[Tagging] Turning circle with island or turning loop (was Re: (Mini)Roundabout: examples

Josh Doe josh at joshdoe.com
Tue May 15 12:06:14 BST 2012


On Mon, May 14, 2012 at 11:02 AM, Martin Vonwald <imagic.osm at gmail.com> wrote:
> Correct - this needs some simplification just like allowing
> junction=roundabout on a node for small roundabouts. But I would
> really like to update the page before we talk about this, because
> otherwise the update won't be any time soon ;-) As it is never wrong
> to map them as a loop I don't think of this as a show stopper? Do you
> agree on this?

No, not a show stopper.

> Now back to the problem:
> * highway=turning_circle is not correct, because a turning circle
> should not have an island for the same reason why a mini-roundabout
> should not have one (-> large vehicles). Using traffic_calming=island
> is therefore a contradiction, although I'm a little tempted to go this
> way. But right now I'm resisting myself ;-)
> * junction=roundabout is not correct, simply because they are no
> roundabouts (one-way, right-of-way).
>
> The longer I think about it, the more I'm asking myself: do we really
> need a tag for this? If someone doesn't want to map it as loop, why
> not simply end the road without any additional tag? What information
> are we missing then, that we are not missing if we use a single tag
> instead of a loop?

A simple answer is that people will want to tag it. :) I think most
people tag highway=turning_circle not because they want to include
information indicating that large vehicles can turn around, but
because it makes the map prettier. Also what NE2 said about 3-point
turns.

Why don't we keep it simple and just use highway=turning_circle and
turning_circle=island, since it's more akin to a turning_circle than a
roundabout, and I doubt any data consumers other than rendering
currently do anything with turning_circles. We could use
highway=turning_loop also, if people have problems with using a
dependent key. I suggest rendering this as a turning_circle with a dot
in the middle, similar to a mini_roundabout but with a larger circle
(indicating that the area is wider than the roadway with a "turning
loop", which is not the case with a mini_roundabout).

-Josh



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