Determination of Actual Derailment Loads on Transit Bridges

Derailment loads in nearly all U.S. transit design criteria documents are similar to each other. Various agencies modified the loads between 1985 and 2005 with no documented or defined basis. Currently, vertical impact is defined as 100% acting on any truck in the train, while horizontal derailment load is taken as 40% of a single carload acting on one truck. Lateral excursion in both cases is taken as a maximum of 3 ft, which assumes that a vehicle will not travel further after derailment. Neither of these loads have been experimentally verified and appears to be based on an arbitrary definition that has become the norm in the U.S. industry. It is unknown whether this load is reasonably accurate, overly conservative, or too liberal.  Research is needed to formulate a rational load within acceptable limits of accuracy to ensure the efficient and safe design of bridges. The transit vehicle industry has the tools to simulate the entire vehicle derailment and use these models to check the safety of the vehicles. The industry can leverage their expertise and knowledge and extend their models to determine the loads on the bridge in the vertical and lateral directions. The objective of this research is to determine accurate horizontal and vertical derailment loads for the efficient and safe design of transit structures.  At a minimum, proposers shall address the following to achieve the research objective:  (1) Select a representative vehicle or vehicles using a rational method. (2) Analyze typical track configurations (e.g., ballast, direct fixation, etc.). (3) Utilize numerical modeling to determine the horizontal and vertical impacts. This might be supplemented by physical testing with a test plan and expected outcomes that are clearly defined.  (4) Validate the derailment loading model that assumes loads on a single truck. (5) Establish derailment load criteria that complement the American Association of State Highway and Transportation Officials (AASHTO) LRFD Guide Specifications for Bridges Carrying Light Rail Transit Loads. (6) Establish extreme event (derailment) load factors and combination.


  • English


  • Status: Proposed
  • Funding: $300000
  • Contract Numbers:

    Project D-24

  • Sponsor Organizations:

    Transit Cooperative Research Program

    Transportation Research Board
    500 Fifth Street, NW
    Washington, DC    20001

    Federal Transit Administration

    1200 New Jersey Avenue, SE
    Washington, DC  United States  20590
  • Project Managers:

    Garcia-Colberg, Mariela

  • Start Date: 20230919
  • Expected Completion Date: 0
  • Actual Completion Date: 0

Subject/Index Terms

Filing Info

  • Accession Number: 01866950
  • Record Type: Research project
  • Source Agency: Transportation Research Board
  • Contract Numbers: Project D-24
  • Files: TRB, RIP
  • Created Date: Dec 13 2022 10:02AM