Tool to assess air quality impacts of elevated roads within the Strategic Road Network

Highways England is working towards developing the Strategic Road Network (SRN) to have minimal air pollution impact on neighbouring communities. The ADMS-Roads air quality modelling software tool is key to this goal because it is used to assess the air quality impact of SRN capital investment schemes and mitigation measures. Better assessments will enable Highways England to design and plan its developments more effectively with regard to air quality, leading to reductions in air pollution concentrations experienced by neighbouring communities.

Highways England sub-contractors use ADMS-Roads to calculate air pollutant concentration levels of pollutants such as nitrogen dioxide and particulates, which arise from the dispersion of toxic emissions from vehicles on the SRN, taking into account road and building geometry, meteorological conditions, traffic flows and changes to emissions due to mitigation measures such as traffic management, speed control, use of ultra-low-emission vehicles and modal shift. The model calculates air quality at high spatial (a few metres) and temporal (hourly) resolution, allowing calculation of population exposure. In these assessments ADMS-Roads is typically used to assess the effectiveness of a range of pollution mitigation scenarios, informing a selection of cost-effective measures for implementation. Better evidence for this decision making will lead to the reduction of air pollutant concentrations in the vicinity of the SRN.

Populations are most exposed to pollution from the SRN in urban areas where the road geometry often includes complex features to improve traffic flow at junctions, such as flyovers and underpasses. There is therefore an urgent need to understand the detailed local air quality impacts of these road features on neighbouring communities, but currently even state-of-the-art models such as ADMS-Roads have limitations with regard to modelling elevated sections of road. In this project, a team of expert air quality scientists at CERC, the UK SME which has created and developed ADMS-Roads over the last 20 years, will address these limitations. The team will undertake research and development leading to the release of a tool specifically designed to predict the air quality impact of elevated road sections. There are over 100 UK users of ADMS-Roads, and its sister model ADMS-Urban, so any model developments resulting from this project will benefit the whole community developing air quality mitigation measures in urban areas, including Highways England and local authority planners.