New Detection System for Rural Signalized Intersections (0-4022-S)

Traffic engineers are often faced with operational and safety challenges at rural, high-speed signalized intersections. Vehicle-actuated control, combined with multiple advance detectors, is often used to improve operations and safety. However, this type of detection and control has not always eliminated rear-end or right-angle crashes. Crashes sometimes continue to occur at high-speed intersections, and delays to traffic movements can be unnecessarily long. The existing multiple advance detector system holds the traffic signal in green until a suitably large gap occurs in the traffic stream. Through this action, the system ends the phase safely because the approach is empty. However, this gap occurs infrequently on high-volume approaches and often causes the corresponding signal phase to extend to its maximum limit (i.e.,max-out). When the phase reaches this limit, it ends without regard to the number of vehicles on the approach and increases the potential for a rear-end crash. If the maximum greensetting is large, then the resulting delays may also be large. The high-speed nature of most rural intersections heightens concerns about phase termination by max-out because crash severity increases significantly with speed. Other problems exist with the multiple advance detector system.