Technology Digests / Laser Broken Rim Detector – Part I

TD22-007

May 1, 2022
Authors
  • Anish Poudel
  • Silvia Galvan-Nunez
  • Brian Lindeman
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Key Findings

  • Statistical approaches were utilized to estimate the probability of hits (POH) and probability of detection (POD) to demonstrate the capability of the laser broken rim detector (BRD) system.
  • This prototype system was designed to find a wheel fracture at least 0.75 inch wide and at least 0.5 inch deep.
  • Under optimal conditions, the POH can reach 100 percent, and the POD can reach 90 percent.
  • The system had low POH for flaws with widths less than 0.25 inch and greater than 1.75 inches.
  • The system had low POD for flaws with widths less than 0.75 inch.
  • False positive probability (FPR) ranged from 0 to 30 percent with average FPR at 13 percent for all test runs conducted. This was irrespective of test speed and test conditions simulated.
  • For this study, high speeds affect the POH and POD rates, and, in MxV Rail’s evaluation, the small sample size also affected these rates.

Laser Broken Rim Detector – Part I

With collaboration from CN Railway and commercial vendors, MxV Rail evaluated the next generation of optical broken wheel detectors capable of detecting broken wheels at speeds up to 70 mph. The installation and testing of one such prototype system, also known as the laser broken rim detector (BRD) system, was conducted under the Association of American Railroads (AAR) Strategic Research Initiatives Program. The main goal of this research was to demonstrate the capability of the laser BRD system for detecting broken wheel rims at revenue speeds over a wide range of testing conditions. BACKGROUND Figure 1.Railroad car wheel tread images: (a) damage zones; (b) broken rim Typically, conventional wheel impact load detector (WILD) systems are installed on a tangent track. The results obtained from these systems are used 1) to detect any out- of-round conditions, whether these conditions are due to wheel polygonization or surface anomalies,…