Be smarter with the existing system.
Start by phasing traffic lights so that anyone on a major road sticking to the speed limit doesn't have to stop every few hundred yards. Pros: no benefit in speeding; fuel econony improves and CO2 emissions go down (some people believe it makes a difference). Cons: probably won't work in big cities; oh and you'll need another bloody sign to tell people.
@ Jon: Please tell me your joking - I do sometimes think there are people who don't recognise a national speed limit sign when they see it.
Biting the hand that feeds IT
