Maybe that bridge gets used for both.
The point made many times here, and quoting the pertinent Acts and the CTA decisions supports exactly that. Until it is abandoned and not petitioned for use by any others wishing to use it, buy it, or continue to run heavy rail over it, it is now, and will remain to be, available for use by any recognized certifiable entity by the CTA for use. And others under the same legislation can petition to share it. If that has a monetary consequence for the primary user/owner, compensation is also addressed in the Transportation and the Relocation and Crossing Acts.
Also, a disused grade separated route seems to exist on the Ottawa side of the Alexandra bridge that runs along but above the Rideau Canal, away from the road that could link up well with the Ottawa LRT station.
That is covered in Paul's link:
[...]
Connections with Ottawa’s LRT are paramount, he said. The plan so far calls for two crossings of the river: on the Alexandra and Prince of Wales bridges, in order to link with the LRT at the east and west ends of Ottawa’s core.
He called the exact locations of the crossings a “delicate” point, but said these two bridges “are extremely interesting” from Gatineau’s point of view, giving access to the Rideau Centre and to the Bayview station and Tunney’s Pasture.
Pedneaud-Jobin said he has been in extensive discussions with Ottawa Mayor Jim Watson, “and we both agree that we have to have a system that is as much as possible fully integrated” into Ottawa.
Discussions about who will pay to fix the Prince of Wales Bridge must wait, he said. “What we presented is a vision for the future. We know that this discussion is going to be very important between the two cities and the two other governments.
“We are not making Gatineau stronger with this project; we are making the whole region stronger and that gives responsibilities to all levels of government.”
[...]
http://ottawacitizen.com/news/local-news/gatineau-reveals-its-plan-for-light-rail-subject-to-changes
It is entirely possible that the Feds take possession of the bridge, either through acting as agents for the NCC, or Transport Canada, and compensate the City of Ottawa for their purchase price to allow OC Transpo (Capital Railways) to further invest in bringing their connections up to legal requirements to allow the bridge(s) to continue to perform their legal status without further cat fights.
The bridge(s), by Law, are open to any CTA recognized (certified) user as per the Acts mentioned.
A private transit company can petition to use Metrolinx heavy rail tracks if they make a bona-fide case before the CTA and offer suitable compensation for shared costs, and not only that, if deemed appropriate, the Feds are also indicated as having to pay a share if it is deemed by the CTA as in the Nation's interest.
Any ruling by the CTA can be appealed to them, Superior Court, or the Transport Minister (ostensibly via the Lieutenant Governor)(the Crown).
A company may *own* a bridge, track or RoW, it doesn't mean that regulation doesn't apply too for federally regulated railways, and any that cross a provincial border are federally regulated.