If you built a dedicated line, Toronto through Peterborough as proposed but constructed it to 100 or 120 mph standards you would only lengthen the HS time by maybe 30 minutes.
But why would you do that when the level of effort is exactly the same whether the line runs at 100 mph or 200 mph? Same issues with expropriation. Same planning. Same consultations. Etc. The only cost differences are:
- Between 100 mph and 125 mph Transport Canada requires all intersections to be protected with 4 way gates.
- Over 125 mph TC requires all intersections to be grade separated. No interaction between road and rail traffic.
Costs are basically the same until 100 mph. Small jump in cost between 100 and 125 mph. Substantial jump in cost at 125 mph because of grade separation requirements, which is why if you're going above 125 mph, you might as well go well above 125 mph, which is exactly what Alto is planning. There's no huge difference in cost between 200 kph and 300 kph because they both require grade separation.
You also end up with a worthwhile Tourist venue and with the addition of VIA1 service meals and drinks you WILL get the business class to switch.
Those are two very different markets. Business customers care about getting somewhere fast (time sensitive). Tourists care about the view (experience sensitive). Leisure travelers care about cost (price sensitive). Given that business travellers are the highest margin, they are what pay for development. That's the market Alto is rightfully aiming at. I'm sure you're well aware of how with airlines the 10% of passengers at the front usually generate over 50% of revenues. Same deal. And just like airlines, the rest of us get the economy seats in between.
I see more plus in service than speed.
What you or I see is irrelevant. They aren't randomly designing these things. The consortium building this has SNCF. I'm sure the folks who build the TGV have some idea of what kind of market segments use rail and what they are willing to pay.
And I'm willing to bet they're building and running customer acquisition models that look at how many more customers they get for going a minute faster or by adding a stop at a different spot, or changing service frequencies, etc. And they are probably doing optimization between their demand and their cost models. Nobody is building multi-billion dollar projects based on feelings.

