About One-way streets, narrow single carriageways, separated carriageways and service roads: which statements are correct? (multiple answers possible)
On a one-way street you may reverse along the carriageway to a turning you missed.
C4 = one-way road: traffic in the SIDE STREET drives in the arrow's direction — a rectangular information sign about that street, not a command for your direction; commands are round (D series).
On narrow single-carriageway roads outside the built-up area: watch out for a sharp road edge and/or lower verge; if your right-hand wheels leave the road, you quickly lose control of the steering.
Sign C4 means the side street is closed; the arrow shows which way the diversion goes.
Explanation
Book p.61-64 (H4) - **C3/C4 are the open side of the one-way road: entering is allowed, in the arrow's direction**; the closed end carries the round C2 — trap: the arrow is the driving direction IN the street, not a diversion.