The assessment of road pavements in terms of their properties and surface features is both complex and difficult. The indicators which describe the surface quality are eg. a longitudinal and transverse profile, a coefficient of friction, the International Roughness Index (IRI) and surface cracks. The article presents a method of using the data describing a real longitudinal profile of pavements, which was obtained by way of a self-constructed device named Walking-Profiler. It also proposes a way of calculating it with the use of numerical modelling of a Planograph, and also (simultaneously) the collected data can be used to calculate the International Roughness Index.