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roundabout back to Key:junction

Description: A roundabout is a road junction where the traffic goes around an island in the middle. Google definition User discussion

Element: help

Useful combination: Key:access Key:name Key:reference

Implies: oneway=yes

Used combinations in: Europe France Germany Italy Netherlands Spain Turkey Great-Britain Switzerland

Contents 1 Summary 2 How to Map 3 Examples 4 See also

Summary

A roundabout is a road junction where the traffic goes around an island in the middle. Roundabouts can be anywhere from tiny (the island is just painted on the road surface) to huge with several lanes.

Small roundabouts are just represented as a node which is tagged highway=mini_roundabout

How to Map

There are different ways of representing roundabouts depending on their size. The segments in the way must go around the roundabout in the direction the traffic flows, but there is no need to tag them as oneway=*. The way should then be tagged with junction=roundabout. The way also gets the same highway=* tag as the connecting streets. If there are several streets of different importance connecting to the roundabout, you should usually use the one with greater importance (so a roundabout connecting unclassified roads and a primary road should be tagged as highway=primary). If there is a longer way with several larger roundabouts in between, you have to break up the way into chunks. See the examples for more information

Examples

Feature	Example	Example Rendering
A standard size roundabout with up to four exits can be drawn simply using four nodes in a diamond shape. A road can be connected to each of the nodes. A larger roundabout may benefit from using eight or even more nodes.
Where a dual carriageway connects to a roundabout, there should be two nodes on the roundabout in place of just one.
In many cases the road approaching a roundabout may split into two separated carriageways (technically, this is called a flare). If these are of a significant size (at least more than just a pedestrian island) then you may want to draw some or all of these out distinctly like the following example. Each of these flares would be a separate way (tagged as one way).

See also

If you want to know more about the design of roundabouts in the United Kingdom then this pdf document (Highways Agency Design Manual for Roads and Bridges -Volume 6, Section 2, Part 3, Geometric Design of Roundabouts) is the definitive reference.