homogenous isotropic linear elastic (what most geotechnical engineers would like to see) and discontinuous inhomogenous anisotropic non-elastic (what most in-situ rock masses actually are). A rock mass rating system provides a method of incorporating some of the complex mechanics of actual rocks into engineering design. Moreover, the system was the first to enable estimation of rock mass properties, such as the modulus of deformation, in addition to providing tunnel support guidelines and the stand-up time of underground excavations. Recently, after over 40 years of use, renewed attention was paid to the RMR System because of its applications to the assessment of rock mass excavability (RME) and, especially, its direct correlation with the specific energy of excavation (SEE) for TBMs used effectively to detect changes in tunneling conditions, in real time, thus serving as a warning of adverse conditions as construction proceeds. Rock Mass Rating presents some difficulties when applied to rock slopes, since the parameter that take into account the influence of the discontinuities orientation is introduced in detail for dam foundations and tunnels but not for slopes. To address this issue, Romana defined Slope Mass Rating scheme that is based on the original Bieniawski's parameters but including a rigorous definition of the parameters considering the effect of the orientation of discontinuities. Specific output charts for tunnel design For convenience in tunnel design, three charts are included which are commonly used to estimate these essential rock mass properties: Stand up time, Rock mass deformability modulus Em and Rock mass strength. In the second chart, an improved relationship for the range of RMR greater than 56 is given. This reflects the idea that, at high RMR, deformations will be dominated by intact modulus, whereas at lower RMR weathering and joint infilling will largely control deformation. This approach has the advantage that modulus values are NOT overestimated at the higher range nor underestimated or overestimated at the lower range. This is more realistic than relying on one sigmoidal equation. A number of sigmoidal equations have been proposed that give rock mass modulus as a function of intact modulus and a rock mass rating. These equations may give a good estimate of modulus given the correct input data, however it is difficult to obtain reliable intact strength or intact modulus values from laboratory tests on samples from highly disturbed rock masses. Because of this limitation, something that is commonly done in practice is