It varies from state to state, but on average Type 1 (the most important) signs are replaced every 7 to 10 years. If you tag each one with some sort of RF beac

It varies from state to state, but on average Type 1 (the most important) signs are replaced every 7 to 10 years. If you tag each one with some sort of RF beacon, not only do you tell the car "this is the spot to stop" you also have an absolute fixed reference point and can correct GPS or other navigational systems. At the point you know where everything is, and cars begin to share their location with each other, you have an absolute map of everything in the environment. If LIDAR detects anything that isn't part of the gold standard of what the world looks like, _that_ is an exception and handled as a danger (the person Uber should have detected had they had all the sensors turned on).