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Suggested Citation:"11. Appendix H." National Academies of Sciences, Engineering, and Medicine. 2017. A Review of the Department of Transportation's Plan for Analyzing and Testing Electronically Controlled Pneumatic Brakes Letter Report (Phase 2). Washington, DC: The National Academies Press. doi: 10.17226/24903.

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34 Appendix H Total Brake Force Graphs from DOT DOT provided the two brake force graphs presented below in response to the committee’s request. The graphs present the total brake force buildup across 100 cars for ECP brakes versus conventional brake systems (Figure H-1) and ECP brakes versus DP or EOT systems (Figure H-2). According to DOT, the graphs illustrate a significant advantage attributable to the ECP brake system. In addition, the graphs present the best possible case for DP or EOT systems relative to ECP, because the derailment initiates at the head end of the train. The benefits attributable to DP or EOT systems relative to ECP will drop off for derailments that initiate farther back in the train.23 FIGURE H-1. According to DOT, there is a significant benefit to ECP brakes in total momentum removed from the train, especially in the initial several seconds (critical time). The advantage for ECP brakes at 10 seconds after initia- tion is about 46 percent. This advantage tapers to about 22 percent at 20 seconds. 23DOT Response to NAS Letter Report on Electronically Controlled Pneumatic Brakes: Total Brake Force Plots, dated July 12, 2017, received from Kevin Kesler (DOT) on July 13, 2017. 0 20 40 60 80 100 120 0 5 10 15 20 25 Pe rc en ta ge  o f T ot al  T ra in  B ra ki ng  F or ce  (% ) Time (s) Total Train Braking Force ECP Conventional Difference

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A Review of the Department of Transportation's Plan for Analyzing and Testing Electronically Controlled Pneumatic Brakes Letter Report (Phase 2) Get This Book
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TRB's Committee on the Review of the Department of Transportation's (DOT) Testing of Electronically Controlled Pneumatic (ECP) Brakes has issued its final letter report. In response to a Congressional request, the committee reviews the conduct of DOT's tests, reports of test results, and analysis comparing the performance of ECP brakes relative to other braking technologies in reducing the incidence and severity of spills of crude oil or ethanol from derailments.

The committee's report reviewing DOT's test and analysis plan, issued in February 2017, recommends that DOT test the timing of brake propagation for alternative systems, conduct statistical analyses of the multiple factors contributing to derailments, and extend its validation of its modeling and simulation approaches for comparing ECP brakes to other brake systems. The committee’s letter report reviewing the results of DOT’s testing and analysis, issued in September 2017, finds that DOT’s efforts to validate its model and simulation approaches are incomplete and unconvincing. Based on the results of testing and analysis provided by DOT, the committee is unable to make a conclusive statement about the emergency performance of ECP brakes relative to other braking systems.

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