What must engineers constantly monitor to ensure safety in relation to stop signals?

Engineers must constantly monitor signal indications to ensure safety in relation to stop signals because these indications provide critical information regarding train operations. Signals control the movement of trains by indicating whether it is safe to proceed, to slow down, or to stop. Stop signals specifically inform engineers that they must halt the train to prevent accidents or collisions, particularly at junctions, crossings, or when approaching work zones.

Constant monitoring of signal indications is essential as they can change rapidly based on various factors, including the movement of other trains and operational directives from the control center. By staying attuned to these signals, engineers can react promptly to ensure the safety of their train, passengers, and cargo, as well as the safety of the rail network as a whole.