Hierarchical-Distributed Optimized Coordination of Intersection Traffic

This paper considers the problem of coordinating vehicular traffic at an intersection and on the branches leading to it in order to minimize a combination of total travel time and energy consumption. We propose a provably safe hierarchical-distributed solution to balance computational complexity and optimality of the system operation. In our design, a central intersection manager communicates with vehicles heading toward the intersection, groups them into clusters (termed bubbles) as they appear, and determines an optimal schedule of passage through the intersection for each bubble. The vehicles in each bubble receive their schedule and implement local distributed control to ensure system-wide inter-vehicular safety while respecting speed and acceleration limits, conforming to the assigned schedule, and seeking to optimize their individual trajectories. Our analysis rigorously establishes that the different aspects of the hierarchical design operate in concert and that the safety specifications are satisfied. We illustrate its execution through a suite of simulations and compare its performance against optimized signal-based coordination over a wide range of system parameters.