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Yard Accident Rate (/train mile) 1.55X10-' 1.98X10-' <br />Total Non -Yard (Mainline) Train Miles 3.254X10 13.48X10 <br />Mainline <br />Non -Yard Accident Rate (/train mile) 1.81 X 10-b 2.47X 10-" <br />The position in train derailment probability was evaluated as a function of train configuration for <br />LNG ISOs as part of the QRA. A derailment model was employed where the probability that <br />LNG ISOs would be derailed in an accident was related to the probability of the first car <br />derailed and average number of cars derailed. It was assumed that a derailment would involve <br />sequential cars starting with the first car derailed. The following two tables provide the <br />probability of being the first car derailed versus position in the train and the average number of <br />cars derailed in an accident. <br />Representative probabilityof first car derailed for Class 1 and 2 Railroads (1995-2015). <br />Car Position in Train <br />Statistic <br />1 11 21 31 <br />Yard Derailment Accident 24.8% 1.60% 1.20% 0.82% <br />Mainline Derailment Accident, Speed < 25 mph <br />17.3% <br />1.80% <br />1.13% <br />0.97% <br />Mainline Derailment Accident, Speed >_ 25 to <_ 60 mph <br />15.8% <br />1.07% <br />1.02% <br />0.80% <br />Average number of cars derailed (1995-2015). <br />Statistic No. of Cars <br />Yard Derailment Accident 4 <br />Mainline Derailment Accident, Speed < 25 mph 5 <br />Mainline Derailment Accident, Speed >_ 25 to <_ 60 mph 11 <br />Seven different train configurations were evaluated to demonstrate the effects of blocking LNG <br />ISOs into sequential car groupings on the calculated risk. The baseline configuration (C-1) <br />placed ELNG ISOs in sequence from train position I to 0 If a train accident leads to a <br />derailment, then each configuration and speed/yard case will represent a distinct probability (4) <br />(4) array for multiple cars being derailed. The probability relationship for multiple <br />cars being derailed from the baseline train configuration C-1 at high speed (> 25 to < 60 mph) is <br />shown in the table below. Similar relationships were developed for each train configuration, yard <br />accidents, low speed accidents, and high speed accidents. <br />Probability of having X number of LNG ISO cars derail in the event of a train accident, <br />where X is the number of LNG ISOs involved, for the baseline train configuration and <br />mainline train movements at high speed. <br />1368194 001 - 5691 Xviii <br />