Rutting due to as[halt flow is the lateral movement of the mix away from the whellpaths, more often appearing as a result of excessive binder content and high temperature, exacerbated by the presence of small rounded aggregates in the asphalt mix material. Asphalt mix stiffness is believed to play a significant role in the rutting resistance of mixes. Stiff asphalt layers which contain well-graded, angular, rough, textured aggregates exhibit a good performance with regards to rutting whereas a low softening point on the binder amplifies permanent deformation. In the present paper, the overall question of rutting due to plastic flow is examined. Factors generating permanent deformation are identified and quantified. This research work in the field of distressed pavements due to rutting was particularly oriented to a factorial analysis of the quantitative effects, leading to a semi-empirical relationship associating the rut depth with the deformation generating parameters. Additionally, a quality control process, carried out in the frame of motorway construction projects, revealed several defects at the stage of mix production and laying significantly affecting at the performance of the asphalt pavement.