On Wed, 10 Aug 2016 03:09:05 -0400, wrote:

Our town recently got one of those Traffic Speed Detecting Signs, that
tell you how fast you're going. I've always wondered how they work, and
why they dont detect cars going the opposite direction.(I assume they
work on radar). I also noticed that they only have TWO digits.
Therefore, if you exceed 99mph, what does the sign do?

It fires a rocket.