Comparison of flexible airport pavement design methods

In airports, paved areas are constructed as rigid, composite, and flexible pavements. For the safety of the aircrafts, these pavements should satisfy structural and surface condition requirements. The design of pavements with high construction costs is an important subject while considering the aircraft costs that are much higher.In airport pavement design, emprical design methods are utilized rather than analytical methods since it is difficult to model flexible pavements mathematically. In this study, USCOE CBR (United States Army Corps of Engineer California Bearing Ratio) and FAA CBR (Federal Aviation Administration California Bearing Ratio) which are both empirical design methods are studied with a mechanistic-emprical design method called FAARFIELD (FAA Rigid and Flexible Iterative Elastic Layered Design).Under same design conditions, flexible pavement thicknesses are calculated by using design methods and the results are compared. According to evaluation of results, it is observed that subgrade bearing capacity, aircraft weight and wheel and gear arrangement affect flexible pavement thickness considerably. It is also observed that as subgrade bearing capacity becomes higher, calculated thicknesses are reduced. Critical subgrade bearing capacity at which rate of thickness reduces are determined as 10 CBR for FAARFIELD, 6 CBR for FAA CBR and 6 CBR at low weight and 10 CBR at high weight for USCOE CBR method.