When must you wait at this traffic sign?

This traffic sign is the "Andreaskreuz" (Saint Andrew's Cross), which marks an unguarded railway level crossing in Germany. Here, you must always be especially careful.

You are required to wait in these situations:
- When a railway employee waves a white-red-white flag, signaling a train is coming or it is unsafe to cross.
- When you cannot drive completely across the tracks without stopping, to avoid being stopped on the tracks if there is traffic congestion.
- When a train or other rail vehicle is approaching, even if no other barriers or signals are active.

All three conditions indicate a risk, so you correctly selected all necessary scenarios. Always approach railway crossings carefully and be ready to stop if any of these situations apply.