Evaluation of Shoulder Pavements for A-380 Operation at Memphis International Airport, TN

Abstract

The Airbus A-380 aircraft is expected to begin operating at United States (U.S.) airports in 2006. Proposed Federal Aviation Administration (FAA) geometric standards require 60 meter (200 feet) runway widths for this aircraft. Since most commercial airports in the U.S. have 45 meter (150 feet) runway widths, runways that will accommodate the A-380 may require widening prior to initiation of service. This can result in expensive and operationally disruptive pavement construction at many of the nation's busiest international airports. Federal Express, one of the major carriers at the Memphis International Airport (MEM), intends to purchase A-380 aircraft for use in Memphis, beginning in 2008. Although pavement strength is not an issue for the concrete runway pavements, since the three parallel north-south runways are 45 meters (150 feet) wide, the runways may require widening to 60 meters (200 feet) prior to initiation of A-380 service. However, the runways do have 11 meters (35 feet) asphalt shoulders, 7.5 meters (25 feet) of which may be considered as operational pavement if it could be demonstrated that the shoulder pavements can withstand A-380 excursions. While this would require relocating the runway edge lights and re-stripping, the costs and operational disruptions would be far less than new construction for widening. Conversely, if the pavements are not structurally sufficient, options for economical and less disruptive strengthening could be explored. This paper discusses the analytical approach that was undertaken to evaluate the suitability of the runway shoulders for use as operational pavement at the runway edges. Analytical elements included nondestructive testing (NDT), combined with layered elastic and conventional structural analyses. NDT was conducted with a Heavy Falling Weight Deflectometer (HWD) to evaluate in-situ pavement layer and subgrade strength and generate inputs for the structural analyses. Layered elastic analyses used the cumulative damage factor (CDF) approach contained in FAA's LEDFAA program and a new FAA pavement design program, COMFAA, was used for conventional design analysis. The conventional and mechanistic design computations were supplemented by recent full scale testing data from FAA's National Airport Pavement Test Facility (NAPTF).