The Red Line (French: Ligne rouge), also known as Line 3 (French: Ligne 3), was a proposed line of the Montreal Metro.
Proposed as part of the Metro in the early 1960s, the line would have run north–south from downtown Montreal, under Mount Royal in the Mount Royal Tunnel, using CN tracks and have ended at Cartierville (western) of Bordeaux-Cartierville.[1]
The line was cancelled because:
The line was still planned for construction as a "regional metro" line in the early 1980s, reduced to a total of 9 stations.
The tracks were used by the commuter rail Deux-Montagnes line between 1995 and 2020, and will eventually form the central section of the Réseau express métropolitain upon the completion of the Deux-Montagnes branch.