Motorway Sign University

Motorways are equipped with various configurable signs on overhead gantries. Some of these signs are single-colour and designed to display simple text messages ("Fog Ahead - Slow Down"; "Lane closed ahead"; "Whelk on Sliproad" etc). Others are a little more complex and can display black-red-and-white road signs such as temporary speed limits.

Most the time, these displays sit there blankly staring at oncoming traffic because there is no fog and no whelks. What a waste!

Instead, therefore, why not use idle signage to display basic but useful facts. For example "Human Genome: 3e9 bases", or "Prime numbers are indivisbible", or "Deimos, Phobos: moons of Mars". Facts can be updated every few hours.