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- #LTPP RIGID PAVEMENT DESIGN SOFTWARE UPDATE#
- #LTPP RIGID PAVEMENT DESIGN SOFTWARE SOFTWARE#
- #LTPP RIGID PAVEMENT DESIGN SOFTWARE TRIAL#
The performance indicators used for asphalt pavements include rutting, fatigue (or alligator) cracking, longitudinal cracking, and transverse cracking. Projected pavement distresses are used as performance indicators. These performance indicators include pavement roughness for all pavements, quantified according to the International Roughness Index (IRI), along with specific indicators according to the pavement type.
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Using the mechanistic models and data, the MEPDG process analyzes the pavement design with respect to performance indicators that reflect the projected impact of stresses and strains on the pavement over time. In using the MEPDG to design pavements, making these comparisons will give you a better sense of what factors have the most impact in a given situation.
#LTPP RIGID PAVEMENT DESIGN SOFTWARE TRIAL#
When the trial design is satisfactory, its assumptions may not need to be changed as dramatically for comparison with potential alternatives, but some tweaks should still be tried to see if they improve the predicted performance.
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Evaluating alternatives helps increase confidence that the pavement design that is ultimately selected is optimal for the circumstances. This is a reminder that fundamentally, mechanistic-empirical design is an iterative process. It is also important to tackle the second question even if the initial design assumptions appear satisfactory. If it is not acceptable, the design process will obviously need to move on and consider alternatives. If the trial design is acceptable, it should be retained as an option for the final pavement design. Or, it may be a matter of whether, in the judgment of the design engineer, the predicted level of performance is acceptable. The agency that owns the pavement will typically have specified criteria that can be used to answer the first question. The first question can be stated as, “Does the predicted performance of the pavement satisfy criteria for the design, such as the desired service life of the pavement, based on the level of distress and potential maintenance and rehabilitation needs?” The second question is, “Are there reasonable alternatives to the initial design assumptions that could generate better predicted performance or lower life cycle costs?” Both traffic and climate are used as inputs in the MEPDG process.Īt this point, there are two design questions that need to be considered.
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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.
#LTPP RIGID PAVEMENT DESIGN SOFTWARE SOFTWARE#
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, 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.
#LTPP RIGID PAVEMENT DESIGN SOFTWARE UPDATE#
The MEPDG is designed to update the 1993 AASHTO Guide for Design of Pavement Structures, which is primarily based on empirical observations from the AASHO Road Test that began in the 1950s.