Technology Digests / Analysis of Undesired Emergency Brake Applications Caused by Air Hose Separation

TD23-007

July 25, 2023
Authors
  • Yi Wang
  • Walter Rosenberger
  • Scott Cummings
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Key Findings

  • Cars equipped with end-of-car cushioning (EOCC) are involved in over 80 percent of the AHS incidents reported
  • There is a significant increase in involvement in an AHS for EOCC cars that are more than four years old.
  • Train handling, terrain, and infrastructure did not appear to be significant factors in AHS.

Analysis of Undesired Emergency Brake Applications Caused by Air Hose Separation

Under the Association of American Railroads’ (AAR) Strategic Research Initiatives (SRI) program, MxV Rail analyzed the service interruption data from train stops caused by end-of-car air hose separation (AHS). These analyses are a part of MxV Rail’s continued efforts to 1) better understand conditions under which undesired emergency (UDE) brake applications and AHS happen during train operations and 2) help mitigate service interruptions caused by end hose-related line-of-road failures (LORF).  BACKGROUND  End hoses are an integral part of the brake pipe that propagates pneumatic signals to apply and release the brakes on a train. With the brakes released, the brake pipe (including the end hoses) is pressurized to the locomotive feed valve setting. A sudden loss of brake pipe pressure will initiate an emergency brake application. An AHS can result in significant service interruptions. After an AHS, the end hoses must be recoupled manually before the brake system can be…