Ottawa's big LRT fix is redesigning train parts. What about the track?

Derailments, mechanical failures, broken wires and tunnel leaks — all within the first four years of Ottawa's LRT.

OC Transpo and its partners say a redesign of the train's wheel hub assembly will fix one of the system's biggest issues, but experts wonder if a more complicated or costly solution could still be on the way.

The latest shutdown of the $2.1-billion system is set to last at least three weeks, as engineers work on more temporary solutions, including a new lubrication system and moving restraining rails.

"It's probably getting to the point of frustrating everybody involved," said rail transport expert and University of British Columbia Prof. Gordon Lovegrove, who describes it as a system that's embarrassing its riders, designers and funders.

"This is not good. And you can bet the engineer — it's their future reputation, their business development."

He said the experts on the LRT are doing all the right tests and checks, and wonders if or when they'll turn to a more extreme solution that's been floated for years: ripping up the track.

Last year's public inquiry drew attention to a melange of issues with the creation and maintenance of the system, ranging from political interference to poisoned business relationships and widespread secrecy.

But when it comes to resolving safety issues, one problem area was identified as the most significant: the wheel-rail interface.

The issue was clear even before service launched, but the inquiry found teams took an "inexcusable" length of time to address it — waiting until after a broken wheel caused a train to come off the track.

Train maker Alstom's preliminary investigation into that 2021 derailment suggested a root cause that proved uncomfortable for the system designer, the Rideau Transit Group: the track's design wasn't what they agreed on.

RTG disputes that assertion, but it prompted inquiry commissioner Justice William Hourigan to recommend teams explore the possibility of modifying how the track bends around sharp corners.

Soon after the latest bearing issue was identified Richard Holder, the city's director of engineering services, told CBC he doesn't see Ottawa ever "getting to that point."

Without access to more data, outside experts say it's difficult to know whether ripping up the track will be necessary or even feasible.

"I don't even know if you can get to that last resort," said Lovegrove. "Just think of the logistics. That's a scary proposition."

For one thing, he said, Ottawa's 12.5-kilometre track includes a tunnel, now enshrined in layers of concrete and rebar.

While the sharpest turns on the track appear on the east end of the system rather than the length of rail that goes under downtown, Lovegrove said crews may find areas with little allowance.

WATCH | What would ripping up the track look like?

It's an expensive and complicated proposition that could make this weeks-long shutdown look like the blink of an eye.

"You'd need to shut down the track. We're talking probably six to 12 months at least. And that's just an uninformed guess," he said. "It could be more. I don't think it's going to be less."

Peter Liu, a mechanical engineer and professor at Carleton University, said it's possible there's a problem with the track, but he suspects if that were the case the bearing problem would be even more widespread.

"If they only identify one severe problem in one variant, it's very, very unlikely that's due to the track problem," he said. "When there's a problem with the track, you see a recurring issues in the bearings … on the same side."

It's well established at this point that the biggest problem area is where the trains — longer and heavier than the usual light-rail design — face the worst pressure, at the tightest curves.

"As the trains are coming into the corner, if the loads are really high and the radius is really tight, the wheel might be kind of skipping along that rail," explained bearing expert Patrick Dumond. "It starts to make waves in the rail."

To address that corrugation, trains have been slowed down. The city is also introducing a new top-of-rail lubrication system that will grease the corners in between each pass, which Dumond said will "allow those wheels to slip along the rails a little bit easier with less friction."

Neither option is a permanent solution.

The temporary mitigations are meant to buy time until designers can create and install a new wheel hub assembly, a process RTG says could take two to three years to fully implement. So far, the city has been tight-lipped on the specifics but Holder told reporters last week that "the wheel will not be replaced."

Dumond finds it strange that the city isn't keeping that option open.

"If they're having a problem with the rails then it would be important to redesign the wheels," especially if that makes it possible to keep the tracks as is, he said.

The city's latest stop-gap measure made it impossible to relaunch July 31, as RTG and Alstom identified new concerns with restraining rails, what Holder describes as a passive safety device that guards against derailments "in the event a wheel would climb up the outer rail."

These rails have been doing something experts agree they should not: consistently rubbing against wheels.

Earlier last month, those rails were moved to a point the maintenance manual considered the maximum threshold, but Holder said tests showed the "contact was still occurring" in a way that Alstom no longer considered OK.

"There has been a change in state of the system," he said, "that is mainly due to the fact that we've been running the system for three years and all systems go through a process of wear on both the wheels and the rails."

Engineers are now assessing the risk of moving the rail beyond what was originally considered tolerable.

Lovegrove calls the latest step part of a "multi-tier approach" likely aimed at ensuring the city is never faced with a costlier re-laying of the track or more complex wheel redesign.

"Changing the bevel, the profile of the wheels, the wheel-rail interface, this is extremely complicated," he said. "This is the stuff of multiple PhDs on different topics: mechanical, civil. It is not easy."

But that doesn't mean it's exceptional.

Central to the problems now facing Ottawa's light-rail system is a simple predicament that's not particularly uncommon, said Lovegrove.

A train designed by one group doesn't perfectly fit onto a track designed by another.

"We are human and mistakes happen. They shouldn't," he said. "But that's why it's called applied science, because engineering at its foundation is the science of learning, often from mistakes."

In that, Lovegrove suggests there's a silver lining: the long process to identify and fix issues will create a rubric for future systems.

"This, going forward, is going to be something that will benefit North America," he said. "So, thank you Ottawa, for the pain."

Journalist

Elyse Skura is a reporter based in Ottawa. Since joining CBC News, she's worked in Iqaluit, Edmonton and Thunder Bay. Elyse spent four years reporting from Tokyo, where she also worked as a consulting producer for NHK World Japan. You can reach her at [email protected].