Scenario-based evaluation of phase optimization, coordinated signal control, and flyover alternative with integrated economic and environmental appraisal: a multi-intersection corridor study in Eastern Thailand

This study develops an integrated evaluation framework that combines lane-based analytical modeling with incremental economic and environmental appraisal to assess congestion management strategies in a developing-country context. The framework is novel in jointly evaluating operational measures (phase optimization and coordinated signal control) and infrastructure-based interventions (flyovers) within a unified structure that translates analytical outputs into monetized performance metrics, including annualized fuel and emission costs as well as incremental benefit–cost ratios. The approach is applied to a critical three-intersection corridor in Chonburi Province, located in Thailand’s Eastern Economic Corridor, a rapidly industrializing region facing severe congestion. Three scenarios were compared against a base case using SIDRA Intersection software, with systematic assessment of average delay, level of service, fuel consumption, and vehicular emissions (CO2, CO, HC, NOx). Results show that phase optimization consistently reduces delays, fuel consumption, and emissions across all intersections, whereas the performance of coordinated signal control is highly site-dependent—providing substantial benefits where geometric continuity supports platoon progression but worsening conditions where geometric bottlenecks disrupt progression. Flyover implementation delivers the largest and most consistent improvements across all intersections. Incremental benefit–cost analysis further confirms the economic viability of flyover investment, with ratios remaining robust under sensitivity testing. Overall, the findings underscore the importance of integrating operational, environmental, and economic dimensions in traffic infrastructure planning and demonstrate a replicable framework for sustainable, cost-effective congestion mitigation in rapidly urbanizing regions.