The vehicle emission simulation feature of the TEXAS (Traffic Experimental Analytical Simulation) Model for Intersection Traffic in its Version 3.2 was used to demonstrate the potential fuel savings that can be realized from the provision of free u-turn lanes at diamond interchanges. More than 2000 runs of the model were made to compare the estimated amount of fuel consumed by u-turning vehicles using a free u-turn lane with that consumed by a similar number of such vehicles reversing direction through the two closely-spaced intersections of this type of interchange. The observed traffic, geometric configuration, and traffic signal control at six existing diamond interchanges in Texas served as the basis for case studies in this research. Each interchange was evaluated over a range of traffic volumes and u-turn demand scenarios with, and without, free u-turn lanes. (Author/publisher)
Abstract