What is the primary function of the Manual Block System (MBS)?

The primary function of the Manual Block System (MBS) is to allow Railroad Traffic Controllers (RTCs) to manually control movements on designated tracks. This system is essential for maintaining safety and efficiency on the railroads, especially in scenarios where automatic systems may not be fully operational or reliable. In an MBS, RTCs have the authority to authorize trains to enter specific blocks of track, ensuring that only one train occupies a block at any given time. This manual control is crucial for preventing collisions and managing train movements, particularly in areas where train traffic is heavy or complex.

The other options, while related to train operations, do not accurately capture the primary function of the MBS. For example, automated signals can enhance efficiency but are not the core purpose of the MBS. Scheduling is an operational function that, while important, does not directly pertain to the specific safety control provided by the MBS. Communicating schedules to passengers is also vital but falls outside the technical control of train movements that the MBS specifically addresses. Thus, the focus on manual control by RTCs distinguishes the MBS as a vital safety mechanism within train operations.