  Transporting hazardous materials (hazmats) using tank cars has more
significant economic benefits than other transportation modes. Although railway
transportation is roughly four times more fuel-efficient than roadway
transportation, a train derailment has greater potential to cause more
disastrous consequences than a truck incident. Train types, such as unit train
or manifest train (also called mixed train), can influence transport risks in
several ways. For example, unit trains only experience risks on mainlines and
when arriving at or departing from terminals, while manifest trains experience
additional switching risks in yards. Based on prior studies and various data
sources covering the years 1996-2018, this paper constructs event chains for
line-haul risks on mainlines (for both unit trains and manifest trains),
arrival/departure risks in terminals (for unit trains) and yards (for manifest
trains), and yard switching risks for manifest trains using various
probabilistic models, and finally determines expected casualties as the
consequences of a potential train derailment and release incident. This is the
first analysis to quantify the total risks a train may encounter throughout the
shipment process, either on mainlines or in yards/terminals, distinguishing
train types. It provides a methodology applicable to any train to calculate the
expected risks (quantified as expected casualties in this paper) from an origin
to a destination.
