"Adaptive Traffic Control Systems in the United States: Updated Summary and Comparison"
The number of adaptive traffic control systems installed and operating in the U.S. has exploded in the last two years. Prior to 2008 there were only 38 adaptive systems known to have ever been in operation. Of these, almost half have been abandoned or removed from operation. Since 2008-2009, there has been a renewed interest in adaptive traffic control. HDR conducted a survey in 2009 to assess the historical experience in the U.S. with regards adaptive traffic control systems. Based on the significant changes occurring in 2009, HDR conducted a follow up survey in the summer of 2010 to assess the technologies that had seen rapid deployment. This paper is a summary of the findings from this updated survey. It also examines the operational benefits of these systems based on the latest before- and after-studies.