Tourism-oriented coastal corridors play a critical role in enhancing regional accessibility, economic development, and sustainable mobility, particularly within environmentally sensitive areas. In Thailands Eastern Economic Corridor (EEC), scenic roads function not only as transport infrastructure, but also as strategic tourism logistics platforms connecting coastal destinations, urban centers, and service networks. This study proposes and applies an integrated Traffic Impact Assessment (TIA) framework to evaluate the Burapha Chollatit Scenic Road Phase 2 Project in Rayong Province, Thailand. The research extends conventional TIA approaches by incorporating tourism demand characteristics, weekend and holiday peak scenarios, intersection-level operational performance, environmental integration, and stakeholder participation. Traffic performance was assessed using volume-to-capacity ratios (V/C), control delay, and Level of Service (LOS) at corridor segments and 28 upgraded intersections under before-and-after scenarios. Results indicate a systematic improvement in network operations, with junctions transitioning from oversaturated conditions (LOS E–F; V/C ≈ 1.05–1.10) to stable flow conditions after improvement (LOS B–C; V/C ≈ 0.72–0.78). Segment-level performance similarly improved, enhancing travel time reliability and supporting tourism-related logistics movements, particularly during weekend and holiday peaks. The project supports and promotes approximately 1.64 million tourist trips annually and generates cumulative economic benefits exceeding THB 27 billion over the project lifecycle. Environmental mitigation measures and real-time monitoring systems further strengthen corridor safety and resilience. The findings demonstrate that integrating TIA with sustainable tourism planning, environmental assessment, and community engagement is essential for coastal infrastructure development. This study contributes a transferable evaluation framework for tourism-oriented road projects in coastal and economic corridor contexts.