The UP Express is running on its regular schedule again, roughly a week and a half after its entire fleet was pulled due to cracks found in train's brake discs.

The train service announced that, as of Tuesday, it is reintroducing its 15-minute service, seven days a week, between downtown Toronto and Pearson International Airport. The UP Express had been running on a 30-minute service between the two spots since Feb. 12.

On Feb. 10, most of UP Express’ fleet had been removed from operation after thermal cracks were found in vehicle brake discs, according to the maintenance and operators union, with only four train cars left in service.

By Feb. 11 at 10:30 a.m., the remaining four trains also had to be pulled from service.

“Over the course of regular inspections this past weekend, our team discovered hairline cracks in the brake discs on some of our UP Express trains,” Metrolinx said in an emailed statement to CTV News Toronto.

“In the interest of safety, we immediately removed the affected trains from service and proactively inspected the rest of our fleet.”

The UP Express said it has since “made some necessary repairs” to its fleet.

With files from CTV News Toronto’s Andrew Brennan and Abby O’Brien