Re: the train willl bring itself to a gentle stop
Not sure whether it is the same on newer tube stock, but with older stock I'm familiar with, the stop is anything but gentle, being analogous to passing a signal at danger, whereupon the compressed air in the braking system is evacuated to atmosphere, forcing the air brakes to assume their fail-safe state (no air pressure) causing them to clamp the wheels to bring the train to an emergency stop.
On the Underground the signalling system is designed to ensure that, even if a train is running at the maximum speed limit enforced on a given section, there is no chance of a train passing a red signal and hitting another train.
Whereas with roads, you get motorists that have a tendency to drive like the lorry in Duel, which is the reason for pile-ups when someone in front brakes unexpectedly. One hopes that self-drive systems work out the safe braking distance added to the thinking distance (like on the tube, there should be a safety factor embedded in the calculation), plus a multiplier for adverse weather conditions, and remain at least that distance away from the vehicle in front. (Is that chart still printed on the back of the Highway Code?). Trouble is, that distance is often big enough for the person behind to want to fill it.
With beacons mentioned in my previous post it should be possible for a self-drive car to signal to the car behind it's exact intentions in a more measured way, rather than relying solely on the binary indications of brake-lights.
With that kind of beacon telemetry in place you could potentially design systems to sync cars together, reducing latency at traffic lights.
Biting the hand that feeds IT
