Normative Signs: The Poetry of "Ought"

This one is aimed at truckers; very few people other than truckers know what engine brakes are, anyway. Engine braking is a way of abruptly slowing a truck’s engine as a way of slowing the vehicle (sort of like shifting down). It’s loud as hell, which is why it’s forbidden in lots of residential areas.

I guess the injunction here is “don’t do something noisy, unless you really need to.”

(photo contributed by Jonas Dow)