New models and data are needed in microscopic traffic simulation tools toallow effective use with newer modal tailpipe emissions models. Traffic simulation models offer the ability to simulate large second-by-second vehicle operation datasets as input for emissions models. However, more data is needed to improve simulation of second-by-second vehicle speed. This research analyzes and models the vehicle dynamics of unconstrained drivers in real-world driving situations based on road geometry. Vehicle dynamicsdata were collected using an instrumented vehicle driven by 22 volunteers, over a 17-mile predetermined test route. The objective of this researchwas to analyze and model the non-random speed variations in unconstrainedlead drivers. The results of this study suggest horizontal and vertical curvature have a significant impact on the second-by-second operation of an unconstrained lead vehicle. Furthermore, these non-random changes in speed are important considerations since they can produce considerable variations in the level of tailpipe emissions.
Abstract