Application of AIMSUN Microsimulation Model to Estimate Emissions on Signalized Arterial Corridors

Tailpipe emissions from on-road vehicles have negative impacts on the air quality of a region and are influenced by several factors including driver behavior, road characteristics, and traffic conditions. Typically vehicles on arterial roads frequently stop and then accelerate, a behavior that produces more tailpipe emissions than does maintaining a steady speed. Microscopic simulation models generate synthetic vehicle activity that can be used to estimate emissions on a facility. For emissions to be estimated accurately from an arterial facility, the simulated activity must closely represent the activity observed in the field. This study investigated whether a selected set of simulation parameters that used speed trajectories observed in the field at high temporal resolution could improve the emissions estimated from a simulated signalized arterial corridor. The simulated trajectories and those observed in the field were characterized by vehicle-specific power (VSP). Emissions were estimated with VSP modal emission rates and the time spent by vehicles in each VSP mode. The emissions were compared for routes along an urban arterial facility and for shorter segments within routes. At both spatial scales, the emissions from parameter-adjusted simulation vehicles that had the same average number of stops and travel time distribution as vehicles observed in the field were closer to real-world emissions than were the simulation vehicles under default model parameters. Adjusting the parameters also allowed the model to capture emissions hot spots along the routes more accurately. Currently, microscopic simulation models are calibrated with traffic performance measures that are improving. The findings from this paper present the potential for using these improving emissions estimates from simulated vehicle activity for the additional calibration of microsimulation models.