In the United Kingdom, yellow zig-zag road markings outside a school prohibit stopping or parking during their operating times.
These markings are placed near school entrances and crossings to keep the approach clear. A nearby sign normally states the times when the restriction applies, although some locations operate the restriction throughout the day. The purpose is to preserve visibility for children and drivers and to prevent parked vehicles from blocking the crossing area.
The markings are not the same as ordinary yellow edge lines. Single and double yellow lines regulate waiting along the road, whereas school zig-zags identify a protected stopping restriction associated with a crossing or school entrance. Drivers should read the accompanying upright sign rather than assume every zig-zag restriction operates identically.
The rule is designed around sight lines and vulnerable road users. Even a brief stop to drop off a passenger can create danger if it obstructs the view of a child stepping into the road or of approaching traffic.