Determining the Consumption of OS/OW Vehicles Using Mechanistic-Empirical Principles

Abstract

This study focuses on developing a methodology to establish load equivalencies between OS/OW loads based on the concept of equivalent damage using Mechanistic-Empirical design procedures for rigid pavements, more specifically for CRC pavements. In the context of this study, a particular load that results in similar response (or pavement performance) as that of a reference load is considered as equivalent. The study focuses on two different failure mechanisms – roughness and punchouts, for the determination of the equivalent damage factors (EDF). Furthermore, the study introduces the partial factors – axle load factor (ALF) and group equivalency factor (GEF), and attributes the EDF for any given axle load and configuration to these two factors. Given that pavement responses are largely influenced by climatic and site-specific features, the study team analyzed a number of CRCP sections that were sampled across the state of Texas so that there is a good representation of sections from each of the five different climatic regions. Results showed that for punchout failures there is a linear relationship between the normalized load and the EDF on a log-log scale. However, there was no noticeable evidence suggesting a relationship between the ALF and slab thickness. Following this observation, the study team obtained a gross average ALF that is independent of the different axle groups and slab thicknesses. In the case of roughness, an exponential relationship was employed in capturing the relationship between the EDF and the normalized load. Just as with the punchout failure, the ALF and slab thickness were found to be uncorrelated. Therefore, an average ALF was computed.