|What *kind* of turning circle is it?
|Used on these elements
|Status: in use
|Tools for this tag
When to Use
If you missed the bit on the main highway=turning_circle description page, a turning "circle" comes from a British English term referring to a bit of road made for turning around, and is not strictly circular.
As wrong as it feels to call non-circular objects circles, there are cases where a turnaround area has some other shape, and some mappers feel this difference is worth noting. That is what this tag is currently used for.
While no mapping practice is explicitly stated elsewhere, it is probably safe to assume that the absence of this tag indicates a circular (or slightly oblong) area. Mappers who want to be explicit are welcome to tag features with turning_circle=circle as well, however redundant it may feel to do so.
Types of Turning "Circles"