有关u-turn

小胡同

最近查google map for directions, 经常会看到需要u-turn。印象之中好像在主路上不可以，不管是否有不可u-turn的牌子。平常也看到有人在红绿灯处做u-turn。
请问u-turn到底是不是合法的？
谢谢！

EightBelow

U-turns
• Do not make a U-turn unless you can do it safely and without interfering
with other traffic.
0 q$ T$ |% p+ i3 \" J! S7 X; [• Outside urban areas U-turns are not permitted on a curve or near the
& z. O; M4 G6 ecrest of a hill where the driver of another vehicle cannot see your vehicle.
U-turns are not permitted in urban areas in the following situations:
+ ^9 B: K/ P/ J  d0 b/ v• On a roadway between intersections.
• Where a sign prohibits making a U-turn.
0 m5 O  t* b% d+ t• At an intersection controlled by a traffic-control signal (traffic lights).
• At an alley intersection.

无语

有红绿灯的地方U-Turn是违规的。