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).
I get the frustration—**five years** since the Confederation Line opened in 2019, and the same core issues (wheel/axle/bearing problems) keep cropping up, disrupting service repeatedly. It's not just this spalling flare-up; it's built on years of prior failures, inspections, and fixes that haven't fully resolved things for riders. You're right to feel like enough is enough.
ReplyDelete### Current Status (as of late January 2026)
- **No official timeline** for returning to full double-car service. OC Transpo's interim GM (Troy Charter) and reports from January 27–28 explicitly say it's "too early to tell" or provide any ETA. They emphasize safety first, but acknowledge the process is "complex and time-consuming."
- **Progress so far**: Rideau Transit Group (RTG) has replaced **24 cartridge bearing assemblies (CBAs)** since the issue surfaced in routine inspections. Spalling was confirmed on 8 of those (and half in initial checks), but not all high-mileage ones show it—it's variable.
- **Replacement rate**: Their subcontractor can do **two axles per day** (each train has up to 10 axles, but not all need replacement—some vehicles only have 1–3 over the 100,000 km threshold, so they're prioritizing those to get trains back faster).
- **Fleet snapshot**: Started with ~18–20 vehicles available (out of 60 total), running mostly single cars. They aimed for ~20 by late January (e.g., Monday after the Jan 21 memo), and some additional ones have returned, but it's gradual—no big jump reported yet.
- **Longer-term**: Charter has publicly said an **axle redesign** (likely full bearing/hub assembly) is probably needed for reliable, sustainable service. Alstom is involved (resuming work on redesigns after past halts), with consultants on bearings/monitoring. Updates on that are expected soon (e.g., possible Transit Committee mention Feb 12), but no dates tied to full restoration.
### Realistic Wait Estimate
Without an official number, here's a rough sense based on what's public:
- Short-term goal: Get more single-car trains running (higher frequency to offset lower capacity per train) by adding back vehicles gradually—could see incremental improvements in days/weeks if they hit the 2-axle/day pace consistently.
- Full double-car/normal capacity: Likely **weeks to a couple months** at best (factoring in inspections, root cause analysis, and testing post-replacement). Past similar issues (e.g., 2021–2023 bearing failures) took months for fleet recovery. If redesign is needed fleet-wide, that could stretch into 2026–2027.
- This doesn't touch the east extension (still eyed for Q1 2026, but spalling could indirectly delay if it ties up resources).
Riders have every right to be angry—it's not just inconvenience; it's repeated reliability failures on a system that's supposed to be the backbone of transit. OC Transpo is pushing RTG hard (replacements at RTG's cost, penalties for shortfalls), and council scrutiny is ramping up (e.g., calls for refunds, updates).
This sucks, and it's valid to demand better. (Grok)
2 axles per day, 10 axles per car, 60 cars
ReplyDelete300 days .. about a year - then start all over again.
The axles on Ottawa's O-Train Citadis Spirit vehicles don't inherently look "flimsy" in a visual sense when viewed in proper engineering context or photos/illustrations of the full wheelset assembly—they're standard-sized for modern low-floor light rail vehicles (LRVs), with typical wheel diameters around 640 mm new (down to ~570 mm when worn), and axles designed to handle the train's weight and loads under normal conditions.
ReplyDeleteThat said, your impression is understandable and echoes some common rider/expert commentary: the **components appear relatively compact or slender** compared to heavier rail systems (like freight or metro trains), partly because of the **low-floor design** constraints. The Citadis Spirit uses **Iponam bogies** (pivoting/articulated for better curve negotiation in low-floor setups), which limit space for larger, more robust axles/bearings. This results in cartridge bearing assemblies (CBAs) that are space-optimized rather than oversized for extra margin—making them look less bulky than traditional high-floor rail axles.
### Why They Might Seem Flimsy
- **Design trade-offs**: Low-floor LRVs prioritize passenger accessibility (floor height ~350–400 mm above rail), so bogies/axles are squeezed into tight spaces with smaller envelopes. The axle itself is a splined stub axle (short, integrated with gearbox on one side and brake disc on the other), not a long through-axle like in older trains. The cartridge bearings are sealed units bolted on, which can visually appear "thin" or less massive.
- **Real issues aren't slimness per se**: The premature failures (early wear, spalling, play >0.1 mm tolerance, overheating) stem from **higher-than-design lateral forces** (sharp curves, track gauge/rail interface mismatches, passenger overloading on Ottawa's specs), not because the axles are undersized for generic light rail.
- They're engineered for ~1.2 million km life under expected loads, but Ottawa's conditions (heavier loaded weight ~113 tons per LRV vs. lighter Citadis variants elsewhere) accelerate fatigue.
- Alstom has argued the infrastructure (e.g., softer rails on curves, lack of lubrication) is the main culprit, not the axle design itself—hence their halt on full redesign in 2024.
- City/OC Transpo experts lean toward needing a strengthened/redesigned axle/hub to better handle those forces long-term.
- **Comparisons**: In other Citadis Spirit deployments (e.g., Toronto's upcoming Line 5) or similar low-floor LRVs, similar axle setups work fine without these issues, suggesting Ottawa's track/operational factors are key amplifiers.
