|junction = circular|
|A road junction where the traffic goes around a non-traversable island but does not always have right of way.|
|Used on these elements|
|Tools for this tag|
A road junction is tagged junction=circular, when the traffic goes around a non-traversable island (or a void in case of elevated roads) in the middle, but the traffic on the circular junction does not always have right of way.
Such junctions can have any size from tiny to huge with several lanes, however the junction must not have any road network inside itself, e.g. ring-roads around a town are excluded.
Such junctions would typically not have the classical roundabout signage, instead individual yield regulations on each connecting road and/or circle segment. Traffic lights can be installed and take precedence over static signposting.
The tag allows routing software to recognise circular junction structures more easily for cases that fail the OSM roundabout definition. OSRM has implemented the tag. There is no impact to expect on visual map rendering.
How to map
Draw the circular shape, which would represent the junction. Furthermore:
- The OSM ways of the junction must be drawn in the direction the traffic flow.
- Tag the OSM way(s) of the circular junction with junction=circular.
- Add oneway=yes for clarity. As this is a new value for the junction key, many data consumers might not be able to assume the oneway property implicitly.
- Connect it with the roads approaching the circular junction. If a road is split into two separated carriageways (one approaching, one departing), draw those explicitly and tag these carriageways with oneway=yes. Pay attention to their correct orientation and use separate nodes of the circular junction for the approaching and departing road.
- Also tag the junction and approaches with highway=*, the same as the connecting roads. If there are several roads of different importance connecting to the junction, you should usually use the one with the greatest importance, that does not begin/end at the junction. More details about selecting the right highway tag can be found on the junction=roundabout page.
- A junction should only be tagged with name=* if the junction itself is named independently and differently from the roads joining it.
- Each road has typically to be connected with the junction in a separate node, i.e. between these nodes a segment of the junction is required. Thus routers can safely recognise that a section of the junction has to be driven through. However there might be an exception to this rule when the junction connects several dual carriageways and the turn:lane layout of the junction allows to leave immediately into the next dual carriageway, thus the incoming and the next outgoing road can share a node to allow a direct turn.
Distinguishing from roundabouts
This tag junction=circular allows to mark junction that are not a roundabout,
- if one of the roads entering the circle has the right-of-way and the other has to yield (Example: Berlin, Strausberger Platz)
- if the circular traffic in the junction always has to yield to incoming traffic (Example: Berlin, Großer Stern)
This form of a junction allows the major and minor road to intersect in one node only, typically in an acute angle. An example is the Strausberger Platz in Berlin, Germany.