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Tunnel boring machine applies in tunnel construction and in mining operation. During the last years, different methods have been introduced to analyze and assess suitable operations of digging systems presented. These methods are divided in two groups: (1) the first group is based on mathematical equations and shear strength applied on each cutter, (2) the second group is based on databanks and experimental relationship. This paper compares and analyzes two experimental methods as introduced by Barton and Norwegian Institute of Technology (NTNU) as well as using a mathematic model introduced by Colorado School of Mines and analyzed the validity scope of each of them. A case study is made in the 16-km Karaj-Tehran water supply tunnel. At the end, it is concluded that mathematical models are not suitable because they are highly dependent on the results of special laboratory tests; also, it attends less to rock mass characteristics. In jointed or nonhomogen rocks, as well as in this project with less value of laboratory data, using Barton model is more creditable. It enjoys high ability for definite measurement. Also, NTNU model attend to machine parameters and in case of availability of laboratory tests data, NTNU model is a suitable method. According to the available information and executing conditions of Karaj-Tehran water supply tunnel project including geology of area, experimental parameters, etc, the Barton method is more valid than the other methods. [ABSTRACT FROM AUTHOR]