Which signal aspect typically signifies to a train to STOP?

The signal aspect that typically signifies to a train to STOP is red. In railroad signaling systems, a red signal is universally recognized as an indication for a train to halt. This is a critical safety measure designed to prevent accidents and ensure that trains have adequate time to stop when necessary.

When a train approaches a red signal, it serves as a clear warning that the track ahead is not clear for progression, whether due to a train occupying the next block, maintenance work, or any other obstruction. The train operator is trained to recognize and respond to these signals immediately to maintain safety on the rail network.

Other signal aspects such as green or yellow indicate different conditions, with green typically meaning proceed and yellow indicating caution or prepare to stop. Blue signals are generally not used to direct train movements but may serve specific purposes related to work zones or signaling for other railway personnel. Understanding these signal aspects is crucial for ensuring safe operations as a tower operator.