Technology Digests / Effectiveness of Cold-Wheel-Based Brake Tests

TD25-001

June 25, 2025
Authors
  • Yi Wang
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Key Findings

  • Brake tests using wheel temperatures (cold wheel processes) are often effective in identifying cars exhibiting low wheel temperatures related to degraded brake system effectiveness.
  • In general, regardless of the job code recorded during the shop event triggered during a cold wheel process, there appears to be a statistically significant improvement in car wheel temperatures after the shop event.
  • Additional verifications in the brake test algorithms or standardized operating practices when passing through a wheel temperature detector could potentially improve the performance of cold wheel processes further.

Effectiveness of Cold-Wheel-Based Brake Tests

Under the Association of American Railroads (AAR) Strategic Research Initiative (SRI) program, MxV Rail conducted an analysis of revenue service data on wheel-temperature-based brake effectiveness tests from two Class 1 Railroads. These tests are employed as a part of a cold wheel process (CWP), where a railroad uses wheel temperature to determine railcar brake system effectiveness. MxV Rail analyzed wheel temperatures over multiple cycles to provide a holistic view of the effectiveness of the CWP. The analysis focused on the changes in the measured wheel temperatures both before and after the shop visit from the cars identified by CWP as having cold wheels (CW). The results showed that, in general, statistically significant wheel temperature increases were observed after the shop visit. The results indicate that CWPs are effective in improving the overall health of the brake system.  Introduction  The CWP is automated and reportedly more effective at identifying cars experiencing…