Effective marshaling and buffering strategies can reduce the likelihood of special dangerous commodity (SOC) cars being involved in a train derailment. The objeclive of these strategies should be to minimize the probability that an SOC car is located in a potential derailment block, subject lo external rail corridor characl· l'istics that affect derailments. A procedure is developed for predicting derailments for different railcar positions in a train, on the basis of the point of derailment and the number of cars involved. The number of cars involved in each derailment is assumed to be a function of the train operating speed, the cause of dc1· ailmcnt and the number of car'folio\ing the point of derailmc. nL anadian rail accident data for the period 1980-1985 are used to calibrate a probabilistic expression of number of cars involved in derailments. The Canadian accident data base is also used to estimate point-of-derailment probabilities for different railcar position and derailment causes. Allernative mar haling and buffering sti· ategies for SDC railears are evaluated using a combinatorial approach. The results of this analysis indicate that SDC car derailments can be reduced appreciably by considering the derailment potential of different positions along a train for various rail corridor conditions.

Prior to 1987, all train accidents in Canada with consequent damages exceeding $750 were reported to the Canadian Transport Commission (1). For the period 1980-85, approximately 75 percent of these reported train accidents involved one or more car derailments. More than 7 percent of railcar derailments that occurred between 1980 and 1985 involved some type of special dangerous commodity (SDC). Commodities that are especially hazardous to population and environment (such as toxic substances, corrosives, flammables, radioactive materials, and explosives) have been designated as SDCs by Transport Canada (2). Recognizing that railcars carrying SDCs are more apt to cause greater damage in a derailment situation, the focus of this paper is to apply efficient marshaling and buffering regulations so as to minimize the likelihood that these SDC cars will be involved in a potential derailment block. A report prepared by AD Little (3) for the US Department of Transportation suggested that the position of a railcar in the train is a major factor determining its involvement in a derailment situation. Swoveland (4) has suggested that the involvement of dangerous commodities in accidents can be reduced through appropriate marshaling and buffering strat-