OTTAWA -- Ottawa’s nine-month-old Confederation Line will be out of service for the next four days for maintenance work.

The O-Train Line will be closed from Sunday to Wednesday to allow Rideau Transit Group to test updated software and do infrastructure work.

This is the third time the Confederation Line has been shutdown since May 2 to allow RTG to address issues that have impacted service since the launch last September.

OC Transpo will operate “R1 bus service” between the stations along the Confederation Line. The city says R1 bus service will operate frequently so there will be enough space for physical distancing.

In a memo to Council, Transportation Services General Manager John Manconi says this will be “one of several closures this summer that will allow RTG to complete the work associated with the rectification plan.”

“During this closure, RTG will continue the testing of updated train control software. Customers and residents will continue to see trains running for testing purposes, but they will not be available for use by customers,” Manconi wrote.

“In addition, infrastructure work will continue on the track and the overhead catenary power supply system.”

The Confederation Line was previously shut down May 2 and 3 so RTG could conduct upgrades to the train control software, and May 9 to 13 for maintenance work.