Why replace a working train system with new technology?
The Deux-Montagnes line is the busiest in the exo train network, with 30,000 trips daily. It would have required major investment to be able to meet demand satisfactorily. The advent of the REM provided an opportunity to change the line to an automated light-rail system.
The new technology will make it possible to substantially increase train frequency, and thus total capacity: at peak hours, 2.5 times the number of passengers will be able to travel. The REM was designed to handle traffic effectively for many decades to come. The route will also include 3 direct connections with the Montréal métro system. Commuters will have greater flexibility, since they will no longer be obliged to transfer via Central Station:
Deux-Montagnes to Édouard-Montpetit: 29 min.
Deux-Montagnes to McGill: 32 min.
Deux-Montagnes to Central Station: 33 min.
Bois-Franc to Édouard-Montpetit: 12 min.
Bois-Franc to McGill: 15 min.
Bois-Franc to Central Station: 16 min.