That's why the Ford Memorandum of Understanding allowed for elevated portions in:
The Don Valley and Kennedy vicinity accounts for well over half the length of the Scarborough portion.
Combine this with the other ideas that were floated;
The compromise is SkyTrain: Toronto should be pursuing this technology and not LRT on Eglinton
Elevated trains: Metrolinx offers subway alternative
And the fact that Ford wanted as much savings as possible on
Eglinton, to use on Sheppard.
Basically, after the March 2011 announcement of the combined line, everyone Toronto was expecting TTC and Metrolinx to work together. I was expecting in late 2011 or 2012, they would announce some type of mostly elevated line through Scarborough. Unfortunately, Ford left it to TTC and Metrolinx. The former was influenced by Council, and a leader who had mayoralty ambitions. The latter was run by the Provincial Liberals. Between them, they decided the best course of action was to sabotage the Ford plan - in order to hurt Ford. Shortly thereafter, they realized that reverting back to the transfer LRT plan would be political suicide, so they opted for the more expensive subway. The plan didn't quite work out for Karen Stintz, but the Liberals did get another majority from it. At the end of the day, Toronto signed on to the idea that defeating Ford at any cost was worthwhile. And it was obvious that the Ford plan was actually the most cost effective.