Seeing Green (1937)

you whether you're in the air on land or sea there are devices to protect the safety of the traveler speed with safety is the tempo of all modern transportation flashing beacons guide airplanes from port to port on the water the lighthouse guide ships safely to their harbors on land trains thunder over derails safely guided by signal lights all over the world control of traffic with safety is of first importance wherever people travel from one place to another in Asia Europe Africa and the Far East it makes no difference whether the traffic is fast or slow heavy or light traffic is directed to guide vehicles safely along the way though languages may different customs change when boundary lines are crossed traffic signals mean stop and go in any language and in America today though great highways stretch across the country the motorist is never away from traffic control sooner or later he comes to a city with its crowded streets where traffic police are the finest in the world and traffic moves under positive safe control streets in the United States are crowded with fast-moving automobiles and in practically every city in town today the motorist finds traffic lights to aid him on his way pedestrians and drivers alike oh the automatic traffic signal of both of thanks when they use it well and treated right they are saving time and making it possible for everybody to get on faster and move along in traffic with less wear and tear with safety first and always in their minds the traffic bureaus throughout the country everywhere have given motorists the guidance of signal lights to tell them when to stop and tell them when to go in safety there are many types of signal lights used in traffic control today some towns use lights with only two colors while other towns use three colors and still others have traffic control built around a four color system in some cities the lights are so arranged that drivers must stop on the amber light in other towns drivers may go on amber and green in still other communities the amber light alone appears on both sides at the same time some cities have lights which are augmented by semaphores while in other cities the lights look like little houses hanging from wires even now traffic engineers are working with safety councils toward a national standardization of the traffic signal system and there is every prospect that as soon as it is feasible motorists will travel from border to border and from coast to coast and meet the same old friend with the same clear message all the way traffic lights play no favorites the traffic signal puts you level with the world and keeps you even with safety regardless of what car you drive and although the perfected hydraulic brakes on modern motorcars will bring the car to a smooth quick stop racing lights is hard on the tires as well as on the nerves automatic traffic signals wait for no driver today's car is fast on the getaway but the safe driver doesn't race doesn't try to beat the signal and the careful driver never rides the amber all automatic traffic signals have minds of their own let's open up this little iron box near the bottom this is the traffic signals brain it controls the three colors red amber and green let's simplify it to see how it works first there's an electric motor which operates on current from an ordinary electric power line the motor drives a train gears which reduces the speed and slowly turns a shaft this shaft carries some little wheels called cams these cams are the thinking mechanism of the traffic lights brain let's look at one of the cams to see how it controls the light as the cam turns it touches a small metal contacts trip this completes an electrical circuit and the stop light goes on as the cam turns around it moves away from the contact strip no more electricity can flow through the circuit and the light goes out at the same instant another cam on the same shaft is just touching another contact strip and the go light turns on the cams are arranged so that the stop-and-go lights alternate or change directions each time the shaft goes around the controls for all the lights on the signal box work on the same principle when the red light is on for say the Main Street the green light is on for the side street and the amber light is off before the lights change the amber light comes on for both the side street and the main street then the side street green and amber lights go off and the red light goes on the main street red light goes off to be replaced by the good old green light this is all very simple but the next thing is to give different traffic lights different timing to take care of different traffic requirements once set up traffic lights run on schedule these schedules are the result of careful planning by experts who study traffic conditions at the location of each signal light for example if north-south traffic is much heavier than east-west traffic the schedule is arranged to give more phim lifetime to the heavier north-south traffic the scheduling of groups of lights is a bit more complicated let's examine the methods of controlling groups of signal lights one method is to time all the lights to operate together first all north-south cars move while east-west traffic halts in the entire section then as the lights change east-west traffic is given right of way however this system will not work in all locations since all the lights work together it is impossible to give extra green light time if there is heavier traffic on certain main streets so on some main thoroughfares a flexible progressive system permits adjustment for heavy traffic and allows main boulevard traffic to move steadily without stops for intersecting streets in order to get the greatest advantage from the lights the driver must time his speed to the schedule of the lights the driver who tries to go too fast has to stop at each intersection to wait for the light to change the green lights won't hurry for anyone but the driver who fits his speed to the schedule of the lights keeps moving comfortably and safely stop when the signal says stop wait when the signal says wait and go only when the signal says go the safest way to drive and the best way to make time is to gear you're driving in with the lights seeing green all the way