LRT root-cause review raises more questions than it answers

Councillors are hoping for more clarity on the root cause of the LRT's bearing woes after getting a summary of years' worth of past reports, some of which have never been released to the public.

It was billed as a root-cause reviewand is set to come before council's transit commission on Thursday.

But an engineer who examinedit for CBC says it sheds little light on what's actually behind the loose bearings that caused a 2021 derailment and prompted a lengthy shutdown this summer.

"I find it odd that they never identify or mention the root cause of all these problems directly, especially in a report that has 'Root Cause Review' in the title," said University of Ottawa professor Patrick Dumond, who specializes in the monitoring and diagnosis ofbearing faults.

The review summarizes reports from the National Research Council, the Transportation Safety Board and MvX, a rail advisory company,briefly mentioning what they studied and recommended. It also references instrumented bogie testing from 2022, without providing any details of what that testing found.

Dumond also called that "odd."

Bogies are the structures on the bottom of trains that hold wheels and axles. The review mentions another2023 bogie testing report being prepared by train-maker Alstom, as well as a separate, undatedreportfrom the same company.

According to the review, that report "contains recommendations, validated by testing and investigations, for a sustainable solution to the Ottawa LRT System."It's unclear ifit'sthesame as a 2022 preliminary root-cause analysis by Alstomthat theLRT public inquiry cited in its own report.

The undated Alstom report is summarized in just a few paragraphs of the city's review. One mentions recommendationsaround "changes to track infrastructure," "changes to wheel/rail profile"and "axle hub assembly," without any further detail about what changes are envisioned.

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During a meeting of Ottawa's transit commission Thursday, train maker Alstom showed this graphic video explainer to demonstrate the sequence of events it says is plaguing the city's light rail system.

Alstom is currently working on redesigning the axle and wheelhub assemblies on its trains. The new design is expected to be in place by the end of next year, according to the review.

The city would not release the original Alstom report to CBC when asked.

"The City is working with Rideau Transit Group (RTG) and its partners to determine next steps regarding requests for documentation," said Richard Holder, the city's director of engineering services.

Dumond said citizens are owed clarity about what's wrong with the LRT.

"I'm split between they know exactly what's going on andnobody wants to take responsibility for it, versus they really don't know at all what's the root cause, which is why they're still trying to guess at all these things," he said.

"I think both are worrying."

'It doesn't say anything explicit'

Dumond said the review leaves him to guess at what the root cause might be from passing mentions.

"If I was to read between the lines of the report, it sounds like, in effect, the bearings and the trucks on the trains and other components on the wheel assemblies are being overloaded by the current system we have in place," he said.

That interpretation comes in part from a summary of the Alstom recommendations, which are meant "to address the root cause by reducing the lateral forces imposed on the wheelset during operation" and design a wheel assembly that can withstand those forces.

Lateral forcesrefers topressureson the wheels from the sides. But there's nothing in the review that explicitly states what's generating those pressures.

Alstom's 2022 analysis blamed "the actual design of the track," according to the public inquiry report, though RTG has disputed that finding.

OC Transpo has previously mentioned contact with restraining rails as a potential force. Crews have since shifted those rails by miniscule amounts. But the review document briefly mentions all sorts of other possibilities that crop up in previous reports, without pinpointing one as the primary culprit.

"The reasons why they're overloaded might be because of the continuous pounding of the lateral restraining systems, because of the wheel profiles not matching the rails, because of the tighter corners than what is normal, because of the higher speeds, because of the larger, heavier trains than what the system was designed for," Dumond said.

"It doesn't say anything explicit in the report."

Councillor wants to see original report

Coun. Wilson Lo, who sits on transit commission, said there might never be one single answer.

"My view of this is we'll never narrow it to one," he said. "I think it really is a combination of everything."

Still, he's looking for transit services staff to provide a more fulsome explanation at Thursday's meeting.

"I'm hopeful," said Lo. "But if not, I think it is more than fair for our transit commission to ask for a copy of that Alstom report."

He said the track infrastructure changesrecommended by Alstom could belimited to restraining rail work, or they may relate to something more significant,likeissues with the geometry of the curves. He doubts the rails will need to be completely ripped up, however.

Lo also wants to learn more about Alstom's trains, especially given longstanding concerns the cityasked the company to push the limits by designing a light-rail train that could do heavy-rail work.

"I really hope that report sheds light on whether or not we even bought the correct trains or if maybe we're just using it incorrectly," he said.

Transit commission chair Glen Gower said the review does provide some answers.

"The key is there's a fundamental flaw in the design of those axle bearings and there's a lot of factors that have played into putting stress on those axles," he said.

"I don't think it's cut and dry to say it's just the axles, but clearly that's a major part of what we're dealing with."

But Gower saidthe reviewalso brings up questions the commission will have to dive into on Thursday. He too wants to hear more from staff. He said commissioners often have the opportunity to review original documents, though there may be commercially protected information that prevents public release of the report.

He suspects that OC Transpo staff are simply being prudent in holding back from a definitive diagnosis for what ails the LRT.

"Until every single test is done, until the mitigation measures are implemented, until even the final reports and additional studies and investigations are done, I think everyone's being cautious about saying we know 100 per cent about every factor in this case," he said.

"There's still work that needs to continue and probably will continue for the lifespan of light rail."