(87b) Minimizing Risk of Unit Trains of Hazmat

In 2020, the CFR was updated to include a rule allowing LNG shipment in DOT113 class tank cars. Prior to this rulemaking, LNG shipment on railroads was only possible via Special Permit approval resulting in a very limited number of LNG shipments on rail. The recent regulation has simplified the regulatory path to shipping LNG in a series of tank cars by rail as a manifest train and by unit train configuration. As a result, we may expect to experience large growth in LNG shipments via rail in the near future.

This paper undertakes a risk-based analysis to evaluate the risks of blocks of LNG tank cars and unit trains to characterize the risk of large LNG shipments on rail. The risk model for train shipments shall consider: rail tank car derailment, loss of containment, and then fire or explosion for the leaking tank cars. We apply a multinomial probability model to approximate the number of tank cars and the release rate/quantity of LNG multi-car incidents. The results of this study can be used to better understand the scale of risk represented by this emergent shipping activity and identify opportunities for risk reduction through operational limits.