Just five days after the city took control of the $2.1-billion LRT system — and a little more than a week before it's supposed to be open to the public — more than half of the Confederation Line was shut down for hours on Wednesday.

The light rail system wasn't running between Tunney's Pasture and Hurdman stations from 4:30 a.m. until 2 p.m.

Three trains were stopped in the downtown tunnel for some time. Two of the trains eventually went to Tunney's Pasture, and the third was taken to the east end, according to an email attributed to Troy Charter, the city's director of transit operations.

The LRT is set to be open to the public at 2 p.m. on Saturday, Sept. 14.

According to Charter's email, "three radio units that are part of the control system needed to be reset."

Although there are human operators on the trains, the Confederation Line is run by an automatic computer system. The control system lost connection with three radios that communicate the locations of the trains.

When the control system loses connection with the radios, it automatically shuts down the system as a safety measure.

According to Charter's email, "the cause of the radio shutdown is under investigation with one possible cause being last night's thunderstorm."

The shutdown raises a number of questions, especially because the system was supposed to be substantially completed in July, which meant that all testing was completed.

The city agreed last month that the trial run had been a success, and took over the system from Rideau Transit Group on Aug. 30.