It not that simple putting in grade separation?
Take a look at the crossing in Weston, as well the cross-town line, Old Weston Rd and you will see major tear down.
Weston is already up in arm over the Blue22 road closing of John St. The best way to do Weston is putting in a trench for the RR. Doing this will allow major streets to return to grade and have a better use of land there compare today. Not cheap to do.
In some places, roads would have to be cut in half and the RR becomes a wall separating the community on both sides of the RR.
Most grade separation bridges will cost between $10-$30 million depending on the width of the street as well numbers of tracks. If you need land, that cost has to be added. You need 25 feet clearance if going over and 15 under the tracks. Going under requires less area, but still can cause connecting roads to the underpass road to be relocated or close.
Even if all the roads are grade seperart, you will have ppl crossing the tracks at some short cut point as well walking along it that will get them kill or injury.
Taking a rough count, I would say you would be looking at close to $2 billion in the GTA to do grade separation, if not more.
Doing this will have major impact not only on GO, but all RR operations.
At it stands now, most grade separation will require 4 tracks if other RR use the same corridor with GO, otherwise, it will be 2 tracks.
It cost $20 million to put in an underpass on Mavis Rd a couple years ago that was the site of the great train derailment. The road was 6 lines with sidewalk and 3 tracks on it 100%. If they are now going to put a 4th track on the Milton line, this bridge will have to be expanded for that extra track.
As for Strachan Avenue, it had 8 tracks at one time and to meet future needs, there has to be 6 tracks in this area. The cost will be a lot higher.