Development of a railroad grade crossing traffic signal warrant

NCHRP funded a study of whether a traffic signal warrant for intersections near railroad at-grade crossings can and should be developed. The work was done under NCHRP 3-76A, and resulted in a proposed Warrant 9 to be added to the next edition of the MUTCD. This followed review and endorsement by the NCUTCD and its Task Forces. This paper presents the approach used in that work, with emphasis on the selection of a fatality-based risk exposure metric that is the foundation of the proposed warrant. A novelty is that if a signal is installed at Location "A" (the nearby intersection), it is based on the risk exposure at Location "B" (the approach crossing the track). The proposed warrant includes adjustment factors for train frequency, percentage of tractor-trailers on the minor approach, and vehicle occupancy (e.g. buses) on the same approach, and advises that alternatives such as providing a path for evasive maneuver and re-designation of the major/minor streets be considered prior to the signal alternative. A validation phase, not reported herein but contained in the project report, solicited data from various jurisdictions, along with their professional judgment on whether a signal is needed (albeit recognizing there is no current applicable warrant). The responses were compared to whether the warrant as written would have been triggered, and good compliance between the proposed warrant and the professional opinion was obtained.