Technology Digests / Simulations of Train Stopping Distance

TD22-020

August 1, 2022
Authors
  • Yi Wang
  • Scott Cummings
  • Shad Pate
  • Tony Sultana
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Key Findings

  • The braking distance of a train can be predicted by a regression model developed by MxV Rail using parameters obtainable from Railinc’s Umlerâ* System, the industry's central repository for registered rail and intermodal equipment in North America.
  • Trains containing large portions of loaded cars built after 2004 (when improved brake ratios took effect) are shown to have consistently better braking performance than trains with older cars even when a small portion of the cars have inoperative brakes
  • A loaded train with cars all built after 2004 has a shorter maximum stopping distance at 95 percent operative brakes than a train made up of the same number of older cars.

Simulations of Train Stopping Distance

MxV Rail (formerly TTCI) has conducted simulations to evaluate stopping distances of trains with a small percentage of inoperative brakes. The analysis, part of the Association of American Railroads (AAR) Strategic Research Initiatives program, showed that trains with newer cars and a small percentage of inoperative brakes are able to stop in the same distance as trains with older cars and 100 percent operative brakes. Car age is relevant in this analysis because cars built since 2004 have higher brake ratios compared to cars built in 2003 or earlier. BACKGROUND Title 49 of the U.S. Code of Federal Regulations (CFR) includes sections on the requirements for train brake systems (49 CFR 232.103) and the movement of defective equipment (49 CFR 232.15). These regulations require that every car in a train must have operative brakes unless the train is moving for brake repair in which case it is required that train…