查看更多>>摘要：The performance metric for tank cars and other hazardous materials vehicles involved in accidents has generally been conditional probability of release given involvement in an accident. This metric considers the probability of a release event occurring but does not take into account the quantity of product lost in a release incident. In this paper, a new metric termed "release risk" is introduced; it is defined as the expected value of the quantity lost from a tank car given that it is in an accident. The quantity of product lost varies depending on the part of the car that is damaged in an accident; consequently, use of release risk can affect how different modifications in tank car design are considered. The metric was developed in terms of tank-damage-caused and non-tank-damage-caused releases. It was found that tank-damage-caused releases had a higher release risk than non-tank-damage-caused releases. Important elements considered are the probabilities of release and the expected quantities of release from the tank components and non-tank components of a tank car, and the effect of increasing tank thickness in increasing accident exposure and decreasing expected quantity of release. The release risk metric is also used as the objective function in a tank thickness optimization model. The results suggest that release risk may be a useful means of assessing the relative benefits of different tank car safety design modifications.
查看更多>>摘要：Allocating the cost of empty railcar miles to partners in a railcar pooling system is an important pricing problem in railway management. Recently, the authors of this paper proposed a cost allocation scheme for empty railcar movements based on game theory that explicitly considers the level of participation and contribution from each partner, the costs generated before and after cooperation, and the overall benefit obtained by each partner because of cooperation. This paper compares the performance of the model with three other cost allocation models with respect to fairness, stability, and computational efficiency. The comparison is made with two scenarios adapted from examples documented in the literature. The results indicate that the cost allocation scheme based on game theory outperforms other methods in ensuring fairness and enhancing stability in a coalition. Most remarkably, it yields reasonable results even in situations in which other models behave poorly. Computationally, it is manageable for practical problems.
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