# Mapping Q: Relation which uses part of roundabout

A roundabout should, as I have come to understand it, always consist of one way.
This however produces some problems when a relation does not use the full length of the roundabout. (i.e. cycle lane, bus route, etc)

As an example, look at this area: http://osm.org/go/0bDm2imuJ

The tertiary road passing through the roundabout has several relations for bus routes (note: different ones in different directions).
If I were to merge all ways to complete the roundabout, those relations would no longer reflect reality.

Any ideas how to solve this?

Note: This is only a simple example, more complex junctions with bus routes, cycle lanes, etc, exists.

Regards,

jetthe

Hi, I don’t know where you got the information that the roundabout must be one way. Usually they are drawn as one way, because it is simpler. But for the use case you describe, you have to split the roundabout. There are several roundabouts in my vicinity that are split because of bus routes.

If you look at the Wiki page for the roundabout you won’t find any indication that one way is required.

regards, lars

I concur. Split up roundabouts as needed, to get the route relations right.

Apart from relations, roundabouts are also split when there are different tags, for example when there are bridges as part of the roundabout. An example is http://www.openstreetmap.org/?lat=51.50459&lon=-0.217&zoom=17&layers=B000FTF.

Of course, I misread the information on the Roundabout wiki page. I’m sorry for this unnecessary question.

On a related matter though, have anyone started using relations for tagging the complete roundabout in such a case?
(i.e as described on http://wiki.openstreetmap.org/wiki/Relations/Proposed/Junctions )

I haven’t. And I doubt if it’s really useful. If the complex junction/roundabout has a name, you just tag each part of the junction with the name. If it hasn’t a name because it’s too small or just another way to implement a junction, there’s no need either. At least in our area, roundabouts have neither name nor number.
On a related note, the page to which this proposal should be merged seems to be overly complicated. I don’t know what good it brings to differentiate between all those junction types.

lars