A model for predicting the deterioration of the international roughness index

Road pavements continuously deteriorate mainly due to the combined influence of traffic load and environmental conditions. The pavement ability to satisfy the road user demands along its designed time of service expresses its performance level. The prediction of performance deterioration curves is a basic part of any Pavement Management System (PMS). Road roughness is an important parameter in determining the performance of pavements. The International Roughness Index (IRI) is the universal standard for measuring the pavement roughness and it has become the most widely employed pavement index. This paper presents the development of a model for predicting the deterioration of the IRI and calibrating its parameters based on the pavement structural factors such as structural number, asphalt layer thickness, subgrade strength, and environmental conditions. The approach adopted for the IRI deterioration model development was based on the combination of the empirical-mechanistic approach and the regressive empirical approach. The predicted results were compared with the measurements of road sections located in various climate zones, which are embedded in the PMS of Netivei Israel (NETI), National Company for Transport Infrastructures. The comparison shows a very good correlation, and most of the predicted results are within the measurement and interpretation error range.