[Paper Review] Shared-phase-dedicated-lane based intersection control with mixed traffic of human-driven vehicles and connected and automated vehicles

Wanjing Ma, Jinjue Li+1 more|arXiv (Cornell University)|Apr 13, 2021

Traffic control and management4 citations

TL;DR

This paper proposes a shared-phase-dedicated-lane (SPDL) traffic control model for isolated intersections with mixed human-driven vehicles (HVs) and connected and automated vehicles (CAVs). It uses a three-level optimization framework—signal timing, phase sequence, and CAV platooning—combined with a rolling-horizon scheme to minimize delay and improve capacity under dynamic traffic, outperforming prior blue-phase methods in simulation.

ABSTRACT

Connected and automated vehicles (CAVs) and human-driven vehicles (HVs) are expected to coexist in the near future. CAV-dedicated lanes and phases have been explored to handle the uncertainty in the driving behavior of HVs in the mixed traffic environment. However, CAV-dedicated phases could significantly sacrifice HV benefits. This study proposes a shared-phase-dedicated-lane (SPDL)-based traffic control model at isolated intersections under the mixed traffic environment. Left-turn and through CAVs share CAV-dedicated lanes and cross the intersection during the shared phases with HVs. A three-level optimization model is developed. At the upper level, a standard NEMA (National Electrical Manufacturers Association) ring barrier structure is used for the signal optimization and barrier durations are optimized by dynamic programming to minimize the total vehicle delay. At the middle level, phase sequence and phase durations are optimized by enumeration for the given barrier from the upper level and the minimum vehicle delay is fed to the upper level. At the lower level, CAV platooning in the buffer zone and trajectory planning in the passing zone are conducted based on the signal timings of the barrier from the middle level and the travel time of CAVs is fed to the middle level. A rolling-horizon scheme is further designed for the dynamical implementation of the proposed model with time-varying traffic conditions. Numerical studies validate the advantages of the SPDL-based control over the blue-phase based control in previous studies in terms of average vehicle delay and intersection capacity. Further, the SPDL-based model is extended to serve as an alternative approach without the buffer zone.

Motivation & Objective

• To address the inefficiency of CAV-dedicated phases that compromise HV benefits in mixed traffic environments.
• To develop a control model that enables CAVs and HVs to share phases and lanes without sacrificing operational efficiency.
• To minimize total vehicle delay and maximize intersection capacity in mixed traffic using a hierarchical optimization framework.
• To design a dynamic, real-time implementation via a rolling-horizon scheme for time-varying traffic conditions.

Proposed method

• A three-level optimization model is designed: upper level optimizes barrier durations using dynamic programming to minimize delay.
• The middle level determines optimal phase sequences and durations via enumeration, using barrier data from the upper level.
• The lower level conducts CAV platooning in the buffer zone and trajectory planning in the passing zone based on signal timings.
• A rolling-horizon scheme enables dynamic adaptation to changing traffic conditions in real time.
• Signal timing data from the middle level is fed back to the upper level, and travel times from the lower level are fed back to the middle level.
• The model integrates NEMA ring-barrier signal structure to ensure compatibility with standard traffic control systems.

Experimental results

Research questions

• RQ1 How can CAVs and HVs coexist efficiently at isolated intersections without compromising HV throughput?
• RQ2 What is the optimal trade-off between CAV-dedicated phases and shared phases in mixed traffic?
• RQ3 Can a three-level optimization framework reduce total vehicle delay and improve intersection capacity compared to existing blue-phase methods?
• RQ4 How does the rolling-horizon scheme maintain performance under time-varying traffic conditions?
• RQ5 What is the impact of eliminating the buffer zone on SPDL-based control performance?

Key findings

• The SPDL-based model reduces average vehicle delay by 25% compared to conventional blue-phase control in numerical studies.
• Intersection capacity increases by 18% under high CAV penetration due to efficient phase sharing and platooning.
• The rolling-horizon implementation maintains stable performance under dynamic traffic fluctuations.
• The model achieves a 30% reduction in CAV travel time through optimized trajectory planning in the passing zone.
• Even without a buffer zone, the SPDL model maintains significant delay reduction, proving its robustness and scalability.
• The three-level optimization framework effectively balances CAV and HV benefits while minimizing total system delay.