Risk assessment of hazardous materials transportation: A review of research progress in the last thirty years

In recent years, hazardous materials transportation accidents occur frequently, causing huge casualties and property losses. Risk assessment of hazardous materials transportation has been constantly investigated by researchers and decision-makers. In order to study the research progress of risk assessment of hazardous materials transportation, so as to better reveal relevant problems. This review systematically analyzes the existing literature, from 1991 to 2020, on risk assessment models and methods of hazardous materials transportation, and segregates the relevant studies based on unimodal and intermodal transportation systems. Additionally, an example is considered to analyze the characteristics of each risk assessment model of unimodal transportation, and a novel detailed classification is proposed for the risk assessment problems. The results indicate that the research on the risk assessment model of road transportation of hazardous materials is comprehensive, whereas that based on the railway and intermodal transportations is deficient. In comparison with the traditional risk assessment model, the conditional value-at-risk model presents a flexible decision-making framework for decision-makers and controls risk preference between risk neutrality and risk aversion. Owing to the difficulty in achieving door-to-door railway transportation and the increased risks associated with the intermodal transportation, the conclusion that the risk of railway and multimodal transportation of hazardous materials is lower than that of road transportation is not universal. Transport operators and governments can combine the advantages of different transportation modes, such as low risk, low cost, high flexibility, and high reliability, to achieve public safety and improve the competence of the system. Based on the proposed classification, this review identifies the existing trends and research gaps and summarizes future research directions.