Application of Flexible Detectors on

High-Speed Intersections

Teresa Flickinger, Graduate Student (taflick@uakron.edu)

and

Ping Yi, Advisor (pyi@uakron.edu)

Department of Civil Engineering

The University of Akron

Akron, OH 44325-3905

Abstract

At-grade, high-speed intersections requiring signal control can substantially impact the safety of the public and the efficiency of the intersection if not designed properly. Traffic signals, when designed and located accurately, can increase safety by reducing the frequency of certain types of accidents and improve efficiency by minimizing system delays and increasing capacity. Signal designs that display the yellow to drivers when they are in the dilemma zone increase accident risks. When this occurs, the driver can neither stop the vehicle safely behind the intersection stop line, nor going through the intersection before traffic on the conflicting direction is released.

Designs that detect approaching drivers and extend the green until they clear the intersection are somewhat safer but can still cause delays. These designs utilize advance detectors and traffic actuated controllers to respond to varying traffic demands. Most detectors in use today consist of wire loops permanently placed under the surface of the pavement. However, speeds vary depending on motorists and driving conditions, and this impacts the location and the size of the dilemma zone. Permanent placement of detectors therefore does not guarantee dilemma zone protection for those drivers whose speed varies from the design.

This research looks into the application of flexible detectors based on machine vision technologies. By obtaining advance speed information from the detectors located upstream of the dilemma zone, the system determines the most appropriate location for detection in real time and relocates the detector accordingly. With such design the driver can safely proceed through the intersection and the intersection operates more efficiently. Field tests on the effectiveness of the flexible detectors were conducted and comparisons with fixed detectors made.