https://en.wikipedia.org/wiki/Mount_Royal_Tunnel
https://en.wikipedia.org/wiki/Mount_Royal_Tunnel#REM
https://rem.info/en/news/first-passage-rem-through-mount-royal-tunnel-and-start-dynamic-testing-area
https://www.montrealgazette.com/news/article144286.html
Even the REM train stations should be expandable to eventually accomodate 6-8 car trains.
The Dunsmuir_Tunnel was rebuilt to become a double deck tunnel providing a split_platform station configuration. https://en.wikipedia.org/wiki/Split_platform#North_America
Unfortunatly, the Burrard_station & Granville_station platforms were only built to be 80m, when they should have been 155m-160m. This would have helped to eventually have 9 car SkyTrains, just like 9 car Montreal Metro trains.
With proper long-range planning in mind, the SkyTrain should have been planned to eventually be a double length LRT system. Instead, its been challenging enough just to establish 5 car trains on the first 2 lines.
Unfortunatly, the 3rd line or Canada_Line was built to only have 50m, whereas the Montreal Metro has 152.5m long stations.
The Canada_Line_Stations have platforms that are only 50 metres (160 ft) long, when all the stations should have been built with a future clearance of 160m. That would have allowed for a future provision to eventually accommodate at least 8 car trains at each station.
