Abstract:
A case study has been carried out to compare the design of airfield pavements
for a major airport using FAARFIELD v1.32 and APSDS 5.0. For the aircraft
departure data used in the study, the pavement analysis shows that the APSDS 5.0
design method yielded pavement structure thicknesses that are nearly the same
as FAARFIELD v1.32 for CBR greater than 10%. An adjustment factor kc is
required for APSDS design thickness to produce designs that are consistent with
FAARFIELD for CBR less than 10%. In May 2017, FAA developed new subgrade
failure models for flexible pavements in FAARFIELD v1.41 using the full-scale
traffic test data collected at the NAPTF for Test Sections in Construction Cycles CC3
and CC5. FAARFIELD v1.41 was subsequently updated and evolved to version 1.42
in September 2017. In this paper, a comparison is carried out using the latest version
of FAARFIELD v1.42 to examine if the new subgrade deformation models compute
the design thicknesses that are compatible with that generated by APSDS 5. For the
Boeing 737-800 (Code C) and 777-300ER (Code E) aircrafts spectrum and 100,000
movements analyzed in the study, the new subgrade failure models developed for the
latest version of FAARFIELD generate the flexible pavement thicknesses that are
not significantly difference from that of APSDS 5.0 for subgrade CBR ≥5%. The
new failure model in FAARFIELD v1.42 produces flexible design thicknesses that
differ less from APSDS 5.0 than FAARFIELD v1.32. The design thicknesses are
more consistent for B737-800 with 2 wheels configuration. However, the differences
are observed to be larger for CBR ≤5% when modelled with B777-300ER having
6 wheels configuration. The differences in the design thickness are attributed to the
different coefficients adopted in the subgrade failure models in the design software.
