Operation of Traffic Signal Systems in Oversaturated Conditions, Volume 2 – Final Report (2014) / Chapter Skim
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Pages 18-26
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Chapter 1: Background and Motivation Traffic congestion continues to grow significantly in North America and throughout the world. Agencies tasked with managing traffic control systems are frequently challenged with moving traffic in congested conditions and situations where the traffic demand exceeds the capacity of the system.
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Manual-type analysis, these research efforts are not directly applicable to this project. Research on queue estimation is dominated by input-output modeling approaches.
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adequate for handling oversaturated conditions. They frequently relied on their personal experience and trial-and-error application than running models or performing extensive analytical analysis.
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conditions was identified by some expert practitioners. This type of condition was either situational or caused by incident conditions such as downstream crashes.
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• Decrease the cycle time when more than one phase is oversaturated. More opportunities to service the queue because there is a reduced efficiency of saturation flow rate in long queues.
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avoided if at all possible since this tends to reduce the maintainability of the location. It was suggested that large systems should have standardized controllers, cabinets, and detection systems, erring towards convention over configuration.
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handle grid issues, particularly due to the lack of detection in most CBD areas. Similarly to the strategies for arterials, two experts offered the strategies for simultaneous offsets in grids to be implemented for three to five intersections, and then apply another set of simultaneous offsets in an alternating fashion (e.g.
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Two expert practitioners noted that adaptive control algorithms need to be advanced to the point where they can explicitly handle oversaturation and accommodate the (inevitable) failures in detection systems when they occur.
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In addition to these four areas, the research also resulted in a rational guide for practitioners to identify oversaturated scenarios and apply appropriate strategies. The research focused on identifying traffic control strategies that can be implemented by traffic signal systems to handle certain types of oversaturated conditions on surface streets.
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