On the area where my team covered, we once had a failure report from a driver relating to a signal that was apparently showing a green aspect when it should not have been.
It was a "wrong direction" signal on a bi-directional line. As it was a mid section automatic signal for a section of plain line, it showing a green when the section of line ahead of it was clear of trains was correct. As a "right direction" train approached, it would step down to single yellow, then to red. Clearing back to green once the train cleared the controlling track circuit.
This was all in accordance with the circuitry design.
The likely reason that the driver was not accustomed to it showing a green aspect, is that most of the time the signallers kept the panel replacement switch in the red position. Hence most of the time the signal was held at red.
Not all signals have a red aspect and not all signals that can show red, will show red when people may expect it. Also, not all signals are "block" section signals.
It may not be obvious to an observer, but a different signal to the one they are looking at may be the protecting signal that is red to protect a train from a possible following train.
Having said that, if it doesn’t look right, do ask
