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。
9 k; c3 _4 M3 ^' h8 G  u请问u-turn到底是不是合法的？
谢谢！

EightBelow

U-turns
$ N7 M1 P/ V; A5 N6 H1 U! _• Do not make a U-turn unless you can do it safely and without interfering
with other traffic.
1 m9 Z& _0 g. Z9 I% W) q& g• 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.
' i; M" z3 W- O8 o7 J4 D9 EU-turns are not permitted in urban areas in the following situations:
• On a roadway between intersections.
• Where a sign prohibits making a U-turn.
3 @7 X  r$ O' X+ R, Y• 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。