Via Headlights

I know of two messages that can be conveyed via headlights.

The first is based on the principle of reflexivity. When an approaching driver has mistakenly left vis high beams on, one can indicate the fact by blinking one's own momentarily. I always assume the other driver is forgetful, not inconsiderate, so I think of the message as a polite reminder.

Actually, these days I usually assume the other driver has one of those newfangled cars with the annoyingly bright normal headlights, and don't even bother to signal.

Similarly, when an approaching driver has forgotten to turn on vis headlights (or, in the daytime, forgotten to turn them off), one can indicate the fact by blinking one's own headlights on and off,

The second message is used to warn other drivers about speed traps. Since it needs to be different from the first message, it can't be represented by a single blink of the headlights, so, naturally, it's represented by two blinks. (Any guesses as to how a third message would be represented?) In the daytime, of course, the blinks involve blinking the headlights on and off, rather than the high beams.

I haven't seen many speed-trap messages in recent years, but I figure that's because I'm living in an area where dense traffic is the norm. The message is more useful in sparse traffic, where it's much easier to speed, and also much easier for police to single out a speeder.

(Should I remind you of my argument for no speed limits? Sure I should.)

Finally, although I'm not sure what the point is, let me mention one more thought I had. Since headlights are wide-angle beams, both of the above messages are broadcast to everyone traveling in the opposite direction. For the second message, that's fine—the message is intended as a broadcast. The first message, however, is intended for a specific person; everyone who receives it has to wonder whether it was intended for ver.