The truth about New York's traffic buttons

From the NY Times comes this story: bq. For years, at thousands of New York City intersections, well-worn buttons have offered people a rare promise of control over their pedestrian lives. bq. The signs say: To Cross Street Push Button. Wait for Walk Signal. Dept. of Transportation. bq. Millions of dutiful city residents and tourists have done just this. Many may have believed they actually worked. Others might have suspected they were broken but pushed anyway, out of habit, or in the off chance that a walk sign might appear more quickly. bq. As it turns out, the cynics were correct. The city disconnected the vast majority of the buttons long ago with the emergence of computer-controlled traffic signals, Department of Transportation officials have admitted. bq. More than 2500 of the 3250 pedestrian walk buttons that still exist function essentially as mechanical placebos. And more: bq. Most of the buttons scattered through the city, mainly outside of Manhattan, are relics of the 1970's, before computers began tightly choreographing traffic signal patterns on major arteries. They were installed at a time when traffic was much lighter, said Michael Primeggia, deputy commissioner of traffic operations for the city's Transportation Department. bq. The first "semi-actuated signal," as they are called by traffic engineers, is believed to have appeared in the city in 1964, a brainstorm of the legendary traffic commissioner, Henry Barnes, the inventor of the "Barnes Dance," the traffic system that stops all vehicles in the intersection and allows pedestrians to cross in every direction at the same time. Barnes was also instrumental in completing the one-way conversion of major avenues in New York. Traffic flow is an interesting logic problem -- how to maximize 'throughput' while preventing gridlock and congestion at all rates of flow. A local scientist Bill Beatty has an excellent page on his website for generalized flow in a set of lanes and how the actions of one car can vastly improve the entire flow of traffic. His home page is here - if you are into science, it's worth spending some time on.