The use of video imaging vehicle detection systems (VIVDS) in Texas has increased significantly due primarily to safety issues and costs. Installing non-intrusive detectors at intersections is almost always safer than installing inductive loops due to greater separation between passing motorists and field crews installing the detectors. Other factors that have contributed to the increased usage of VIVDS include the flexibility offered in terms of adjusting detection zones (e.g., with lane reassignments), the ability to send an image of the traffic stream to a traffic operations center, and no damage to the pavement structure as with inductive loops. Despite these advantages, there are situations where VIVDS needed further research to ensure safe operations. The objective of this research was to determine how well the current video imaging systems deployed by the Texas Department of Transportation (TxDOT) provide dilemma zone protection at high-speed signalized intersections. Preliminary findings of this research following data collection at one of the three planned sites indicate that VIVDS demonstrates significant detection discrepancies compared to in-pavement sensors. However, these discrepancies were not always critical to safety but would increase intersection delay.
Abstract