Via Brake Signal

The slowdown should have come as no surprise. As a general rule, whenever there is a decrease in the overall speed of medium-dense traffic (here, due to the change from downhill to uphill driving), the decrease doesn't happen smoothly. Instead, there is a small, persistent area where the traffic slows down more than it needs to. I'm not sure why this happens; my best guess is that when the drivers see brake lights come on ahead of them, they overcompensate, and slow down a little more than they need to, then the next set of drivers slows down even more, and so on. The whole thing could probably be modeled mathematically—the initial state of smoothly decreasing traffic speed would be found to be unstable to a perturbation where the traffic slows down too much. But I digress.

In situations like this, where the traffic is slowing down suddenly, I like to pump my brakes in a leisurely way as I slow down, as a signal to the drivers behind me. Pumping the brakes is a good signal for two reasons. First, it appears to the drivers behind me as flashing red lights, which is a good attention-getting signal; second, it has the right connotation, because pumping the brakes is what one does when trying to slow down very rapidly without skidding (unless one has antilock brakes).

So, I pumped my brakes a little, saw the cars behind me slow down, and was ready to go back to normal braking, when I noticed there was a tractor-trailer behind the cars, and had a new thought: it won't do any good for the cars to slow down if the tractor-trailer plows into all of us at full speed, so maybe I should keep pumping my brakes a bit longer. My experience has been that the average truck driver is much more aware of the dynamics of traffic than the average car driver, so I didn't really expect an accident—I just thought it couldn't hurt to keep signaling.

It was at this moment that the amazing thing happened: the truck driver put on vis hazard lights. There was an incredible sense of communication—it was exactly as if the driver had spoken to me, and said, “you know, you could use your hazards instead”. Not only was it communication, it was a kind word from a stranger, and that is a rare thing. Of course, the hazards also served to communicate to the drivers behind the tractor-trailer, but I like to think that both intentions were present. Afterward, I wished I had had the presence of mind to flash my hazard lights back, to acknowledge and say “thanks”.