About One-way streets, narrow single carriageways, separated carriageways and service roads: which statement is correct?
The main road is intended for fast and through traffic, the ventweg for slow and local traffic (sign C5 at the entrance).
Sign C4 (blue rectangle, sideways arrow) obliges you to turn the way the arrow points at the junction.
If your right-hand wheels leave the road surface on a narrow single carriageway, you can simply steer calmly back to the middle.
If your right-hand wheels leave the asphalt, the only risk is damage to tyres or rims; the steering stays under control.
Explanation
trap: a quiet road mistaken for a fast road. Book p.66 - the main road is intended for fast and through traffic, the ventweg for slow and local traffic (sign C5 at the entrance)