This image, published in a compilation of William Phelps Eno’s recommendations in 1909, shows an innovation introduced early in the century. The “block system” was simply the idea that one street of traffic would come to a halt, allowing the crossing street to progress. The system would then reverse. Today this is the way nearly every intersection in New York (and much of the world) is navigated, regulated by an army of traffic lights.
New York’s traffic commissioner witnessed the block system in London in 1902 and shortly thereafter instituted it in New York. Some of the traffic officers, numbering nearly 700 by 1909, were on foot, as the picture shows, while many were on horseback. Eventually some would even be placed in elevated crows’ nests at the busiest intersections.
These basic innovations progressed rapidly to deal with a newly congested city. The block system was the beginning of a science related to traffic engineering that would become increasingly complicated as the city demanded more from the streets of the grid. Today the block system is second nature, but some cities rely on the “Barnes dance,” an alternative approach introduced in the 1940s where all traffic stops at an intersection to allow pedestrians to cross diagonally. JR