Assessing the Environmental Impact of Traffic Signal Optimization: CO₂ Emission Reduction Potential at a Signalized Intersection in Tobruk, Libya

Abstract

     Urban intersections in developing cities contribute significantly to vehicular CO₂ emissions due to inefficient traffic signal timing. This study investigates the environmental benefits of optimizing traffic signal coordination at a congested intersection in Tobruk, Libya, using SIDRA Intersection 5 software. Field data were collected during morning (7:30–8:30 AM) and evening (1:30–2:30 PM) peak hours via video recording and manual counting. Three signal timing scenarios were evaluated: (1) existing fixed-time operation, (2) coordinated fixed-time, and (3) coordinated actuated control. Environmental performance was assessed based on estimated CO₂ emissions, alongside operational indicators such as average delay, travel speed, and fuel consumption. Results show that the coordinated actuated scenario reduces CO₂ emissions by approximately 27–34% compared to the existing condition, while also improving average travel speed by 25% and reducing delay by 30%. The study concludes that signal coordination offers a low-cost, high-impact strategy for mitigating environmental externalities in mid-sized cities. Recommendations include adopting actuated control systems and integrating environmental metrics into traffic management policies in Libya.