Road design is a complex, time-consuming, and very responsible process. To develop a high-quality and viable road project, it is very important to start with an accurate geological survey in order to define the best road layout. Moreover, the geotechnical characterisation of foundation soils and construction materials as well as the analysis and assessment of geotechnical works are mandatory. Laboratory and in situ investigations are complementary and should be carried out by defining a cost-effective investigation campaign. Most often, Dynamic Cone Penetrometer (DCP) or Cone (static) Penetration Test (CPT) are performed because they are economic and quick. In addition, it is also possible to perform the Marchetti Dilatometer Test (DMT). From the obtained test results, the data are interpreted by determining the properties of the soil layers. Although all probing methods are similar, each of them gives slightly different results. The aim of this study is to analyse and compare the results of the probing test, to determine the difference between the obtained data and to find out how the obtained results affect the development of constructive solutions from the safety and economic point of view.