New York City Traffic Guides
“In November, 1903, one hundred blue and white enameled signs, directing slow-moving vehicles to keep near the right-hand curb, were put in use in New York. These were probably the first traffic regulation signs ever used.”
(From Eno’s “The Science of Highway Traffic Regulation.”)
There are several types of signs in use. Most of them are made of enameled metal and may be placed on stationary or portable standards. The stationary standards may be made of iron pipe set in cement with the sign attached to its top. The sign should be just above a tall man’s head, say 6 feet 6 inches from the walk. Portable standards are frequently used, having an elongated (nearly elliptical) iron base, sufficiently heavy to hold them upright, and a pipe extending from a hole in the center vertically about 4 feet high, to bear the sign. These signs are placed on sidewalks to designate parking and no parking places, safety zones, etc.
Dummy Cop.
—A post, column, or monument designed to stand at the intersection of streets in place of a traffic officer has been called a dummy cop. Mushrooms or cement bumps are sometimes utilized in the same manner. Bumpers are used, too, to indicate restricted and safety zones, isles of safety, etc. A dummy cop at night ought to carry a lantern or be illuminated from some outside source.
Semaphores.
—A traffic officer sometimes uses a Go-Stop sign so arranged at the top of a standard that by turning a handle he can present one or the other of these two words to the traffic. Some of them carry a light at night, and an umbrella to shade the officer during the day. They are objected to on the ground that there is no neutral position, they always say either “Go” or “Stop.” If by a change in plan they could be designed so as to show neither word when the officer was not at his post they could act as dummy cops.
Crow’s-nest, or traffic tower, is a term given to a lookout or sentry box supported about 7 feet 6 inches above the street by a strong post. The crow’s-nest has a roof for shade and shelter and may carry a semaphore above it, and another lower down to attract the eye of nearby persons. As used in New York the arms have electrical control, and at night carry red lights. The semaphore is for the block system and may be made superfluous when rotary traffic methods are in vogue. Mr. Eno, who is given credit for the suggestion of the crow’s-nest, does not believe that they should be installed at every intersection, as a “continuous block system wastes too much of the traffic capacity of the street because between the time the signal is given to stop and the time the signal is given to go the vehicles (just ahead of the break) have gone ahead a long distance.... This leaves a large proportion of the street surface unoccupied by vehicles.”[233] The rotary system is advocated as one which will distribute the traffic uniformly over the whole surface of the street, and also equalize the speed of vehicles to a safe mean. Crow’s-nests may be used where there are street cars by making them high enough to clear the top of the cars.