That is why you can never rely blindly on a single light signal. View it primarily as additional information from another road user. Ultimately, you must always judge for yourself whether a maneuver is safe. So, the next time a truck briefly flashes its lights after overtaking, you don’t need to panic immediately. Chances are there isn’t an irritated driver behind you at all. He is probably just trying to tell you that you have completely passed him. A small gesture, but one that can make driving behind long vehicle combinations a lot easier.
After overtaking, the truck behind you flashes briefly once: this is what the driver wants to tell you.
