A model developed by civil engineers with the support of federal transportation agencies may help airport officials build, improve, and maintain aircraft runways.

The model is called Pavement Analysis using Nonlinear Damage Approach, or PANDA, and is being used to predict damage that is measured and recorded under the repeated loading of heavy aircraft.

PANDA is the product of almost seven years of development by the research team under a contract with the U.S. Department of Transportation, the Federal Highway Administration and the Federal Aviation Administration. The team includes the University of Kansas, Texas A&M University at Qatar, The University of Texas at Austin, Virginia Tech and more than a dozen student researchers.

The idea behind PANDA is to create a computational model that takes into account variables such as time under pressure, temperature dependency of the asphalt, different types of stress and other environmental factors that impact the usage of runways by aircraft, including diffusion of moisture and oxygen into the asphalt layer.

The model is intended to offer an accurate prediction of the damage the pavement would take over repeated usage and allow designers of airfield and major highway pavement to create or maintain a product that would react optimally to a variety of conditions.

The team is using PANDA to develop a platform that can become a user-friendly software package for industry and commercial usage.

PANDA is not the first model of its kind, but has the ability to specifically account for mechanical damage caused by airplane traffic and model this data in conjunction with environmental effects and damages such as moisture, oxidation processes, temperature and other factors.

As the team has developed PANDA, what has been made clearer is the effect of all the differing variables that have impacted the pavement in ways that are not necessarily intuitive. For example, the coupling of moisture diffusion with mechanical damage may substantially alter the life prediction of the pavement, as well as change the location of damage.

Location of damage is of great importance in today’s move toward the design of perpetual pavements that do not require replacement from the subgrade up, but only periodic replacement of the upper surface. One goal is to make sure localization of damage does not occur in the lower part of the asphalt layer.