Emissions Modeling and Integration into Traffic Micro-simulation

PI:  Scott Washburn, Ph.D., University of Florida

Co-PI:  Nagui Rouphail, Ph.D., North Carolina State University; H. Christopher Frey, Ph.D., North Carolina State University

Final Report (pending)

UTC Project Information

Transportation accounts for 28% of all U.S. energy use (EIA, 2006). Highway transportation accounts for 32% of national annual emissions of nitrogen oxides (NOx), 50% of CO, and 22% of volatile organic compounds (VOC) (EPA, 2012). The USDOT recognized the significant effect of the transportation system operation on environmental impacts in its latest draft Strategic Plan (USDOT 2010), with two of its five strategic goals dealing with issues of livability and environmental sustainability. This increasing concern regarding air quality has motivated the need for accurate measurements or estimates of micro-scale (i.e. second or sub-second) vehicle Energy Use and Emissions (EU&E). This proposal addresses such a need from measurement, estimation, and information dissemination perspectives.

The objectives of this research are to expand the emissions inventory database to include vehicle activities at the high emission modes and during cold starts, to gather and interpret measurements of emissions on steep upgrades and downgrades, and to incorporate emissions estimation into CORSIM using the VSP approach. The overall methodological approach is: (a) to calibrate and validate a reduced form model (RFM) of the relationship between vehicle dynamics and energy use and emissions; (b) to incorporate the RFM into CORSIM; (c) to test and evaluate the coupled CORSIM and RFM; and (d) to apply the coupled model to demonstration case studies. The latter will demonstrate how the coupled model can be used to quantify the energy use and emissions impacts of transportation control measures and transportation improvement projects. Calibration and validation of the RFM will be based on PEMS field measurements of light duty gasoline vehicles. We will focus on tailpipe emissions of CO2, CO, HC, and NOx during cold starts and vehicle operation on the road network. Since over 98 percent of the U.S. passenger car and passenger truck fleet uses gasoline, we will focus on light duty gasoline vehicles.

The principal desired outcome of this research is to develop and disseminate a tool for transportation engineers and planners that will enable them to assess the environmental impacts of a host of traffic management strategies. A subset of these strategies that is already included in the latest CORSIM model will directly benefit from the inclusion of state-of-the-art fuel use and emission models.