ostione

9 hours ago, ToxiK said:

There can if:

-The Mirabel of Chambly metro gets more cars off the road than the other options.

-Those municipalities get more dense neighbourhoods in exhange for the métro.

-Geography or other factors make that the extension can be had at a very low relative cost.

I doubt that Chambly or Mirabel fill all these conditions, but I am not ready to push the idea away with the back of my hand.

It wont get cars off the road.

What it will do is increase the value of the land because transit time has been reduced. This will encourage development. The development will most likely be very low density or car centric medium density (as is always the case with suburbs).
This means that the cars taken off the road will be replaced within a few years (probably around three years if we follow most induced demand traffic models). Also, the people that do decide to commute by REM will be using cars for every other trip (going to the grocery etc) because of the low density land use.

This will ultimately add more cars to the road. 

There is no alternate end game than worsening GHG emissions.