Impact of Pavement Surface Distress on Road Capacity

Abstract: This study investigates the impact of road surface distress on road capacity, recognizing the essential role of capacity in maintaining efficient and safe traffic flow. Road surface distress, which encompasses various forms of pavement deterioration such as cracks, potholes, and unevenness, is considered a critical factor due to its potential to significantly reduce road capacity. The primary objective of this research is to examine the relationship between road capacity and pavement distress, offering insights that are essential for enhancing traffic efficiency and safety. To achieve this objective, data were collected on road surface distress and traffic flow across two road sections: one with visible pavement distress and the other without such deterioration. Data collection took place during two peak traffic periods, morning and evening, on a designated road in Ambatale, Sri Lanka, an area characterized by varied traffic conditions. Road capacity was estimated by analyzing the relationship between traffic flow and vehicle density, while road distress data were quantified using International Roughness Index (IRI) values. These values were obtained via a smartphone-based application, which enabled measurement of surface irregularities. The findings revealed a significant reduction in road capacity within the distressed section, with an average capacity loss of 13.54 percent, underscoring the negative effect of pavement distress on traffic flow. The IRI values further supported these results, showing 1.9 meters per kilometer in the non-distressed section and 8.02 meters per kilometer in the distressed section. This substantial difference in roughness indicates the severe impact of surface distress on road capacity, emphasizing the need for effective road maintenance strategies to ensure safe and efficient traffic movement. The outcomes of this study offer valuable information for traffic engineers and policy makers aiming to improve roadway conditions and optimize traffic performance.