This paper aims to find out the optimum configuration of a fundamental mod-ule which can be assembled into the temporary bridge to secure the traffic lifeline rapidly, when the natural disaster ocurries. After verification that the optimum configuration of periodic structure becomes also periodic, the opti-mum configuration of simply supported beam isolated from 3-span continuous beam is searched as a fundamental module. The parametric analysis with com-bination of load position and support position are carried out, and two types of prototype can be proposed. Moreover, the optimum configuration of cantilever bridge is also investigated with relation to the analytical domain and support conditions, and the analogy with Forth railway bridge is recognized.
