What does the no left turn sign mean?

This sign is mounted over your lane at a busy downtown intersection. Which movement does it forbid?

Turning left at this intersection

The ban is on the left turn itself, not on the turn under one particular signal. Going straight or turning right stays legal, so the plan is to carry on and turn where the movement is allowed rather than stopping in the lane to think about it.

You are in the left lane at a set of lights and you see this sign across the intersection. Your route needs a left turn here. What should you do?

Go straight through and find another way around to your route

The sign bans the movement outright, so no signal phase and no gap in traffic makes it legal. Left turns are removed where turning vehicles would block a through lane or cross a stream of traffic with poor sightlines, and the normal fix is three right turns around the block.

This sign is above your lane as you approach the intersection where you meant to turn left. What should you do?

Carry on through and reach your destination another way

The turn is banned because at that spot it cuts across traffic that cannot see you in time, or blocks a lane with nowhere to overflow into. Waiting for a gap makes the second problem worse and still breaks the rule. Take the next permitted turn and come back around.

You are in the left lane at a set of lights with your signal on when you notice this sign above the intersection. The street you want is to your left. What now?

Cancel the signal, go straight through, and come back to that street another way

The turn is banned at that intersection whatever the traffic is doing, usually because the sightlines or the signal timing make it dangerous. Drivers behind you and oncoming drivers are all working on the assumption that nobody turns there. Go through and come back on a street where the turn is allowed.

You need to reach a street on your left, but this sign faces you at the intersection. What is the correct response?

Carry on and reach the street by turning where turns are allowed

A banned left turn is usually banned because the sightlines or the traffic make it dangerous, and the ban does not soften when the road looks quiet. Turning right and going round the block reaches the same street without any of that risk.

The destination sits on the left just past this junction, and the sign faces you on the approach.

Go past, turn where it is allowed, and come back so the door opens onto the curb

The ban covers every vehicle and a drop off is not an exception to it. Thinking one junction ahead gets you to the same door legally and puts the passenger door against the curb rather than the traffic side. The extra distance is worth far less than the safer side to step out on.