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？
& ^2 C, W! d7 f# Q* q谢谢！

EightBelow

U-turns
• Do not make a U-turn unless you can do it safely and without interfering
with 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.
% z6 B1 h8 L6 |4 }4 BU-turns are not permitted in urban areas in the following situations:
) u( n( g2 e5 P; m• On a roadway between intersections.
' Q+ U* q3 k4 X8 i3 J7 n  ^• Where a sign prohibits making a U-turn.
# F* h$ b2 ^, g& Z1 R• At an intersection controlled by a traffic-control signal (traffic lights).
( \: W" D, X6 S# B0 e• At an alley intersection.

无语

有红绿灯的地方U-Turn是违规的。