National Transportation Safety Board
Office of Public Affairs
Washington, D.C. - In a report adopted today, the National Transportation Safety Board (NTSB) determined that fatigue caused the failure of the engineer and conductor on a Union Pacific Railroad train to respond appropriately to wayside signals governing the movement of their train leading to a fatal collision with another train.
"Get enough sleep - it sounds so simple and yet we continue to see accidents caused by fatigue," said NTSB Acting Chairman Mark V. Rosenker, "How many more tragedies have to occur before employers and employees get the message that being well rested is critical to job performance?"
The accident occurred on June 28, 2004 near Macdona, Texas. A Union Pacific Railroad (UP) train was traveling westbound on the same mainline track as an eastbound BNSF Railway (BNSF) train. As the BNSF train was entering a parallel siding, the UP strain struck its midpoint. The collision derailed four locomotive units and the first 19 cars of the UP train as well as 17 cars of the BNSF train.
As a result of the derailment the 16th car in the UP train, a tank car loaded with liquefied chlorine, was punctured. The chlorine vaporized and engulfed the area surrounding the accident site. Three people, the UP conductor and two local residents, died from the effects of chlorine gas inhalation.
The Board's investigation determined that sleep debt, disrupted circadian processes, limited sleep during the weekend preceding the accident, and long duty tours reduced the capacity of the UP engineer and conductor to remain awake and alert the night of the accident trip. The Board also noted that the UP conductor's consumption of alcohol on the evening before the accident likely added to his fatigue.
An examination of the UP engineer and conductor's off duty time revealed that neither made effective use of the time available to them to obtain adequate rest. Therefore, the Board determined as contributing factors, the crewmembers' failure to obtain sufficient restorative rest prior to reporting for duty because of their ineffective use of off-duty time, and UP train crew scheduling practices that created inverted crewmembers' work/rest patterns.
As a result the Board recommended that UP, the Brotherhood of Locomotive Engineers and Trainmen (BLET), and the United Transportation Union (UTU) use the Macdona accident as a case study in fatigue awareness training to illustrate the shared responsibility of rail carriers to provide opportunity for adequate rest and employees to understand the importance and obtain sufficient rest to perform at a safe level of alertness. Further, the Board recommended that the Federal Railroad Administration (FRA) require that railroads base their crew scheduling on scientific measures designed to reduce fatigue and to limit the railroads' use of limbo time.
In addition to crew fatigue, the Board's probable cause cited, as a contributing factor, the tank car's puncture and the subsequent chlorine release. During the derailment the tank car on the UP train was punctured by impact with a flatcar loaded with steel plates located four cars ahead on the train. Although the puncture was relatively small and did not result in a catastrophic failure of the tank, approximately 9,400 gallons, about 60 percent of the tank's load, were released. The Board's metallurgical examination of the tank car shell determined that the car would have been susceptible to a catastrophic failure if it had experienced a large penetration of several feet or more.
Improving the impact resistance of tank cars has been an on-going concern for the Safety Board highlighted by investigations of derailments with a subsequent hazardous materials release in Minot, North Dakota in 2002, and Graniteville, South Carolina in 2005. In the Macdona report the Board reiterated previous recommendations to the FRA to improve tank car safety:
** R-04-4 -- determine the impact resistance of tank car shells constructed before 1989;
** R-04-5 -- establish a program to rank tank cars according to their risk of catastrophic fracture and implement measures to mitigate this risk;
** R-04-6 -- validate the predictive model the FRA is developing to quantify the maximum dynamic forces acting upon tank cars under accident conditions;
** R-04-7 - develop and implement tank-car design- specific fracture toughness standards for steels and other materials of construction of pressure tank cars used in the transportation of hazardous materials.
** R-05-16 - implement operating measures to minimize impact forces and reduce the vulnerability of tank cars transporting poisonous inhalation hazardous materials.
The Board also reiterated recommendation R-05-17, originally issued in the report on the Graniteville collision, calling for the FRA to determine the most effective methods of providing emergency escape breathing apparatus for crewmembers on freight trains carrying hazardous materials.
Finally the Board noted that the lack of a positive train control system in the accident location contributed to the cause of the accident. In 2001 the Board recommended that the FRA facilitate actions necessary for development and implementation of positive train control systems. The recommendation is on the NTSB's list of Most Wanted safety improvements.
A synopsis of the Board's report, including the probable cause and recommendations, is available on the Board's website, www.ntsb.gov. The Board's full report will be available on the website in several weeks.
NTSB Office of Public Affairs: (202) 314-6100
The National Transportation Safety Board (NTSB) is an independent federal agency charged with determining the probable cause
of transportation accidents, promoting transportation safety, and assisting victims of transportation accidents and their families.