ITS sensor data-based control methods for optimal traffic system operations

In the last two decades, dramatically increasing travel demands and insufficient traffic facility supplies have induced severe traffic congestion problems. It is of practical importance to manage the existing transportation facilities more efficiently with advanced traffic control and management technologies. Actuated signal control, freeway ramp metering, and High Occupancy Toll (HOT) lane systems are three vital traffic management technologies. Research and development of operational control strategies that optimize these systems are essential to enhance overall infrastructure efficiency and improve traffic mobility.;With the rapid development of Intelligent Transportation Systems (ITS), several advanced traffic detection technologies have been proposed and employed to provide a high-quality platform of data to support optimized control strategies for transportation system operations. In this study, control and operation schemes of these three traffic control systems were investigated. Optimal control methods were developed respectively for enhancing these system operations based on ITS sensor data. These optimal control strategies include: (1) A multi-objective control algorithm based on stochastic vehicle arrivals was developed to enhance fully actuated signal control at isolated intersections. Using real-time queue length measurements and traffic arrival predictions, green time boundary for each phase is dynamically optimized to avoid cycle failure, minimize control delay, and maximize total traffic throughput; (2) An area-wide coordinated ramp meter control algorithm was developed to effectively respond to freeway congestion. A hierarchical control scheme with a three-priority-layer structure was proposed to optimize entire system performance by quickly mitigating freeway congestion and balancing traffic demands on ramps; (3) A feedback-based tolling algorithm was developed to optimize HOT lane operations. By dynamically adjusting the toll rate based on traffic conditions, traffic allocations between GP and HOT lanes can be controlled and overall system efficiency can be maximized.;VISSIM-based simulation experiments were performed to evaluate the effectiveness and practicality of the proposed control algorithms. External controller modules will be developed to implement the proposed algorithms through the Component Object Model (COM) and Application Programming Interface (API) provided by VISSIM. The test results show the proposed control algorithms performed reasonably well in optimizing traffic operations of these three traffic systems under various traffic conditions.