The paper is devoted to the perspective trend of researches on estimation of physical and mechanical characteristics of dispersive soils by means of non-destructive methods of in-situ testing by wave analysis. The paper presents the results of comparison of the values of the transition coefficient between the soil dynamic elastic modulus, which can be calculated from the results of in-situ tests by means of non-destructive technique of Multichannel Analysis of Surface Waves, and the soil deformation modulus. Application of such a transition factor makes it possible to estimate the soil deformation modulus according to the soil elastic characteristics determined using modern non-destructive express techniques of wave analysis of the low velocity zone of the upper part of the profile. Due to the application of such express methods, labor and time costs of field investigations are significantly reduced during preliminary geotechnical site assessment. Comparison of different values of the transition factor was made on the basis of the results of laboratory standard triaxial tests and numerical experiments with the values calculated on the basis of dependencies proposed by the results of in-situ tests with Plate Load Tests and Multichannel Analysis of Surface Waves in previous in-situ studies. The results of standard triaxial tests on samples of cohesive and non-cohesive soils confirm the dependence of the transition factor on the soil unit weight, obtained in the previous stage of in-situ researches. The values of the transition factor based on the results of numerical experiments do not exceed the results obtained by field research methods. The results of the research will be useful in estimating the physical and mechanical properties of the soil during preliminary geotechnical calculations of the foundations. All in-situ investigations are carried out using non-destructive technique. No permits or approvals are required to perform the work according to the proposed methodology.