The MTQ claims that the new plan for the Turcot does not increase its capacity. Yet they also claim that the new configuration provides sufficient capacity to accommodate the projected increase in vehicles kilometres traveled (VKT) in Quebec in the coming 20 years. Clearly this is a contradiction.
The number of lanes through the Turcot exchange itself will be unchanged; however the speed of vehicles moving through will be increased, allowing greater vehicle capacity. This occurs by increasing the turning radius of various ramps, which permits higher speeds, and by using "modern" design standards which include wide shoulders.
Before/after: A-15/20 in Côte St-Paul. The MTQ claims not to be adding additional capacity, yet longer merge lanes and wide shoulders will do just that
Smaller turns = slower speeds
These images show how the radii of several connections between the highways 15 and A-20/A-720 will be increased, permitting vehicles to travel faster and thus increasing capacity; this will take up even more valuable urban land, making “integration” of this highway even more improbable.
Wider turns = faster speeds
Images drawn from Projet Montreal proposition, Turcot 50-50