The concept of perpetual pavements was developed with the idea to keep the advantages coming from the long-life pavement, and, at the same time, improving the methodology, avoiding possible economic risks. The purpose of this thesis work is first to analyse the state of the art of Perpetual Asphalt Pavements, going to define what are the limiting responses so that we can define a pavement as perpetual, characterizing also the layered structure and the materials. But, a large part of the thesis focuses on the design method and on perpetual pavement software, with the aim to compare the available software used for the design of PP, and also to demonstrate that an acceptable increment of the total thickness of the bituminous layer will make an huge structural improvement of the pavement..