Evaluating the Effects of Rail Preemption Strategies on Highway Safety and Operations

Abstract

Previous research related to signal preemption near highway-rail grade crossings has emphasized safety considerations, which are paramount due to the severity of potential train-vehicle collisions. The purpose of this research was to quantify the safety and efficiency implications of several common preemption strategies using the conditions in a small urban context. The research evaluates several important characteristics of rail preemption, including track clearance time, advance preempt time, and dwell cycle strategy, particularly with regard to surface street operational efficiency, that current traffic engineering practice do not adequately address. The context and preemption strategies were modeled using simulation software VISSIM. The results identified two separate and potentially serious safety issues related to the interaction of advance preempt time, track clearance time, and existence of four-quadrant gates at railroad crossing. In addition, the research also highlighted the negative effect of excessive track clearance time and dwell cycle on adjacent surface street operations.