Risk Comparison of Transporting Hazardous Materials in Unit Trains versus Mixed Trains

Transportation Research Record: Journal of the Transportation R

Kim

et al. 2022

Recent changes in freight train operating practices call for improved understanding of the effect of hazmat car placement on hazmat release risk. In existing models, placement of hazmat cars in a train is either assumed to be random or in blocks of grouped cars. There has been little investigation of how different train configurations affect the number of hazmat cars that could potentially derail in an accident. This paper presents a probabilistic model that calculates the probability and number of hazmat cars derailed based on accident characteristics and train configuration. The model distinguishes between hazmat and non-hazmat cars in manifest trains and provides probability distributions and the expected number of hazmat cars derailed under a set of train placement scenarios. The results indicated that the number and distribution of hazmat cars derailed were affected by speed, percentage of hazmat cars in the train (given the same train length), train configuration, and number of hazmat cars in the train (given the same percentage of hazmat cars in the train). The model presented here could be used as a stand-alone tool to evaluate train-configuration-based hazmat car derailment risk, as well as an integral component of an enhanced, comprehensive rail hazmat transportation risk analysis framework. The model results could be used to answer questions in hazmat transportation risk assessment, rail shipment planning and optimization, and tradeoffs related to unit train versus manifest train operation. The results could also inform potential policies about hazmat car placement in trains and operating speed.

Section: Hazmat Car Train Placement Modelmentioning

confidence: 99%

General Model of the Effect of Hazardous Materials Car Placement in Trains and their Probability of Derailment

Lin

Transportation Research Record: Journal of the Transportation R

Kim

et al. 2022

“…Prior research related to train derailment risk has covered many aspects of the situation including the wheel–rail interaction ( 1 ), derailment causal analysis ( 2 , 3 ) and hazmat transportation risk ( 4 – 12 ). These studies have focused on various risk mitigation strategies, related to infrastructure ( 4 , 7 ), rolling stock ( 13 ), tank car safety enhancement ( 13 – 16 ), train makeup ( 17 , 18 ), or mitigation of release consequence ( 19 ).…”

Section: Literature Reviewmentioning

confidence: 99%

Accident-Cause-Specific Risk Analysis of Rail Transport of Hazardous Materials

Transportation Research Record: Journal of the Transportation R

Turla

Zhang

2018

Self Cite

Rail plays a key role in the transportation of hazardous materials (hazmat). Improving railroad hazmat transportation safety is a high priority for both industry and government. Many severe railroad hazmat release incidents occur because of train accidents. The Federal Railroad Administration identifies over 300 accident causes, including infrastructure defects, rolling stock failures, human factors, and other causes. Understanding how hazmat transportation risk varies with accident cause is a key step in identifying, developing, evaluating, and prioritizing cost-justified accident prevention strategies, thereby mitigating hazmat transportation risk. The objective of this paper is to develop an integrated, generalized risk analysis methodology that can estimate accident-cause-specific hazmat transportation risk, accounting for various train and track characteristics, such as train length, speed, point of derailment, the number and placement of tank cars in a train, tank car safety design, and population density along rail lines. Using the two major causes of accidents on freight railroads—broken rails and track geometry defects—as an example, this paper demonstrates a step-by-step analytical procedure and decision support tool to assess how accident frequency, severity, and hazmat transportation risk vary by accident cause. The research method can be adapted for risk analysis at corridor- or network-level accounting for other accident causes.

“…14,27 For hazardous material transportation, the number of tank cars releasing was used to measure the severity. 2,12,13,28,29 In some train collisions, even though there are no casualties, there exist damage costs due to infrastructure damages, etc. In this paper, we use the number of injuries, fatalities, and the damage costs as the proxy to measure collision severity.…”

Section: Severity Analysismentioning

confidence: 99%

Analysis of freight train collision risk in the United States

Turla

Proceedings of the Institution of Mechanical Engineers, Part F:

Zhang

2018

Self Cite

Rail transportation is pivotal for the national economy. Despite being rare, a train accident can potentially result in severe consequences, such as infrastructure damage costs, casualties, and environmental impacts. An understanding of accident frequency, severity, and risk is important for rail safety management. In the United States, extensive prior research has focused on risk analyses of train derailments and highway–rail grade crossing accidents. Relatively less work has been conducted regarding train collision risk. The US Federal Railroad Administration identifies various accident causes, among which the authors of this study have analyzed the major collision causes. For each major accident cause, the authors have analyzed its resultant collision frequency, severity (in terms of damage cost or casualties), and correspondingly the risk, which is the combination of the frequency and severity. The analysis was based on train collision data in the United States from 2001 to 2015. This analysis focuses on freight trains in the United States, due to their immense traffic exposure. On the temporal scale, collision rate (the number of collisions normalized by traffic exposure) has an approximately 5% annual reduction. In terms of collision cause, failures to obey signals, overspeeds, and violations of mainline operating rules accounted for more collisions than other causes. Two alternative risk measures, namely the expected consequence and conditional value at risk, were used to evaluate the freight train collision risk on main tracks, accounting for both the average and worst-case scenarios. This collision risk analysis methodology may provide the US Department of Transportation and railroad industry with information and decision support for identifying, evaluating, and implementing cost-effective risk mitigation strategies.