基于条件风险价值的危险品道路运输时变路径选择

危险品运输中的风险评估是危险品运输路径选择的基础,条件风险价值模型通过变换置信水平来反映决策者的风险偏好,并能控制风险超过风险价值的部分。为研究时变条件下的路径选择问题,基于决策者不同的风险偏好,建立基于条件风险价值的危险品道路运输时变路径选择模型,以此评估各可行路径的风险,选择最优CVaR路径。结果表明:该模型能使风险评估更适合现实道路的时变特性;合理的出发时间和运输路径可以有效降低运输风险,最优CVaR及最优路径依赖于出发时间,且不同风险偏好对应不同的最优CVaR及最优路径。

Variable path-ways selection for the transportation of hazardous goods based on the conditional value

The present paper is aimed at introducing a study of the risk-relieving preference for the decision makers with effects of time varying conditions taken into account. For the said purpose, we have worked out a conditional model for the risk avoidance in view of transforming the confidence level into the risk control of the excessive or redundant information by applying the conditional value of the risk model,for which,it is necessary first of all to study and select the minimum total risk pathways for transportation, by assessing the demands of the hazardous materials transportation. To better reflect the time-varying characteristics,it is necessary to take into account the variations of the populationscattering situation,the accident probability and the traffic density during the different periods of a day. For the said purpose,it has to modify the accident probability with the road linearity,the road type and the weather condition,as well as all the other factors that may affect the accident probability. All the above said influential factors can help us to gain a comprehensive view and establish a model of the road choice for the suitable time moments for the hazardous materials transportation based on the conditional risk evaluation,known as the optimal CVaR pathways. Through the example analysis,it has been found that the optimal VaR value and the optimal CVaR value turn to vary as does the confidence level range at the same departure time. Under the same confidence level,the optimal VaR value should be equal,though the optimal CVaR value can be different. Moreover,for the optimal CVaR value should be greater than the optimal VaR value. And,both of the optimal CVaR value and the optimal CVaR pathway at the same confidence level can be different under the different moments of the departure time. Based on the risk-evading preference of the decision maker,it has been proved that it is possible to gain the optimal path in correspondence with the different departure times,so that the reasonable departure time and the proper choice of the transportation pathways can help to reduce the transportation risks effectively and significantly.