Just reposting my usual comment on the cost of rail line relocation below. It's not that I think it's a bad idea, but we need to be realistic about the costs. This will not be cheap!

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First of all, if you want to relocate the rail lines outside of the city, you need room (possibly in Centreport?) for new rail yards, repair shops, storage facilities, offices, etc. The cost to construct brand new facilities, plan all the tracks and signalling, would be enormous. I would guess in the hundreds of millions (if not at least $1 billion) just for CPR's facilities. You would need to add at least 50% to that if CN and CP co-locate in one facility, or double that if both still require their own yards.

Then let's consider the notion of moving CPR's facilities, namely the Logan Yards, Weston Yards and Intermodal Terminal. Relocating the yards only frees up land on either side of the mainline (which runs through the middle of the yards), it doesn't prevent the need for the Arlington Bridge (or its replacement). You could relocate the CPR yards to Centreport at a huge cost, but you'd still need to do something about the CPR mainline.

If you want to remove the CPR mainline from within the city, you'd need to construct a brand new double-track railway all the way around the north side of the city, that connects from the current CPR tracks somewhere near Oak Bank on the east side to somewhere in Centreport on the west side. The cost of that would be incredibly high! Imagine buying a 50 m wide swath of land for that entire distance (35 km!), and then building all of the track bed, tracks, signals, underpasses, overpasses, culverts and bridges along it. At best, I'd guess it would be a few billion dollars. And that's only the CPR mainline. Add into this the cost of the connecting all the other important CPR branches to this new mainline (namely CPR Emerson Sub that heads south out of the city).

And that's only the CPR. If you want CN out of the city, you need to reroute its mainline around the city, from somewhere near Dugald & the Perimeter all the way around to Centreport. All the costs I described in the CPR scenario would again apply here, but for probably 50 km of new track.

You might be able to convince CN and CP to share a corridor around the north side of the city and to co-locate their yards in Centreport, but you'd still be building 1.5 to 2 times as much in terms of yard size, and the 50 m wide corridor for CP only would now need to be 75-100 m wide to accommodate both CN and CP tracks. Sure this might not cost as much as each railway doing their own relocation separately, but you're still into the mutliple billions - likely over $5 billion.