♫ music ♫
Pavement performance is a complex interaction among four factors:
traffic loads, climate conditions,
the materials used to construct the various pavement layers,
and the soil or subgrade that the pavement is built on.
For each unique combination of these factors that impact pavement performance,
proper selection of an appropriate combination of materials and layer thickness is necessary
to achieve the desired design life and performance with a high degree of confidence.
This is typically accomplished with the help of a pavement design procedure.
The latest pavement design procedures employ mechanistic principles.
The basis of the mechanistic-empirical (or ME) design approach is the structural response of the pavement,
such as: stresses, strains, and deflections determined using mechanistic models.
Actual field performance data is used to empirically calibrate the relationship
between modeled, structural responses, and pavement performance.
The resulting calibrated, performance models are used to design pavements to a desired level of performance.
To accurately model pavement performance, design software calculates structural responses
for a range of traffic loading, as well as climatic and subgrade conditions that the
pavement is anticipated to encounter for the trial pavement design.
These structural responses are used to model the progression of key pavement distresses
and smoothness loss over time.
The outputs are the basis for checking the adequacy of a trial design.
AASHTOWare Pavement ME Design is the next generation of pavement design software,
based on mechanistic principles.
Shreenath Rao: "Pavement ME provides us a framework to use all the data that we have,
all the knowledge that we have about how pavements perform."
AASHTOWare Pavement ME Design includes the calibration-assistance tool to help:
determine if there is any bias in the predictions, establish the cause of any bias if it is found
through the calibration process, and optimize the calibration coefficients of the transfer functions
for each distress to eliminate bias and minimize the standard error of the estimate.
"With proper materials and proper construction, there is no reason why we cannot design a pavement
to last 30, 40, 50, or even 100 years, as long as we have the models and the knowledge
to know how this pavement will perform."
FHWA provides several resources to assist practitioners with ME Design.
The ME Design page on the FHWA Pavements website provides:
links to a comprehensive list of documents and a series of pre-recorded webinars covering
a variety of topics associated with ME Design, as well as a link to the Pavement ME User Group website.
[typing on keyboard]
ME Design reflects a change in the methods and procedures
engineers use to design pavement structures.
It takes advantage of the advances in: material mechanics,
axle-load spectra, and climate data for predicting pavement performance.
It is a leap forward from previous pavement design procedures and facilitates future development
in pavement modeling and analysis.
For more information on ME Design and other available resources, visit our website at
fhwa.dot.gov/pavement or follow FHWA on social media.
♫ music ♫