In this paper, we focus on downhole seismic testing conducted in two geotechnical boreholes located along the Isfahan-Bafq railway. Accurate assessment of the mechanical and dynamic properties of subsurface layers is crucial in civil engineering and geotechnical projects; however, conventional (non-geophysical) methods are often costly and time-consuming. The primary objective of this study is to determine the compressional wave velocity (Vp) and shear wave velocity (Vs) in the subsurface layers, estimate the effective velocity, and evaluate the borehole locations based on Iran's Standard 2800. To achieve this, downhole seismic tests were performed at one-meter intervals within the boreholes. The results indicate that the effective velocities of P and S waves in the first borehole are estimated to be 1400 m/s and 800 m/s, respectively, while in the second borehole, they are 1170 m/s and 310 m/s, respectively. According to the obtained results, borehole number 1 falls into Group I and borehole number 2 falls into Group III of Iran's Standard 2800. In addition to the velocity estimates, other geotechnical properties, including Poisson's ratio, Young's modulus, shear modulus, and bulk modulus, were also calculated and presented in the paper. These calculations provide more precise data beyond what is typically available in standard studies.