Risk Assessment Of Hazmat Transportation Network Under Terrorist Attack

Terrorist attack is becoming more and more serious nowadays when economic and global situation changes rapidly. On the other hand, more tons of hazardous materials are transporting on the road. Due to its hazards, hazmat transportation becomes the potential target for terrorists. This paper evaluated the risk of hazmat transportation network under terrorist.This paper reviewed and summarized related papers and latest research. The research on hazmat transportation risk has accumulated many research experiences. Many researchers devoted their time and energy. The main research areas are following,1) the hazmat transportation accident consequence2) the risk assessment model of hazmat transportation3) model to search the optimal path. Traditional risk assessment model is the most widely used. But the research on terrorist is still limited, especially in China. The research on terrorist attack focuses on two areas,1) how to identify attack scenarios2) how to assess the attack likelihood, attack consequence and vulnerability. However, there is still no research on risk assessment of terrorist attack on hazmat transportation.This paper analyzed the records of terrorist attack since9*11. Characteristics of terrorist attack and possible attack way can be concluded. Then, the normal hazmat transportation accidents and those under terrorist attack are compared. There are3differences between them,1) the reason of accident2) the frequency of accident3) the accident consequence. The risk computation method of hazmat transportation network under different scenarios is given. As the evaluation is subjective, risk acceptance and risk rank become necessary. So the risk acceptance concept and existing values used for decision are introduced. How to make final decision based on risk values and risk rank are also presented.This paper put emphasis on these differences when conducting the research. First, the point hazmat source of link is analyzed. With combination of TNT explosion model and TNO multi-energy model, the overpressure and fatality rate of someplace some distance from the source can be computed. With this, the fatality can be known. Summing the fatality, the source consequence is defined. Similarly, summing the source consequence, the link consequence is computed. But summing the source needs integration, which is quite complex and almost practically impossible to realize. So this paper uses GIS software, and the continuous surface is replaced by continuous raster. Besides, as TNO multi-energy model has to make computations according to the chart, this paper provides the curve fitting and gets its function, which can be better used in GIS analysis.In attack likelihood analysis, the game theory is used. This method is widely used for terrorist attack. The difference between this paper and others is that, two entropies are added into the constraint conditions, one to describe the terrorist behavior---links with more volume are more vulnerable, the other for road users behavior---roads are used as evenly as possible. To solve the model, it is transferred into the Lagrangian dual problem to reduce the number of variables. Then genetic algorithm is used to. To illustrate the model, an example is shown. Results show that even attack likelihood and road volume can be optimized, the model is quite complex, which is unsuitable for large scale network. But result of this model is similar to that of relative attractiveness model. So this paper considers the relative attractiveness model. Though the formula is the same as that of before, the computation is conducted in GIS software according to land use model. The method used in this paper is suitable for large network, which combines relative attractiveness mode with practical problem.Finally, an example is presented. The results show that, the death radius(50%fatality) of terrorist attack is40meters, while the normal is only6meters; the impacted area of terrorist attack is6times of that of normal accidents.