The Evolution of Accelerated Pavement Testing for U. S. Military Airfield Pavements at the Waterways Experiment Station

Since the early 1940s, researchers at the U.S. Army Waterways Experiment Station (WES) in Vicksburg, Mississippi have relied on accelerated pavement testing (APT) to develop airfield pavement design and evaluation procedures critical to the construction and safe operation of military airfields. In 1941, the U.S. Army built the XB-19 bomber that weighed 711.7 kN (160,000 lb). At that time, all asphalt pavements on airfields were constructed using extrapolated criteria from highway pavement designs. The XB-19 sunk through the under-designed asphalt pavement and destroyed an entire airfield during its maiden voyage. Army leaders turned to WES to develop procedures for designing pavements capable of supporting such massive aircraft loads. After the new California Bearing Ratio (CBR) design procedures for flexible airfield pavements were developed, APT was immediately used to begin validating the new procedures. As the years went by, aircraft continued to advance. Multiple wheels were added to distribute the heavy loads across larger sections of pavements. New APT devices were developed to adapt these more complicated landing gear structures. Gross weights increased to nearly 4,448 kN (1,000,000 lb) by the 1960s. Advanced fighter aircraft were developed with tire pressures as high as 2.76 MPa (400 psi). With each new advancement, APT devices were required to validate design procedures and to evaluate new materials and construction techniques. This paper discusses some of the challenges researchers faced and how they used unique APT solutions to evaluate emerging pavement designs as they developed criteria for constructing military airfields for the United States.