CTM-based traffic signal optimization with variable speed limit and dynamic lane allocation

Abstract

Since its introduction more than a decade ago, the lane-based signal timing method has become a popular approach to optimizing signal timing plans because it treats lane markings as decision variables and does not require pre-defined signal phases. A major limitation is that this method assumes point queues at stop lines and uses non-linear delay formula. To address this challenge, This study integrates the cell transmission model (CTM) with lane-based signal timing. Variable speed limit (VSL) is additionally introduced to advance traffic control as follows: (1) Lane allocation, speed limit, and signal timing are simultaneously optimised; (2) The CTM is combined with the lane-based model to model spatial queues and lane blockage; and (3) A rolling horizon approach is proposed to optimise the VSL and signal settings based on real-time traffic volume. Numerical experiments are conducted to validate the proposed model.