One Way and Rotary Traffic.
—In the crowded cities it has been found necessary to confine traffic to one direction in some of the streets. All streets not wide enough for two vehicles must of course have one-way traffic. Streets a little wider may wish to park or rank cars along one side and have one-way traffic on the other. With parallel streets near together, wide streets even, may be used advantageously as one-way streets with two or more lines of vehicles.
For the convenience of the public clear and distinct signs should be placed at every entrance to a one-way street. Of these more will be said further on.
At intersections there are two methods of procedure: The block and the rotary. The block requires a traffic officer who stops for a short time the traffic in one direction to allow the other to pass, then in the other. Even the short spaces of time between his whistle blasts are productive of much congestion. To alleviate this condition a movement about the center of the intersection in one direction has been devised. On the intersection of streets where there are small parks, monuments or safety zones the rotary method is most successful. The movement around is such as to leave the center of the intersection, the park or monument, on the left, thus avoiding all left-hand turns. In establishing one-way streets attempts are usually made to avoid left-hand turns whenever possible. The figures on [pp. 424] and [426] show sketch plans for rotary service. When there are street-car tracks or other local obstructions slight changes may have to be made. Note only two full passing places for vehicles, A, and as only a part of the traffic will want to cross congestion and danger are largely eliminated. There may be one, two, or more lines of traffic at B; depending on the width of the street. This scheme, according to Eno, is so practical that after it was put into use in New York in 1908, it was adopted the same year at Boston, by Paris in 1909, by Buenos Aires in 1910, and now is in use in many cities throughout the world.
Rotary scheme for traffic around a danger zone where streets meet at an acute angle. Right angle passing at A. One, two or more lines of traffic depending on width of street at B.