OTTAWA -- The Confederation Line LRT is operating with just 8 trains running in the Friday afternoon rush hour.

The reduction in service comes as the city is gripped in one of the coldest days of winter.

Yet again, it appears the train system breaks down in extremely cold temperatures.

Customers on the Confederation Line LRT have been noting trains have been making clunking noise on the tracks and moving slower from station to station.

OC Transpo is launching extra buses to supplement afternoon peak service on the Confederation Line, after reported "debris" on the tracks caused issues Friday morning.

In a memo, Transportation General Manager John Manconi said the presence of debris caused damage to four transponders that communicate the location of the train to the control centre, forcing trains to move very slowly between Tunney's Pasture and Bayview Stations.

"As trains pass over the transponders, the location of the trains is communicated to the control centre. When a loss of communication occurs, trains stop and must be given authorization from the control centre to proceed," Manconi said. "The safety systems functioned as designed and as trains experienced this loss of communication (train position location not communicated to the control centre), the trains came to a stop."

Manconi also said four of the trains that experienced the loss of communication developed flat spots on their wheels and had to be removed from service. At the time, Manconi mentioned there would be 10 trains in service.

During midday service, riders had to transfer trains between Lyon and Tunney's Pasture Stations, which caused some delays. End-to-end service with no transfers was restored by 2 p.m.

In an update just after 2 p.m., Manconi said the damaged transponders, which were on the westbound track, had been repaired. He said there would still be only 10 trains available for the afternoon peak, but 20 R1 buses would also be deployed, along with 10 additional buses that will be pulled from high-frequency routes.

Exactly what was on the tracks was not immediately explained. CTV News has asked OC Transpo to elaborate. Manconi's update only said "the debris issue and the cause of the damage to the transponders is being investigated."