It might take you longer to get around downtown this weekend.
A section of the subway system will be shut down starting Saturday, so shuttle buses will pick up the slack.
Subway trains will turn back at Bloor and St. Andrew stations until 6:00am Monday.
Almost 50 shuttle buses will operate on Yonge Street, between Rosedale and King stations, and over to St. Andrew Station.
Union subway station will be closed, so if your destination is the Air Canada Centre, you'll will need to walk from King or St. Andrew stations, or take the No. 6 Bay Street bus.
The extra buses on the roads will likely back up traffic along Yonge Street, from south of St. Clair Avenue and all the way into the downtown core.
Work crews are replacing signal switches, as part of an ongoing project to upgrade to a new system the TTC hopes will make service faster and more reliable.
Transit officials know there is never a 'good' time to interrupt service but they promise the work is being done for long-term gain.
TTC spokesperson Brad Ross points out crews can complete as much work in a full day closure as they can over the course of 5 weeks of overnight closures.
Ross says when stations are shut down overnight, workers have only 90 minutes to do as much as they can before trains get back on the rails for the morning commute.
It'll be another four years before the new signal system is finished, so subway shut-downs will be a fact of life until then.
This video shot by the TTC explains how the high-tech signals should make for faster service.