Traffic signal optimization on a square lattice with quantum annealing

TL;DR

This paper presents a new method for optimizing traffic signals using a quantum annealing machine, showing better performance than traditional methods in reducing traffic imbalance.

Contribution

A novel global traffic signal control method using quantum annealing is proposed and shown to outperform conventional approaches.

Findings

The global control method reduces traffic imbalance more effectively than local control methods.

Quantum annealing provides better solutions than simulated annealing for the traffic signal optimization problem.

Analytical proof shows convergence of local and global methods under equal turning and straight probabilities.

Abstract

The spread of intelligent transportation systems in urban cities has caused heavy computational loads, requiring a novel architecture for managing large-scale traffic. In this study, we develop a method for globally controlling traffic signals arranged on a square lattice by means of a quantum annealing machine, namely the D-Wave quantum annealer. We first formulate a signal optimization problem that minimizes the imbalance of traffic flows in two orthogonal directions. Then we reformulate this problem as an Ising Hamiltonian, which is compatible with quantum annealers. The new control method is compared with a conventional local control method for a large 50-by-50 city, and the results exhibit the superiority of our global control method in suppressing traffic imbalance over wide parameter ranges. Furthermore, the solutions to the global control method obtained with the quantum annealing machine are better than those obtained with conventional simulated annealing. In addition, we prove analytically that the local and the global control methods converge at the limit where cars have equal probabilities for turning and going straight. These results are verified with numerical experiments.

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