Sensitivity Analysis of Highway Economic Requirements System Pavement Performance Models

Abstract

The Highway Economic Requirements System (HERS) is an analysis tool that was developed with the primary purpose of estimating the future investment requirements of the US road network, which directly informs the biennial report on conditions and performance submitted to the US Congress. One of the four primary investment types considered in HERS is pavement surface improvement, or the investment requirements and performance effects resulting from maintaining or rehabilitating pavement segments on the national highway system over a significant time period (typically 20 years). Pavement performance models are a fundamental part of the HERS analysis, and ensuring that they produce reasonable results is a critical step in ensuring that the predicted resource needs of the US road network are within a reasonable range. This paper presents a comprehensive sensitivity analysis of the HERS pavement performance models for asphalt pavements. The sensitivity analysis was performed using Monte Carlo simulation accounting for the correlations of the many input variables, and its results indicated that many improvements to the models were required; those improvements are also detailed in this paper.