Lancashire County Council: Highways Decarbonisation Strategy

The Council used research to determine how close they could get towards their 2030 Net Zero targets in the next two years, through state of the art, innovations in materials and processes currently available.

They are collaborating with the highways sector to:

• establish carbon modelling and carbon usage for highway works
• understand the CO₂e of different products and process
• inform the decision-making process for choice of materials, treatments and intervention timing
• identify how far towards Net Zero they can go with known and emerging materials and technologies
• establish procurement and contractual arrangements for Net Zero delivery.

With the overall aim to reduce CO₂e of the highway surfacing programme both in the immediate term and whole life cycle.

They have engaged with highway authority benchmarking organisations to start developing modelling that will allow the impact of various carriageway treatment options on whole life CO₂e.

Through engagement with partner authorities and the supply chain they recognised and then utilised three initial solutions for reducing CO₂e associated with the Council's carriageway surfacing works:

• warm mix asphalt
• in-situ carriageway recycling
• ex-situ carriageway recycling.

Along with the physical processes they also collaborated with other highway authorities and suppliers to ascertain the CO₂e equivalence values for each process, including traditional hot mix asphalt and the new alternative treatments/materials. This allowed a baseline CO₂e of the surfacing programme to be developed and subsequent values of CO₂e when using the alternative treatments, enabling us to calculate the savings possible.

The next step, focused on the condition of the Council's network, how they were constructed, existing and emerging materials and processes. This allowed us to identify the carbon footprints of previous and potential carbon footprint reductions for future networks. This work also indicated savings that can be made in the short term, long term and contextualise these savings in terms of impact on the current Highways Capital Programme.

The third solution focused on the development, procurement and mobilization of an ex-situ recycling framework, with three industry partners. This will allow easier collaboration with the supply chain, easier implementation of innovation and removal of barriers to the use of lower carbon materials.

The Decarbonisation Strategy and the assessment of the reduction of carbon for the current capital programme are published on the Council's website. Once approved a summary of the propensity to change work will also be made available.

For the 2022/23 Capital programme they estimated that through measures such as warm mix asphalt on the majority of resurfacing and reconstruction schemes and the continued development of in-situ recycling they reduced their carbon footprint by 150 tonnes of CO₂e, which represented a 15 per cent carbon saving.

Looking at further opportunities to reduce Carbon through the adoption of cold mix processes and alternative binders, such as biogenic bitumen and higher levels of recycled aggregate, there is a potential carbon footprint saving of 50 per cent over the remainder of Transport Asset Management Plan Phase 2 (2023-25) and a 46 per cent saving can be made of the third phase of the TAMP (2026-2030).

These savings were calculated through looking at the existing materials and processes used, their carbon footprints and the contributing factors to their footprints. A hierarchy of savings was then developed, in the first instance material production was the biggest item for resurfacing and reconstruction works, so a switch to cold mix asphalts across all base and binder layers and warm mix on the majority of surface courses. Subsequent biggest hitting item were the asphalt binders, so either bitumen and/or cement. Remobilising and reusing the bitumen bound into existing RAP and partial replacement of fossil fuel bitumen with biogenic derived binders provides significant savings. This can be applied across all material classes including surface dressing, so provides a significant saving. In addition, the location of batching plant and optimising aggregate source locations will all contribute to further savings.

The work has stimulated innovation and collaboration in the pursuit of circular economy solutions. The Highway Asset Team is now engaged with the supply chain and academia to develop lower carbon solutions. an example being the use of biogenic binders, reclaimed asphalt and warm mix additives can realistically start getting closer to a true carbon neutral treatment for road resurfacing schemes. This will be particularly applicable on unclassified roads and enable LCCs objective to tackle the maintenance backlog.

There appears to be a nervousness for engineers to try new and innovative products and stray from the 'tried and tested'. Work is required to build confidence with the existing workforce, management and front line, as well as senior decision makers to move towards new products if the Council are to release potential to move towards Net Zero. As well as Highway Authorities the supply chain has a role in building this confidence and there is a need to support their transition through developing their skills and knowledge on the topic.

Paul Binks: [email protected]