A mechanical problem that forced OC Transpo to pull several light rail trains out of service last month could be related to a similar issue that caused a derailment at Tunney's Pasture station last August, when an axle broke and a wheel snapped off.
On July 23, OC Transpo reported the "failure" of an axle wheel hub assembly on one of its trains after the operator noticed unusual vibration.
As a result, Rideau Transit Group (RTG) and its maintenance arm Rideau Transit Maintenance (RTM) are replacing the axle wheel hubs in the front and rear wheel assemblies on all LRT vehicles with more than 175,000 kilometres of service.
According to a memo issued late Thursday be Renée Amilcar, the city's general manager of transit services, the "precautionary" job of replacing the wheel hubs continues, and the components that were removed will undergo further testing.
"To date, no further issues have been discovered during the replacement of the axle wheel hubs. There are sufficient trains available to meet daily service requirements," Amilcar wrote.
Precautionary measures in place
According to Amilcar, RTG and train maker Alstom characterized the July incident as a "unique event," however "the ongoing investigation has revealed that the issue of the recent incident could be the same or related to the axle issue that led to the August 8, 2021 derailment."
Root cause analyses of both incidents continue, Amilcar wrote.
In the meantime, a number of precautionary measures have been put in place. They include "an enhanced inspection regime, and temporary speed restrictions along sections of the track," Amilcar noted.
"In addition, we continue to review with RTM, Alstom and Transportation Resource Associates (TRA) options to provide longer term solutions to the axle issue, which may include recommendations arising from the final root cause analysis report, track design and vehicle interface analysis."
The Transportation Safety Board of Canada (TSB) is investigating the most recent incident.
"We are fully co-operating with the TSB's investigation. TRA is also on-site to support OC Transpo and monitor the work of RTM and Alstom," Amilcar wrote.
She noted that even with the ongoing axle wheel hub assembly replacement, there are "sufficient trains available to meet daily service requirements."