There are a few maps in the Documentation folder to aid in describing specific locations, signals, and switches in the instructions below. The keyboard keys instructed to be pressed represent Open Rails default settings.
To reproduce the oscillation in Open Rails:
- Explore the route with a short consist, starting at location Left Leg.
- Once the Explore activity has started, press 8 to leave the cab of the locomotive, which should not be past the first signal ("Signal A"). (Map.)
- Fly the camera along, following the left track path your locomotive is already on, and find the third signal ("Signal C"), the first one with the diamond sign.
- Throw the switch next to Signal C ("Switch 3") by ALT+clicking it.
- Fly to and observe Signal E. The home arm stutters as it constantly fluctuates between Danger and Caution (STOP and APPROACH_1). This can be observed on the Track Monitor as well.
- (Also observe Signal D does not go back to showing Danger, despite there no longer being a train pathed past it.)
- You can press G to throw the first switch to see the behavior start and stop as the selected path changes and alters the signals.
- You can move your locomotive forward to approach the signals. Once the locomotive passes Signal B, the oscillation stops. Reversing the locomotive back to in rear of Signal B will restart the oscillation. SignalNumClearAhead is set to 3.
You can also be observant for signals in Signal Debug Mode (CTRL+ALT+F11) which do not display any indication name (e.g. CLEAR_2) where their track marker should be. Such signals still seem to work correctly otherwise. I've been surprised to rarely observe this on several routes.