no
"Under a traffic light" implies that it is at an intersection. You are not allowed to change lanes while passing trhough an intersection, you must maintain the lane you are travelling in.
yes and dangerous
Check your blind spot if you are changing lanes. Sometimes it helps to know if you are planning on turning right or left next so you don't have to switch lanes later
Yes, at least in Florida according to the drivers handbook. It's illegal to change lanes within 100 ft of an intersection also. I've never actually seen anyone get pulled over for it though.
I do not believe that is is lawful to change lanes in the middle of an intersection in any state in the US, regardless of the circumstances.If you are 'stacked up' in a turn lane PRIOR to the intersection, you may pull out and move into the travelled lane, unless the turn lane is separated from the main travelled roadway by a solid white stripe. THEN, you must complete theturning maneuver to which you have committed yourself.
blocked lanes
It depends how long the intersection is, how many lanes there are, and how wide the lanes are.
no
No. They just do it here because we are 'graced' with some of the most ignorant drivers you ever did see, especially along the Front Range.
Yes it is
Check your blind spot if you are changing lanes. Sometimes it helps to know if you are planning on turning right or left next so you don't have to switch lanes later