TSB Recommendation R22-02

Transport Canada has invested substantial resources in rigorously evaluating the readiness, efficacy, and safety implications of automatic parking brakes (APB) in 2022/2023, particularly in cold weather scenarios to evaluate safe operations within Canada.All responses are those of the stakeholders to the TSB in written communications and are reproduced in full. The TSB corrects typographical errors and accessibility issues in the material it reproduces without indication but uses brackets [  ] to show other changes or to show that part of the response was omitted because it was not pertinent.

Transport Canada recognizes that technology plays a pivotal role in the safety of the transportation system. However, it is essential to recognize that not all technological advancements are fully mature and ready for implementation. It is crucial to consider the readiness factor before pursuing implementation and operation of any technology as it directly impacts the intended success and efficiency.

To assess the effectiveness and safety implications of APBs, Transport Canada entered into two contracts – first with a research consultant, the Volpe National Transportation Systems Center. The final report submitted to Transport Canada in August 2023 emphasized that APB technologies are not advanced enough to be implemented at present. The report highlighted several challenges, including the lack of standardization and the absence of a fully matured technology platform. These findings indicate that further development is required to ensure that APBs can consistently and reliably perform in a variety of real-world scenarios. It is evident that pursuing APBs at this stage could expose the Canadian rail network to unnecessary risks and potential safety concerns.

Transport Canada’s second research and testing agreement focused on assessing the safety implications of APBs in cold-weather conditions and validating the performance of prototype APB systems. Initial testing was performed by the National Research Council (NRC), in a simulated air brake system arrangement on an instrumented APB system. The NRC's initial round of testing revealed significant brake force reduction on simulated APB-equipped brake tests, suggesting a potential lack of reliability and performance of the technology. More recent NRC testing observations of an APB system installed on a rail car seem to indicate better brake shoe force measurements than measured in the initial trials. A full analysis of the latest testing data is currently being processed and is expected to be shared with stakeholders in Spring 2024. Real world track testing and further engagements with other APB manufacturers must be considered to ensure the safe implementation of APB technologies across Canada. It is crucial to ensure that APBs are capable of consistently delivering optimal performance prior to their integration in an operating environment. Additional testing activities are currently underway with the NRC to test the impacts of cold weather on traditional air brake systems.

In 2022, a working group was established with railway companies to consider APB designs and explore safe testing and implementation approaches. The working group met seven times in total.

While TC understands the recommendation R22-02 to pursue APBs for enhancing safety in the railway industry, the current state of readiness and availability of APBs, alongside the challenges identified in the research findings, suggest that further development and testing by the manufacturers are necessary. The feasibility of deploying this technology would be evaluated following progress on testing and research, as Transport Canada seeks to understand the state of readiness, availability and functionality of APB technology, and its ability to mitigate uncontrolled movements of railway equipment, including in cold weather conditions.

TC will continue to actively monitor the progress and development of the APBs. By doing so, we can stay informed about advancements and ensure that they align with the desired outcome of the recommendation. This approach mitigates potential risks associated with premature implementation and maximizes the chances of a successful deployment of APBs. In the meantime, and until the technology is proven, the Department continues to work on other measures to address performance of air brakes and securement on mountain terrain, such as recent approval of revisions to the Railway Freight and Passenger Train Brake Inspection and Safety Rules.

The industry collaborated as part of the APB working group established with TC. Reports were submitted to, and reviewed by, the working group from both the NRC and the Volpe Center. One major railway participant conducted limited field testing of APB and this testing was abruptly halted due to significant safety concerns with the APB based on the results of the NRC laboratory tests.

The Recommendation does not appear to be based on any assessment of APB readiness, nor its effectiveness as a physical defence layer, nor its viability within the complex North American rail system.

It is evident that APB is not close to being an effective, viable, available or safe technology for freight railway operations.

TC advised the industry on December 20, 2023 of the following:

“While TC’s preliminary research and assessment have indicated that APB technologies are not ready for deployment, we judge that future research should include track testing and rail car installation of APBs to thoroughly assess technology readiness.

For your information, Rail Safety has completed its leg of research and testing, and future advancements would be led through TC’s Innovation Centre, with Rail Safety providing support as appropriate.”

Based on this, R22-02 should be closed.

Given the status of TC’s and RAC’s responses, the TSB referred to a manufacturer of commercially available APBs to obtain an update on its APB technology to better understand its status with regards to receiving AAR unconditional approval.

