By resorting to rational methodology it is possible to predict any future distress affecting roadways with asphalt mixtures, permitting the planning of a maintenance policy. This policy is based on: a more exact knowledge of all the factors affecting the roadway, both at its initial stage and over years; a systematic measurement of different characteristic percentages during its use and throughout its lifetime; the definition of priority classification criteria; prioritizing them with respect to any intervention. To prepare this systematic maintenance plan using the numerical modelling of Rational methodology, the following data are needed: a knowledge of mathematical modelling of pavement and the materials, based on elastic modules and fatigue methods; visual auscultation of the roadway to quantify the degradations or the use of GERPHO, the analysis of the pavement’s traffic load, based on determining its aggressiveness and its equivalence to a number of axles of reference; and the structural diagramming of the pavement so as to calculate the theoretical risk it is exposed to considering its future traffic load.