People that pull U-turns at traffic lights really grind my gears because the traffic turning right (into the lane they are trying to u-turn too) have the right of way and the people pulling the u-turn ALWAYS stop and block traffic from the left turn light.
Do not do a U-turn unless you can do
it safely. U-turns are not permitted:
• at an intersection controlled by a traffic
control signal (traffic lights) unless
permitted by a traffic control device
• where a sign prohibits U-turns
In urban areas U-turns are not permitted:
• on a roadway between intersections
• at an alley intersection
• at an intersection where one or more of
the roadways is an access to a public or
private parking lot which the public can
access
Outside urban areas (rural) U-turns are
not permitted:
• on a curve
• approach to or near the crest of a hill
where the driver of another vehicle
cannot see you that is approaching
within 150 metres from either direction
From Here!
http://www.transportation.alberta.ca/2000.htm