High-level timeline of Wabtec’s Automatic Parking Brake (APB):

• 12/2018 – Completed Detailed Product Design
• 12/2019 – Field shoe force test at CSX (Cumberland, Maryland)
• 02/2020 – APB request for AAR Conditional Approval
• 09/2021 – Completed and issued design for APB
• 10/2022 – CN Field Test Installation (4x Devices)
• 12/2022 – TC/NRC Evaluation – Round 1 (one device)
• 03/2023 – TC/NRC Evaluation – Round 2 (two devices)
• 10/2023 – Evaluation of returned NRC Unit (APB2)
• 12/2023 – Field shoe force test at Curry Rail (Hollidaysburg, PA) with APB2
• 02/2024 – Witness on-car testing of APB1 at NRC

Summary of Wabtec’s APB

Wabtec’s APB concept has been under development for 6+ years. The design has progressed through much of our Product Development Framework (a standardized methodology for R&D Projects, including design iterations, design reviews, verification and validation) to the point that the design has evolved into what is believed to be well beyond the prototype phase and it is appropriate to be evaluated by the industry.

Wabtec’s APB was validated to applicable AAR Specifications as follows:

• AAR S-400 (Figure 8.2): I.D. of Hollow Rod, mounting holes and envelope dimensions.
• AAR S-4004 (Performance Testing):
  • Force Test (Section 3; -40/RT/150°F)
  • Leakage Tests (Section 3; -40/RT/150°F)
  • Vibration Tests (Section 4)
  • Cycle Tests (Section 5)

Wabtec’s APB was also validated beyond the above-mentioned AAR specifications to internal guidelines:

• Single Car Test Rack – Simulated Brake applications (-40/RT/150°F)
• Force Output and Force Retention
• Endurance/Proof Tests
• On-Car – Brake applications and shoe force

Based on these successful validations and documented on-car testing, it is believed that the current APB is ready to be evaluated in further field tests. Specifically, it is hoped that the successful recent NRC on-car testing of the APB will result in the resuming of the field test of the APB on CN. The introduction of this technology into actual service will provide an assessment of the durability of the design as well as valuable feedback on operation of cars equipped with the APB. Additionally, APB testing at MxV Rail is to begin in May.

Wabtec’s APB will provide operational and safety benefits:

• APB engages after Brake Pipe pressure decreases below 20-psi and retains shoe force developed after an emergency application in the event that brake cylinder pressure decreases due to leakage.
• The engagement of the APB following a UDE, hose separation or an intentional emergency application allows for the securement of cars so that a thorough evaluation of the situation can be executed – avoiding the potential urgency to take corrective action that may be required in some critical situations.
• The APB Pneumatic Control Valve – APB isolation from Brake Pipe pressure – provides the ability to maintain shoe force while the brake system is recovered.
• The APB Pneumatic Control Valve – access from the ground replaces the need to set hand brakes – eliminating the demanding physical task of applying and releasing the hand brakes.
• An automatic parking brake is believed to be a major enhancement to the brake system to prevent uncontrolled movements. The basic functionality of a parking brake becomes even more significant when the prospect of autonomous train operation is considered.

Comments related to NRC’s (National Research Council Canada) evaluation of two APBs:

Wabtec provided a detailed report to the NRC in a letter/report dated February 27, 2024; this was subsequently sent to the TSB. The following is a high-level summary from that report:

APB2 was sent to the NRC for testing on 1/20/2023. During performance testing, NRC noted that APB2 occasionally yielded a low force output. This device was shipped back to Wabtec for further evaluation (Wabtec received on 10/19/2023). APB2 was tested in the ‘as received’ condition from NRC.

Wabtec was unable to re-produce the results documented in the NRC report.

The returned APB2 cylinder was found to be compliant with the force output requirements prescribed in the AAR S-4004 specification.

A direct comparison of force output between a standard ABU cylinder and the returned APB2 cylinder shows a maximum of 4% lower APB2 force output with no spring/rigging simulation.

Tests performed with the Wabtec spring/rigging simulation configuration on APB2 exhibit 107% to 149% of the lower output measured by NRC on the APB2 cylinder. It is believed that the NRC test arrangement, simulating a car’s rigging, may have contributed to the documented disparity in the spring/rigging simulation force output measurements of the APB2 cylinder.

By design, the APB force retention target is to retain greater than 80% of the shoe force generated by an emergency application. The returned APB2 cylinder retained more than 80% for all test conditions.

Preliminary data from recent on-car NRC tests with APB1 show that the Automatic Parking Brake produced greater than 90% of the average un-tapped shoe source generated by the standard ABU cylinder. This testing was performed in February 2024 on a 100-ton loaded covered hopper car (AVL 003) at NRC’s facility (Ottawa, ON). Tests were performed indoors as well as outdoors (approx. temperature 15°F). This data appears to further corroborate Wabtec’s in-house testing and the on-car testing at Curry Rail.

