Abstarct: According to the population growth and urban traffic, necessity of use of rail transportation systems is increasingly developing. Today, underground constructions play an important role in urban transportation development. One of the most dominant factors in tunneling industry evolution and improvement, are developments that has been done about excavation methods. There are different methods for excavation and construction of tunnels such as tunnels of subway network, railway, water conduction, industrial tunnels, mine tunnels, etc. These methods are classified in two main groups as traditional and mechanized excavation methods. Traditional excavations in urban areas often include "Cut & Cover" method, "Cover & Cut" method and New Austrian Tunneling Method (NATM). The case study in this research is Tehran- Tabriz Railway Tunnel. This tunnel is under construction in region 17 in Tehran. Each tunnel has 11 meter width and 7.7 meter height. Initial studies show that this tunnel can also be continued with NATM method. Large cross section and shallow overburden are special characteristics of this tunnel. In this study, at first, feasibility of tunnel construction by NATM with numerical modeling of finite difference method by FLAC 3D software has been performed and then parametric sensitivity analysis has been done on influence of excavation and support sequence, round length value and existence or absence of appropriate support on the feasibility. Finally, gained results have been compared with the "Cover and Cut" method designs and the best method of excavation with appropriate support system in this section has been selected. This suggested plan includes a twin NATM tunnel with 13 meter width, 9 meter height and cross section of 109 m^2 under 6 meter overburden and 2 meter pillar width which there is no construction or building on the ground surface. Also Cover and Cut tunnel was modeled in three cases, with vertical trench, with a steep 45 degrees trench and with a steep 60 degrees trench. The results of modeling showed that in this section, the tunnel with a steep 45 degrees trench or under lower slopes can only be constructed. According to the modeling of NATM tunnel and "Cover and Cut" tunnel by the software, the suggested NATM tunnel is more suitable and optimized in terms of ground surface settlement and also stress regions rather than Cover and Cut tunnel with a steep 45 degrees trench and has been introduced as an alternative to the Cover and Cut operational method.