Derailment probe indicates no pre-existing defects
An investigation of the August 2004 derailment of 18 Canadian National tank cars near Saint-Henri-de-Lévis, just outside Lévis, Quebec, has so far indicated no pre-existing defects that might have contributed to the derailment, the Transportation Safety Board of Canada (TSB) reported last week.
In an update on its continuing probe of the accident, the TSB noted that an axle with a shifted wheel and three pieces of broken rail were recovered and sent to its engineering laboratory, where an examination of these parts revealed that the wheel displacement and rail fractures resulted from excessive stresses during the derailment.
The derailment occurred shortly after the 68-car train, bound for Montreal carrying diesel fuel and gasoline, left the Ultramar Canada refinery in Lévis. The accident site is in a section where the track crosses a marshy are know as the Grande plée Bleue.
Approximately 200,000 litres of gasoline and diesel fuel spilled into the marshy area, but the spilled product was recovered. Because of the presence of hydrocarbon fumes, the area within a one-kilometre radius of the derailment site was sealed off for a period of four days. The hydrocarbons that spilled into the ditches and marshy areas were contained by booms and dikes. Two cleanup companies subsequently recovered the hydrocarbons and decontaminated the water and soil.
Soil testing in the derailment area was conducted this past summer by an engineering firm hired by CN. Further tests will be required to provide a better understanding of the influence of differential settlements. Since some tests cannot be conducted until the spring thaw, the investigation team will review the results of the study when available.
A previous derailment at the same location in 1999 led to significant rehabilitation work to reinforce the roadbed on which the track was built. The current investigation has indicated no safety issues, although Transport Canada reduced speed limits approaching the site to 25 mph and to 10 mph in the immediate vicinity of the derailment site after the 2004 accident. At this point, the investigation is focusing on track infrastructure.
Once the analysis of factual information and test results are completed, the draft report will be submitted to the TSB for its approval, and then released as a confidential draft report to designated reviewers. Input from the designated reviewers will be taken into account in making any required amendments to the report. At the end of this process, the Board will issue the final investigation report to the public.
If safety deficiencies are revealed at any time during the investigation, the TSB will issue a safety communication promptly to those best able to address the issue.
As an independent agency, the TSB is responsible for investigating marine, pipeline, railway and aviation transportation occurrences. Its mandate does not extend to assigning fault or determining civil or criminal liability.
More information is available on the TSB Web site, www.tsb.gc.ca.