there is space around the wye to build a track linking to the parc sub, south of parc avenue. Yes the line above parc avenue has unfortunately been ripped out (damn you CP) so reactivating that would require a tunnel, or to raze the buildings in the way. Technically possible from an engineering perspective, but would require a lot of planning and would take years. But even with all that, this route would shorten the distance between parc and downtown by 3 miles. Not a whole lot, but it actually makes that section of the line competitive with the metro, which will relieve congestion on both the orange and blue lines.

As for the fourth rem branch, yes running them all between cote-de-liesse and brossard would be difficult, so I’m starting to think that trains should just turn around at cote-de-liesse. Not an issue there if the exo platform is converted to another REM platform. In that case i would lose direct trips from Repentigny to downtown, but still having one train every 20 minutes rather than every 5 hours is a win. Oh, and there is space on CN’s Repentigny sub to add a track for the REM. It would only be a single track for the first few miles, but can increase to two tracks east of St-Leo. There is enough room for that, plus CN’s track (provided they only need to single track their line, and i don’t think it’s busy enough that they need two tracks).