Dynamic Estimation of Freeway Large-Truck Volumes Based on Single-Loop Measurements

Because of heavy weights and large turning radii, large truck (LT) movements have very different characteristics than those of smaller vehicles, such as passenger cars. This difference makes collection of LT volume data very important for accurate analysis of traffic stream characteristics in transportation planning and engineering. Since LT travel patterns are seasonal, data obtained by surveys conducted for a short period of time every one to three years may not be adequate for safety planning, traffic management, and infrastructure maintenance. Therefore, the ability to collect such data continuously via loop detectors is highly desirable. In this paper, an algorithm for estimating LT volumes using only single-loop outputs is presented. LT volumes estimated by the proposed algorithm were compared with those observed by dual-loop detectors, and the two LT volume series fit each other very well, especially when traffic volume was low. Y. Wang and N. Nihan 2