Robert Thomson has a great little story in the Post, on two gray-haired speeders in Silver Spring, caught on camera going 100 mph on a winding road. They paid their $40 fine, as good citizens and guilty people should.
If I knew how to hide the rest of this, I would, because you really ought to read it.
But, I don't--the bottom line was the IT types screwed up. The camera system was set to diagnose itself if it had problems, and communicate the fact to humans by displaying either 100 mph or 0 mph as the speed.
Wrong, wrong, wrong. Some lazy IT specialist saved herself a little bit of code by doing that (or some person who specified the user requirements was ignorant of good design). You should never use a piece of data (as in recorded speed) for another purpose (to communicate a message). Once the system knows there's a problem, it should display or print an error message (ideally one that's meaningful). To do otherwise is bad design.