Comments by "ke6gwf - Ben Blackburn" (@ke6gwf) on "Sandy checks out Tesla's Full Self-Driving Beta Version 9" video.

@craigamills8492 he changed lane position through an intersection. If he had continued in his lane he would have stayed in the left lane. The practical reason to use signals is to let other drivers know what lane you are going to use, because you can have people wanting to make a right turn into that right lane, and the turn signal lets them know your intentions, and since you are actually leaving the center lane and changing to the curb lane, the law requires you to use your turn signal. Remember, prior to that intersection he not in the curb lane, he was next to the bike lane, next to the center line, and he changed lanes away from the center line. It's also important for any bikes that may be in the bike lane who are now going to be using the curb lane, because he's entering their route.
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@yusha27 probably because in towns the right lane is often full of churn from people coming into and out of driveways. As a truck driver in smaller towns I will often ride the left lane through the business districts because of how messy the right lane is. But I also get back into the right lane as soon as possible lol He may just not be a polite driver and prefer camping in the fast lane... Lol
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