manner. The truck driver is not trying to rush his colleague; he is simply helping him to better estimate the length of his vehicle.
Motorists can also get such a flash.
The signal is primarily used between truck drivers. However, you may also encounter it as a car driver. This happens, for example, when you are traveling with a caravan or trailer. With just a passenger car, you can usually clearly see when you have passed a truck. With a caravan behind the car, that is much more
