#PAVEMENT DESIGN AASHTO METHOD FULL#
#PAVEMENT DESIGN AASHTO METHOD SERIES#

This is required when existing pavements are being upgraded or replaced. AASHTO IRI Calculator - This spreadsheet calculates the pavements current IRI value from the pavement condition.AASHTO MEDG Method Design Spreadsheet - This spreadsheet takes the results of the elastic analysis and uses them to calculate the maximum design loadings for three different failure mechanisms as described above.The results of this analysis are taken forward as inputs to the AASHTO MEDG Method Design Spreadsheet. Boussinesq Analysis Spreadsheet - This spreadsheet can be used to complete a multi-layer elastic analysis of the proposed flexible pavement structure using the Boussinesq method.The CivilWeb AASHTO MEDG Design Method Spreadsheet Suite includes 6 spreadsheets to allow the designer to complete the flexible pavement design. The CivilWeb AASHTO MEDG Design Method Spreadsheet Suite The key design parameters for longitudinal cracking are the tensile strain at the top of the asphalt layer and the dynamic modulus of the asphalt. Longitudinal cracking occurs when cracks begin at the surface. The key parameter for deformation failure is the resilient strain and the thickness of the asphalt layer. The main design parameter for fatigue failure is the tensile strain at the base of the asphalt layer which is taken from the multi-layer elastic analysis.ĭeformation occurs when the asphalt layer is slowly compressed from the top. Each failure mechanism requires different design inputs.įatigue failure occurs when cracks slowly propagate through the asphalt from the base. These three failure mechanisms are fatigue failure, deformation failure and longitudinal cracking failure. The spreadsheet evaluates the proposed pavement using the three failure mechanisms included in the MEDG method. Once the Boussinesq analysis is complete, the results are input into the MEDG method spreadsheet which determines whether the design is valid or not. The AASHTO MEDG Method Design Spreadsheet suite includes a powerful elastic analysis tool which completes a multi-layer elastic analysis of the proposed pavement using the Boussinesq theory. The MEDG method is not suitable for hand calculations as it uses the strain results from a complex elastic analysis of the pavement layers as a primary input. AASHTO MEDG Method Design Spreadsheet - Inputs This is why the model is mechanistic-empirical. While all possible efforts were made to understand the design of pavements, the model still needed to be calibrated which was done using experimental data. The MEDG is still not 100% mechanistic in nature. After a long period of research the AASHTO Mechanistic-Empirical Design Guide (MEDG) was published and the transition from the original AASHTO method began. This required a greater understanding of the underlying mechanistic reasons behind pavement performance. The idea behind the MEDG was to make the design equations applicable to more environmental conditions and for any type of pavement construction. Road testing of pavements is expensive and so when pavement types began to deviate from those used in the original AASHTO Road Test new methods of design needed to be found. However empirical designs cannot be used where site or pavement conditions deviate substantially from those used for the test. This is the basis of the AASHTO Design Method.Įmpirical equations work very well when the road and site conditions are similar to those included in the original test. This was repeated with several different pavement constructions and design equations were derived from the results.

#PAVEMENT DESIGN AASHTO METHOD SERIES#

These equations were derived from road tests which recorded the loads acting on a series of test pavement sections and then recorded the damage caused by this loading. The structural design of flexible pavements has long been determined using empirical equations.

#PAVEMENT DESIGN AASHTO METHOD FULL#

Alternatively the full CivilWeb Flexible Pavement Design Suite is available for just £20. The CivilWeb AASHTO MEDG Design Spreadsheet suite is available to purchase at the bottom of this page for just £10. The CivilWeb AASHTO MEDG Design Spreadsheet suite includes a tool to complete these calculations which are then used to determine the validity of the proposed pavement design. To determine these strains a multi-layer elastic analysis must be undertaken which can take many hours to complete by hand. The AASHTO MEDG Method of flexible pavement design is not generally suitable for hand calculation as it includes complex calculation of the horizontal strains induced in the pavement structure under load.

This suite of spreadsheets includes 7 spreadsheets which provide all the tools required to complete a flexible road design. The CivilWeb AASHTO MEDG Method Design Spreadsheet is a powerful collection of design spreadsheets which can be used to design flexible pavements in accordance with the AASHTO MEDG Method.

Pavement design aashto method