Firstly I feel that it could be helpful in debugging some of the interesting bugs regarding blinking signals.
Secondly it would be a useful tool for the player with helping to answer two pretty common questions when designing rail systems:
1. Why is that signal blinking?
2. Why is that signal red? There is no train that is even remotely close to there?!?!?!??
But it also gives the player a quick way to see if intersections are sufficiently signalled.
Thoughts? Mod suggestions?
