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Backgrounder (R19C0015)

Findings from TSB investigation R19C0015 – February 2019 fatal uncontrolled movement of rolling stock and derailment near Field, British Columbia

Investigations conducted by the Transportation Safety Board of Canada (TSB) are complex since an accident rarely results from a single cause. In the case of the Field, British Columbia, accident on 4 February 2019 several factors led to the uncontrolled movement, derailment and the fatal injuries of 3 crew members. The 23 findings below detail the causes and contributing factors that led to this occurrence. Additionally during the course of the investigation, the TSB also made 19 findings as to risk and 9 other findings.

Findings as to causes and contributing factors

These are conditions, acts or safety deficiencies that were found to have caused or contributed to this occurrence.

  1. Once the train passed Mile 126, it had entered one of the steepest grades on Field Hill. At this point, the sequence of service brake applications made by the inbound locomotive engineer, combined with the available locomotive dynamic brakes, could not maintain the train’s speed below the maximum allowable limit of 15 mph. Therefore, as required by company instructions, the crew applied the brakes in emergency, bringing the train to a stop on Field Hill at Mile 127.46.
  2. The inbound crew and the trainmaster opted for retainers only, and the conductor subsequently set them to the high pressure position on 75% of the cars (84 cars) per the Field Hill Operating Manual (FHOP). Because the crew were close to the end of their shift, the rail traffic control director ordered a relief crew, who would recover the emergency brake application and complete the trip to Field.
  3. About 10 minutes after the crew-to-crew transfer, the train began to roll on its own.
  4. The train accelerated down the mountain, negotiating the steep descending grade and sharp curves, until it reached 53 mph, a speed well beyond the maximum authorized speed of the track. This excessive speed resulted in high centrifugal forces that, combined with lateral forces generated by moderate in-train buff forces, caused the locomotive to tip over in a 9.8° curve and derail at Mile 130.6.
  5. Even though the inbound crew had experienced poor train braking performance that had required an emergency stop, the Field Hill operating procedures did not lead the crew and the trainmaster to conclude that the situation warranted applying hand brakes in addition to setting retainers.
  6. Since braking performance degradation occurred seasonally on Canadian Pacific unit grain trains in extreme cold temperature, this condition had become normalized such that it was expected that close to maximum available braking would be required while descending Field Hill.
  7. Although the applied air flow events were noticed and discussed, their significance as a leading indicator of brake system malfunction may not have been fully understood, resulting in a missed opportunity to accurately diagnose the diminishing effectiveness of the train’s air brake system.
  8. After the job briefing, during which there was no discussion of the critical factors such as ambient temperature, brake system performance, and the significance of the applied air flow events that might have prompted the application of hand brakes, the trainmaster decided that setting retainers was sufficient after this first emergency stop.
  9. Gaps in the training program meant that the inbound conductor was not aware of the need to observe brake cylinder piston position while setting retainers, and therefore retainers were likely applied to cars with ineffective brakes.
  10. The trainmaster was not Field Hill–certified and had not previously experienced an emergency stop on Field Hill. As a result, his decision making likely relied on the direction outlined in the Field Hill operating procedures, which were commonly interpreted to mean that only retainers were to be applied after a first emergency stop on Field Hill.
  11. The trainmaster’s training and experience did not adequately prepare him to evaluate abnormal circumstances in the complex operating environment of Field Hill.
  12. Based on post-occurrence testing, it is likely that about 52 of the 112 cars on the occurrence train had reduced air brake effectiveness during the initial descent of Field Hill, and consequently an emergency brake application was necessary.
  13. For the occurrence train, given the extreme cold temperature and the length of time the cars were stationary with the brakes applied, the rate of brake cylinder pressure loss on some cars with retainers set was likely excessive.
  14. Twenty-seven cars on the occurrence train had DB-10 CCV service portions. It is likely that the response from these service portions to the small incremental brake applications that were made as the train was operating between Stephen and Partridge contributed to the difficulty in controlling train speed that led to the emergency brake application at Partridge.
  15. It is highly probable that the air brake system on the 27 grain cars equipped with NYAB-Knorr’s DB-10 service portions and DB-20 emergency portions manufactured more than 13 years ago could not maintain adequate braking effectiveness due to excessive leakage from worn and deteriorated rubber seals on these portions.
  16. Three hours and 14 minutes after the initial brake application at Stephen, the average brake cylinder pressure likely decreased to below 31 psi. This rendered the retarding force insufficient to prevent the train from starting to roll uncontrolled down the mountain grade.
  17. Brake shoe friction fade occurred on the cars with effective brakes, contributing to the high speed during the uncontrolled movement.
  18. Both the wheel temperature detector measurements and the safety hazard reports filed by train crews of westbound loaded unit grain trains confirm that the No. 1 brake tests performed in Alyth Yard did not adequately identify cars whose brakes would not be fully effective in the extreme cold temperature experienced by the occurrence train while descending Field Hill.
  19. From 2015 to the time of the occurrence, Canadian Pacific had not imposed restrictions on the operation of unit grain trains on Field Hill in extreme cold temperatures.
  20. Even though the wheel temperature detector data were being collected and showed high percentages of ineffective brakes on grain trains in the 2 cold days before the occurrence, Canadian Pacific was not analyzing these data and did not initiate any specific action or corrective measures.
  21. Although Canadian Pacific’s procedure for safety hazard reporting was actively followed at the Calgary terminal, the follow-up process was not effective at analyzing trends and resolving safety issues related to the performance of air brake systems in extreme cold temperatures on the grain car fleet operating on the Laggan Subdivision.
  22. Canadian Pacific did not consider that the trend in safety hazard reports represented a “safety concern,” per the Safety Management System Regulations, 2015, and it did not take sufficient action to address the underlying causes of ineffective braking of unit grain trains descending Field Hill in extreme cold temperatures.
  23. Transport Canada’s oversight of the occupational health and safety committee in Calgary did not identify the lack of corrective action on the reported substandard braking performance of unit grain trains descending Field Hill.

