For those who are advocating solutions which involve extended full closure of Yonge-Bloor, consider how even now the TTC is pussyfooting around closing Eglinton-St Clair to do a proper job of undercutting the Yonge Line. Y-B is the sciatic nerve of the system and will be closed only to minimal extents.
@aquateam was looking for attention upthread with wasn't relief Line supposed to avoid this. Well, to a certain extent it was, but then the City (under Mayors "Downtown Has Enough Subways" Ford and "SmartTrack will relieve" Tory) didn't build it. Now a decade has passed and Crosstown is nearly open.
Someone else observed something along the lines that B-Y is almost unsafe. It is unsafe now; the fact that no-one has yet been harmed does not indicate otherwise, merely that all the holes in the Swiss cheese have yet to line up. We are already seeing instances of TTC bypassing Yonge on L2 due to unsafe crowding.
As a user of B-Y an average of 10/weekly, this project can't start fast enough, but given the timeframes TTC needs to urgently explore how to enhance surface alternatives like Bay, Sherbourne and 504/505/510 if for no other reason that they will be needed to absorb construction impacts to the extent TTC is unable to avoid them.