Currently, 5G communications systems are already commercially available in China, and the first version of 5G has been standardized. The LTE-M system has been widely adopted in urban rail train wayside communications, and an overview and the requirements of urban rail train wayside communications based on LTE-M are first presented in this paper. Then, the key technologies and the feasibility of 5G communications in urban rail train wayside communications are analyzed. Certain design schemes for the application of 5G systems are presented in the following section, and LTE-M along with NR-R are considered as candidate schemes in future urban rail communications systems. The 5G communications system will play an important role, possibly in the development of communications services in urban rail systems.