Findings as to risk

These are conditions, unsafe acts or safety deficiencies that were found not to be a factor in this occurrence but could have adverse consequences in future occurrences.

  1. If the classroom training does not address the unique needs of the territory where the employees will be working, and if the employees do not obtain the relevant on-the-job training on that territory, then they will not be adequately prepared and sufficiently trained to perform their duties safely, increasing the risk of an accident.
  2. When specialist duties are transferred to a generalist position, unless technical training and operational experience bridge the gaps that exist between the 2 positions, there is an increased risk that these duties will not be performed adequately.
  3. When operating employees do not receive adequate initial and recurrent training in crew resource management, including how to make decisions when authority gradients are present, crew coordination and interaction may not be effective, increasing the risk of human factors–related accidents.
  4. If train crews routinely operate under hazardous circumstances, such as braking performance degradation in extreme cold temperatures, each successful trip will increase risk tolerance and reduce a crew’s ability to recognize, accurately evaluate, and manage the hazards in future, increasing the risk of an accident.
  5. If established design principles are not applied to the display of safety-significant information on the locomotive’s operator display screen, important cues can be missed, increasing the risk of accidents.
  6. When trains operate in extreme cold temperatures, brake cylinder leakage will occur, increasing the risk that the use of retaining valves as a means to preserve braking capacity will not be effective.
  7. For a train negotiating a long descending grade, where a brake application may be held for over 20 minutes, even with a brake cylinder leakage rate within the maximum acceptable limit specified in AAR Standard S-486 SCT (1 psi/minute), there is a risk that brake cylinder leakage will render the air brake system ineffective.
  8. If guidance on how to respond to an emergency situation is not explicit but instead relies on employees’ interpretation of the situation, employees’ decision making may not be precisely informed, increasing the risk of an unsafe course of action being implemented.
  9. If appropriate seasonal operational restrictions are not consistently activated year to year to ensure the safety of unit train operations during extreme cold temperatures in mountain grade territory, there is an increased risk of loss of control and derailments.
  10. Until train brake test methodologies accurately evaluate air brake effectiveness, trains operating in extreme cold temperatures may continue to have ineffective braking, increasing the risk of loss of control and derailment.
  11. Until the use of fade-resistant brake shoes is made mandatory on unit trains operating through mountain grade territory, there is an increased risk that these trains will experience brake shoe friction fade and loss of control while descending long mountain grades.
  12. Until additional physical defences are put in place, there is an ongoing risk that unplanned and uncontrolled movements of railway rolling stock will continue to occur, resulting in derailments, collisions and unacceptable risk to railway employees, the public and the environment.
  13. Without sufficient proficiency tests on all train crews, and without test results that consistently provide qualitative feedback, there is a risk that deficiencies in an employee’s skills, qualifications, or knowledge will not be adequately identified and that corrective actions will not be taken to improve safety.
  14. When designated rest facility conditions are not conducive to employees obtaining restorative rest, there is an increased risk that employees will be not be fully rested at the end of a designated rest period.
  15. When operating practices to use a train’s full braking capacity to control speed on mountain grades become normalized, the safety margin is seriously compromised, increasing the risk of an accident.
  16. If railway companies modify their policies and procedures without identifying all hazards in advance, appropriate risk mitigation measures may not be implemented, increasing the risk that safety margins will erode.
  17. If hazards are not properly identified and analyzed, gaps in safety defences can continue to go unnoticed and remain unmitigated, increasing the risk of accidents.
  18. If a railway company’s safety management system is not supported by a positive safety culture, its effectiveness at identifying and mitigating hazards is reduced, increasing the risk of accidents.
  19. If there is no regulatory oversight of the relevance and effectiveness of training programs for railway operating employees, there is an increased risk that these programs will not be sufficiently robust to ensure that railway operating employees have adequate knowledge and experience to work safely.

