Assessing the efficacy of contraflow strategies and ripple effects on peripheral road network performance: Insights from Brigjen Sudiarto Road, Semarang

Traffic congestion is a significant challenge in Semarang, Indonesia, a rapidly urbanizing metropolitan area. To address this issue, a contraflow strategy was implemented on Brigjen Sudiarto Road, aiming to alleviate congestion and enhance traffic efficiency. The assessment of the contraflow system's effectiveness utilized the Indonesian Highway Capacity Manual (PKJI). Data were obtained through direct observation and secondary sources, focusing on traffic volume, road capacity, and level of service (LOS) comparisons before and after implementation. Findings revealed a 75% reduction in westbound traffic saturation, attributed to adding one lane, while eastbound congestion increased slightly due to lane reduction. The analysis also highlighted the contraflow’s impact on surrounding roads, such as Soekarno Hatta and Supriyadi Streets, which serve as alternative routes during peak hours. Simulations indicated that the contraflow system improves flow efficiency and travel time, especially during morning and evening rush hours. This evaluation underscores the potential of contraflow strategies as practical interventions for managing urban traffic, providing insights for cities facing similar challenges globally.