Adrain said: > No. There are systems (e.g. the ADEPT project one) which work by > having on-board equipment that keeps track of the average speed of the > car. If that drops below a set speed for more than a set length of > time (or if the car stops more than a set number of times in a set > period or distance), a unit of congestion charge is levied against the > car. Such a system requires no SatNav (or, indeed, any other method > of determining the car's location) at all. And it's relatively > inexpensive.
Silly me, and there was I thinking that I was talking about driverless taxis that are required to make turns at junctions. What a fool I am. Mea culpa. Roger
