Define "rutting" in asphalt pavements.

Rutting refers to the deformation of the pavement surface that occurs primarily as a result of repeated traffic loads. This phenomenon is characterized by the development of depressions or grooves in the wheel paths of the roadway, which can significantly affect the ride quality and safety of the pavement. Rutting is typically a result of the combination of factors such as inadequate pavement design, insufficient material quality, or poor construction practices that lead to the accumulation of permanent deformation in the asphalt mix due to the repeated stress from vehicle loads.

In this context, while surface cracking under high temperatures, maintenance of the surface layer, and methods of assessing pavement stability are important aspects of asphalt pavement management, they do not accurately define the specific issue of rutting. Instead, rutting is uniquely related to deformation under load, making the second choice the most accurate definition in the context of asphalt pavements.