Adaptive Signal Control for Multimodal Traffic: Concurrently Offering Multi-Path Progression and Transit-Friendly Signal in Real-Time

Conflicting objectives of traffic signal settings for arterials with multimodal traffic often trouble practitioners, particularly when one needs to consider various modes and competing flows en masse. Although many sophisticated real-time adaptive signal control systems have been developed over the past decades, how to offer transit-friendly signals while responding to the fluctuating demand of general traffic remains an ongoing issue that has yet to be fully addressed. As such, this study has proposed an adaptive traffic control system adjusting cycle length, offsets, and splits featuring the capability of 1) generating progression bands for both through and turning vehicles in real-time; 2) offering transit-friendly signal for high-frequency service without disrupting the general traffic; and 3) a decision process to select the signal plans among a pool of candidates that concurrently satisfy multiple objectives while offering a stable plan when altering the signal plan in real-time. The signal plan adjustment is on a cycle-by-cycle basis, and its short computation time allows the plan to be ready prior to the beginning of the next cycle. The promising results can be seen in the case study: the proposed model has shown improvements in the networkwide delay, ranging from 4.7% to 5.7%, compared to state-of-the-practice coordination-actuation. By integrating the objective of reducing bus delays, the system has further shown a significant reduction in bus delays, ranging from 6.6% to 15.0%.