The train control system needs to accommodate various operational scenarios through the design of distinct working modes, each triggered by changing input conditions. These modes correspond to specific speed limits and safety requirements, ensuring the safety, efficiency, and continuity of train operations. The future of next-generation urban rail transit lies in train control systems based on train-to-train communication. Due to structural changes, traditional CBTC (Communication-Based Train Control) model designs are no longer applicable, and there is currently no comprehensive model design available. This paper examines the mode-switching function and processes appropriate for train-to-train communication control systems. A new mode definition and switching scheme is proposed. In the event of train-to-train communication failure, the train switches to a backup operation mode using train-to-ground communication to acquire position information from ground equipment. To describe this transition, we use the theory of Colored Petri Nets to establish a mode-switching model based on Hierarchical Timed Colored Petri Nets (HTCPN). The model effectively transitions trains from train-to-train mode (T2T) to train-to-ground mode (T2G) under failure conditions. We studied the impact of different operational intervals in the backup mode on system performance through simulations, which show that trains can effectively switch to train-to-ground mode during communication failures. Analysis of successful mode switches and switching times under different backup mode intervals reveals that the success rate increases with longer intervals. An interval of 240 s minimizes train operation delays to within 3 min. The HTCPN model established serves as a reference for verifying and analyzing other multi-mode train control systems.