The National Transportation Safety Board determined today that the probable cause of the derailment of a Norfolk Southern Railroad Company train was the railroad's inadequate rail inspection and maintenance program that resulted in a rail fracture from an undetected internal defect. Contributing to the accident was the Federal Railroad Administration's inadequate oversight of the internal rail inspection process and its insufficient
requirements for internal rail inspection.
On Friday, October 20, 2006, a Norfolk Southern freight train (68QB119), en route from the Chicago, Illinois area to Sewaren, New Jersey, derailed while crossing the Beaver River railroad bridge in New Brighton, Pennsylvania. The train consisted of a three-unit locomotive pulling three empty freight cars and 83 tank cars loaded with 660,952 gallons of denatured ethanol. Twenty-three of the tank cars derailed. Several of the cars fell into the Beaver River. Approximately 20 of the cars released ethanol, a flammable liquid that ignited and burned for 48 hours. A seven-block area of New Brighton was evacuated. There were no injuries or fatalities.
"Because Norfolk Southern did not have an adequate rail inspection and maintenance program, they put the public, crew, and environment at risk," said NTSB Chairman Mark V. Rosenker.
The track where the derailment occurred was installed in 1977 and had experienced significant rail head wear prior to the accident. Norfolk Southern had hired a contractor to inspect the track for internal rail defects. In 2006, three ultrasonic/induction inspections for internal rail defects were conducted on the accident track. The last inspection on August 1, showed an intermittent loss of bottom signal over a 9-foot length of rail in the area where the derailment subsequently occurred.
FRA regulations require that all railroads conduct a continuous search when inspecting rail for internal defects. Additionally, according to the FRA, any rail inspection that is interrupted, as a result of rail surface conditions that inhibit the transmission or return of the signal, is not considered to be continuous and therefore is not considered a valid inspection of the affected rail segment.
However, about a year and a half before the accident and without consulting the FRA, Norfolk Southern gave new procedures to the inspection contractor for inspecting rail for internal defects. The procedures permitted inspection equipment operators to ignore any loss of bottom signal, as long as the continuous loss of signal distance did not exceed 5 feet of linear rail. The Safety Board investigation found that the initiating defect that caused the rail fracture was located in the length of rail that had the loss of bottom signal during the August 1 inspection. The equipment operator did not stop the inspection vehicle for a re-inspection or to hand inspect the rail, consistent with the procedures provided by Norfolk Southern.
"Norfolk Southern was not conducting a continuous search of their rail for internal defects, which left segments of rail uninspected and in service indefinitely," Rosenker said. "This accident illustrates the importance of having a comprehensive rail inspection and maintenance program that will account for factors such as rail head wear and loss of signal during internal testing."
As a result of this accident, the Safety Board made the following recommendations:
To the Federal Railroad Administration:
1. Review all railroads' internal rail defect detection procedures and require changes to those procedures as necessary to eliminate exceptions to the requirement for an uninterrupted, continuous search for rail defects.
2. Require railroads to develop rail inspection and maintenance programs based on damage-tolerance principles and approve those programs. Include in the requirement that railroads demonstrate how their programs will identify and remove internal defects before they reach critical size and result in catastrophic rail failures. Each program should take into account, at a minimum, accumulated tonnage, track geometry, rail surface conditions, rail head wear, rail steel specifications, track support, residual stresses in the rail, rail defect growth rates, and temperature differentials.
3. Require that railroads use methods that accurately measure rail head wear to ensure the deformation of the head does not affect the accuracy of the measurements.
4. Assist the Pipeline and Hazardous Material Safety Administration in its evaluation of the risk posed to train crews by unit trains transporting hazardous material, determination of the optimum separation requirements between occupied locomotives and hazardous material cars, and any resulting revision of 49 Code of Federal Regulations 174.85.
To the Pipeline and Hazardous Materials Safety Administration:
5. With the assistance of the Federal Railroad Administration, evaluate the risk posed to train crews by unit trains transporting hazardous materials, determine the optimum separation requirements between occupied locomotives and hazardous material cars, and revise 49 Code of Federal Regulations 174.85 accordingly.
To Norfolk Southern:
6. Revise your ultrasonic rail inspection procedures to eliminate exceptions to the requirement for uninterrupted, continuous search for rail defects.
A synopsis of the Board's report, including the probable cause and recommendations, is available on the website, www.ntsb.gov, under Board Meetings. The full report will be available on the website in several weeks.