Research On Route Optimization Methods For Hazardous Materials Road Transportation

In this paper, two route optimization methods of hazardous materials road transportation have been studied:the one based on quantitative risk assessment as well as on mathematical programming and the other based on comprehensive evaluation.For the route optimization method based on quantitative risk assessment as well as on mathematical programming:first of all, based on the calculation of the costs and the occurrence probability of various possible losses, such as environmental damage, property damage, fatalities, traffic incident delay and evacuation in hazardous materials road transportation accidents, a quantitative transportation risk evaluation model has been established, which expresses all the relevant consequences in monetary terms; secondly, by imposing an uniform capacity restriction on the dangerous goods freight volumes of each road section, a bi-objective global route optimization model with the weighted combination of minimum transportation cost and minimum transportation risk has been built in order to improve both the safety and the economy of the route, while ensuring the equitable distribution of risks; thirdly, to select the best route scheme from the solutions of the above model, the Gini coefficient and the coefficient of variation have been chosen as measures of risk equity based on road sections, and the suitability of the two indicators have been discussed; last but not least, the case study shows that on the one hand, regularly changing the weight between the two optimization objectives, the Pareto optimal solution set of the above optimizing model can be get; on the other hand, it is probable that the total social cost of the ultimate route scheme be greatly reduced and the equity of the risk distribution be improved to some extent by setting an appropriate capacity limit of the dangerous goods freight volumes for each road section and by choosing a proper weight value between the two goals of the global route optimization model.For the route optimization method based on comprehensive evaluation:Firstly, through the analysis of the six aspects including the road features, the meteorological conditions, the traffic conditions, the natural environment, the emergency response capability and the population in the affected area, a comprehensive evaluation index system of hazardous materials transportation route optimization has been proposed. Secondly, the uncertainty of objective things and the vagueness of human thought have been fully embodied by the use of triangular fuzzy numbers as the form of the judgment values in the analytic hierarchy process and the consistency requirement in the AHP has been easily satisfied by constructing the judgment matrix according to the properties of the fuzzy complementary matrix. Thirdly, the subjective weight determined by the analytic hierarchy process and the objective weight by the entropy method have been combined to calculate the initial combination weights based on the idea of maximizing deviation. Fifthly, according to the initial evaluation results calculated by the initial weights, the rough set theory and the information gain theory, the feedback weights NO.1and the feedback weights NO.2have been calculated respectively. Fifthly, the complementary advantage has been realized by the combination of the subjective weight, the objective weight, the feedback weights NO.1and the feedback weights NO.2to calculate the final combined weight. Sixthly, through the example analysis, the fact has been shown that the deviations between the weight values and the evaluation results calculated by different mehods have been corrected well by the final combination weights and the final evaluation results respectively.Finally, the comparative analysis of the two kinds of route optimization methods has been done and the applicable scope of the two route optimization methods has been given.