GUIDELINES FOR RAILROAD PREEMPTION AT SIGNALIZED INTERSECTIONS

Preemption of traffic signal controllers near railroad grade crossings equipped with active warning devices is often required because queues from the intersection can extend back over the tracks, thereby creating the potential for a serious vehicle-train accident. This paper reports on the findings of a research study recently completed at the University of Wisconsin-Madison. The objective of the study was to develop methods for determining when preemption is required at isolated intersections, and for specifying the duration of the preemption intervals. Macroscopic traffic flow models and probability theory were used to describe the behavior of traffic under preemption conditions. Human factor considerations pertinent to the driving task were adapted from criteria currently used in establishing intersection sight distance and passing sight distance requirements. Limited resources precluded implementation and field evaluation of the developed methodologies.