definitely take the 20. it's faster and you get to cross over the jacques-cartier bridge when you leave montreal (spectacular view) and the pierre-laporte bridge when you enter quebec city (also spectacular).
Originally Posted by MonkeyRonin
Well 20 = 401, so thats probably why they'd say that.. and just looking from Google maps, they appear to be the same size (2 lane each way near QC). so, you might as well take 40 if thats what you want, and if its too slow or whatever, you can always just cross the St. Lawrence.
not really feasible, unfortunately, since there is only one bridge over the st. lawrence between montreal and quebec city. also, since the highways are pretty far inland, switching sides would add another 30 minutes or more onto the trip: you have to pass through trois-rivères and then a bunch of winding country roads to get between the 20 and the 40.