lifetime.
Local road authorities also face the challenge of managing multiple types of road, with almost every council responsible for a different mix of rural and urban, heavily and lightly trafficked roads. The lowest whole life carbon solution will differ, depending on these factors.
Councils also need to understand what the impact of their decisions might be on local suppliers and hence local economies. For example, if specification decisions mean that existing asphalt plants need to be upgraded, that might mean that small local asphalt producers, who can’t make significant investments, could not compete with national companies.
Perhaps local authorities need some ‘rule of thumb’ guidelines which look at what the best options are to cut carbon, given the type of road. For inspiration, the UK asphalt industry could look to the National Asphalt Pavement Association (NAPA) in the US, which this year published a reference document for decarbonisation, The carbon footprint of asphalt pavements.
Obviously, the figures won’t be the same for the UK and US highway sectors, but the document has some helpful pointers. For instance, it says that the best way to cut carbon is to include higher proportions of recycled asphalt planings (RAP) in a mix. And it points out that for roads with low volumes of traffic, authorities should focus on low carbon materials but that for high- volume roads, using hard-wearing mixes that give longer life will have the best carbon-saving impact.
In the UK, the AIA plans to share information on decarbonisation methods and strategies through its Sharing Best Practice 2024 event, a free webinar, to be held on 19 November. Speakers from the Department for Transport, various councils, contractors and consultants will talk attendees through case studies aimed to decarbonise roads and improve resilience.
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