In a nutshell:
"In summary, the 3 ALSTOM bearing cartridge assemblies examined by the Transportation Safety Board TSB exhibited numerous failure modes including:
*fatigue fractures,
*rolling contact fatigue,
*surface wear,
*impact wear,
*environmental erosion, and
frictional wear," the TSB said
Higher than expected lateral loads are the root cause of issues with Ottawa LRT axles, Alstom says https://share.google/iIy5LWexCLOGx1wmW
So how the does the axle-play get generated; how do the parts start moving within the cartridge," RTG president Nicholas Tauchon said.
Assemblies are being swapped out every 100,000 km though previously expected to last 1.2 million km
Lateral loads means side to side motion! < ---- >
Alstom says that the lateral loads (the dynamic at the wheel/rail interface) experienced by the wheel assembly during operation exceed design limits, causing bending loads on the axle hub assembly and leading to development of play into the assembly, the restraining nut unscrewing and a derailment.
"This failure mode that we see here in Ottawa we have not observed in our other fleets around the world," David Van der Wee, vice-president of Alstom, told the Transit Commission
Tight corners!
Don't the Luccini wheels allow for greater lateral movement? They have a rubber insert.!!
What about the Luchinni wheels?
Rail Safety Advisory Letter 01/23 - Transportation Safety Board of Canada https://share.google/Fo0ExCEsV9cALgY42
Why do the LRT bearing cassets wear out?
How were they approved?
Ask Manconi, Watson, Hubley, Kanalakous
The end section of an axle or shaft that rotates within a bearing is called the axle journal.
Note wheel lip runs on the inside of the track
THIS nut coming unscrewed IS a key portion of THE PROBLEM and how that needs to be a focal point no matter what is the sequence of events that brings the nut to being unscrewed,"
Alstom decided to pin it in place.
Ottawa LRT vehicle's layout and Alstom Iponam bogies— identified by the following technical characteristics:
Wheel Type:
Luchini Resilient wheel assembly consisting of a *steel wheel tread,
*rubber blocks,
*a steel ring, and
*a steel wheel centre with an integrated wheel hub.
Dimensions: New wheels have a diameter of 640 mm, which can wear down to approximately 570 mm over their service life.
Safety Features: These wheels can be equipped with the Lucchini Syope® noise-reduction system to mitigate squealing in narrow curves.
Configuration: Each train car (LRV) is equipped with 20 wheels distributed across five bogies.
Cross section..note yellow ring is shown as purple above
The brake disc is mounted on the axle stub.
Luchinni axles allow a lower floor
Alstom has submitted several recommendations to Rideau Transit Maintenance for a sustainable solution to the issue, including
*moving the restraining rail,
*the deployment of top-of-rail friction modifier,
*ballast shoulders improvement and
*replacing the existing soft rail with harder rail.The "soft" rails were wearing down too quickly under the weight of the trains.
Note:
And ballast shoulder improvement?
By strengthening the ballast (the rocky material supporting the ties), the track is better secured, reducing the movement that causes wear on the wheel assemblies.
Rideau Transit Maintenance told the Transit Commission the top-of-rail lubrication is a water-based product and is environmentally friendly.
Data showed a 40 per cent reduction on lateral loads using top-of-rail lubrication along the O-Train line.
Alstom has also developed an improvement to the axle nut locking, which will prevent the nut from unscrewing..basically a pin.
Additional improvements under investigation include replacing rails in curves with a harder rail, extending the restraining rail and reducing track buckling.
How did all this hapoen?
During the 2018–2019 trial running (pre-revenue commissioning) for Ottawa's Confederation Line (Line 1), the trains were not loaded with actual passengers or even simulated full passenger loads in the same rigorous way later phases or other systems have been.**
### Key Details on Trial Running for Confederation Line - The trial running phase was a **12-day test period** (agreed upon by the City and Rideau Transit Group/RTG) to demonstrate system reliability before opening in September 2019. - It focused on operating trains under near-service conditions: running multiple trains (initially aiming for 15 during peaks, but relaxed to 13 due to challenges), achieving high on-time performance (AVKR lowered from 98% to 96%), stopping at stations, and simulating scheduled service. - **No evidence of full passenger load simulation**: Reports, inquiry documents (e.g., from the public inquiry and Mott MacDonald independent review), and contemporary news coverage do not mention using sandbags, water tanks, ballast weights, dummy passengers, or any other method to replicate full passenger weight during this phase. - Testing emphasized **system integration**, vehicle performance, track interaction, signaling, doors, propulsion, and operations under controlled/light conditions. - Passenger loading/unloading times at stations were considered in some specs, but this was more about dwell times than actual weight loading. - The phase was criticized in the later public inquiry for being too lenient (e.g., criteria relaxed mid-process, no "soft launch" with extended full-capacity testing), and issues like reliability cropped up post-opening when real passenger loads ramped up. ### Contrast with Later/Other Lines - For **Stage 2 extensions** (Trillium Line/Line 2 & 4, ongoing in 2024–2025), trial running explicitly includes **"simulated passenger service"** over 14 days at full capacity (as if carrying passengers), plus failure scenario testing. This is a longer, more demanding process (21+ days total) with higher performance thresholds (e.g., 98.5% on-time rolling average). - The original Confederation Line trial did **not** incorporate this level of simulated loading—likely contributing to why overload-related wear (e.g., higher lateral forces exacerbating bearing issues) only became evident in revenue service with actual crowds. In essence, trial running stressed the system dynamically (speeds, curves, braking, multiple trains) but without the full axle/bearing loading from passenger weight that occurs daily now. This could explain why early fatigue signs (like those leading to spalling) weren't apparent then—real operational stresses, including variable passenger loads on sharp curves, accumulated over years of service. Ongoing investigations still point to track/vehicle mismatches as key factors.
- Full, proactive disclosure of risks and issues — Critical problems (e.g., trial-running failures, safety concerns) should be reported promptly and fully to all city council members, not just the mayor's office or select chairs. No selective withholding or "controlling the narrative" to protect political timelines (like election dates). Hourigan stressed that elected officials' involvement must be transparent and follow council's governance rules, including delegation policies with built-in accountability mechanisms (e.g., mandatory "reporting out" on delegated decisions).
- Better procurement and P3 (public-private partnership) models — Evaluate alternatives to P3s for large projects; involve stakeholders (suppliers, operators, maintainers) early in planning/procurement to align incentives and reduce conflicts. Update city policies to require clear communication responsibilities in project agreements, enhanced oversight, and public transparency for major contracts (e.g., proactive disclosure of executed contracts over certain values).
