What does the no U-turn sign mean?

You have missed your turning and see this sign at the next set of lights. What does it forbid?

Turning around to head back the way you came

This ban goes up where drivers cannot see far enough, or where the road is too narrow to turn round in one movement. Carrying on to somewhere you can turn safely costs a minute, while turning here leaves you sideways across traffic that is closing fast.

You have gone past the street you wanted and you see this sign at the intersection ahead. What does it stop you doing?

Turning around to head back the way you came

The sign bans turning across the road to travel in the opposite direction. That movement leaves your vehicle broadside across both directions of traffic for several seconds, so it is removed near curves, crests and busy intersections where nobody would see you in time.

You have driven past the street you wanted, and this sign is posted at the next intersection. What is the right move?

Carry on and turn around where it is allowed and where you can see well both ways

A U-turn ban usually sits where the road bends or crests, or where traffic arrives fast, so a vehicle turning across the road is invisible until it is too late. Reversing on a through road creates the same problem with less control. Going on to a proper turning place costs you a little time and nothing else.

You have driven past the address you were looking for and see this sign at the next intersection. What does it stop you doing?

Turning around to head back the way you came

The sign bans the turn that puts you back in the opposite direction at that spot, usually because oncoming drivers cannot see far enough or the road is too narrow to finish it in one movement. A left turn into a side street, then a normal turn around, is still open to you. Going round the block costs a minute and removes the risk.

The building your passenger wants is on the other side of the road, and this sign faces you at the intersection you are approaching.

Carry on and turn around where it is allowed, then approach from that side

A ban on turning around is posted where the sight lines are short or the traffic behind is moving too fast for a vehicle to swing across it. Reversing into a driveway to achieve the same thing is the same move with worse visibility. The extra distance is measured in seconds, and it is the reason the passenger is paying you rather than driving themselves.

The address your passenger gave is on the other side of the road, and this sign faces you.

Carry on and reach the far side by a legal route, telling the passenger why

A turn ban applies to a working driver exactly as it applies to everyone else, and what the passenger would prefer does not lift it. Bans like this usually sit where the sight lines are short or where a turning vehicle blocks a lane for a long moment. Saying out loud that you will come round stops the passenger thinking you are padding the trip.