When the Calnev 14-inch liquid petroleum pipeline ruptured on May 25, 1989, in the immediate area where a Southern Pacific freight train had derailed 13 days earlier, the Safety Board’s investigation developed a bifold focus: (1) to determine the factors that led to the train derailment on May 12, 1989; and (2) to determine the factors that led to the pipeline rupture, including the effect, if any, that the train derailment and the postderailment wreckage clearance and pipeline inspection activities had in causing the pipeline to rupture. To facilitate a discussion of the accident investigation, this report will address first those issues that relate exclusively to the train derailment; second, those issues pertinent to the time period between the train derailment and the pipeline rupture; third, those-issues that relate exclusively to the pipeline rupture; and fourth, those issues germane to both the train derailment and the pipeline rupture, such as emergency response.
No anomalies or deficiencies in the track structure, track geometry, or signals were noted that would have contributed to the train derailment. The crewmembers of Extra 7551 East were qualified by the Southern Pacific for their respective positions. The Calnev pipeline dispatcher on duty at the time of the pipeline rupture had successfully completed the training program established by the company. Weather was not considered a factor in either the train derailment or the pipeline rupture.
The Train Derailment
The investigation of the train derailment on May 12, 1989, revealed that when Extra 7551 East crested the hill at Hiland to descend the 2.2-percent grade, the head-end engineer believed he had a trailing tonnage of 6,150 tons and 69 tons per operative brake, based on the tonnage profile that had been given to him at the Mojave yard office and 24 axles (four 6-axle units) of dynamic brakes, based on his assumption that two of the head-end locomotive units and the two helper locomotive units had functioning dynamic brakes. Based on this information, the operating rules required that the engineer crest the hill at 5 mph under the maximum speed allowed, 30 mph, and not exceed the maximum speed during the descent. The general road foreman testified, and the results of the train dynamics analyzer tests corroborated, that the engineer should have been able to easily control the train and maintain a speed of 30 mph down the grade with 24 axles of dynamic brakes and a trailing tonnage. of 6,150 tons. The Safety Board’s investigation, therefore, examined (1) the accuracy of the information—particularly the number of axles of functioning dynamic brakes and the trailing tonnage—on which the engineer based his operation of the train, and (2) whether or not the engineer’s acceptance of this information as being accurate was reasonable. The investigation then attempted to determine what action, if any, the engineer could have taken to control the train down the 2.2-percent grade or to prevent the train from derailing given the information that was provided to him.