Show the Turning Signal and Switch Lanes no Matter What
In Vancouver BC there is a belief that the turning signal gives you the privilege to switch lanes without taking into consideration anybody who is in the lane you want to move in to.
Here is what the ICBC rules say:
Pulling into a lane
Whenever you enter a lane, whether you’re pulling into traffic or changing lanes, the vehicles in the lane you’re moving into have the right‑of‑way. When you pull away from the roadside into a lane of traffic, you need to make sure you are not cutting anyone off. Watch carefully for smaller traffic - bicycles and motorcycles - that may be approaching faster than you think.
The same rule applies when you’re planning to change lanes. Make sure there is a large enough gap so that when you pull in front of another vehicle, that driver doesn’t have to slow down to avoid crashing into you. Legally, you must signal when you change lanes.