The O-Train will be shut down for 18 weeks starting in the spring for renovations to the track and trains, says the chairwoman of the city's transit commission.

Diane Deans has confirmed work will begin Apr. 27, 2013 and it is expected to be complete Sept. 2, which aligns with the beginning and end of the Carleton University school year.

This work is part of an overall expansion of the O-Train system, which will see changes made to the tracks to allow for sections of the line to be twinned.

There will also be two passing tracks, signal upgrades, station modifications and Walkley Yard upgrades.

This process will increase the frequency of trips in time for next fall from every 15 minutes to every 8 minutes. The city has already purchased new trains to be ready for the changes.

There will be more buses on Ottawa roads next summer to help passengers travel on public transit while the trains are off the track.

The overhaul also includes maintenance on all bridges and tunnels holding O-Train tracks.