Adaptive Traffic Signal Control With Deep Reinforcement Learning and High Dimensional Sensory Inputs: Case Study and Comprehensive Sensitivity Analyses

Despite the constant rise in global urban populations and subsequent rise in transportation demand, significant expansion of infrastructure has been hampered by the constraints of space, cost, and environmental concerns. Therefore, optimizing the efficiency of existing infrastructure is becoming increasingly important. Adaptive traffic signal controllers aim to provide demand-responsive strategies to minimize motorists’ delay and achieve higher throughput at signalized intersections. With the advent of new sensory technologies and more intelligent control methods, the contribution of this paper is an adaptive traffic signal controller able to receive un-preprocessed high-dimensional sensory information such as GPS traces from connected vehicles and self-learn to minimize intersection delays. We use deep neural networks to operate directly on detailed sensory inputs and feed them into a reinforcement learning-based optimal control agent. The integration of these two components is known as deep learning. Using deep learning, we achieve two goals: (1) We eliminate the need for handcrafting a feature extraction process such as determining queue lengths, which is challenging and location-specific, and (2) we achieve better performance and faster training times compared to conventional tabular reinforcement learning approaches. We test our proposed controller against a tabular reinforcement learning agent, a reinforcement learning agent with a fully-connected Neural Network as a function approximator, and a state-of-practice, actuated traffic signal controller.