Other findings

These items could enhance safety, resolve an issue of controversy, or provide a data point for future safety studies.

  1. Because the continuity of the brake pipe was never compromised in any way, and an unintentional brake release did not occur on the train before the derailment, the only remaining cause of the applied air flow was excessive leakage of air on one or more cars. This can result in depletion of brake cylinder pressure or the release of the air brakes on individual cars.
  2. The running brake test at Eldon did not reveal any consequential braking anomaly because brake system leakage had not yet been exacerbated by the extreme cold, the duration of the brake applications was not long enough for the leakage to adversely affect the air brake system performance, and the train was not on the mountain grade.
  3. Small incremental reductions in brake pipe pressure may not be sufficiently robust to propagate along the length of the brake pipe when there is a high-level air flow occurring simultaneously. They also can result in a pressure wave that cannot trigger the intended brake application response effectively on older or less sensitive car control valves.
  4. The single car test, which is usually conducted in a shop or outdoor repair track environment at warmer temperatures, does not identify defective car control valves conditions that manifest themselves in cold and extreme cold operating conditions.
  5. Based on braking calculations, cars on the train yielded, on average, about 61% brake effort in response to the emergency brake application at Partridge. About 3 hours later, when the train began to roll on its own, the brake effort had degraded to less than 40% of theoretical maximum braking effort.
  6. Based on the comparison of wheel temperature detector data for similar unit grain trains operating in extreme cold temperatures, i.e., below −25 °C, calculations indicate that the occurrence train was operating with at least 50% cold cars, as defined by the railway’s wheel temperature detector criteria, at the time of the occurrence.
  7. Wheel temperature detector data collected in winter for trains operating in temperatures of –25 °C or less provide valuable insight into overall train braking health. These wheel temperature detector data results could be used to establish winter operating criteria for the safe operation of unit grain trains in extreme cold temperatures.
  8. Neither Canadian Pacific nor Transport Canada, who were integral participants in the development and implementation of the automated train brake effectiveness research, used the study’s findings on the condition of the grain hopper car fleet to initiate a risk assessment of unit grain train operations.
  9. Even though federally regulated railways have been required to have a safety management system since 2001, and the new Railway Safety Management System Regulations were introduced in 2015, the effectiveness of every railway company’s safety management system has not yet been evaluated by TC.