Investigators:
Dr. Randall L. Guensler, Georgia Tech
Dr. Michael O. Rodgers, Georgia Tech
Xiaodan Xu, Ph.D. Student, Georgia Tech
Haobing Liu, Ph.D. Student, Georgia Tech
Project Overview:
Estimating transportation network emissions requires multiplying estimates of on-road vehicle activity (by source type and operating mode) by applicable emission rates for the observed source type and operating conditions. Coupling micro-simulation model runs with emissions modeling can provide fast assessment in transportation air quality planning. This thesis presents a tool with automated linkage between the VISSIM microsimulation model and the MOVES vehicle emissions model. To link the two models, MOVES-Matrix is applied, which was prepared by iteratively running MOVES across all possible iterations of vehicle source-type, fuel, environmental, operating conditions, and other parameters (hundreds of millions of model runs) to create a multi-dimensional emission rate lookup matrix [1]. To facilitate and automate the linkage, a tool is developed in Python to integrate VISSIM outputs with applicable MOVES-Matrix emission rates, assigning each second of vehicle activity to the applicable MOVES-Matrix emission rate for that source type, model year, and operating mode bin.
A VISSIM simulation of the major arterials and freeways at I-85 and Jimmy Carter Boulevard in Gwinnet County, Georgia provides the case study for this MOVES-matrix application. The team presents predicted emissions and the results of a sensitivity analysis to identify the potential impacts of various internal VISSIM modeling parameters (such as minimum headway, maximum deceleration rate for cooperative braking, and emergency stop distance) on case study emissions outputs. The sensitivity analysis found that internal VISSIM parameters impacted emissions and that proper care should be taken in using VISSIM for emissions analysis at the corridor and link level. The case study demonstrates that VISSIM coupled with MOVES-Matrix can be an effective tool for emission analysis. Part of this thesis has been published on Transportation Research Record [2].