Center Truck Performance on Low-Floor Light Rail Vehicles

Low-floor light rail vehicles are used by many transit systems with increasing popularity. The typical design includes a three-section articulated vehicle body with the center section connected to a center truck with non-powered, independently rotating wheels. The leading and trailing sections of the vehicle are each supported by a motored truck at one end and by the common non-powered center truck at the other. The low-floor height prevents the use of wheel sets with solid axle connections between right and left wheels of the center truck. In acceleration and braking modes during curving, because there are two articulations connecting the center section, the center section and truck may rotate excessively causing a high angle-of-attack and flanging. Also, the independently rotating wheels of the center truck do not promote self-steering through the curve, increasing the angle-of-attack and flange forces. This condition leads to increased flange wear, gauge face wear, stick/slip noise, and potential for derailment at curves and special trackwork. Wheel life of the low-floor center truck can be significantly less than that of motored trucks. Research is needed to better understand the performance of the center trucks of low-floor light rail vehicles, compile lessons learned to date, and provide guidance to transit agencies and light-rail vehicle manufacturers on how to mitigate performance problems. The objective of this research is to provide guidance to transit agencies and low-floor light rail vehicle manufacturers for the mitigation of problems associated with the design and operation of non-powered center trucks on a three-section, articulated vehicle body with the center section fixed to a center truck with independently rotating wheels. This research will, at a minimum, identify contributing factors that can cause events such as derailments, excessive noise, excessive wheel and rail wear, and reduced ride quality (e.g., hunting and excessive curving). The research will provide (1) guidance for existing light rail systems, and (2) guidance for future vehicle procurements and track design. The guidance will identify mitigation actions related to vehicle and track (including curved and special trackwork) design specifications, the wheel/rail interface, track construction and maintenance tolerances, and the use of turnout point protection and friction modifiers.


  • English


  • Status: Completed
  • Contract Numbers:

    Project C-16

  • Sponsor Organizations:

    Federal Transit Administration

    1200 New Jersey Avenue, SE
    Washington, DC  USA  20590

    Transit Cooperative Research Program

    Transportation Research Board
    500 Fifth Street, NW
    Washington, DC    20001
  • Project Managers:

    Jencks, Crawford

  • Performing Organizations:

    Interfleet Technology, Incorporated

  • Principal Investigators:


  • Start Date: 20041019
  • Actual Completion Date: 20060418
  • Source Data: RiP Project 10157

Subject/Index Terms

Filing Info

  • Accession Number: 01460737
  • Record Type: Research project
  • Source Agency: Transit Cooperative Research Program
  • Contract Numbers: Project C-16
  • Files: RiP, USDOT
  • Created Date: Jan 3 2013 1:31PM