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The Mechanistic-Empirical Pavement Design Guide (MEPDG) made available by the National Cooperative Highway Research Program in 2004 uses a power model that incorporates dynamic modulus (DM) as a factor in predicting rutting performance of asphalt concrete. The rutting model is empirical and the rutting profiles obtained from the model are based largely on the adjustment of calibration constants, not the DM. Various DM values would be capable of producing similar rutting profiles based on the current model. This study evaluates using accumulated strain data obtained from the Repeated Load Test (RLT) as an alternative to using DM. In addition, a model to represent the accumulated strain data obtained from the RLT is developed. The accuracy and behavior of the current model and the model developed in this study in representing a mix from Louisiana are compared. Alternatives for incorporating the RLT data into the MEPDG are also presented. DOI: 10.1061/(ASCE)0899-1561(2007)19:11(993) CE Database subject headings: Pavement design; Cyclic loads; Load tests; Regression models; Repeated loads; Asphalt; Concrete.

The dynamic modulus of asphalt concrete mixtures is a key property in assessing asphalt pavement performance based on its role in the mechanistic-empirical design method. The dynamic modulus is also considered to be used as one of the major characteristics in performance-related specifications for quality assurance. However, no feasible method to estimate the mean and variance of the in-place dynamic modulus for the as-built asphalt pavement has been suggested. This paper presents a methodology of stochastically evaluating the in-place dynamic modulus of the as-built asphalt pavement using a relationship of in-place air voids and a set of single dynamic modulus values measured in the laboratory. The methodology was validated with asphalt mix collected from a construction site. The comparison plot between the estimated in-place dynamic modulus and as-designed asphalt mix demonstrated a simple way to evaluate the as-built mix quality. This methodology provides several practical advantages to determine the quality of as-built mix compared with that of as-designed mix in terms of the dynamic modulus. In addition, the methodology envisions the possibility of incorporating the dynamic modulus into performance-related specifications. [ABSTRACT FROM AUTHOR]

A risk-based approach to manage traffic sign inventories was developed for application in local public agencies (LPAs). The method incorporates key aspects of safety such as accident history and hot spot ranking and allows agencies to develop sign inventories strategically for a variety of staffing resources and budget levels. This method would enable LPAs to more easily comply with Federal Highway Administration Manual on Uniform Traffic Control Devices (MUTCD) retroreflectivity guidelines and to prioritize the signs to be included in the inventory. A procedure has been developed that puts priority on reducing the risk of liability for sign-related accidents. The inventory developed as part of this research also supports the broader focus of better management of LPA roadway assets. Consistent and strategic updates of the inventory would provide the LPAs with a sustainable asset management system to utilize in the future. [ABSTRACT FROM PUBLISHER]

In areas of high population density, widening all classifications of roadways for growing traffic volumes becomes increasingly complex and expensive to complete. For major highways in Europe and the United States (US), use of the shoulder as a part-time lane is becoming progressively common and may be a solution to growing traffic on lower roadway classifications. This approach is known as hard shoulder running internatio nally and part-time shoulder use (PTSU) in the US. For interstates or other major highways, the shoulder design is a full-depth paved shoulder, the same pavement cross-section as the mainline lanes, and is structurally sound. For arterials and collectors, the shoulder design commonly has a different pavement cross-section from the mainline lanes, a partial-depth paved shoulder design. This study focused on evaluating the design strength of typical partial-depth paved shoulder designs in the US for PTSU using the American Association of State Highway and Transportation Officials (AASHTO) Guidelines for Design of Pavement Structures 1993 design. The study sites were also redesigned according to the AASHTO design methodology to handle the PTSU design traffic vol umes. This study found that two of the nine states evaluated could withstand PTSU with minor to no reconstruction. [ABSTRACT FROM AUTHOR]