Wellington Street, from Church Street to York Street will have lane reductions beginning April 10 until September 2017.
Richmond Street or King Street will be alternative routes for westbound cyclists and drivers.
The City of Toronto is taking steps to minimize disruption to the public during the closure by extending work hours, with some overnight and weekend work as necessary to reduce the duration of the project.
To help manage traffic in the area, enhanced signage will inform drivers of the road closures and signal-timing changes will be made on parallel routes.
The City has a web-based map to help residents and visitors make their travel plans, available at http://www.toronto.ca/roadrestrictions.
Details about transit diversion routes are available from the TTC at http://www.ttc.ca.