|The key turn can be used to specify the direction in which a way or a lane will lead.|
|Used on these elements|
|Tools for this tag|
The turn=* key can be used to specify the indicated direction in which a way or a lane will lead. It is used on the way or ways:
- from the first indication via road markings, signposts or similar indications
- to the junction or completion of merge.
|At intersections where turn=* and turn:lanes=* keys are used, legal turning restrictions are expected to be correctly specified to allow navigation programs to calculate driver lane assistance properly. These turning restrictions are explained in the restriction relation article.|
Note: Due to concerns that turn lanes are infrequently explicitly marked with signposts or pavement markings, and how data consumers are already using this data, it has been suggested that explicitly tagging turn lanes where the turn lane values are assumed by context should also be done.
Turning indications per lane
Usually the turning indications of a road differ from lane to lane. To specify those indications for every lane, the
:lanes suffix is used. For details about the
:lanes suffix in general, see Lanes.
- The key changes to turn:lanes=*
- View the road in the direction of the osm-way.
- Add the lane-values to the value, starting with the leftmost lane and ending with the rightmost. Separate each lane-value with a | (vertical bar)
If you want to describe only the lanes of one direction of the road, use either turn:lanes:forward=* or turn:lanes:backward=*. The key turn:lanes:forward=* describes only the turning indications on the lanes in the same direction as the osm-way. The key turn:lanes:backward=* describes only the turning indications on the lanes in the opposite direction as the osm-way; doing so view the road in the opposite direction of the osm-way for this.
Example for a one-way
There are three lanes on a one-way, and the leftmost lane will turn left, the rightmost lane will turn right and the lane in the middle will go straight through the next junction.
Example for a road with both directions
There are two lanes on the road in each direction. Those lanes running in the same direction as the osm-way are considered to be "forward"; the others "backward". The left lane of the forward direction will turn left and the right lane will go straight through and also turns right. The left lane of the backward direction will go straight through, the right lane will turn right and also continue straight through.
The following example shows a motorway with two links.
- TurnLanes-tagging plugin - graphical tag editor for uni and bidirectional turnlanes
Bryan Housel has stated they are adding a visual turn lane editor to iD during July-August 2016.
- Lanes for the description of the
- Forward & backward, left & right for describing the direction of the highway and how to determine this in the Potlatch 2 editor.
- destination:lanes=* for describing the name of the city the street is heading to.
- The proposal for the lanes suffix
- Legal turning restrictions using the restriction relation
- Lane_assist - best practices for lane assistant using turn=* and destination=*
Renderers and data consumers
OsmAnd supports turn:lanes to show lane recommendations in navigation mode.