Drivers who use the off-ramp from the eastbound Gardiner Expressway to York, Bay, and Yonge streets to get to work have to find another route.
The ramp is now closed to traffic for nine months so it can be demolished and reconstructed.
The current ramp, which is about 50 years old, begins at Reese Street and travels eastbound to York Street where it ends in a roundabout that connects with Harbour Street.
The new ramp will be shorter and will end at Lower Simcoe Street.
Harbour Street will be widened from three to four lanes from Lower Simcoe Street to Bay Street in order to accommodate the added traffic flow.
Drivers will also be able to access the eastbound lanes of Lake Shore Boulevard from Spadina Avenue, which they are not currently able to do.
Construction will take place between 7 a.m. to 7 p.m. Monday to Saturday.
The new off-ramp is expected to open to traffic in January.