In photos or cutaways (like the ones we've generated earlier), the axle looks sturdy—solid steel shaft with robust flanges, multiple rollers in the cartridge, and wheel hubs bolted securely—but the tight integration and exposed wear points (when damaged) can give a less "heavy-duty" vibe than bulkier freight axles.
Ultimately, the visual "flimsiness" perception aligns with why redesign discussions keep resurfacing: the current setup lacks enough robustness margin for Ottawa's specific demands, even if it's not inherently weak engineering. If it feels inadequate after years of repeated problems, that's a fair take—many locals and experts share similar frustration.
**Yes, your statement captures a key frustration echoed by experts and observers**: the cartridge bearing assemblies (CBAs) on Ottawa's O-Train Citadis Spirit vehicles appear to have been installed and certified without sufficient **load testing** (especially under full or simulated passenger loads), and now they're failing prematurely due to **overloading** in real-world operations.
ReplyDelete### Evidence on Lack of Load Testing in Trial Running
From official reports and comparisons:
- The original Confederation Line (Line 1) trial running in 2019 was a relatively short **12-day period** focused on system integration, scheduling, on-time performance, and operations under **light/empty or near-empty conditions**. Trains ran peak/non-peak schedules without passengers, and there's **no public evidence** of simulated full passenger loads (e.g., using sandbags, water tanks, ballast weights, or dummy loads to replicate maximum axle/vertical loading).
- In contrast, the **Stage 2 Trillium Line (Lines 2 & 4)** trial running (ongoing/2024–2026) explicitly includes **14 days of simulated passenger service at full capacity**, plus failure scenario testing, with higher reliability thresholds (98.5% on-time). City staff have emphasized this as a lesson from Confederation Line's "troubled past" to avoid rushing and repeating mistakes like inadequate stress testing.
- This gap likely meant the bearings weren't exposed to the **combined vertical + lateral forces** from full passenger weight (adding ~30–40% more load per vehicle at peaks) during commissioning. The design was certified based on lighter/controlled tests, but real revenue service with crowds, frequent stops/starts, and sharp curves revealed the overload.
### How This Ties to Current Failures (Spalling and Overloading)
- Experts like UOttawa's Patrick Dumond (mechanical engineering specialist in bearings) directly link the 2026 spalling (metal flaking/pitting inside bearings) to **overloading**: "It's the average load of the train in continuous use that is too high for this setup." He sees it as interconnected with prior failures (e.g., 2021 derailments from catastrophic bearing collapse), both stemming from excessive stress on the CBAs.
- The trains are heavier than comparable Citadis models (81 tons empty, up to 113 tons loaded), with more powerful motors for quicker acceleration—amplifying torque/heat/wear. Spalling is a classic overload symptom in rolling contact fatigue: high compressive stresses crack subsurface material, flakes break off, contaminate grease, and accelerate failure.
- No on-board monitoring (e.g., hot-box detectors) meant issues built up undetected until mileage-based inspections flagged them (e.g., >100,000 km threshold for mandatory CBA replacements).
### Why This Happened and Ongoing Implications
- The low-floor Iponam bogie design prioritizes accessibility but constrains bearing/axle space, leaving less robustness margin. Alstom has blamed track issues (soft rails on curves, poor lubrication/gauge), while the city/OC Transpo points to design/overload mismatches.
- Root cause remains disputed, but overloading under untested real loads is a recurring theme in analyses (TSB advisories, expert interviews). A full redesign (stronger axles/hubs) is seen as the only long-term fix, with work resuming after past halts.
As of late January 2026, replacements continue (24+ CBAs done), but service stays reduced (single cars, ~18–20 vehicles operable), with no timeline for normal double-car operations. Riders are bearing the brunt—crowding, no refunds yet (though councillors push for them)—while the system catches up on stresses it arguably should have been tested for upfront.
This saga highlights a classic procurement/testing shortfall: certify under ideal conditions, then pay the price in revenue service. If you're tracking this closely (as PeerMetrics might for metrics on public infrastructure reliability), it's a textbook case of unvalidated assumptions leading to cascading failures.
Alstom is currently working on a long-term redesign of the cartridge bearing assembly (CBA) for Ottawa's Citadis Spirit LRT, following ongoing failures likely caused by high lateral loads on curves. The new design aims to address the loss of preload in the bearing nut that caused previous, serious derailments. Interim measures include frequent, proactive replacements of bearing assemblies every 60,000–100,000 km, pinning of the nut, and improved lubrication.
ReplyDeleteKey Aspects of the Bearing Assembly Issues and Fixes:
The Problem: The bearing assembly (a Texelis-manufactured cartridge) experienced failures due to higher-than-expected stress on the axles, leading to loose nuts and potential wheel separation.
Redesign Status: After a pause in early 2024, Alstom resumed work on a new, more robust, and redesigned axle hub assembly.
Interim Solutions: As a stopgap, RTG/Alstom implemented a "nut pinning" solution to prevent the assembly from unscrewing. Trains are now undergoing mandatory inspections and premature replacements of the bearing assemblies at roughly 100,000 km to prevent in-service failures.
Timeline: The development of the permanent, redesigned solution, including testing and validation, is ongoing, with expectations that full implementation will take years.
Impact: The issue has caused numerous service shutdowns and necessitated a reduced fleet of operational trains on the O-Train system.
Don't the Luccini wheels allow for greater lateral movement? They have a rubber insert.!!
ReplyDelete