AlvinofDiaspar
Moderator
I believe the original justification for Exhibition station is one of those forced transfers like the one at Kennedy from the subway to the SRT. It's to allow GO to terminate some trains at Exhibition instead of Union and make the passengers take the Ontario line the rest of the way. Metrolinx is hedging its bets on Union Rail Corridor track capacity.
There's also a (badly concealed) desire to flip Exhibition land into a new mega-development, which I will admit is needed given our housing shortage and the inability to build anything in "stable neighbourhoods". Ontario line will allow commuters to escape the new Exhibition neighbourhood and hopefully get somewhere.
Broadly correct - I think the original scheme envisioned this happening at a new Spadina station. The extension to Exhibition while providing additional stations at Queen/Spadina and King/Bathurst is beneficial.
AoD