The aim of this paper is to evaluate the different rock supports that have been installed in road tunnels of Tehran-Shomal freeway of Iran to choose efficiency rock supports from economic point of view. Tunnels pass through the Karaj green Tuff that moderately weathered and fractured with interlocked joint set in most part. Factor of safety using finite difference code, FLAC3D and RocSupport software is compared. The plastic zone radius and maximum displacement around the two D-shape tunnels are determined and new support system is proposed. In this project, the excavation and support system were not based on NATM or "build as you go" so the pre-deigned support by consultant engineers was challenged. According to the numerical stability analysis and monitoring of tunnels during excavation, it was observed that the four meters long rockbolts with twenty centimeter of shotcrete cover and lattice girders should be replaced with slightly light support include three meters long rockbolts and ten centimeters of shotcrete cover.

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