In the US highway driving, sometimes the traffic is so heavy that if you waited for a safe opportunity to put on the blinker, you might not be able to get over at all. But you have to because your exit is on the other side and you have limited time to get over, etc.

What I’ve had to do is put on my blinker indicating my intention, and then wait, and change lanes when it is relatively safe to do so – sometimes only if people let you in. Otherwise you have to cut someone off or trust that they will stop in time. Obviously this is undesirable.

But while I’m waiting for my chance, the drivers behind me will know my intention and can better predict my future actions. They won’t think I’m driving slow and unpredictably. They’ll understand what I’m doing and why.