One second. That's the time it takes most drivers to say 'What the F..' as the car in front does an emergency stop. At motorway speeds the car will have travelled about eight car lengths before the F word is finished.
That is how, put very crudely, motorway pile-ups happen, the time taken to realise what's going on is the time desperately needed for braking or swerving. Of course good drivers always allow enough space and look several cars ahead so they don't get caught out, but the sad fact is that the vast majority of drivers on the road today are not the slightest bit interested in driving, for them its all a bit of a chore and long range observation simply doesn't happen. And the frightening thing is that we have to share the roads with them.
Luckily help is at hand; imagine a system where the cars talked to each other, so the one at the front of the queue alerts all the others of the danger. Then all the cars could start braking at the same time and come to a serene rest with absolutely no drama. Its a wonderful concept and its not just a flight of fantasy, its actually happening.
But don't think that the technology is in any way simple, just think of how a car recognises what is and isn't danger, how does it decide what message to broadcast and when does the car decide to take control of the brakes away from the driver?
These are all tricky technical challenges, but with ever more crowded roads, not to mention ever more driver distractions, the need for assistance is very pressing, and this is driving the technology forwards with relentless pace. This technology has real potential to save lives, and that is what we in the trade call 'a biggy'.
But the effects of cars being able to chat amongst themselves spread wider than just motorway crash avoidance, oh yes indeed. By allowing cars to follow each other closely, acting as if they were a train with invisible couplings, traffic density can be increased, overall traffic speed increased and the reduction in drag as each car slip streams the one in front will reduce fuel consumption and thus save the planet. Well, a little bit anyway.
At road junctions cars will not only be able to detect each other and avoid collisions, but they could let cars join the main traffic flow in an orderly manner, as if saying 'after you sir' to waiting cars. This brings the long term possibility of making roundabouts and traffic lights redundant, with intelligent traffic organizing itself in perfect harmony.
Of course the problem with this utopian world is that belligerent old buggers like me will insist on driving classic cars in amongst the traffic, with complete and fallible human control, and enjoying the hec out of it by the way. How long will there be a place on the public roads for car enthusiasts and people who still enjoy the pleasures of driving? When facing an argument about saving lives, reducing global warming, and improving traffic flow, the counter argument about freedom and enjoyment sounds a bit weak.
Luckily there is a solution, systems could be integrated as a retro fit on older vehicles, although they would be quite pricey. The system would be similar to fitting a cruise control system, but with an actuator for the brakes too. The level of sophistication would be reduced and there are many technical problems, particularly if the car has not got ABS to control emergency braking manoeuvres. But it could be done, and if its the only way for us to continue to enjoy classic cars into the future then surely its a price we have to pay.