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
  X7 x& j8 M! l! T# }/ rwith 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.
  o' f5 P& O( d! vU-turns are not permitted in urban areas in the following situations:
, P  C/ Q3 c" g) D9 h• On a roadway between intersections.
• Where a sign prohibits making a U-turn.
• At an intersection controlled by a traffic-control signal (traffic lights).
9 \0 G! {0 O: C& m: M0 j& W, P• At an alley intersection.

无语

有红绿灯的地方U-Turn是违规的。