US-36 Environmental Impact Statement and Basic Engineering: Methodology of Grade Crossing Evaluation

Abstract

A study was conducted in support of the US-36 Environmental Impact Statement for the proposed commuter rail corridor between Denver and Boulder, Colorado, which determined when consideration of a grade separation may be appropriate for rail crossings in the corridor. The analysis involved three criteria: safety, vehicular travel delay, and feasibility. The methodology for evaluating crossings for grade separation is presented for agencies undertaking roadway–railroad intersection projects to consider. The analysis uses an accident prediction tool in the FRA GradeDec.NET software to assess safety risk and proposes a risk threshold. The evaluation of vehicular travel delay uses standard equations from the Highway Capacity Manual to compare estimated delay with intersection level of service and thus to define an allowable threshold for the project. This paper discusses physical, environmental, social, public, and financial feasibility to help users determine quickly whether any of these factors constitutes a fatal flaw for the analysis. The procedures described establish a methodology for planners and engineers to determine the feasibility of maintaining a roadway–railroad crossing in its existing configuration when implementing a higher-frequency service along an existing railroad corridor. With this method, planning level information may be derived and applied to perform the safety and vehicular travel delay analyses. Users may do a quick screening to eliminate crossings that can operate safely and efficiently with minimal modifications; the responsible agency can then focus time and money on areas that may present challenges to safe and efficient operations.