Geotechnical parameters were used to determine subsurface rock quality for construction purposes. We summarize the mathematical relationships used to calculate the geotechnical parameters from P- and S-wave velocities and density values. These relationships are applied to two field examples; the first is a regional seismic study in Egypt and the second is a 2-D seismic profile recorded in Saudi Arabia. Results from both field examples are used to determine the subsurface rock quality and locate zones that should be avoided during construction. We suggest combining all geotechnical parameters into one map using a normalized-weighted relation, which helps to locate the zones with high versus low rock quality for engineering purposes.