As always, Wabtec will continue to assist both regulators and industry stakeholders in the development of new technology that improves safe operation.

In 2022–23, Transport Canada (TC) entered into 2 contracts—one with the Volpe National Transportation Systems Center (Volpe) and another with the National Research Council Canada (NRC)—to evaluate the readiness, efficacy, and safety implications of automatic parking brake (APB) technology, particularly in cold-weather scenarios in Canada.

TC has also indicated that a working group was established with railway companies to consider the design and safety parameters of APB technology. The working group met seven times in total. TC has made industry aware of the TSB recommendation, and held discussions about APB technology, but has not secured a willing partner railway to work with APB technology manufacturers toward achieving Association of American Railroads (AAR) unconditional approval.The APB technology developed by Wabtec, and evaluated by the NRC, has achieved AAR conditional  approval. To achieve AAR unconditional approval, and therefore allow the technology to be used by railways in operational service, APB technology manufacturers require willing industry partners to test the new technology in service for a specific period of time and in a wide range of applications and situations to demonstrate its suitability for long-term use.

In its final report submitted to TC in August 2023, Volpe emphasized that APB technology is not advanced enough to be implemented at present. Volpe also highlighted that further development is required to ensure that APBs can consistently and reliably perform in a variety of real-world scenarios.

Testing completed by the NRC on behalf of TC in 2023 focused on assessing the safety implications of APB technology in cold-weather conditions. However, the NRC testing revealed significant brake force reduction during APB-enabled brake tests using an instrumented APB unit manufactured by Wabtec. APB technology involves the operation of a mechanical latch that, manufacturer testing has shown, is not adversely affected by ambient temperature. As designed, an APB, once activated, will maintain a braking force regardless of the ambient air temperature until the brake pipe pressure increases and the mechanical latch is released. The TSB notes that the NRC testing involved the use of a simulated air brake system arrangement (i.e., a test rig) that was not approved by the APB technology manufacturer (Wabtec) and likely led to invalid results and erroneous conclusions about the effectiveness of the APB unit’s performance.

The APB unit that was tested by the NRC was subsequently shipped back to Wabtec for evaluation. Wabtec did not identify any issues with the unit and was unable to reproduce the results obtained by the NRC testing using the test rig. The testing performed by Wabtec revealed that the APB unit performed as expected, maintaining the desired brake force.

Following the initial testing, NRC, on behalf of TC, conducted additional APB testing in February 2024 using a 100-ton loaded covered hopper car at NRC’s facility in Ottawa, Ontario. Tests were performed indoors as well as outdoors (at a temperature of approximately −9°C). Preliminary data shows that the APB unit produced better brake shoe force measurements than measured in the initial NRC testing and the results are similar to those reported by Wabtec during its testing.

Wabtec’s APB technology has been under development for over six years. Wabtec contends that the design has evolved beyond the prototype phase, having received AAR conditional approval and having completed numerous successful tests, and it is ready to be evaluated by the industry in an operational environment.

In the meantime, TC continues to rely on improvements to its regulatory framework to address performance of air brakes and train securement on mountain terrain, such as the approval of revisions to the Railway Freight and Passenger Train Brake Inspection and Safety Rules on 29 September 2023 that will come into effect on 01 December 2025. These are positive steps that are expected to improve safety. However, as indicated in the preamble to the recommendation, TSB testing conducted as part of investigation R19C0015 has shown that the application of hand brakes required by Canadian Rail Operating Rules (CROR) Rule 66 could be insufficient to secure a train in many circumstances due to, amongst other items, human performance limitations resulting in lower-than-expected minimum torque values. This supports the need for physical defences such as APB technology to enhance safety and prevent uncontrolled movements of railway rolling stock.

The Board is encouraged that TC recognizes and acknowledges that uncontrolled movements of railway equipment can create high-risk situations that may have catastrophic consequences. The initiatives taken by TC to date have been aimed at evaluating the readiness, efficacy, and safety implications of APB technology to ensure that APB technology is capable of performing as intended prior to its integration in an operating environment. However, unless TC takes steps to plan for the further testing of this technology in an operational environment, the Canadian railway industry is not likely to volunteer to partner with APB manufacturers to test this technology in service in order to achieve AAR unconditional approval. TC indicated that its research for the next year will focus on APB testing in addition to testing the impacts of cold weather on traditional air brake systems. Consequently, the Board considers TC’s response to Recommendation R22-02 to be Satisfactory in Part.