Rail grinding is a critical maintenance process that restores worn railway tracks by removing irregularities and reshaping the rail profile. However, evaluating the load carrying capabilities of the rail steels for each pass such as hardness, yield strength, and fracture toughness can be very challenging since most non-destructive testing (NDT) approach cannot effectively measure these mechanical properties during maintenance. In this study, a novel technique for evaluating the fracture toughness and hardness, yield strength of high strength rail steels is introduced using spherical indentation method, based on a modified limit load analysis. This approach defines a crack-initiation point (CIP) within the fully plastic deformation region of the indentation, indicating the onset of a theoretically defined virtual crack. By combining this method with the J-integral, the fracture toughness (KJC) is determined. However, localized hardening effects encountered necessitated the use of the expansion cavity model in conjunction with the modified limit load analysis to accurately estimate the indentation pressurenormalized depth curve, indentation plastic area (Apl) and the CIP for fracture toughness evaluation. The evolution of the plastic zone beneath the surface of the rail steels was also examined, assessing its potential as anon-destructive testing (NDT) method, proffering the minimum indenter sizes required for structural integrity inspection for different rail grinding applications. Ultimately, spherical indenters proved effective in estimating fracture toughness, and the advantages and limitations of this method are discussed, highlighting its potential asa quick and reliable NDT technique for the railway industry in the future.