This paper presents a person-based traffic responsive signal control system for transit signal priority (TSP) on conflicting transit routes. A mixed-integer nonlinear program (MINLP) is formulated, which minimizes the total person delay at an intersection while assigning priority to the transit vehicles based on their passenger occupancy. The mathematical formulation marks an improvement to previous formulations by ensuring global optimality for undersaturated traffic conditions and intersection design and traffic characteristics that lead to convex objective functions in reasonable computation time for real-time applications. The system has been tested for a complex signalized intersection located in Athens, Greece, which is characterized by multiple bus lines traveling in conflicting directions.
Testing includes cases with deterministic vehicle arrivals at the intersection and emulation-in-the-loop simulation (EILS) tests that incorporate stochasticity in the vehicle arrivals. The results show that the proposed person-based traffic responsive signal control system reduces the total person delay at the intersection and effectively provides priority to transit vehicles, even when perfect information about the auto and transit arrivals at the intersection is not available.Index Terms-Mathematical model, person delay, traffic signal control, transit signal priority (TSP).
This paper presents a real-time signal control system that optimizes signal settings based on minimization of person delay on arterials. The system's underlying mixed integer linear program minimizes person delay by explicitly accounting for the passenger occupancy of autos and transit vehicles. This way it can provide signal priority to transit vehicles in an efficient way even when they travel in conflicting directions. Furthermore, it recognizes the importance of schedule adherence for reliable transit operations and accounts for it by assigning an additional weighting factor on transit delays. This introduces another criterion for resolving the issue of assigning priority to conflicting transit routes. At the same time, the system maintains auto vehicle progression by introducing the appropriate delays associated with interruptions of platoons. In addition to the fact that it utilizes readily available technologies to obtain the input for the optimization, the system's feasibility in real-world settings is enhanced by its low computation time. The proposed signal control system is tested on a four-intersection segment of San Pablo Avenue arterial located in Berkeley, California. The findings show the system's capability to outperform pretimed (i.e., fixed-time) optimal signal settings by reducing total person delay. They have also demonstrated its success in reducing bus person delay by efficiently providing priority to transit vehicles even when they are traveling in conflicting directions.
Transit signal priority (TSP) is a control strategy that has been used extensively to improve transit operations in urban networks. However, several issues related to TSP deployment—including the effect of TSP on auto traffic and the provision of priority to transit vehicles traveling in conflicting directions at traffic signals—have not yet been addressed satisfactorily by existing control systems. This paper presents a real-time, traffic-responsive signal control system for signal priority on conflicting transit routes that also minimizes the negative effects on auto traffic. The proposed system determines the signal settings that minimize the total person delay in the network while assigning priority to the transit vehicles on the basis of their passenger occupancy. The system was tested through simulation at a complex signalized intersection located in Athens, Greece, that had heavy traffic demands and multiple bus lines traveling in conflicting directions. Results showed that the proposed system led to significant reductions in transit users’ delay and the total person delay at the intersection.
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