This paper is concerned with the development of the requirements for railway safety support information systems. The five safety elements at the system level have been modeled based on the enterprise architecture approach. Specifically, the modeling has been carried out as follows. First, the requirements are derived according to EIA-632 process. Also, the possible scenarios on the accident-investigation-support are developed from the help of relevant personnel in the area. The developed scenarios are reflected in modeling the operational and system architectures of DoDAF approach using a CASE tool. From this architecture model, we can easily get the specifications required for the operations. These results can give the improved understanding of the railway safety system to the members of diverse teams and areas working for the system development.