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2. ANALYSIS PLAN 2.1 Coefficient of Friction-(Post derailment tank car kinetic energy dissipation) The HHFT RIA used results of computer models of tank cars sliding along the ground after derailment until they came to rest or collided with another tank car. DOT will test the sensitivity of the benefits of ECP brake benefits to different values of coefficient of friction between the tank car and the ground. The range of values of coefficient of friction used in this sensitivity test will be based [on] the results of full-scale tank car sliding tests on different ground conditions (specified later in this plan). Plan to measure force required to drag tanks with various loads across various surfaces. 2.2 DOT-117 Puncture Resistance The HHFT RIA used a histogram of impact forces and the puncture resistance of different types of tank cars to calculate the number of punctures and to determine the benefits of ECP brakes. As part of meeting the FAST Act requirements, DOT will use a histogram of impact forces calculated using the structural properties (stiffness, mass, etc.) of a DOT-117 tank car and then applied to the calculated puncture resistance of the same type of car. DOT will calculate the puncture resistance, stiffness and other required properties of a DOT-117 tank car from a finite element model of the car. DOT will validate the model from full-scale impact tests (specified later in this plan). Test complete. Model was validated. Puncture predicted at 13 to 14 mph. Preliminary test results showed ânear punctureâ at 13.6 mph. Currently no plans for a second puncture test. 2.3 Curved Track DOT will calculate the benefits of ECP brakes on curved track that is representative of the distribution of curves on the rail network. Using LS Dyna simulations with a revised initial condition at derailment to reflect negotiating a curve. 2.4 Derailment Initiation The HHFT RIA used the results of modeling with derailment initiated by a lateral force applied to the leading truck of the first car to be derailed. As part of meeting the FAST Act requirements, DOT will analyze alternative derailment initiation events to determine additional scenarios to the lateral force that was modeled for the HHFT RIA. Initiation events will include broken rails, broken wheels, bearing burn offs, wide gage, and track buckles. DOT will model the additional scenarios if they are found to be significantly different in nature to an applied lateral force. 2.5 End-of-Train Device vs. Distributed Power DOT will compare the sequence of events in a derailment of a train fitted with an end-of-train device to that of a train outfitted with distributed power at the front and rear. The events will include brake pipe pressure changes throughout the train, emergency brake applications and locomotive engineer responses. DOT will develop and model scenarios that describe these events. 2.6 Model Validation DOT, with support of its contractors, will model a sample of previous derailments. DOT will compare the results from the modeling to what happened in real life. The comparison will include, but not be limited to, the number of punctures, distances traveled by cars from derailment to rest, the ratio of cars derailed to those that stay on the track, the ratio of head to side impacts and punctures. In progress with preliminary results presented [to the committee on October 14, 2016].
