Rail Safety Recommendation R17-01

Assessment of the response to Rail Safety Recommendation R17-01

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Factors affecting severity of derailments involving dangerous goods

Background

On 14 February 2015, at about 2335 Eastern Standard Time, Canadian National Railway Company (CN) crude oil unit train U70451-10 was proceeding eastward at about 38 mph on CN's Ruel Subdivision when it experienced a train-initiated emergency brake application at Mile 111.7, at Gladwick, near Gogama, Ontario. A subsequent inspection determined that the 7th through 35th cars (29 cars in total) had derailed. Nineteen of the tank cars were breached, and about 1.7 million litres of petroleum crude oil were released to either the atmosphere or surface. The released product ignited, and the fires burned for 5 days. About 900 feet of mainline track was destroyed. There was no evacuation, and there were no injuries.

The Board concluded its investigation and released Railway Investigation Report R15H0013 on 16 February 2017.

TSB Recommendation R17-01 (February 2017)

The severity of the outcome in any derailment is directly related to train speed and other factors. One of the ways that the rail industry manages the risk of derailment is through the reduction of train speed. Train speed is restricted based on the class and the condition of the track. When additional track maintenance is required on the track, slow orders can be implemented to further restrict train speed. This is a regular practice in the industry.

While train speed contributes to the severity of outcome in any derailment, other factors also play a role, including train length, the cause of the derailment, the position of the first car(s) derailed, the position of the tank cars in the train and tank car safety design. Although managing train speed based on the condition of the track will help minimize the severity of outcome in the event of a derailment, the risk profile of each train should also be considered. For example:

  • "Non-key" mixed merchandise trains that transport few or no dangerous goods (DGs) and unit trains transporting non-DG commodities (i.e., grain, potash, coal) have the lowest risk profile.
  • "Key" mixed merchandise trains transporting the minimum number of DG tank cars that are dispersed throughout the train are exposed to less risk in a derailment since the derailment could occur in an area of the train that is either not transporting DG tank cars or only transporting a few.
  • Similarly, "key" mixed merchandise trains that transport larger blocks of DG tank cars are exposed to more risk in the event of a derailment.
  • "Key" unit trains of DG tank cars transporting Class 3 flammable liquids have the highest risk profile. When a derailment occurs that involves a unit train transporting Class 3 flammable liquids, the risk of release and adverse consequence is high no matter where the derailment occurs within the train, because all cars are carrying Class 3 flammable liquids.

To some extent, Transport Canada (TC) has recognized the role that train speed and train risk profile play in the severity of the outcome of a derailment, and has put some measures in place to limit the speed of "key trains" under certain conditions. The TC-approved Rules Respecting Key Trains and Key Routes restrict "key trains" to a maximum speed of 40 mph within the core and secondary core of census metropolitan areas. Although the restrictions contained in the rules were a step forward at the time issued, the current maximum speed of 40 mph was selected without being validated by any engineering analysis.

Furthermore, the fact that the new tank car standards (TC-117) will not be fully implemented before 2025 means that less robust tank cars, such as those involved in this occurrence, will continue to transport Class 3 flammable liquids. In its reassessment of TC's response to Recommendation R14-01, the Board stated that, until flammable liquids are transported in tank cars built sufficiently robust to prevent catastrophic failure when involved in an accident, the risk will remain high. Therefore, the Board called upon TC and industry to ensure that risk control measures during the transition are effectively managed. The Board is concerned that the associated train speed and residual risk may be too high for some "key trains." Therefore, the Board recommends that

the Department of Transport conduct a study on the factors that increase the severity of the outcomes for derailments involving dangerous goods, identify appropriate mitigating strategies including train speeds for various train risk profiles and amend the Rules Respecting Key Trains and Key Routes accordingly.
TSB Recommendation R17-01

Transport Canada's response to Recommendation R17-01(May 2017)

Transport Canada acknowledges the recommendation and will conduct a literature review of existing studies, beyond those the department has already reviewed. This may provide additional analysis of speed and other factors which can directly influence the severity of the outcomes of the derailment of trains carrying dangerous goods.

The results of this literature review will be used to determine whether additional scientific and engineering analysis would be meaningful to further the department's understanding of factors affecting the severity of derailments to determine whether changes are warranted to the Rules Respecting Key Trains and Key Routes.

TSB assessment of Transport Canada's response to Recommendation R17-01 (July 2017)

Transport Canada has acknowledged this recommendation.

TC will conduct a literature review of existing studies on the factors affecting the severity of derailments involving dangerous goods. TC will then assess the results of the literature review to determine if additional scientific and engineering analysis would be meaningful to further understand the derailment severity factors. This assessment will allow TC to determine if changes should be made to the Rules Respecting Key Trains and Key Routes.

The Board notes that, although no timeline has been proposed, TC has committed to conducting a literature review of existing studies and to assessing the results of the review. However, beyond this commitment, there are no explicit plans for TC to conduct its own study on derailment severity factors.

Therefore, the Board assesses the response to Recommendation R17-01 to be Satisfactory in Part.

Next TSB action

The TSB will monitor the progress of the planned actions.

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