Influence of Measurement Variability of International Roughness Index on Uncertainty of Network-Level Pavement Evaluation

Abstract

International roughness index (IRI) is widely employed for evaluating pavement performance. It is a critical indicator used by state transportation agencies to identify the maintenance demands for road sections. However, the determination of IRI is susceptible to measurement variability, especially for network evaluations where the IRI value of a road section is determined only based upon a single test run. Therefore, it is necessary to understand and quantify the influence of measurement variability on pavement evaluation. In this paper, the uncertainty of pavement evaluation due to the run-to-run IRI errors was defined and quantified utilizing raw data from long-term pavement performance (LTPP). Three factors contributing to the uncertainty of pavement evaluation were investigated. They are (1) the performance thresholds, (2) variability of IRI measurement, and (3) distribution of IRI for a road network. Probabilistic relationship was constructed to consider the influence of run-to-run variability of IRI for network-level pavement evaluation. Results indicated that the uncertainty of road sections rated as good were the lowest, whereas those rated as fair were generally high. The variability of IRI measurement significantly affected the pavement evaluation for state routes.