sure but the word visiting suggests something.....if I drive through a town on the 401 have I actually visited it? Anyway, good luck riding all the GO lines end to end in one day...even without stopping at each station it will be tough!
Visit all GO stations in one day?
That's a toughie.
Let me have a crack at a theoretical journey:
The Grand GO Transit Journey
Kitchener Train 5:24am
This is your starting point, so you should book a hotel or friend there and be well-rested.
Kitchener First Morning Peak: 05:24 - 07:27 .... Catch that first.
59 Minute Self-Repositioning: Quickly go from Union station to Milton GO station:
Get an expert trusted taxi driver pre-waiting for you at Union, ready to take you immediately to Milton GO expeditiously (offpeak is doable, but peak traffic will make this a big challenge to fight your way to Milton from Union station. Use historical traffic statistics to time the best days of the week / best days of the years to do this attempt. Alternatively, a helicoptor ride would be prudent if one can be arranged -- e.g. publicity stunt!)
Milton Train 8:26am
Catch the last morning Milton train towards Union
Milton Last Morning Peak: 08:26 - 09:30
Lakeshore East train
Lakeshore West train
This is what you will do to kill time between morning/evening peaks.
Catch the first "through train" (~9:45am) and bounce to Aldershot (10min layover), then Oshawa (10min layover), and then back to Union. Nearly 5 hours single seat ride! Catch some Z's because you got up early, and you will be staying up very late.
Stoufville train 3:11pm
Catch the first peak Stoufville train going north to Lincolnville. Arrives there at 4:24pm.
2 hour 11 min Self-Repositioning: Quickly go from Lincolnville GO to Union Station
Go back to Union station immediately: Have a driver pre-waiting for you at Lincolnville (or a pre-positioned car of your own), ready to take you immediately back to Union to be on time for your next train ride.
Barrie train 6:35pm
Catch the last train going from Union to Allandale Waterfront station. You'll arrive at 8:21pm.
Then immediately return to Union Station via GO bus #68 from Allandale. A painfully long ride with a transfer taking 2.5 hours to return to Union.
Richmond Hill
Tough luck for the trains, but you can catch the GO Bus #61 to tour all stations thru Gormley. That bus runs rather late (last bus 2:40am) so you didn't have to rush back to Union from Allandale Waterfront. Plan to crash for the night at a motel near Gormley GO, there's no return service.
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So a pretty tough
Grand GO Transit Journey "Around The World In 80 Stations", but barely doable, though that means skipping Hamilton GO stations and the Niagara GO train service. Any GO delays will screw this attempt up, requiring you to re-attempt this another day.