All Confederation Line trains that have travelled more than 175,000 kilometres have been taken off the tracks after an inspection found a "failure" in one vehicle's wheel hub assembly.

In a Saturday evening memo to Ottawa city council, transit services general manager Renée Amilcar said the vehicles were removed from service "for additional inspections out of an abundance of caution."

The problem was found after an operator reported vibrations on their train, Amilcar said. 

In her memo, Amilcar said train manufacturer Alstom had already indicated the failure affected the train's axle and bearing — but in a different way than the issue that caused an out-of-service train to derail near Tunney's Pasture station in August 2021.

In that incident, the wheel broke off the axle due to a problem with the bearing, the device installed at each end of the axle that helps the wheel spin without resistance.

Amilcar said both Alstom and Rideau Transit Maintenance (RTM) were conducting "in-depth testing" to figure out what caused the wheel hub assembly to fail.

They have both confirmed "verbally and by letter that all trains in operation" on the Confederation Line are safe, she said.

There are currently 10 trains running on the Confederation Line, Amilcar said, making stops roughly every five to six minutes.

The trains will be returned to the line once they've been inspected and deemed safe, according to her memo.

"It's frustrating that these ongoing issues with these trains continue. It really erodes trust in our public transit system," said Somerset Coun. Catherine McKenney, a member of Ottawa's transit commission who led calls for the recent public inquiry into the Confederation Line.

"I am very worried that the same mistakes could happen on Stage 2. So it is very frustrating for residents, for taxpayers, of course. We really need to see these issues dealt with."

The Transportation Safety Board of Canada has also been notified, Amilcar added. OC Transpo and RTM are expected to provide another update on Tuesday.

In an apparently unconnected incident, city officials told CBC on Sunday that one of the Trillium Line's recently unveiled Stadler trains struck a derailer Friday while at the Walkley maintenance and storage facility.

The train was "travelling at very low speed" when it hit the derailer, said Michael Morgan, director of the city's rail construction program, in an email.

"A derailer is a safety device that sits on the rail and is designed to push a wheel off the rail in order to prevent the train from moving outside of a specified safe zone," Morgan said. "A thorough investigation is underway."

The city recently held an event showing off one of the seven new diesel-powered Stadler trains, purchased for a total of $106 million in 2019 for the north-south line's expansion.

With files from Trevor Pritchard, Joseph Tunney and Radio-Canada

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