A New Approach in Estimating the Overall Condition of Asphalt Pavements Using a Combined Index: An Iranian Case Study

Abstract
Maintenance activities are of the utmost importance during the pavement lifecycle. Pavement assessment methods can be implemented to discover the leading cause of deterioration and select a proper maintenance activity. Agencies use economical and rapid pavement condition assessment approaches to address maintenance needs. It is understood that recruiting pavement engineers or technicians for field surveys or using automatic equipment for data acquisition are costly approaches. Past studies suggest that a more attractive solution can be using pavement surface images to inspect the condition based on an inclusive subjective index such as Pavement Surface Evaluation and Rating (PASER). Besides, it is also understood that any individual indices do not represent the overall condition of the pavement. The use of only the International Roughness Index (IRI) or visual surface distresses in the maintenance decisions may not be adequate. Therefore, this study proposed a new combined condition index that compensates for the insufficiency of each index. The pavement conditions in 367 sections in Kermanshah, Iran, were evaluated using PASER and IRI. Then, by combining both indices using a weighted summation approach, an Overall Surface Condition Index (OSCI) was developed that can supremely express the overall condition of the pavement and propose a superior maintenance strategy compared to PASER and IRI. The outcome or result gained from this study could be a practical approach for road agencies to estimate the road network condition cost-effectively and make proper decisions for pavement maintenance at the network level.

Keywords: Pavement Maintenance, PASER, IRI, Combined Condition Index, Weighted Summation.