Roundabouts signs

[worker]

Does anyone know why the sign for a roundabout (with various roads coming off) is never a complete circle?

[Hippy]

I think it is a convention to suggest that the normal use for the roundabout is for the approaching motorist to gain access to the various routes leading off, rather than to go round in giddy circles. The little break makes the sense of the sign more recognisable at a glance,

[worker]

Yep. That sounds reasonable Hippy.

[Jenny Tools]

It lets you know which approch road your on. The gap is to your right. Otherwise it could appear you could be entering from any direction.