RTG, Alstom haven't agreed on LRT solution
'We are, I believe, within weeks of getting to a root cause, but we are not at root cause yet'
Rideau Transit Group (RTG) says it still doesn't fully understand the root cause of LRT bearing issues and is reviewing recommendations from train-builder Alstom that would require a shutdown of the system.
Alstom says it has a plan to reduce forces that are putting pressure on wheels and loosening bearings, an issue linked to a 2021 derailment and the summer shutdown this year. But RTG isn't yet completely on board with its plan.
"We are, I believe, within weeks of getting to a root cause, but we are not at root cause yet," said RTG head Nicolas Truchon.
He said RTG and Alstom agree that components are coming loose in the wheel assembly, but don't yet agree on why that's happening.
David Van der Wee, a vice-president of rolling stock and components for Alstom in North America, said the company submitted a 1,000 page report and believes that it does identify the cause.
"We are confident that we understand the root cause and what is the best path forward to resume service at a level that the citizens of Ottawa expect and deserve," he told reporters after his presentation.
"The root cause is that we have excessive lateral forces, and those forces come from a multitude of factors and we are starting to address those factors one by one."
The report made nine recommendations to do that. Some call for changes to track infrastructure, such as replacing soft rails with hard ones at curves and improving the rocky ballast under the tracks.
WATCH: The 'complex phenomena' observed during LRT derailments, according to train maker
Truchon said doing that requires further study and independent assessment. He said the issue is not cost, but warned the changes could be disruptive to the system and that needs to be weighed against the benefits.
"Those are longer lead time recommendations; certainly not something we could hope to implement before winter," he said. "Those are the kind of improvements that, if we go ahead, will need shutdowns and will need time. So these need to be properly planned."
In the meantime, RTG is continuing with temporary safety measures like speed reductions and frequent inspections. It also plans to install top-of-rail lubrication systems to reduce friction, something that was promised during the most recent shutdown but hasn't yet been completed.
"This is going to result in a real significant benefit in a really short period of time," said Van der Wee, who explained that it reduces the lateral loads by 40 per cent.
Problem nut blamed for issues
Van der Wee highlighted another short-term solution in the works, after showing a video of what Alstom believes is going on inside the wheel assemblies when those forces loosen the parts.
He said the company's research has identified a nut that could be a primary culprit in disrupting the wheel assembly.
"One of the key things that everyone agrees about is the nut coming unscrewed as being a key portion of that, and how that needs to be a focal point no matter what is the sequence of events that comes to bring the nut being unscrewed," he said.
Van der Wee said Alstom is working on installing a pin to hold the nut in place and, eventually, adding a counternut screwed in the other direction. There are already prototypes of the pin, he said, and it could be ready for Ottawa's trains in months.
Truchon called that a "mitigation" measure that will avoid the kind of service interruption the system suffered this summer and allow a reduction in the frequency of inspections.
It could also reduce how often axles need to be replaced. Right now, that's happening every 60,000 kilometres, so often that OC Transpo is worried about a supply crunch.
"It's not sustainable forever," said city engineering director Richard Holder. "There is a challenge with the supply chain to replace the axles."
That's why OC Transpo is running single-car trains when it can — in a bid to save on wear and tear.
Van der Wee said Alstom would be comfortable with axle replacement every 400,000 kilometres after the nut issue is fixed. He said it will provide "breathing room."
"This is an absolute step change in reducing the burden on the maintenance team and reducing the exposure to not having appropriate material to keep the level of service going," he said.
As a longer term solution, Van der Wee explained what Alstom is doing to redesign the axle to make it better able to withstand unusual forces.
There are three possible changes: create a tighter fit between the shaft and the bearing, make a thicker more robust bearing, and apply a heat treatment to make the material more durable.
But those new axles aren't expected to begin rolling out until 2026.
Changing curves would be 'hugely expensive'
Members of transit commission listened to those presentations in rapt attention. Commission chair Glen Gower asked if there was any possibility of another axle failure happening under the current short-term safety regime in place.
"With the safety measures that we've put in place the likelihood is virtually zero," said Van der Wee.
Coun. Tim Tierney asked how much it would cost to implement a truly radical solution: tearing up the tracks around Hurdman station and moving them in areas with the tightest curves.
Holder said moving a pumping station near the curve alone would cost about $100 million, while the cost of moving stations and a bridge would be "hugely expensive" and extremely time consuming.
"We're looking at years and years and years," he said.
Tierney wasn't satisfied.
"Hopefully we have a solution," he said. "At the end of the day, if the new bogey system doesn't work because we haven't made the curves to what the specs are, I feel that the citizens of Ottawa are going to be failed again for another decade."
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