Urban rail transit systems are characterized by their large scale and complex operational environments. In the event of signal system failures, traditional safety management methods struggle to provide dynamic distance detection and real-time alerts between trains and between trains and construction zones, leading to inefficient on-site safety management and delayed emergency response. To address safety issues during signal system failures or construction activities, a radar-based Train Assistant Operation System (TAOS) has been developed. This system supports multiple operational scenarios for train-to-train and train-to-ground interactions, enabling precise train positioning, real-time distance measurement, two-way communication, and active warning. It forms a highly reliable safety protection system independent of the signal system. This not only enhances operational efficiency and emergency response capabilities but also provides critical technical support for driver-assisted operations, effectively facilitating the transition of urban rail transit safety management from reliance on human vigilance to technology-driven protection.