Sorry if I come off a little hostile, I've been havign personal problmes lately, it has nothing to do with you.
In the past, I have been totally against the idea of a nother route for Milton line, but I have warmed up to it, but not the way you suggest.
I have thought about this before, and I think a diversion through Mississauga Valleys is much better than under Hurontario for several reasons:
1. Much cheaper. Built along an exisitng right-of-way. Cut-and-cover, elevated, at-grade, below-grade... lots of options, all cheaper than tunneling under Hurontario.
2. Can have a stop at the City Centre Transit Terminal. A diversion along Hurontario would be too far north to connect to the terminal.
3. Doesn't truncate one of the busiest and densest transit corridors in the GTA into three separate parts. Or create overlap between completely different modes of transit. Even as dense as Hurontario is, that kind of overlap is sort of a waste.
4. Less interference with Cooksville and Erindale stations. These rare stations that are perfectly located. Cooksville surrounded by high density, and Erindale at two (!!!) major intersections. Erindale is served by 4 different major bus routes even though none of them actually enter the station itself! It doesn't get any better than that. Most stations, even on the Lakeshore Line, are in very inaccessible locations, but not these.
You can see my proposed diversion of the Milton line here on
this map, which many of you have seen already.
The "diversion" should act like a branch of the existing line. I don't like the idea of abandoning that section of Milton line, not only because of the aforementioned stations, but also because some sections here are already triple-tracked. So it seems like it would be a waste.
As for the Hurontario LRT, I think it should built with underground sections no matter what, and be upgraded to full subway at a later date.