ShonTron
Moderator
It seems to me that a lot of the hassle associated with Peterborough rail (starting with Don Branch rehab and Agincourt Yard bypass) would be sidestepped by using the upgraded Stouffville line to get as far as Mount Joy, and then split off east (7-9km depending on routing) to join the CP west of Claremont. That does put even more pressure on the Union-Scarborough Junction LSE section, of course.
Or better yet, re-build the CN Uxbridge Sub to Lindsay, and the CN Campbellford Sub to Peterborough. Lindsay has been building things on top of the old railway rights-of-way, but the rural sections are completely intact!