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. 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. 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