Разве нельзя? Если нельзя, пишут "No U turn". Если можно, рисуют знак на левую полосу явным образом.
http://www.dmv.ca.gov/pubs/hdbk/pgs2...9.htm#illegalu
Legal U-Turns
A U-turn is turning around in the street to go back the way you came. To make a U-turn, signal and use the far left lane or the center left turn lane. You may make a U-turn:
- Across a double yellow line when it is safe and legal.
- In a residential district:
- if no vehicle approaching you is closer than 200 feet.
- whenever a traffic sign or signal protects you from approaching vehicles.
- At an intersection on a green light or green arrow unless a “No U-turn” sign is posted.
- On a divided highway only if an opening is provided in the center divider.
Illegal U-Turns
Never make a U-turn:
- On a divided highway by crossing a dividing section, curb, strip of land, or two sets of double lines.
- Where you cannot clearly see 200 feet in each direction because of a curve, hill, rain, fog, or other reason.
- Where a “No U-Turn” sign is posted.
- When other vehicles may hit you.
- On a one-way street.
- In front of a fire station. Never use a fire station driveway to turn around.
- In business districts. Areas with churches, apartments, multiple dwelling houses, clubs, and public buildings (except schools) are also considered to be business districts. Turn only at an intersection or where openings are provided for turns.