Warranting traffic signals on the basis of proximity of railroad grade crossings

Elena Shenk Prassas, William R. McShane, Edward Lieberman, Roelof Engelbrecht

Research output: Chapter in Book/Report/Conference proceedingChapter


There were two concurrent paths in this research. Path 1 estimated the probability, pvehicle/train, that a vehicle will be in the train dynamic envelope given that a train arrives. This was done by an extensive simulation effort that included some data collection on relevant gap acceptance patterns. Path 2 identified the exposure factors, selected a risk metric, and established a target or threshold for the risk, which is expressed as an upper bound on pvehicle/train. As a result of the investigation, the warrant is based on the principle that the expected fatality rate at the crossing should not exceed rates found at unsignalized intersections. The two paths converged by expressing the constraint p vehicle/train ≤_(where_is in terms of traffic terms in common use - e.g., volumes, composition, track location distances). This constraint led to the warrant, which was then validated with data acquired or collected for the purpose. The draft warrant was prepared as a result of the undertaking, was endorsed by the National Committee on Uniform Traffic Control Devices, and is currently in the formal review process, culminating in final edits and a decision on inclusion in the next edition of the Manual on Uniform Traffic Control Devices.

Original languageEnglish (US)
Title of host publicationTraffic Control Devices, Visibility, and Rail-Highway Grade Crossings 2007
PublisherNational Research Council
Number of pages10
ISBN (Print)9780309104579
StatePublished - 2007

ASJC Scopus subject areas

  • Civil and Structural Engineering
  • Mechanical Engineering


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