Finally, PaveXpress incorporated the FHWA RealCost methodology for life cycle cost analysis.Structural Behavior of Asphalt Pavements Book Description :
In 2018, PaveXpress added the Structural Porous Pavement Design methodology developed by Dr. In addition to the 19 AASHTO Guides, PaveXpress uses the EverStress models for performing mechanistic analysis of existing pavements and new pavement structures. For rigid pavements, the application utilizes the 1998 Guide. The 1993 Guide is used for new flexible pavements and the rehabilitation of existing flexible pavements. Known as PaveXpress, this application incorporates the 1993 AASHTO Guide for the Design of Pavement Structures and the 1998 AASHTO Supplemental Guide for the Design of Pavement Structures. In 2013, the asphalt industry began development of an Empirical and Mechanistic-Empirical Pavement Design application. Mechanistic and Empirical Design – PaveXpress VDOT is in the process of implementing the new AASHTO Mechanistic-Empirical Pavement Design Guide (MEPDG) for pavement rehabilitation and new construction structural design. This leads to an estimate of the level of damage the pavement will sustain over time, in terms of pavement distresses and deterioration in ride quality.
MEPDG software can compute how the trial design will respond to the load and environmental stresses created by these inputs. In mechanistic-empirical design, the design of the pavement structure is initially assumed on a trial basis, along with inputs for traffic and climate. In conventional design methods, various inputs are considered and used to produce the design requirements for the pavement structure. One of the significant changes with the MEPDG is that the approach to pavement design is effectively reversed. In conjunction with the MEPDG research project, a software was also developed to assist in organizing and performing these design calculations. By using newer data collected as part of the Long-Term Pavement Performance (LTPP) program, the MEPDG allows for design inferences that would be harder to justify from the limited designs and traffic levels covered by the Road Test.
The MEPDG is designed to update the 1993 AASHTO Guide for Design of Pavement Structures, which is primarily based on empirical observations from the AASHTO Road Test that began in the 1950s. Mechanistic-Empirical Design – AASHTO MEPDG This method is used by VDOT for higher-volume secondary roads, primary roads, and interstate highways. The most commonly used empirical pavement design method is the 1993 AASHTO Guide for Design of Pavement Structures. Specifically, it is not prudent to use an empirically derived relationship to describe phenomena that occur outside the range of the original data used to develop the relationship. Although the scientific basis for these relationships is not firmly established, they can be used with confidence as long as the limitations of such an approach are recognized. This means that the relationships between design inputs (e.g., loads, materials, layer configurations and environment) and pavement failure were determined using experience, experimentation or a combination of both. Many pavement structural design procedures use an empirical approach. Vaswani Design Guide for Subdivision and Secondary Roads in Virginiacan be found on the VDOT website. Today, this method is still in use for low-volume secondary and subdivision roads. The Vaswani method was developed for use on all new asphalt pavement designs as well as overlay of asphalt pavements. Nari Vaswani, a researcher at the Virginia Highway and Transportation Research Council (today known as the Virginia Center for Transportation Innovation and Research), took the results of the AASHTO Road Test and developed a modified procedure known as the Vaswani method. A recommendation from this national report was for transportation agencies to modify the design approach to local conditions and materials. In the early 1960’s, AASHTO (formerly AASHO) released a pavement design methodology based on the results of the national road test in Ottawa, Illinois. Empirical Design – Secondary and Sub-Division Roads (Vaswani Method) The principal methods of structural design in use today are (from simplest to most complex) empirical and mechanistic-empirical. Calculations are chiefly concerned with traffic loading stresses other environmentally related stresses (such as temperature) are accounted for in mix design asphalt binder selection. Structural design is mainly concerned with determining appropriate layer thickness and composition.
This section is focused on the structural design of new pavement. This includes the surface course as well as any underlying base or subbase layers. The goal of structural design is to determine the number, material composition and thickness of the different layers within a pavement structure required to accommodate a given loading regime.