Rainforest
Senior Member
The ideal solution WAS grade-separating Eglinton in Scarborough and interlining the Scarborough LRT with Eglinton.
There has been much discussion on why it is very difficult to elevate the B-D line (mostly it takes 750m ot 1000m to switch a subway from underground to elevated, and all cross streets, entrances, etc. are blocked for this length).
The compromise to all of the above is a mostly elevated ICTS/SkyTrain line going from STC with no transfers all the way downtown. (yes - I found an opportunity to raise this again)
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This plan has it merits, but it would cost a lot.
The underground downtown section of the blue line alone (from Don Valley to the west end) is likely to cost more than the whole SSE, because of the need to deal with utilities and the PATH.
The rest of the blue line would presumably run either on surface (in the natural corridors or Hydro corridors) or elevated; that's cheaper per km than in a tunnel, but the whole 25 km would cost quite a bit, too.