Development of Present Serviceability Index (PSI) for Flexible Pavements

Abstract

One of the most key challenge on road pavement is to determine the quality and condition of existing pavements. Irrespective of design and construction, road pavement deteriorate with time and most credential factors of determining pavement condition is its surface roughness and distress. Although, Department of Road, Nepal measures the roughness as International Roughness Index (IRI) and distress as Surface Distress Index (SDI) separately, but there is no any single composite index that can predict the pavement condition. This research work deals with condition surveys which aims is to develop the Present Serviceability Index (PSI) to evaluate the pavement condition in effective way which comprise the both roughness index IRI and distress index SDI, where roughness is measured through vehicle mounted bump integrator and distress is accessed through visual inspection and manual measurement. And the model developed using regression analysis is PSI = 10.0745 – 1.107 * SDI – 0.4645 * IRI, where correlation coefficient value is found to be 0.9397. Performance curve of any flexible pavement section can be drawn out from this PSI value and also indicates the treatment measures needed for those sections.