The only down side that I see to using the Don route is the need to build bridges. Yes, more expensive, perhaps.....but after deciding to spend liberally (pun intended) on double track all the way to Quebec City, is that cost element a showstopper ?
I have more concern that Alto going along the Kingston (and either up the Stouffville route, or a new alignment further east) is bolting on to (and forcing further redesign and rework of) a GO Expansion system that was designed with a certain capacity for commuter and regional service. Adding Alto puts the squeeze on that. Whereas using the Don Branch gives Alto its own, unencumbered routing into downtown Toronto and on its own rails. Are we really happy with putting so many eggs in one basket ? ML seems indifferent to VIA today, how seriously will they support both HSR and legacy VIA service on the Kingston Sub?
The Kennedy route seems to imply speed limiting curves at Agincourt, and again at Scarborough Jct.... and doubtless a less than optimal speed between Agincourt and Kennedy, even with new tracks added, Whereas a Leaside route could support HSRish speed much closer into the city. Again, it seems odd to accept a constrained speed and hence longer timimgs on the Toronto access after going to the max the rest of the way.
The tunnel under the 401 will be almost as expensive as a bridge over the Don.
As to Pickering-Ajax-Oshawa - do not discount the need to unbundle CN freight and legacy passenger before scheming to build HSR tracks. The obvious first step would be to extend the York Sub further east, restoring the ability for freights to pass in this area (requiring a bridge span over Duffins Creek) and then a flyover to route VIA to the north side of the row to reach Oshawa station without level crossing of the freight path.
There will need to be provision for regional service, probably GO taking over the VIA legacy service which Ottawa seems quite happy to sacrifice. I would imagine this will eventually demand new track construction eastwards from Oshawa, perhaps sharing with CN but more likely dedicated regional rail.
(There are likely more autos using the 401 to reach destinations along the Cobourg-Belleville-Kingston path than through drivers to Ottawa and Montreal. I am determined to tenaciously make noise about the need for enhanced legacy service on this route, up to and including hourly or bihourly service all the way to Kingston, to seize this modal share. Alto should not be allowed to preempt this regional system, it is equally important).
I would be far more dismissive of the whole Kennedy idea if the suggestion was coming from anyone other than
@Urban Sky , whose detailed knowledge and inside insight into the actual planners' thinking exceed all us other posters. So maybe this is truly what is planned and should be taken very seriously. It may be doable, but it seems like an odd place to pinch pennies, and is the inferior route, to this guy in the bleachers anyways.
- Paul