A new method to calculate emissions with simulated traffic conditions

Microscopic traffic simulation models coupled with instantaneous emission models have the potential to provide improved assessments of the environmental impact of traffic networks, management strategies and technology implementations. This paper describes a toolbox, which links the microscopic traffic flow simulator VISSIM with the instantaneous emission model PHEM (Passenger car and Heavy-duty Emission Model). PHEM was developed to simulate a full fleet of heavy-duty vehicles, passenger cars and light commercial vehicles. The supporting data-set includes gasoline and diesel vehicles from EURO 0 to EURO 6. PHEM calculates vehicle fuel consumption and emissions, using speed trajectories as model input. VISSIM is able to supply these necessary speed profiles for all vehicles within the network. In order to supplement realistic traffic volume with traffic control strategies an interface between VISSIM and the adaptive Urban Traffic Control System MOTION by Siemens has been developed. This paper discusses the evaluation of the modeled traffic situations in urban road network with VISSIM and PHEM by measurements on the road and on the chassis dynamometer. Intensive calibration of the traffic How simulation has been conducted to match the vehicles' 'acceleration' and 'desired-speed' parameters to the local conditions. Comparative driving cycles, from the 'on-road' measurements recorded via GPS instrumented vehicles and the 'virtual' network simulations were selected. The 'on-road' and 'virtual network' driving cycles were measured on the chassis dynamometer with a EURO 4 diesel car. The measurements were compared with the PHEM predictions. This approach allowed the uncertainties associated with modeling speed profiles to be compared with the uncertainties related to the emission model. The overall model performance was evaluated by comparing the PHEM emission calculations based on simulated speed profiles with the measured emissions from the 'on-road' driving cycles.