Enhanced tactical and strategic control methods for traffic signal operation
State of the practice signal timing techniques used at isolated actuated controlled intersections often result in sub-optimal operation. This thesis proposes two new tactical control algorithms and two new strategic procedures. The first tactical control algorithm implements gap out logic on a lane by lane basis. In comparison with traditional movement based detection, observed green times were reduced by 5% with a 51&feet; stop bar detection zone and 2.4% with a 6&feet; advance detector. A second tactical control algorithm integrated real time stop bar presence detection with real-time flow rate information to identify a downstream flow restriction. If a flow restriction was identified, a phase with a constant call could be terminated earlier than the specified maximum or split time. This algorithm was validated by using the real-time data to predict downstream bottleneck conditions and then viewing the archived video for confirmation of the condition. In 88% of the cases, visual inspection confirmed the algorithm made the appropriate choice. The real-time flow rate information was also used to estimate real-time volume-to-capacity (v/c) ratios that could be used as input into a strategic control algorithm. Data was collected to confirm public reports of a short left turn phase and identify during which time periods this occurred. As a result, a 5 second split reallocation was implemented. Graphs illustrating before and after performance document the impact of this change.* *This dissertation is a compound document (contains both a paper copy and a CD as part of the dissertation). The CD requires the following system requirements: Windows MediaPlayer or RealPlayer.
Bullock, Purdue University.
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