ABSTRACT
E-moduli for single points on existing runways, taxiways or aprons can be determined from back-calculation of Falling Weight Deflectometer measurements. Point PCN values can then be calculated according to a methodology based on ICAO ADM3.
For flexible pavements, a criterion is developed linking point subgrade E-modulus to number of passes and allowable vertical stress on the layer caused by the DESWL corresponding to the PCN-value.
For points with identical PCN numbers but different subgrade categories, the allowable gear load for airplanes with dual wheel or bogey main gear configuration increases with the CBR value. Simple mathematical models have been developed linking PCN, subgrade CBR/E-modulus to allowable airplane weight. To determine a branch PCN value, point PCN values are transformed to corresponding allowable aircraft weight at a selected characteristic CBR value. For this population of weights is determined an appropriate statistical quantile, which is then transformed back to a branch PCN value.
The methodology is demonstrated for two runways at an actual Brazilian airport. Calculated point PCN values fall in subgrade categories B, C and D, but are transformed to PCN reporting at subgrade category B only.
The methodology can be applied to extended airport maneuver areas, where the airport operator may choose to report PCN values at all branches at a common subgrade category, in order to simplify the determination of allowable weight for different airplanes.
