Civil and Environmental Engineering


First Advisor

Aemal Khattak

Date of this Version



Iranitalab, A. 2018. Statistical Investigation of Road and Railway Hazardous Materials Transportation Safety. PhD Dissertation. Department of Civil Engineering, University of Nebraska-Lincoln.


A DISSERTATION Presented to the Faculty of The Graduate College at the University of Nebraska In Partial Fulfillment of Requirements For the Degree of Doctor of Philosophy, Major: Civil Engineering (Transportation Engineering), Under the Supervision of Professor Aemal Khattak. Lincoln, Nebraska: November, 2018

Copyright (c) 2018 Amirfarrokh Iranitalab


Transportation of hazardous materials (hazmat) in the United States (U.S.) constituted 22.8% of the total tonnage transported in 2012 with an estimated value of more than 2.3 billion dollars. As such, hazmat transportation is a significant economic activity in the U.S. However, hazmat transportation exposes people and environment to the infrequent but potentially severe consequences of incidents resulting in hazmat release. Trucks and trains carried 63.7% of the hazmat in the U.S. in 2012 and are the major foci of this dissertation. The main research objectives were 1) identification and quantification of the effects of different factors on occurrence and consequences of hazmat-related incidents, towards identifying effective policies and countermeasures for improving safety and; 2) quantifying components of risk of hazmat transportation for costs prediction, planning purposes, or short-term decision-making.

A comprehensive review of literature, study framework, and available data led to identification of six foci for this dissertation: 1) estimation of hazmat release statistical models for railroad incidents; 2) estimation of rollover and hazmat release statistical models for Cargo Tank Truck (CTT) crashes; 3) analyzing hazmat-involved crashes at highway-rail grade crossings (HRGCs); 4) model-based and non-model-based methods for classifying hazmat release from trains and CTTs; 5) estimation of macroscopic-level statistical models for frequency and severity of rail-based crude oil release incidents; and 6) estimation of statistical models for types and consequences of rail-based crude oil release incidents.

Some of the findings of this research include: train derailments increased hazmat release probability more than other incident types; non-collision CTT crashes were more likely to result in rollovers, while rolling over increased the likelihood of hazmat release; at HRGCs, flashing signal lights were associated with lower hazmat release probability from trucks; increase in volume and distance of crude oil shipped from one state to another led to greater frequency and severity of incidents between the two states; and in rail-based crude oil release incidents, non-accident releases were associated with higher probability of gas dispersion, and lower probability of fire and explosion. Based on the results, recommendations regarding policies and countermeasures for improving safety are provided.

Advisor: Aemal Khattak