Introduction
The Trunk Road Network
The Trunk Road Network (TRN) is a strategic network of major roads and motorways connecting Scotland’s cities, major towns, airports, and ports. Extending over 2,300 miles and valued at more than £30 billion, it includes a wide range of assets such as carriageways, bridges, structures, and associated infrastructure.
Transport Scotland is responsible for the operation, maintenance, and improvement of the TRN, working in partnership with private sector Operating Companies who oversee, coordinate, and undertake cyclic and routine maintenance, winter service, and emergency response. In addition, Transport Scotland undertakes structural road maintenance, bridge strengthening and maintenance, safety and condition inspections, road safety, and minor improvement schemes.
A Net Zero Trunk Road Network
Activities associated with operating, maintaining, and improving the trunk road network generate greenhouse gas emissions through the energy used, materials consumed and waste produced. The Scottish Government has committed to achieving Net Zero greenhouse gas emissions by 2045, and the transport sector has a critical role in delivering this ambition.
Transport Scotland aims to achieve Net Zero emissions from the operation, maintenance, and improvement of the trunk road network by 2045. To support this ambition, the Net Zero Route Map sets out the actions required to reduce emissions across the TRN in line with national climate targets.
Development of the Net Zero Route Map
Baseline Greenhouse Gas (GHG) emissions (in tonnes of carbon dioxide equivalent (tCO2e)) were estimated for financial years 2021-22 and 2022-23 and averaged across the two years. Transport Scotland emissions were used as well as those generated by our supply chain through work on our behalf (Scopes 1, 2 and 3 according to the Greenhouse Gas Protocol). The scope of the study was kept to the emissions directly attributable to the operation, maintenance, and improvement of the TRN; emissions associated with running our organisation are counted within our corporate reporting.
Data to inform the baseline was sourced from our Asset Management Performance System (AMPS), which captures detailed information about the work carried out by our Operating Companies. This was used to understand the materials used on different schemes, and assumptions were applied on how far they have been transported based on the locations of our materials suppliers. Further data was provided by our Operating Companies in Annual Reports which contain sustainability metrics such as fuel, electricity and water use in plant, fleet, and depots. The most appropriate emission factors were applied from a range of authoritative sources including Inventory of Carbon and Energy and UK Department for Energy Security and Net Zero (DESNZ) to attribute GHG emissions to all these activities.
Using the baseline, a Business-as-Usual projection to 2045 was generated, assuming no further decarbonisation interventions are applied beyond background reductions such as UK electricity grid decarbonisation.
Collaborative workshops were led by industry experts with representatives from Operating Companies and Transport Scotland to identify the key opportunities for decarbonisation of the TRN. The following themes were considered which aligned with our main emissions sources; materials, fleet & plant, depot & asset operation, and finally policy, process, and behaviour “enablers” to drive emissions reductions. These emissions reductions were set out in a timetable from 2025 through to 2045 to deliver reductions which are ambitious and challenging, but not unachievable.
A bespoke Route Map model was developed to carry out calculations at all stages of the process, from baseline data entry through to the Route Map pathway output.
Delivery of the Net Zero Route Map
Delivery of the Net Zero Route Map is overseen by Transport Scotland, implemented through Operating Companies and the supply chain, and monitored through defined governance and assurance arrangements.