The soils used as trackbed in Korea are selected using USCS utilizing basic soil properties such as Grain Size Distribution(GSD), % passing of #200 sieve (P 200 ), % passing of #4 sieve (P 4 ), Coefficient of uniformity (C u ), and Coefficient of curvature (C c ). Degree of compaction of the soils adapted in the code by KR should be evaluated by maximum dry density (γ d-max ) and deformation modulus E v2 . The most important influencing factor that is critical to stability and deformation of the compacted soils used as trackbed is stiffness. Thus, it is necessary to construct a correlation between the modulus and the basic soil properties of trackbed soil in order to redefine a new soil classification system adaptable only to railway construction. To construct the relationship, basic soil test data is collected as a database, including GSD, maximum dry unit weight (γ d-max ), OMC, P 200 , P 4 , C u , C c , etc.; deformation modulus E v2 and E vd are obtained independently by performing a Repeated Plated Bearing Test (RPBT) and Light Weight Deflectometer Test (LWDT) for ten different railway construction sites. A linear regression analysis is performed using SPSS to obtain the relationship between the basic soil properties and the deformation modulus E v2 and E v . Based on the constructed relationship and the various obtained mechanical test data, a new soil classification system will be proposed later as a guideline for the design and construction of trackbed foundation in Korea.