Development of a Reliable Methodology for Assessing the Structural Performance of General Aviation Pavements

Existing airport pavement evaluation and design methodologies are primarily oriented toward heavy, air carrier size aircraft, and often do not adequately address the lighter loading conditions at General Aviation (GA) airports. Although GA pavements generally serve light aircraft, many GA airports need to accommodate heavier corporate or military aircraft on an occasional or periodic basis. Existing GA design methods cannot handle mixed traffic, or overload operations. To address these shortcomings and to augment its formal strength rating program, the North Carolina Division of Aviation (NCDOA) conducted a two year study during 1997–1999 to develop standardized procedures for nondestructive testing (NDT) and evaluation of GA airport pavements and analytical software based on layered elastic design theory for evaluating pavement strength and "overload" operations. This study focused on flexible pavements and consisted of the following four primary elements: 1) Field Testing — Nondestructive and conventional tests were performed on one runway at each of six North Carolina (NC) GA airports. 2) Data Analysis — Back-calculated NDT subgrade moduli were correlated with California Bearing Ratio (CBR) and laboratory resilient modulus test data for development of failure algorithms and to allow direct input of back-calculated Falling Weight Deflectometer (FWD) subgrade modulus into the evaluation procedure. 3) Subgrade Strain Criteria — The results of a literature search and design of Federal Aviation Administration (FAA) compliant pavements over a broad range of subgrade and traffic inputs formed the basis for a new subgrade strain failure criterion. 4) Development of Analytical Software — Layered elastic evaluation and design software was developed using the FAA's LEDFAA software for air carrier pavement as a model. The new software, termed LEDGA for Layered Elastic Design — General Aviation, incorporates the new subgrade strain criterion and permits multiple aircraft analysis and evaluation of "overload" operations based on cumulative damage concepts.