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E.2.1 Accident Model An accident model was developed as part of the QRA to address yard movements and mainline movements of LNG ISOs in freight trains. The intermodal facility risk also included considerations for lifting ISOs onto and off of trains. For train movements, loss of containment of LNG from an ISO was assumed to occur as the result of a derailment accident. LNG was assumed to be the only hazardous material involved in any incident. FRA data and Pipelines and Hazardous Material Administration (PHMSA) data were used to build the accident model. A flowchart depicting the sequential steps of the accident model is provided in Figure E-1. The sections of the report where each analysis block is described are listed in Figure E-1. Probability `"I ILCI IIII liCi1` Prnhahilitv Figure E-1. LNG ISO train accident model overview. Based on the assumed daily movement of -W ISO containers, the analysis accounted for lifts per day at Hialeah Yard, and another gifts per day at the receiving intermodal facility. The (4) (4) frequency for dropping an ISO that results in a 50 mm hole was found in the literature to be (4) 6.7x 10-7 per lift. For# lifts per day, this resulted in the following release frequency for each intermodal facility. LOC frequencyfor dropping an LNG ISO container. Event Release Frequency Dropped ISO, large leak (50 mm hole) 2.2X10' yr' FRA accident data from 1995 through 2015 were analyzed to develop train accident rates. Based on the available data, the train accident rate was calculated as accidents per train mile as shown in the table below. The accident rates for the last five years is provided for comparison and are approximately 20-25% lower than the historical average. However, the QRA conservatively applied the higher accident rate in order to provide an upper bound for the risk. Train accident rates from FRA data. Statistic Total Yard Train Miles 0.446x10y 1.853X10y Ya rd 1308194.001 - 5691 XVII