Rail Recommendation R07-04
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- Assessment of the Responses from Transport Canada to Rail Safety Recommendation R07–04 – Non-pressurized tank car construction standards (PDF Version, 100 kb)
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Assessment of the Responses from Transport Canada to Rail Safety Recommendation R07–04
Non-pressurized tank car construction standards
At approximately 1440 eastern daylight time on 17 August 2004, 18 tank cars of Canadian National train U-781-21-17, a petroleum product unit train travelling from the Ultramar Canada Inc. refinery in Lévis, district of Saint-Romuald, Quebec, and bound for Montréal, Quebec, derailed at Mile 3.87 of the Lévis Subdivision, in the marshy area of the Grande Plée Bleue, near Saint-Henri-de-Lévis. Approximately 200 000 litres of gasoline and diesel fuel spilled into the marshy area, but the spilled product was recovered. There were no injuries.
The damage sustained by the Class 111A tank cars involved in this occurrence and the risks posed by the subsequent product release are typical of that identified in previous TSB investigations. In this occurrence, there was a significant spill of hydrocarbons when the tank shells and heads were breached even though the derailment happened in a marshy area where the surrounding terrain was particularly soft. Other occurrences investigated by the TSB have also revealed the vulnerability of this type of car to puncture, even in low-speed accidents (TSB report R99D0159 (Cornwall) and TSB report R05H0011 (Maxville)).
The Class 111A tank cars’ weaknesses have been acknowledged by the regulator and industry, resulting in measures to mitigate risk in the event of a derailment. The number of products that these cars are allowed to transport was reduced when the Transportation of Dangerous Goods Regulations were amended and new tank car construction standards were established by TC. These standards, which have been incorporated into the Association of American Railroads (AAR) Specifications for Tank Cars, M-1002-2003, require that new Class 111A tank cars with a gross weight of 286 000 pounds be constructed to more stringent criteria, including improved puncture resistance through better material selection and inclusion of half-head shields. However, the safety enhancements included in the standards do not apply to Class 111A tank cars with a maximum gross weight of 263 000 pounds or less, or to other non-pressurized tank cars. Consequently, a large number of the existing tank cars carrying dangerous goods will be vulnerable to puncture, even during derailments at moderate operating speeds.
Considering that the difference in product volume between the two types of car is less than nine per cent, the risks presented by a product release from a 263 000-pound car would not be significantly lower than in the case of a 286 000-pound car. Therefore, the Board believes that further attention is required to address the issue of puncture resistance of cars of lower weight and recommends that:
The Department of Transport extend the safety provisions of the construction standards application to 286 000 pound cars to all new non-pressurized tank cars carrying dangerous goods.
Transport Canada’s response to R07-04 (April 2008)
In response to TSB Recommendation R07-04, TC intends to table this recommendation for discussion and adoption at the upcoming CGSB Standards Committee CAN/CGSB 43.147. This Committee is responsible for drafting and approving Canadian tank car standards related to the “Construction, Modification, Qualification, Maintenance and Selection and Use of Goods by Rail”. These standards are referenced in the TDG Regulations as mandatory requirements. The next meeting of the Committee is expected to take place later this year.
Board assessment of response to R07-04 (June 2008)
TC has acknowledged the deficiency and indicated that they are following up with tank car stakeholders North America wide. As it is too soon to evaluate the outcome of TC’s and the efforts of the other stakeholders, the Board assesses the response to Board Recommendation R07-04 as having Satisfactory Intent.
Additional response to R07-04 (June 2010)
TC acknowledged the deficiency and indicated that they are continuing to follow-up with tank car stakeholders North America wide.
Board reassessment of response to R07-04 ( 16 September 2010)
As TC has expanded their address of the safety issue North America wide but have not concluded the issue, the Board reassesses the response to Recommendation R07-04 to remain as having Satisfactory Intent.
Additional response to R07-04 (January 2012)
TDG and the Federal Railroad Administration (FRA) have recently been part of an Association of American Railroads (AAR) task force that was tasked to identify safety enhancements that could be made to new non-pressure tank cars to improve their accident survivability and safety in general.
TDG had requested the Task Force to extend the inclusion of all the safety enhancements currently required for tank cars operating at increased gross rail loads (GT 286 000 lbs. vs 263 000 lbs.) to all new non-pressure tank cars. The Task Force agreed and the AAR has petitioned the Canadian and United Sates regulators to adopt it in their respective regulations.
These suggested enhancements also include the mandatory use of normalized steel when carbon or low-alloy steels are used in the construction of the tank car’s shell and heads. This use of normalized versus as-rolled steel would represent an important enhancement for the fracture toughness of steel used for non-pressure tank cars.
TDG expects to table the AAR petition at the next meeting of the committee overseeing the soon to be published TC standard on the Containers for Transport of Dangerous Goods by Rail. In addition to normalizing, TC will also be introducing for discussion specific fracture toughness requirements which could take the form of additional Charpy test requirements for the steels used in the construction of the tank cars and/or potentially assigning tank cars with a minimum service temperature, with materials of construction having to meet certain fracture toughness requirements at that temperature.
Board reassessment of response to R07-04 (February 2012)
TC has progressed this issue but has not yet fully addressed the safety deficiency. Therefore, the Board reassesses the response to Recommendation R07-04 to remain as having Satisfactory Intent.
Additional response to R07-04 (January 2013)
TC has reviewed the petition from the AAR and is proposing to modify its tank car requirements so that all new class 111 tank cars for Dangerous Goods in Packing I or II are enhanced relative to the current minimum requirements for class 111 tank cars used at gross weights of 263 000 pounds or less. The enhancements proposed include:
- Protection of service equipment on the top shell.
- The use of reclosing pressure-relief devices.
- A high discharge capacity with a low pressure setting for pressure-relief valves used for petroleum crude oil, UN 1267 or Ethanol/gasoline mixtures, UN 3475 service.
- For carbon steel tank and heads, the steel will have to be normalized.
- The minimum thickness for all tank cars not equipped with an insulation jacket is increased. The minimum thickness for jacketed tanks made of 516-70 steel is increased.
- All tank cars must be equipped with at least ½ in half head shields.
- Coupler forces used to make fatigue calculations must be increased by a factor of 1.09 over those used for tank cars with maximum gross weights of 263, 000 lb.
These changes will be discussed with stakeholders during the next consultative meeting.
Board reassessment of response to R07-04 (07 March 2013)
TC has reviewed the petition from the AAR and will address it during a consultative meeting with stakeholders. TC is progressing towards new regulations, but has not yet fully addressed the safety deficiency. Therefore, the Board reassesses the response to Recommendation R07-04 to remain as having Satisfactory Intent.
Next TSB action
The TSB will monitor the industry for any progress on this issue.
This deficiency file is assigned an Active status.
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