TTC boss Andy Byford will speak with Bombardier officials Friday about technical problems that are causing passenger delays aboard the new Toronto Rocket subway vehicles.

A total of 27 of the new trains are currently in service on the Yonge-University-Spadina line, with the full fleet of 70 trains to be operating by end of 2014.

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Problems with the TTC's new Toronto Rocket trains are causing delays on the Yonge-University-Spadina line, according to a commission report. (TTC)

The new trains, which are built by Bombardier, have increased capacity and other service enhancements but problems with the doors are causing delays, according to a TTC report that calls the performance of the new vehicles "unacceptable."

Door circuit problems

TTC spokesperson Brad Ross said the problem is related to a safety feature on the train doors that prevents the train from moving until the doors are closed.

"If the doors get held or they’re jammed in some way, then they won’t close and we need to cycle them again," Ross told CBC News. 

"That means we need to reopen them and reclose them. If after the third time of having to do that, then the system needs to be rebooted and that causes us to take the trains out of service."

The report says the new trains are on time 92 per cent of the time; The on-time target is 96 per cent.

Ross said Byford will meet with Bombardier officials on Friday for an update on resolving the door problem.

"Bombardier is well aware of the issue and we’re working with them to come up with a solution," said Ross. "With new technology, there are always going to be teething problems."