Land-use, transport and vehicle technology futures: An air pollution assessment of policy combinations for the Cambridge Sub-Region of the UK

This paper reports on an investigation of the impact on air-quality of combinations of urban form development scenarios and vehicle fleet technology changes. The scenarios combine policies affecting urban land-use plans within the Cambridge Sub-Region of the UK, alongside technological changes within the projected vehicle fleet. Broadly, the scenarios consist of the 'Trend' for urban form policy and vehicle technology and the urban form policy options of 'Planned expansion', 'Market-led development' and 'Urban compaction', each combined with form-appropriate technological scenarios addressing the uptake of current, and future, technologies in the vehicle fleet. The framework developed for environmental assessment is described, from land-use transport interaction, through traffic assignment and emissions modelling, through to dispersion calculations. The urban form-vehicle technology combinations have been assessed in terms of overall vehicle kilometres travelled (VKT), greenhouse gas (CO2) emissions, and local air quality (NOx, NO2, PM, HC). Results are presented for 2021 and show that overall network emissions change from -13% (Compaction) to + 8% (Market-led) relative to the Trend, but effects on emissions in individual districts (NOx) may much greater, -40% to +50%. Annual mean concentrations of NO2 at the street level may vary by -7 to 8 mu g/m(3). The use of electric vehicles in the 'Urban compaction' scenario aids mitigation of air quality issues in the city centre. The results are discussed with respect to the feasibility of scenario implementation, current approaches to planning, and trends in vehicle technology. Limitations of the modelling framework are also identified, and future developments outlined.