Time-risk trade-off of hazmat routing problem under emergency environment by using linguistic variables

Transport risk and cost are important factors in hazmat routing problem (HRP) in which authorities and transport companies are interested in minimising public risk and reducing agencies cost, respectively. When a certain part of a country is affected by a natural disaster, the proper emergency responses including first aid, fuel and other necessary materials should be safely transported to the related area on time. Risk is mainly obtained through accident data, but due to lack of data, particularly in the developing countries, risk assessment is getting to be more complicated. In this study a network risk assessment methodology has been developed in which the extent analysis method is utilised to convert the linguistic variables of risk components including accident, population, environment and infrastructure network to crisp values. Based on the proposed methodology, a tradeoff between travel time and transport risk has also been considered to enhance transport safety. Using three methods of path-finding for validation shows that different alternatives or paths can be available for long-term trips whereas the results revealed that the safest path is independent on path-finding approaches, so decision makers would be able to make more reliable decisions on HRP.