This sign is used to warn road users of a road layout change from a duel carriageway to and single carriageway with two-was traffic. Often placed directly after a duel carriageway ends sign. Diagram 521 has no variations.
Material: R2/RA2 reflective overlay on aluminium composite backing
5.1.1. The signs to diagrams 520 (S2‑2‑15, see Figure 5-1) and 521 (S2‑2‑16, see Figure 5-2) indicate the resumption of two-way traffic on a single carriageway road after a length of dual carriageway and, in the case of diagram 521, after a one‑way road. The sign to diagram 522 indicates a two‑way road crossing ahead (S2‑2‑17, see Figure 5-3 and 5.2.2).