Book Description

The coordination of highway-railroad grade crossing warning signals with nearby traffic signals is of vital importance due to potential safety consequences. Interconnections between traffic signals in close proximity to railroad crossings provide an important safety function by allowing the railroad warning system to preempt the normal traffic signal operation and provide special phasing to clear vehicles queued over the railroad tracks, prohibit others from joining the queue, and maintaining traffic flow for non-conflicting traffic movements. In Michigan, there are approximately 200 interconnected highway railroad grade crossings that are all under regulatory control of the Michigan Department of Transportation. The MUTCD provides guidance concerning the use of preemption where the signalized intersection is within 200 feet of a railroad crossing. There is however, minimal guidance for locations where intersections are more than 200 feet beyond the railroad crossings. Some of these locations experience queuing problems due to high traffic volumes. The purpose of this research was to compile and review literature and current practices related to interconnected traffic signals and preemption in order to determine solutions for providing safe and efficient timings for the traffic signals and nearby highway-railroad grade crossing warning signals. A series of highway-railroad intersection configuration templates was developed as a part of this research. A set of guidelines was also developed with accompanying software to provide additional assistance for identification of possible interconnection locations that could utilize preemption concepts. The guidelines also assist in the determination of signal timing parameters for the phasing and timing design required as a part of the concept.