ENHANCED ALGORITHM FOR RAILROAD PREEMPTION OF TRAFFIC SIGNALS

The guidelines and standards that exist to govern the operation of traffic signals near railroad grade crossings have only been slightly changed over the last 20 years. Yet, even with the instituted changes, many crossings operate each day in an inefficient and potentially unsafe manner. The strategy described offers one method to help improve the efficiency and safety of highway-railroad grade crossings located near signalized intersections. The Transitional Preemption Strategy (TPS) relies on advanced train detection to notify intersections controller that a train is approaching the crossing. The smooth transition possible using TPS differs from existing treatments, which often curtail pedestrian clearance times and/or vehicular minimum green times so that the intersections signal controller unit can reach the signal phase(s) that clear vehicles from the tracks as quickly as possible. The TPS algorithm has been software encoded and integrated into a signalized traffic environment and highway-railroad grade crossing simulator that makes use of actual traffic signal control hardware. The simulator was used to test and refine the TPS logic under a range of operating conditions, and the results show improved performance in comparison to normal railroad preemption (without TPS) >