O-Train closed all day on Saturday

Ottawa LRT trains run on the Confederation Line Tuesday, Jan. 18, 2022. (Peter Szperling/CTV News Ottawa)

The O-Train will be out of service on Saturday to allow Rideau Transit Group to continue the investigation into the cause of the axle hub issue on the trains last summer.

The full Confederation Line will be closed starting at 6 a.m. on Saturday, with R1 replacement bus service running at the same frequency between the stations.

"This work is scheduled on a Saturday, when ridership is lower, to minimize customer impacts," OC Transpo General Manager Renee Amilcar said in a memo to council.

Service will resume on Sunday morning along the full line from Blair station to Tunney's Pasture.

In July, all O-Train vehicles that had travelled more than 175,000 kilometres were pulled out of service for additional inspections after a failure was discovered in one of the wheel hub assemblies on a train. Rideau Transit Maintenance and Alstom proactively replaced axle hubs on all train cars with more than 175,000 service kilometres.

Temporary speed reductions and an enhanced inspection regime for the wheel hubs remain in place as RTG continues to work to identify the root cause of the axle hub issue.

"This testing is required as part of the ongoing root cause investigation of the light rail vehicle axle hub issue," Amilcar said.

Twenty vehicles were pulled from service to undergo inspections and to have the axle hubs replaced.  No other issues were discovered during the replacement of the axle wheel hubs.

In August, Amilcar said the axle hub assembly "could be or may be", related to the issue that caused an O-Train vehicle to derail in Aug. 2021.

“RTG and Alstom categorized this as a unique event," Amilcar said on Aug. 19.

In documents filed to the public inquiry looking into Ottawa's light rail transit system, Alstom said the 2021 derailment was caused when an axle hub and its bearings failed.

Alstom said the "unanticipated loads experienced in Ottawa that have led to the axle hub failure are outside the specified operating parameters" for the project.

"Alstom’s preliminary root cause analysis indicates that the cause of the fretting is a combination of forces arising from the track, the wheel rail interface, and the System’s operating profile," Alstom said.

"Due to the complicated nature of the wheel and rail system, 'The only conclusion that [Alstom] could really draw absolute was that [the trains] were taking excessive loads in the curves.'

"Rather than the wheel taking the brunt of these loads, these forces are being transmitted deeper into the Vehicle and presenting at the wheel bearing, causing excessive heat."