Originally Posted by
01RedDX
Regardless of how you feel about this form of zipper merging, their behaviour is not illegal however, what you describe as "never letting them back in" and trying to prevent a merge is actually illegal in Alberta:
A person driving a vehicle on a highway where the highway is
marked by a “merging traffic” sign near the intersection of another
highway marked by a “merge” sign shall take all reasonable
precautions to allow a merging vehicle to enter in safety onto the
highway on which the merging is to take place.
Regardless of merge sign:
a person driving a vehicle that is being overtaken by another vehicle
(a) shall give way to the right in favour of the overtaking
vehicle, and
(b) shall not increase the speed of the overtaken vehicle until
the overtaken vehicle is completely passed by the
overtaking vehicle.