The Red Line (French: Ligne rouge), also known as Line 3 (French: Ligne 3), was a proposed line of the Montreal Metro that never made it past its planning stage. The line was supposed to have 15 stations and end at Cartierville (western) of Bordeaux-Cartierville, using CN tracks and Mount Royal Tunnel under Mount Royal. The line was cancelled because:
The line was still planned for construction in the early 1980s, reduced to a total of 9 stations.
The tracks are now used by the commuter rail Deux-Montagnes Line and will form the central section of the planned Réseau électrique métropolitain.