Preemption of Traffic Signals Near Railroad Crossings
Preemption of Traffic Signals Near Railroad Crossings
The Institute of Transportation Engineers (ITE) is preparing this report to reflect the current state-of-the-practice and to provide the user with a broad overview of key considerations for the preemption of traffic signals near railroad grade crossings.

Members who purchase this report will receive the final version for free when it is made available.

Where a signalized intersection exists in close proximity to a railroad crossing and either queues from the intersection impact the crossing or queues from the crossing impact the intersection, the railroad signal control equipment and the highway traffic signal control equipment should be interconnected. The normal operation of the traffic signals controlling the intersection should be preempted to operate in a special control mode when trains are approaching.

This proposed recommended practice was written primarily for an audience of engineers working for public agencies, railroads, and public transit agencies engaged in signal design and operational timing. The objective of this proposed revision to the Preemption of Traffic Signals Near Railroad Crossings is to include new information on the design and operation of traffic signal preemption that has been learned since the previous edition was published, including:

  • Information has been added on the concept and the function of diagnostic teams.
  • Explanation of the critical factor for determining the need for preemption is not the distance to the crossing, but the likelihood that a traffic queue will extend onto the tracks, regardless of what the distance is. Additional methods for estimating queue lengths are provided.
  • New definitions have been added as well as new drawings illustrating the definitions of the Clear Storage Distance and the Minimum Track Clearance Distance.
  • Explanation of the procedure for preempting traffic signals of diagonal crossings at intersections with accompanying illustration.
  • Discussion with illustration of use of pavement markings to warn drivers of the area of a railroad crossing that must not be blocked. There is mention of the use of roadway edge lines and pavement arrows in the vicinity of railroad crossings.
  • Discussion of ADA considerations in the design and timing of preemption.
  • Additional discussion on the need for special traffic control when there is construction in the vicinity of a railroad crossing consistent with the requirements of the Manual on Uniform Traffic Control Devices (MUTCD).
  • Detailed information regarding the use of pre-signals and queue-cutter signals as well as hybrid systems when the distance between the traffic signal and the railroad crossing is long.
  • Expansion of the section on the design of preemption interconnection circuits.
  • More information regarding the timing of traffic signal preemption to accommodate pedestrians. Although the MUTCD permits the truncation of pedestrian change intervals when preemption is initiated, some jurisdictions are now providing pedestrian change intervals to increase pedestrian safety, particularly in the vicinity of train stations.
  • New information regarding the need for preemption of flashing beacons or hybrid beacons at pedestrian crossings near railroad crossings.
  • References to preemption timing worksheets from two roadway jurisdictions as examples of methods for developing preemption timing.

  • The development of the revised recommended practice has been coordinated with the forthcoming update version of the Railroad Crossing Handbook so that the information on preemption will be consistent in both documents.
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Pub. No.: RP-025C-E

ISBN: ISBN-13: 978-1-933452-97-5 and ISBN-10: 1-933452-96-X

Author: Joint Rail Grade Crossing Committee of the Traffic Engineering Council

Publisher: ITE

Format: PDF

Pages: 80

Publishing Date: 04/19