TSB Recommendation R17-01

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