What should a train operator expect after observing a signal aspect that allows proceeding on the main route?

When a train operator observes a signal aspect that allows them to proceed on the main route, it indicates that the track ahead is clear and safe for travel. Typically, this situation anticipates that the following signal will also be indicative of safe movement, primarily through yellow or green aspects. A yellow signal usually signifies that the next signal may be red, but it encourages the operator to reduce speed and prepare to stop, while a green signal indicates that it is safe to continue at track speed. Thus, expecting the next signal to be either yellow or green is consistent with the signaling system's design, ensuring both safety and effective communication of track conditions.