Effects of Off-Road Tires on Flexible and Granular Pavements

Abstract

The impact of off-road equipment on flexible and granular pavements was evaluated through a combination of field testing program and theoretical modeling. The pavement damage caused by Terragators, grain carts, scrapers, and tracked tractors was evaluated relative to the damage caused by 18,000-lb single axle truck. Field test sections were constructed and instrumented to measure strain, pressure, and deflection caused by the loading of off-road equipment on thin and thick flexible pavements, gravel, and blotter roads. The pavement responses were measured during the fall, spring, and summer seasons. The field collected data were used to assess the impact of the various off-road equipment and to validate the 3D-MOVE theoretical model. The validated model was then used to expand the study over the range of typical pavement structures and soil types in South Dakota. Both the field testing program and the theoretical analyses showed that loaded Terragators and loaded grain carts are more damaging than the 18,000-lb single axle truck and the legal limit of 20,000-lb single axle, the empty scraper is significantly more damaging than the 18,000-lb single axle truck and the legal limit of 20,000-lb single axle, while the tracked tractor is less damaging than the 18,000-lb single axle truck. Based on the findings of this research, it was recommended that the loaded Terragators and grain carts should be regulated while the empty scraper should be prohibited from driving over highway pavements.