Northern Light
Superstar
Even if Metrolinx owned the whole corridor, without significant track bed upgrades (and the resulting heighted speeds they would permit), I don't think hourly service to Niagara is in any way worth it. It's a 2 hour trip one way so you're still eliminating St. Catherine's commuters and I'd say the number of tourists going to the falls mid-week is minimal.
Hourly is a big leap, particularly outside tourist season..........however.....
I think you're a bit low on your demand estimates.
Off-season, weekday, in addition to 3 daily train trips, GO is running 30M bus service for large chunks of the day, from Niagara to Toronto.
That demand is in place with a current travel time of ~ 2hrs 30. * (the buses serve Burlington)
A time that will be reduced by ~20M with the West Harbour changes coming online this year.
29 daily bus trips, 3 train trips. That's already a good sized level of pasenger demand (a majority of these are bus meets train in Burlington, so its important to remember we're talking about extending trips that already reach from Toronto to either Burlington or West Harbour; and that that the latter will soon be Confederation Station in Hamilton.
Flixbus is also doing six daily runs, off-season.
Mega bus is doing 7 daily runs, off season.
I would note that not all demand for travel in the corridor is Toronto-Niagara tourism. Students bound for Brock/McMaster will account for a portion, in addition to work commuters.
So when you consolidate, you've got at least 13 private buses daily, plus 29 GO Bus trips, for 42 daily trips, with 3 train runs, plus the one Via/Amtrak run.
That seems like a pretty solid demand base.
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I am told that with no latent demand growth, and no population growth or commuting pattern shifts, there is demand for 4 daily trains off-season (plus hourly from Confederation) and more during peak tourist season. Each train trip would remove 2 existing bus departures.
However, given that there is expected to be latent demand, that the trip time could be dropped substantially from today, and that service frequency would induce additional demand, I don't think its a reach to suggest bi-hourly service at all, with hourly in rush hours, in the off-season.
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To be clear that doesn't justify unlimited investment in the corridor, but significant improvement could be obtained for far less than maximum investment.