Analysis of the Impact of Road Damage on Traffic Characteristics

The deterioration of road infrastructure significantly degrades traffic performance encompassing speed, volume, and density parameters—while simultaneously impeding regional economic growth. This decline in service standards triggers inefficiencies in logistics distribution, reduces average travel speeds, and escalates travel times. The evaluation of pavement surface condition was conducted utilizing two visual survey methods: the Pavement Condition Index (PCI), which is based on distress type and severity level, and the Surface Distress Index (SDI) according to Bina Marga standards. Concurrently, the interrelationships among traffic characteristics were analyzed using four macroscopic mathematical models, namely Greenshields, Greenberg, Underwood, and Bell. The fundamental parameters including flow, speed, and density derived from the best-fit model were subsequently correlated with the PCI and SDI values of each road segment. This study examines the impact of road infrastructure damage on macroscopic traffic parameters. The results confirm a strong causality between pavement deterioration and reduced level of service. For degraded roads, the Greenshields linear and Underwood exponential models best represent the traffic flow dynamics (0.748–0.936). In contrast, the Greenberg logarithmic model shows the highest goodness of fit ( 0.820–0.977) for well-maintained road sections. The deterioration drastically impairs traffic efficiency, reducing space mean speed by 45% - 72%, traffic volume by 19% - 94%, and density by 5% -96%. Additionally, the Pavement Condition Index (PCI) demonstrates superior reliability over the Surface Distress Index (SDI) in predicting these traffic characteristics. A strong positive correlation exists between PCI and operational speed ( 0.9902), maximum volume (0.863), and maximum density (0.9474). Regression analysis indicates that a 10-point improvement in PCI corresponds to an absolute increase in average speed by 4.5 km/h, capacity by 120 pcu/h, and maximum density by 18 pcu/km.