Investigation of Vehicle Detector Performance and ATMS Interface

This research supplemented findings of previous research projects on the topic of vehicle detection. Because improvements in performance aspects and in functionality of non-intrusive vehicle detectors continue to occur at an ever increasing pace, there were reasons to continue testing of the most viable products and determine their interface potential with other components of the Texas Department of Transportation’s (TxDOT’s) existing system. Like previous vehicle detector research, this research tested the latest and most promising non-intrusive vehicle detector technologies. The ones included in this research were: video image vehicle detection systems (VIVDS), acoustic, magnetic, inductive loops, and microwave radar. Besides evaluating detectors, the research scope also included investigating an interface with TxDOT’s current Advanced Traffic Management System (ATMS) using contact closure inputs to current Local Control Units (LCUs) for collecting vehicle count, speed, and occupancy data. Findings of this research indicate that, of the detectors tested, the following technologies appear to be most promising for freeway applications based on cost, accuracy, and ease of setup: microwave radar and magnetometers. One of the VIVDS units tested was also accurate but its cost and ease of setup were inferior to the other two. Neither of the two technologies is affected by weather and they are capable of consistently achieving 95 percent count accuracy (or better) and can detect speeds to within 5 mph of true speeds.