Evaluating zone of influence for traffic-related emissions generated near bus stops: a case study in Nanjing, China

The estimation of zone of influence (ZoI) at bus stops is the basis for accurately modelling vehicle emissions and assessing the exposure of pedestrians to airborne toxins at emission hotspot locations. The purpose of this study was to investigate the changes in ZoIs for traffic-related emissions at different bus stops. An integrated approach coupling a traffic simulation model (VISSIM) with an emission model (MOVES) was implemented to estimate the vehicle emissions in ZoIs at bus stops for different scenarios. The results demonstrated that lane management mode and traffic conditions had a significant impact on vehicle emissions near different bus stops, and the emission factors (EFs) of pollutants were highest in the acceleration sublink. In addition, the length of the acceleration and queue sublinks mainly determined the length of the ZoIs of bus stops. Owing to the stop-and-go condition, the average contribution of CO, PM2.5, and PM10 towards the ZoI at curbside bus stop and bus bay without exclusive bus lane was significantly higher than under cruising condition. The sensitivity analysis also showed that the emission was more sensitive to acceleration than deceleration. Therefore, the emissions of the departure links for bus stops were significantly higher than those of the approach links. Commuters should reduce the long-time waiting at bus stops, wait downstream of bus stop when waiting for the bus stop, and the vehicles at the bus stop should accelerate slowly when leaving, which will all help to minimize the exposure of commuters to pollutants.