Comparing Unit Trains versus Manifest Trains for the Risk of Rail Transport of Hazardous Materials -- Part I: Risk Analysis Methodology

TL;DR

This paper develops a comprehensive risk analysis methodology for hazardous materials rail transport, quantifying expected casualties for different train types across the entire shipment process, including mainline and yard risks.

Contribution

It introduces a novel methodology that quantifies total risks for unit and manifest trains throughout the shipment process, incorporating various probabilistic models and data sources.

Findings

Quantified expected casualties for different train types and risk scenarios.

Differentiated risk profiles for unit trains and manifest trains in yards and mainlines.

Provided a generalizable risk calculation framework for rail hazardous material transport.

Abstract

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.