It is necessary to develop innovative communication technologies to ensure efficient operation and effective data transmission in “smart railway” systems. For these systems, information security is of paramount importance. Fifth-generation (5G) technology is safe, reliable, and cost-effective for wireless communication in transportation systems. However, the robustness of the links between devices in a 5G network needs to be ensured for the safety of railway operations. Thus, Terrestrial Trunked Radio (TETRA) must be used with 5G technology for secure data transmission and communication. Safety monitoring, early warning, inspection patrols, and passenger services are required in smart transportation systems to prevent accidents and increase operation efficiency. TETRA and 5G technology have been integrated into an international airport in Japan and the railway system of Taiwan. In this study, we analyzed the advantages of the application of 5G technology and TETRA in a system. The integrated system with 5G technology and TETRA allows various applications and cost-effective smart railway systems.