The yellow line of the Montreal metro, which links Montreal to Longueuil, will close for 25 weekends starting Saturday.
The closing will allow for repairs on the tunnel's ceiling.
The work will take place from March 8 until May 25, resume in September and will continue until the end of the year.
The repairs will being halted through the summer months due to scheduled activities and events on Ile-Sainte-Helene.
"We are in the process of maintaining our assets," said newly-appointed STM chair Philippe Schnobb when the closing was announced.
"We have to do certain renovations and this is one of those that was planned a long time ago. It's just a coincidence with the problems with the Champlain bridge."
Schnobb said the work is essential but not urgent, and if the Champlain Bridge faces any emergency closures, the work can be postponed.
When the metro is not running the STM plans to run shuttle buses along three routes between Berri-UQAM and Longueuil, with stops along the way.
The approximate travel time on the three routes is between 12 and 20 minutes. Two of the three routes are wheelchair-accessible.
Almost 20,000 commuters use the metro's yellow line on weekends.
