Technology Digests / Wheel/Rail Vertical Impact Force Measurement Comparisons

TD25-003

June 25, 2025
Authors
  • Nate Stoehr
  • Yuqing Zeng
  • Tony Sultana
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Key Findings

  • The difference between the wheel/rail vertical impact forces measured by onboard high accuracy IWS and in-track HAC was within ±5 percent.
  • The difference between the impact forces measured by onboard high accuracy IWS and low-cost NBA was within ±10 percent. However, the stability of NBA needs to be further improved to meet the requirement for an onboard application.
  • Combined with the operation speed, the portable rail bump (PRB) can:
    - Effectively control the magnitude and location of the impact load.
    - Reach the AAR actionable limit (90 kips) as expected.
    - Be a practical device for generating impact load.

Wheel/Rail Vertical Impact Force Measurement Comparisons

Under the Association of American Railroads’ (AAR) Strategic Research Initiatives (SRI) program, the MxV Rail research team developed enhanced and robust measurement techniques that integrate: 1) AAR-qualified, high-accuracy, onboard instrumented wheelsets (IWS), 2) a new bearing adapter (NBA) that incorporates load cell force measurments with an acceleration compensation approach, 3) a wayside high-accuracy in-track bi-circuit (HAC), and 4) portable rail bumps (PRBs) of varying thicknesses to provide a detailed comparison of the wheel/rail (W/R) impact vertical force measured onboard and in-track. The MxV Rail team also conducted preliminary on-track testing to verify and validate the performance of the new proposed methods. The end goal of this work is focused on establishing an industry benchmark for validating any Wheel Impact Load Detector (WILD) systems, which are commonly used to inform wheel removal decisions.   BACKGROUND  In prior studies,1,2 MxV Rail explored the use of PRBs to generate W/R impact loads and collected…