Phase-free traffic signal control for balanced flow in sensor-limited environments

Area of Science:

• Civil Engineering
• Transportation Engineering
• Intelligent Transportation Systems

Background:

• Traditional Adaptive Traffic Signal Control (ATSC) systems can lead to inequitable green time allocation, especially during oversaturated traffic conditions.
• Limited sensor coverage in urban environments poses challenges for real-time traffic management and queue length estimation.
• Existing systems often struggle to balance traffic throughput with equitable service for all movements.

Purpose of the Study:

• To develop and evaluate a phase-free traffic signal control system that improves both traffic efficiency and equity in sensor-limited environments.
• To address the limitations of traditional ATSC in managing oversaturated traffic and ensuring fair green time distribution.
• To propose a Cell Transmission Model (CTM)-based approach for estimating queue lengths and waiting times beyond sensor detection zones.

Main Methods:

• Utilized a Cell Transmission Model (CTM) to estimate real-time queue lengths and waiting times for traffic movements.
• Implemented a distributed approach where adjacent intersections exchange traffic information.
• Developed a phase-free system that dynamically allocates green time based on estimated traffic conditions.
• Conducted numerical experiments on a two-intersection and a 3x3 grid network.

Main Results:

• Achieved a 15% reduction in average control delay compared to traditional control systems.
• Demonstrated small deviations in the level of service between different traffic movements, indicating improved equity.
• Successfully estimated queue lengths and waiting times in congested conditions beyond sensor detection zones.
• Validated the system's performance on various network configurations.

Conclusions:

• The proposed phase-free traffic signal control system offers a scalable solution for improving traffic efficiency and equity in urban areas.
• The CTM-based approach effectively addresses challenges posed by limited sensor coverage and oversaturated traffic.
• The system's ability to balance throughput maximization with equitable treatment of traffic movements shows significant potential for real-world application.