In the early 1980s, the TTC ran ads in all subway trains encouraging passengers to transfer at St. George if their destination on Yonge was Dundas, Queen, or King.
When the integrated 3-route system ran in the 60s, 65% of BD passengers from the east-end used the Bloor-University wye (via Bay Lower) to get downtown for a direct transfer-free ride. And, a staggering 85% of BD passengers from the west-end used the wye to get downtown on an all-day basis. As a result, transfer movements at Bloor-Yonge were very light.
The problem at Bloor-Yonge today stems from the TTC's refusal to operate the wye as the system designer originally intended. By connecting the Spadina subway to St. George, they effectively killed any hope of reactivating the old system in the 1980s when the signalling on the line had been automated and improved to the point where the wye could have been operated smoothly.
When the wye was closed in '66, passenger movements shifted dramatically. Those that used the wye (despite the longer trip) changed their behaviour and started changing trains at Bloor-Yonge instead of using St. George. There was no longer any incentive to take the longer ride via University. By 1969, transfers at Bloor-Yonge had DOUBLED from 1966 levels. The TTC refused to re-test the system with additional dispatching equipment along the line (to regulate train arrivals at the junction points).