User:Imagic/Turn Lanes
Turning indications
The turn=* key can be used to specify the direction in which a way or a lane will lead. It is used on the way segment from the first indication via road markings, signposts or similar indications to the junction or completion of merge.
turn=[left|slight_left|sharp_left|through|right|slight_right|sharp_right|
reverse|merge_to_left|merge_to_right|none]
| Value | Description | Road marking example | Signpost example | Other example |
|---|---|---|---|---|
| left | left turn (only) | |||
| slight_left | slight left turn (only) | |||
| sharp_left | sharp left turn (only) | |||
| through | going straight through (only) | 
| ||
| right | right turn (only) | |||
| slight_right | slight right turn (only) | |||
| sharp_right | sharp right turn (only) | |||
| reverse | reverse/U-turn (only) | |||
| merge_to_left | this lane merges with the lane to the left of it (only) | 
| ||
| merge_to_right | this lane merges with the lane to the right of it (only) | 
| ||
| none | there are no turn indications on this lane.
Used especially for better readability in case of many lanes |
If more than one indication is present, separate the different values with a ; (semi-colon). For example:
turn=left;through
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 extension is used. For details about the :lanes-extension, see TODO.
In short:
- 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; also 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.
turn:lanes=left|through|right
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 trough.
turn:lanes:forward=left|through;right turn:lanes:backward=through|through;right