9.2.2 Pavement Design Method:
Before 2008, the FAA's standard method for flexible pavement design was known as the CBR
method. The CBR method was based on approximation charts that factored in the CBR value of the
subgrade and the number and the gross weight of equivalent annual departures of the design aircraft.
Separate approximation charts were provided by the FAA for different generic aircraft landing gear
configurations and aircraft greater than 300,000 Ib maximum gross weight.
As the design aircraft of Al-Auja International Airport is assumed to be Airbus A-380 (specified in
section 5.1), the approximation charts for pavement design are needed. But the A380-800 Airport
Planning Manual (APM) pointed that the pavement requirements curves are no longer provided
since all corresponding data is available through free software like FAARFIELD which depends on
the layered elastic method.
This chapter presents the pavement design procedures that are implemented by the FAARFIELD
computer program.
9.3 Design of Flexible Pavements by FAARFIELD
Flexible pavements consist of a hot mix asphalt (HMA) wearing surface placed on a base course and
a subbase (if required) to protect the subgrade. For flexible pavement design, FAARFIELD depends
on the layered elastic method, which uses the maximum vertical strain at the top of the subgrade and
the maximum horizontal strain at the bottom of all asphalt layers., as shown in Figure 9-2.