Ottawa's Confederation Line is down to 10 trains from "the required 13" because of a series of mechanical issues, the head of OC Transpo said this afternoon.

The train shortage led to slight delays and longer waits on crowded platforms for this afternoon's commute.

O-Train Line 1: The afternoon peak has ended. We are sorry for the higher than normal crowds and longer wait times earlier due to a shortage of trains. —@OCTranspoLive

The Confederation Line had 13 working trains available when it launched Sept. 14. But a CBC source said only 11 double trains went into service Friday and Monday mornings.

In a statement sent shortly before 3:30 p.m., OC Transpo's general manager John Manconi confirmed that 11 trains were in operation during the morning commute.

He wrote that two more were taken out of service this morning due to technical issues — a compressor fault and a wheel issue.

Manconi said Rideau Transit Maintenance advised the city that it would be running 10 trains "instead of the required 13" this afternoon and evening.

Trains would operate approximately every five minutes during the afternoon peak, leading to wait times a minute longer than usual, Manconi said.

This is the first time OC Transpo has blamed delays on a train shortage.

OC Transpo was originally going to have 15 trains running on the Confederation Line before reducing that to 13 during rush hours. (Andrew Lee/CBC)

One train was sent to the service garage for repairs on Thursday after its overhead power line "snagged" as it entered St-Laurent station.

On Monday morning, OC Transpo tweeted about a mechanical issue on a train during a morning peak that caused delays, crowding and the closure of a platform at Tunney's Pasture.

Monday's issues are the fifth and sixth announced by OC Transpo on the Confederation Line over the last five days, and eighth and ninth so far this month.

Initially, OC Transpo planned to run 15 double trains during morning and afternoon peaks, plus another two kept aside as spares. That number was eventually reduced to 13 trains on the track at rush hour.