#35 - Turn Lanes in San Francisco (Archived)

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This project was archived.

Mapping turn Lanes on highways tertiary and up in SF

Created by saikabhi - Updated - Priority: medium


Entities to Map
Changeset Comment
Add missing turn lanes from satellite imagery in SF Bay Area https://github.com/mapbox/mapping/issues/180
When saving your work, please leave the default comment but add what you actually mapped, for example "added buildings and a residential road".

JOSM Workflow


  • Activate the following in from JOSM preferences > Map Settings
  • Map Paint Styles: Lanes and road attributes
  • Tagging Presets: lane attributes
  • Filter out non road features with boundary: | leisure: | landuse: | waterway: | amenity: | natural: | building:
  • Add inverse filter: highway=motorway | motorway_link | trunk| trunk_link | primary | secondary | tertiary
  • Read turn lanes wiki
  • Read mapping guide for turn lanes
  • Start by mapping turn lanes in the priority areas and then moving onto the other areas.


  • Check the roads until tertiary and up for turn lanes at exits and entry points
  • Split the road into segments based on the total number of lanes for the segment
  • For each road segment tag the turn lanes based on the road markings in the direction of the way. Eg. turn:lanes=left|through|right. See OSM turn:lanes
  • For bi-directional segments, use turn:lanes:backward= and turn:lanes:forward= to specify turn lanes in each direction.
  • Verify correct tagging using the Lane attributes style

Issues to keep in mind:

  • For QA and edge cases in turn lanes mapping and how to handle them(parking lanes, splitting roads for start and end of turn lanes, handling of dual carriageways, etc) look into the QA for turn lane data document.

Source: Bing/Mapbox/USGS Large Scale Imagery

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