Montreal transit users wait to board a shuttle bus outside a Metro station on Thursday morning. (CBC) Thousands of Montreal commuters shivered outside commuter train stations and packed sweltering underground subway platforms after problems with two of the city's major public transit services Thursday morning.

Half of the Green line of the Montreal metro shut down twice during the rush hour after two undisclosed incidents. At the same time, the morning's cold temperatures were interfering with the commuter train service from the city's western suburbs.

Several doors stopped working on a train on the Dorion-Rigaud line just before 7 a.m.

'I know it's not a good, satisfying answer.'— Marie Gendron, Metropolitan Transit Agency spokesperson

Marie Gendron, a spokesperson for the Metropolitan Transit Agency that runs the commuter trains, said that caused a domino effect.

"That caused a delay of 40 minutes on that first departure. People were transferred to the next train," she said.

Gendron said she understands commuters are frustrated by frequent problems with the commuter trains this winter.

"I know it's not a good, satisfying answer. Dorion-Riguad is actually performing as it has historically, which is not great in the winter time," she said.

The problems with the metro system were resolved by mid-morning.

Montreal Transit Corporation spokesperson Isabelle Tremblay said the agency responded quickly to Thursday's shutdowns by putting shuttle buses on the road.

However, she admits getting the buses to the affected metro stations took time.

"We have to call the buses. The buses have to come. They carry less people than a train. So therefore obviously there are line-ups. So we're doing in those circumstances obviously the best we can," said Tremblay.

Both agencies said service should be operating as normal as commuters make their way home Thursday afternoon.