DEVELOPMENT OF ADVANCE WARNING SYSTEMS FOR END-OF-GREEN PHASE AT HIGH SPEED TRAFFIC SIGNALS

This report describes a research study that developed an effective advance warning for end-of-green phase at high-speed (>/= 45 mph) traffic signals in Texas. This report contains the research conducted, hardware developed, and field testing performed on the Advance Warning for End-of-Green System (AWEGS) designed by the Texas Transportation Institute for the Texas Department of Transportation (TxDOT). Two companion reports present guidance on the design, installation, and operation of AWEGS. A series of advance warning technologies were tested over the two-year study. A base Level 1 technology was initially proposed using "trailing overlaps" to provide a fixed amount of advance warning of the end-of-green phase, but this method was rejected because it gave up existing dilemma zone protection. A new Level 1 technology, using average speed while still predicting when the traffic-actuated controller would gap-out, was substituted. More advanced AWEGS technologies (Level 2) added vehicle typing (car, truck) and individual speed measurement to better estimate when the signal controller would gap-out. AWEGS was field tested at two sites in Waco and Brenham, Texas. The Waco site was a high-speed, two-lane rural road. The second site was a high-speed four-lane divided highway located on the US 290 bypass of Brenham, Texas. AWEGS reduced red-light-running, during the targeted first 5 seconds of red, by 40 to 45%. Level 2 AWEGS is much preferred because it also minimizes negative impact on the existing traffic-actuated controller, and it provides new and effective dilemma zone protection for trucks and very high-speed cars.