The shortest path problem is discussed to develop an automatic control system of the railroad in a factory. The super-network is proposed and an algorithm is given to find the shortest path on the super-network. The super-network is useful to model the railroad system because it can represent important factors in finding paths which cannot be represented by an ordinary network. An example is also given to show how a railroad system can be modelled using a super-network and how the shortest path can be found by the proposed algorithm.