TSB # R 06/2002
RELEASE OF THE TRANSPORTATION SAFETY BOARD OF CANADA
REPORT R99T0256 DERAILMENT OF A CANADIAN NATIONAL FREIGHT
TRAIN AND RELEASE OF DANGEROUS GOODS NEAR BRITT, ONTARIO,
23 SEPTEMBER 1999
(Gatineau, Quebec, 28 June 2002) - The Transportation Safety Board of Canada (TSB), in its investigation report released today, found that the derailment on the Canadian National (CN) track near Britt, Ontario, on 23 September 1999, occurred because of track defects. Although there were no serious injuries, some personnel were overcome by fumes from the derailed cars.
The 26 derailed cars of the 94-car southbound freight train included 19 tank cars, 2 box cars and 5 covered hopper cars. Some of the cars caught fire, including a tank car containing anhydrous ammonia that was punctured in the derailment. Approximately 38 minutes after the derailment, a tank car, full of liquefied petroleum gas (LPG), exploded, damaging other cars and sending pieces of the LPG car more than 100 metres from the site.
Action has already been taken on some of the safety deficiencies uncovered in this investigation. CN has changed its track geometry maintenance standards to clarify the action maintenance personnel must take when these track defects are found. The Board has made two rail safety recommendations on safety deficiencies that need further attention: the dangerous goods classification of anhydrous ammonia, and thermal protection inspections and maintenance programs on 112J tank cars. The Board is also concerned about the level of preparedness and human resource management of emergency response personnel in small communities.
In this accident, one of the anhydrous ammonia cars caught fire and several personnel were overcome by its toxic fumes. The Board feels that this brings into question the new dangerous goods classification system recently adopted by Transport Canada (TC) which recently reclassified anhydrous ammonia as a non-toxic and non-flammable gas.
As a result of this classification change, the safety mark (the placard on the tank car) presently required for bulk shipments of anhydrous ammonia has been changed from white to green. The green colour, which is used to identify products such as compressed air, is frequently interpreted to mean a product with lower risk, whereas the white colour, which was previously used for anhydrous ammonia, is associated with products that pose a higher risk. First responders in small communities, with little exposure to dangerous goods, may incorrectly make their first estimates of danger based in part on the colour and shape of a placard, instead of relying on the specific characteristics of the product. The Board has therefore recommended that:
- The Department of Transport review the classification and safety marks for anhydrous ammonia to ensure that it is in a class and division consistent with the risks it poses to the public. [R02-01]
The visual inspection of the tank car that leaked anhydrous ammonia, as well as five other similar 112J tank cars, revealed that the thermal protection material has a tendency to shift over time.
The performance requirements for thermal protection systems require tank cars to withstand a pool fire (a fire that envelopes the tank or a large portion of it) for 100 minutes and a torch fire (a localized fire source that causes higher temperatures over a small portion of the tank) for 30 minutes. When the thermal insulation shifts, areas of the tank can be left without protection, degrading the thermal resistance of any such car in a fire situation.
At present, tank cars are subject to a re-qualification inspection which includes the thermal protection; however, the standards do not contain requirements on methods of inspection, nor the relationship between thermal protection degradation, such as shifts or voids in the insulation, and the actual thermal resistance of the cars.
Where fire is present, there is a risk to the public that hazardous products may be prematurely released to the atmosphere in the time-critical initial stages of an emergency response, before proper isolation and evacuation procedures can be implemented. The Board has therefore recommended that:
- The Department of Transport, in conjunction with the tank car owners, review the existing inspection and maintenance program for thermal protection of tank cars already in service, and ensure that their thermal protection systems confer acceptable thermal resistance to reduce the risk of the premature release of dangerous goods in a fire. [R02-02]
Although the emergency response personnel worked diligently to serve and protect their communities, some of the volunteer fire-fighters had little knowledge of dangerous goods or of the hazards they were confronting, and others did not have basic protective equipment (e.g. protective footwear). They worked at the site for nearly 40 hours without sufficient rest or proper meals. The Board is concerned that emergency response personnel in small communities may not be provided with the necessary tools, protective equipment, and training to be fully aware of, and prepared for, the risks associated with the dangerous goods being transported through their communities, nor provided with adequate human resource management to allow them to perform their oftentimes hazardous duties safely.
The Transportation Safety Board of Canada is an independent agency operating under its own Act of Parliament. Its sole aim is the advancement of transportation safety. It is not the function of the Board to assign fault or determine civil or criminal liability.
The TSB is an independent agency that investigates marine, pipeline, railway and aviation transportation occurrences. Its sole aim is the advancement of transportation safety. It is not the function of the Board to assign fault or determine civil or criminal liability.
For more information, contact:
Transportation Safety Board of Canada
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