Integration of Mechanistic–Empirical Pavement Design Guide Distresses with Local Performance Indices

Abstract

The pavement management system (PMS) is the organizational entity within a state highway agency responsible for the condition of the pavement network. Visual distress surveys are typically combined into an index to provide an overall measure of performance. Decision makers use these familiar indices in a number of facets. A recent survey suggests every state highway agency has implemented or plans to implement the Mechanistic–Empirical Pavement Design Guide (MEPDG). As they do so, maintaining the role these local indices play is critical for upholding the system's continuity. However, using the MEPDG output directly in calculating performance indices becomes problematic because local distresses and MEPDG distresses are not always congruent. Therefore, there is a need to develop procedures for calculating local performance indices with locally calibrated MEPDG output. Doing so will allow interchangeable use of both while preserving the role of the local indices. The Nebraska Department of Roads (NDOR) PMS serves as a model case. NDOR employs three indices in network-level PMS analyses for flexible pavements. MEPDG flexible distress models were calibrated by using local agency data and input into the existing index functions. This paper explores how the current measures of network condition used in decision making can coexist with the new design methodology. This connection allows mechanistic–empirical analyses of fund allocation, needs estimations, performance modeling, planning, and remaining service life. In addition, local indices can provide much more meaningful failure criteria in the MEPDG to local designers. Practical methods for index calculations are introduced. Detailed guidance for local calibration is also presented.