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.