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of trona for a total lading weight of about 6,900 tons. Given the total light weight of the 69 cars was 2,130 tons, the Safety Board concludes that the total trailing tonnage of the train was about 9,000 tons.
At the time the cars were loaded and moved to the siding at Fleta, SP procedures required that yard clerks release Lake Minerals Corporation from the per diem charge for empty cars by accessing SP’s computer system and entering information into the car file of the computer system, including the estimated tonnage of the car lading. The yard clerks estimated what they thought to have been the weight of the material in the car, believing that the estimated weight they entered would be overridden by the proper weight when the shipper’s bill of lading was later received at the billing office in Los Angeles, and the computer system’s car file updated with that information. The yard clerks had routinely estimated the weights of cars that were being released and had no reason to believe in this instance that the estimated weights would not be replaced with the actual weight as provided by the shipper. The yard clerks’ actions, while ultimately a factor in the information provided to the traincrew concerning the weight of their train, were consistent with accepted SP practices for releasing cars. Although one yard clerk testified that it was necessary to estimate as closely as possible the actual weight of the material, he could not provide a reason why. Because all cars were loaded with about the same amount of material, the estimated weights of 50 tons each for 32 cars, 75 tons each for 15 cars, and 60 tons each for 22 cars suggest, however, that there was no consistent method for estimating the actual weight of material at the time cars were being released. The Safety Board concludes that the established practice of estimating weights at the time the cars were released, coupled with the belief that these weights would be changed at a later time, created a potentially hazardous situation in which yard clerks were merely satisfying a requirement of the SP computer system in order to obtain a release of the affected cars.
The bill of lading submitted by the superintendent of Lakes Minerals Corporation to a shipping clerk at SP’s yard office at Mojave did not indicate the weights of the cars. The document was reviewed and signed by both the shipping clerk and the superintendent, but testimony indicates there was no discussion regarding the lack of weight information. According to the shipping clerk, he realized, after the superintendent had left the office, that the billing office in Los Angeles would require a weight to be listed on the document. After an unsuccessful attempt to contact Lake Minerals Corporation about the weights of the cars, he estimated the weight of each car to be 60 tons and wrote the figure of 129,000 pounds per car on the bill of lading. Contrary to company procedures, however, he did not indicate on the bill of lading that the weight listed was an estimated weight. The clerk's actions, particularly because he had never before received a bill of lading without the weights provided, again indicate an unsafe practice in preparing train documents.
The investigation revealed that the tonnage profile document generated by SP’s computer system and given to traincrews was based, in part, on information contained in the car file of the system. Because of the design of the computer system, when the billing clerk received the shipper’s bill of
