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
+ R3 N$ n8 w- x( S' U& L• Do not make a U-turn unless you can do it safely and without interfering
% G$ o1 D* A" T: k6 Q0 Wwith other traffic.
• Outside urban areas U-turns are not permitted on a curve or near the
crest 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:
4 F7 L; ?* ]) Y+ X4 W. d2 }( E' g) l• On a roadway between intersections.
' I; j2 Z- W+ ^: v1 U4 H* X• Where a sign prohibits making a U-turn.
% ^' b- H; w& c  w5 p- ~/ F• 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。