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 v Abbreviations AAR Association of American Railroads ABDX Current air brake valve manufactured by Wabtec ATCCRP Advanced Tank Car Collaborative Research Program BP brake pipe CCD car control device CPR conditional probability of release DB-60 Current air brake valve manufactured by New York Air Brake DOT U.S. Department of Transportation DP distributed power ECP electronically controlled pneumatic EOT end-of-train device FAST Act Fixing Americaâs Surface Transportation Act fps feet per second FRA Federal Railroad Administration GE General Electric HHFT high-hazard flammable train HHFUT high-hazard flammable unit train mph miles per hour NAS National Academy of Sciences NASEM National Academies of Sciences, Engineering, and Medicine NBR net braking ratio NS Norfolk Southern NTSB National Transportation Safety Board NYAB New York Air Brake Corporation OL overlay PHMSA Pipeline and Hazardous Materials Safety Administration POD point of derailment psig pounds per square inch gauge RAIRS Rail Accident/Incident Reporting System RIA regulatory impact analysis RSI Railway Supply Institute TRB Transportation Research Board TTCI Transportation Technology Center, Inc. DEFINITION OF KEY TERMS Emergency braking Application of maximum pneumatic braking force to stop a train as quickly as possible. Emergency braking can be initiated by the locomotive engineer moving the brake handle, or it can be initiated by episodic events, such as a break-in-two, in which the train separates between cars and the brake pipe hoses separate. Load Force exerted on a surface or body.
vi Model peer review A tool for improving model quality by attempting to ensure that the model is technically adequate, is competently performed, is properly documented, and sat- isfies established quality requirements through the review of assumptions, calcu- lations, extrapolations, alternative interpretations, methodology, acceptance crite- ria, and conclusions pertaining to the model or its application. Model validation Execution of tasks involving computational modeling and measurements designed to assess the predictive capability of models for specific applications in a focused, well-structured, and formal manner. (See Hills, R.G., D. C. Maniaci, and J.W. Naughton. V&V Framework. Sandia Report SAND 2015-7455, Sept 2015. Availa- ble at http://prod.sandia.gov/techlib/access-control.cgi/2015/157455.pdf) Model verification Assurance activities intended to determine whether software errors or algorithm deficiencies are corrupting the simulation results (code validation) and whether human procedural errors or numerical solution errors are corrupting simulation conclusions (solution verification). (See Hills, R.G., D. C. Maniaci, and J.W. Naughton. V&V Framework. Sandia Report SAND 2015-7455, Sept 2015. Availa- ble at http://prod.sandia.gov/techlib/access-control.cgi/2015/157455.pdf) Model vetting The performance of a critical appraisal of a model by one or more independent and recognized subject-matter experts in a relevant discipline. Sensitivity analysis An investigation of the effects of changes in a modelâs internal parameter values, assumptions, and input values on the modelâs output to determine the variation that these changes cause in the output. Stochastic Refers to being randomly determined or having a random probability distribution that can be analyzed statistically but cannot be predicted precisely. Test rack A laboratory setup that physically simulates the operation of and documents the response of the piping, valves, pneumatic brake equipment, and any ECP compo- nents of a train consist. Train consist The coupled cars and locomotive units making up a train. Uncertainty analysis An investigation of the effects of lack of knowledge and other potential sources of error in the model. Variability Differences in attributes due to heterogeneity in the system being considered.