Sustainable Engineering, Maritime Systems, and Applied Technology
On-street parking can reduce effective roadway width, increase side friction, and disrupt traffic flow. This study evaluates the effects of on-street parking on roadway performance across five road segments in Sumedang Regency, Indonesia, using the 2023 Indonesian Highway Capacity Guidelines (PKJI 2023). A descriptive quantitative approach was applied. Traffic counts and roadside activity were observed continuously for 24 hours a day over seven consecutive days on Kebun Kol, Prabu Geusan Ulun, Tampomas, Sebelas April, and Pangeran Santri roads. Data were analyzed in one-hour intervals to assess traffic volume, side friction, free-flow speed, road capacity, degree of saturation, and level of service, including weekday–weekend differences. The study aims to provide an empirical basis for managing on-street parking in a regional urban context. The authors report that measures such as peak-hour parking restrictions, designated parking zones, and side-friction management can improve roadway performance by restoring effective carriageway width. The results are intended to inform traffic-management strategies that support more efficient and sustainable mobility in Sumedang Regency.