Overview
Advance warning signals installed upstream of a high-speed signalized intersection (HSSI) warn motorists of impending signal changes in an effort to reduce the frequency of red-light running (RLR) and crashes. A new advance warning signal design was tested on an approach to a HSSI in Salt Lake County to study the effects of the design on motorist behavior. The new design utilized an overhead dynamic blank-out sign and flashers. A state-of-the-art Digital Wave Radar TM evaluation system was installed at the study site to collect continuous data of vehicle speeds and RLR events by a non-intrusive method. Crash data were collected from the jurisdiction responsible for the study site. Data were collected prior to, immediately after, and eight months after installation of the system. Initial results to the installation showed that motorists were adhering to the advance warning as evidenced by the speed data and a reduction in RLR events. Eight months after installation, however, vehicle speeds and RLR had returned to their original conditions. As a result, recommendations were made to begin to improve performance of the system, while additional monitoring was recommended to evaluate the limited recommendations made