Development of Relationship between Roughness (IRI) and Visible Surface Distresses: A Study on PMGSY Roads

Roughness has been universally accepted as a measure of functional condition of a pavement. It constitutes the smoothness and frictional properties of the pavement surface and in turn is related to the safety, and the ease of the driving path. It is determined using the international roughness index (IRI), which is a measure for texture of the pavement surface, and also depends on the amount of other functional distresses present on the road surface. The present study focuses on developing a relationship between the roughness and other surface distresses of PMGSY roads. Accordingly, eight PMGSY roads were selected in Jhunjhunu and Churu districts of Rajasthan, India. Distress data was collected for every 50m separately. Roughness data was collected using Bump Integrator, which was calibrated using MERLIN on the couple of selected study stretches. Unevenness data was also collected from a newly laid stretch of pavement, and the value thus obtained was subtracted from the observed unevenness values of the test stretches, to get the net effect of the distresses on the pavement condition. A regression equation was then developed with the IRI value and the visible distresses based on the data collected in the field.