Messages you may see in the Status column of the Train List window, opened by pressing the F2 key. It is important to remember that in real life, signallers do not see status messages of this nature since these messages are generated by SimSig software. For example, signallers whose information comes from the state of track circuits have no way of knowing a train's exact speed in real time. If the message indicates excessive delay or an error of procedure on your part, you may incur penalty points.
After a train has had an adverse change of aspect, the driver will report to his control, and this message will be displayed on the train list.
Run out of valid track
The message appears when a train can't proceed because of the state of the track. This can be because:
The third case needs a bit more explanation. In older sims, if a track wasn't specifically made bidirectional, you'd get this if you tried to send a train the wrong way down a track. Nowadays it's limited to complex track situations. Suppose you have a track circuit with back to back points, so that a train on the main line in either direction can turn off on to a branch or crossover. If there's no expectation that a train will come off one branch and on to the other, and it isn't a signalled route, it might not be included in the simulation. In that case, a train approaching the track circuit with both points reversed will go into this state.
Discussed here. Note: Again, this is a sim-generated message, not a real-life message and should be interpreted as indicating that a routing procedure was not carried out correctly. It does not mean that some incident or accident has occurred, though you may incur penalty points if it arises.
Timetable Rule in force
A rule in the Timetable is preventing the train from departing from this location. Timetable rules are found under the 'Rules' tab in the Timetable Editor (F4). To force departure, right-click the train, Timetable Options>Abandon Rule
Waiting at red signal [number]
Self-explanatory. To locate the train:
Waiting for right-away at x
The train is ready to depart from a station. This message will always briefly display while platform duties are being carried out (closing the doors, etc.), however if the signal at the end of the platform is at danger, it will continue to display until the signal is cleared.
TODO Add further messages and meanings (please list in alphabetical order)
TODO Create example pages with screenshots to expand these explanations