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？
5 m/ n3 s: P5 |& i+ r* ~谢谢！

EightBelow

U-turns
* Q, g7 S1 V* ~" J5 v! W• Do not make a U-turn unless you can do it safely and without interfering
with other traffic.
* P( s8 I" o: P! h, t* b1 `• 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.
/ X. l6 i4 I. n. Q/ r& M/ `4 @U-turns are not permitted in urban areas in the following situations:
• On a roadway between intersections.
7 X9 W( J5 {2 S2 Y0 T' y) t5 E• Where a sign prohibits making a U-turn.
& |2 ~- t8 o- R! N6 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。