The task of a computer responsible for ensuring safety in the air would be similar to the kind of fully-automatic traffic regulation planned for other means of transport The New York subway is working on the electronic control of switches, signals and trains. Such a system was tried out successfully on a short line, the Grand Central shuttle train, between Times Square and Grand Central Terminal. Everybody was very pleased with it - except the union, which demanded that a man travel in the driving cab of the driverless trains in place of the unnecessary driver, although he had nothing to do there and could find nothing to do-except read the papers.
Street traffic, which unlike the railway is not subject to time tables, presents harder problems. Certainly there are traffic signals, showing red, yellow and green lights, in all large cities. But this kind of automatic installation needs no computer; an electric motor driving a drum controller is enough. But computers can do more: they could adapt the switching times of the fight signals to fit the flow of traffic to prevailing needs. Experimental work showed long ago how this could be done. Electrified strips are laid down in the street surface at appropriate places. Every vehicle crossing one of these strips breaks an electric contact, and this is communicated to the computer. In consequence, there is an uninterrupted traffic census going on for every street in the city. The computer can draw its own conclusions from the information it obtains and always give the green light to just those lines of streets which most need it. In this way, an almost frictionless flow of traffic ensues, exactly adapted to requirements.
The experiments were tempting. An electronic computer might be able to direct the traffic of an entire city so that the queues of vehicles now usual when work ends every day would break up in no time at all. All would be sweetness and light in the souls of car drivers...
But, unfortunately, only in theory. For experience has shown that the only obstacle - but it is a weighty one - is the car driver himself. Man as a car driver is no suitable partner for a computer. He is not capable of keeping exactly to a definite speed. And if he were, he wouldn't want to. He dozes at crossings and starts off again too slowly or too fast. Or else, just before he comes to a red light and contact strip, he brakes to a stop; while miles of halted cars are piling up behind him, the computer believes that the street is dead. Most drivers, too, are unreasonable enough to lose their temper if they have to wait two hours in a side street for a red light to change, and it doesn't change because the traffic on the main highway is very heavy and thus deserves, in the opinion of the computer, green lights for a hundred and twenty minutes.