The lack of good rail service between Mississauga and Toronto is embarassing. The GO buses between Square One and Union are packed and now have 30 minute frequencies most of the day so clearly more service is needed, this is got to be the busiest GO bus route from Union now. Plus there is massive commuter flow between Mississauga to Toronto in both directions now, the 401 and Gardiner/QEW are both heavily congested both ways in rush hour, and there has been a lot of new development in the Mississauga City Centre area. The section between Cooksville and Union could EASILY support subway-like frequencies and have packed trains.
GO needs to bite the bullet and make this line 4 track the entire length between Milton and Union, with Cooksville-Union being top priority, giving GO 2 dedicated passenger tracks. This certainly won't be cheap, since certain sections of the Milton line (particularly around Cooksville) will need lots of expropriation and/or tunneling to expand.
Given the fact to upgrade the Milton Line is over a Billion $$ and no funds for it at this time, hard for GO/Metrolinx to bit the bullet.
At the same time, there is major issues what to do with the industry between Dixie Rd and Dundas St in the west, as the ROW is not wide enough for 4 tracks, as well tracks to service some of those industry.
Then you got to build a flyunder over by Lampton Yard and using the 2 south tracks 100% for GO. CP use the #1 track at Kipling as a storage track for the Auto-racks cars these days and can't remember the the last time GO used that track.
Then what do you do with all the grade crossing, especially Mississauga Rd that is on a curve with no room to put any grade separation without destroying that area. There are 16 grade crossing at this time.
The bridge at Cawthra had its centre support extended a few years ago for 4 tracks when work was done on the existing 3 track bridge. 2 other 3 track bridges would need a 4th track and that no issues. One of those bridges is over 403. There are a few bridges crossing creeks that will have to be rebuilt.
9th line crossing is to be grade separated once the 2nd track is added for the Lisgar station. The new #1 track will go on the north side of the current platform and will require tunnels and elevators to it.
The Cooksville station area will have some issues with the NIMBY's, since the track will required to take some of their backyard. Then what do you do with the 2 bridges over Hurontario St that waiting for a pedestrian bridge that was supposed to be built this year, so the 103 can service the station safety.
Over all, Mississauga is better service than most areas feeding Toronto. All lines need more service, but you need $$$ to do it as well train crews to run the service.
Crews are in short supplied now with some more coming on line in 2012. Crews don't grow on trees like bus drivers until the government changes the 2 year rule. Again, not everyone can be a bus driver or an engineer, more so an engineer.
The one thing Metrolinx needs to do when they surface the EA for the line, have the electrification of the line in the study also, as it will have an impact on the land also. Also, land use at the major hubs with the view to get rid of these surface lots.
You will not find this EA taking the line west to Cambridge as far as I know. It may take the line west to the new west Milton station. It should include the 2 new station plan between Milton and Lisgar.