OTTAWA -- The Transportation Safety Board of Canada is recommending the City of Ottawa speed up the replacement of cracked wheels on Confederation Line LRT vehicles.

The TSB began its investigation in July after six wheels on three LRT vehicles developed cracks. The TSB found two additional cracked wheels on the fleet for a total of eight, it said.

In an interim report released Tuesday, the TSB confirmed that a protruding screw on the wheel hub likely caused the cracks.

"Although ongoing daily inspections by OLRT maintenance staff are being observed, the preliminary TSB examination results demonstrate that some wheel hub cracks may go undetected and the development of cracks in the area of jacking screws installed in the hub of resilient wheels may be more widespread than initially thought," the TSB said in a letter to the City of Ottawa. 

"Therefore, it is suggested that OLRT and Alstom expedite the removal of all Lucchini resilient wheels that were originally installed on the OLRT LRV fleet and were equipped with jacking screws."

The jacking screws are used during routine maintenance to assist in wheel removal but, if a screw is not properly aligned, it can put extra stress on the wheels, which leads to cracks. 

OC Transpo and Alstom have already begun replacing the original wheels. OC Transpo also suspected it was a bad screw placement which was putting stress on the wheels.

The TSB interim report also highlighted the scope of the problem.

"To date, Alstom and the TSB have examined all the new Alstom resilient wheel stock and identified that 116 of the 185 new wheels examined (62.7%) had 1 or more jacking screws protruding from the rear surface of the wheel hub," the TSB wrote.

OC Transpo had committed to changing the wheels of the Citadis Spirit vehicles by the first quarter of 2021.

The City’s Transit Commission is expected to get an update at its regular meeting Wednesday, Dec. 16.

Replacement of wheels underway: Manconi

In a memo to city council, Transportation Services General Manager John Manconi said the Rideau Transit Group (RTG) has been working to replace the the wheels.

"To date, 13 of 38 have had all impacted wheels replaced," Manconi said. "Vehicles that have had their wheels replaced now go through the regular maintenance inspection cycle. Daily inspections continue on the remaining vehicles in our fleet. All newly replaced wheels do not have jacking screws."

He also said RTG is securing additional resources to speed up the process.

"RTG and the City will continue to inspect vehicle train wheels until such time as all impacted wheels are replaced and misaligned jacking screws are removed. We also continue to work with and support the TSB in their on-going investigation," Manconi said.