What is the initial step when closing up to a stalled train in a station under CBTC?

When closing up to a stalled train in a station under Communication-Based Train Control (CBTC), the initial step is to proceed in a normal operating mode. This approach allows the operator to maintain a safe distance and situational awareness while monitoring the environment and the status of the stalled train.

By continuing to operate normally, the operator can assess the situation effectively, ensuring that any necessary adjustments are made based on real-time data communicated through the CBTC system. This method also helps to prevent any abrupt actions that could potentially compromise safety, such as sudden stops or changes in speed that may lead to further complications.

In contrast to the other options, transitioning immediately into a Release mode could lead to unintended consequences if the situation requires careful handling. Similarly, waiting for authorization from the Trainmaster could unnecessarily delay the response to an emergency, while activating emergency brakes is typically reserved for critical situations where immediate action is required to prevent an accident. Therefore, proceeding in a normal operating mode is the most prudent first step.