Optimising U-turn efficiency at median openings: a simulation study of traffic-responsive signal control

This study proposes a methodologically novel approach to optimise the simulation and control of U-turn movements at central median openings. By integrating traffic dynamics in opposing lanes, we develop a parameterised signal control logic that determines optimal headway detector placement and calculates minimum green duration for U-turn phases, enabling adaptive phase adjustments. The model enhances simulation fidelity by directly linking field-observed traffic parameters to signal control logic in VISSIM. A calibrated micro simulation framework is established using real-world data, allowing for dynamic calibration and validation of control strategies. Comparative simulations demonstrate that the proposed method significantly improves traffic efficiency - reducing vehicle delays and increasing travel speed - particularly during peak periods. This work advances the simulation-driven optimisation of urban median openings, offering a replicable framework for adaptive signal control in complex traffic environments.