Mapping vehicle emissions through urban streets and intersections

Microscopic traffic simulations coupled with instantaneous emission models are able to assess the environmental impact of traffic networks, management strategies and fleet renewal at a high temporal and spatial resolution. The approach couples traffic microsimulations, which model the movement of individual vehicles through a well specified study area road network, with instantaneous vehicle emission models that provide second-by second fuel consumption and tail-pipe emission predictions. As the traffic microsimulations consider all the vehicle movements second-by-second (stationary, accelerating/ decelerating, cruising), unlike alternative more aggregate approaches, they can study congestion effects, stop-start driving and local traffic flow conditions. The highly spatially resolved predictions also mean the vehicle emission source strength can be mapped through urban streets and intersections. The mapping results will be of interest to atmospheric modellers simulating the dispersion of vehicle emissions within City streets e.g. canyon environments (local-scale). Visualising the variations in emissions can support traffic Network Managers and Policy Makers working to minimise the environmental and health impacts of road transport emissions, helping them understand which locations have the highest source strengths, so facilities where people congregate and are exposed to emissions such as Bus stops and Pedestrian crossings can be located away from emission ‘hotspots’.