The city deactivated most of the pedestrian buttons long ago with the emergence of computer-controlled traffic signals, even as an unwitting public continued to push on, according to city Department of Transportation officials. More than 2,500 of the 3,250 walk buttons that still exist function essentially as mechanical placebos, city figures show. Any benefit from them is only imagined. … At $300 or $400 per intersection, it would cost about $1 million to remove the disconnected mechanisms, Mr. Primeggia said. About 500 have been removed during the course of major reconstruction projects. But city officials over the years decided it was not worth the cost for the rest, given other needs like rebuilding roads or installing new traffic signals.