The purpose of this study is to present an innovative and effective method for temporary works in mega structures such as tunnels with respect to construction cost and workabilities by using a specific structural system. In order to achieve the goal, a well-known space truss structure is evaluated for the specific structural system. It can be especially moveable through tunnels and can easily assemble and disassemble truss members in tunnels. This study produces technical ideas by technology tree, which result in evaluating the specific space truss which consists of high strength circular steel tubes with tensile stress of about 700MPa, their connection parts, and supports. The space truss system can be expanded to carry out temporary works such as space frame buildings.