I’ve been playing around with differing OSM data with OSMNX, and I’ve found that for certain cities there’s a junction field in the edges dataframe but in others there is no flag for junction.
Is there a way to know which cities have a flag for junctions and which don’t?

In general, this is not tagged anywhere, except for =roundabout and =circular. junction=intersection is only a proposal. You need to do your own processing in GIS software or a PostGIS database, use Overpass to query online, or look into how routers handle junctions.

Got it.
I’m most curious about finding roundabout and circulars as opposed to regular intersections. Was curious to know if most roundabouts are tagged, and if there’s no field then it’s safe to assume there’s no roundabout in that map.

If you go to https://overpass-turbo.eu/ and zoom to the location, in the Wizard you can start the query junction=roundabout (or any other tag*) and click ‘build and run query’. This is a query at Wexford in Ireland: https://overpass-turbo.eu/s/1lqQ Some of the roundabouts are small and mapped with a single way (line), e.g. here: https://www.openstreetmap.org/way/39237393 while others are made up of several lines, e.g. here: https://www.openstreetmap.org/way/159756843 so this can affect count numbers. Sometimes junctions have names name=New Ross Road Roundabout, other times they have reference numbers ref=5 or junction:ref=5

As to whether roundabouts are tagged, that will depend on the quality of the mapping in a location. For example, someone might have simply mapped the roundabout as a circular one-way street. In some places, the mapping may be primitive and only the main road is mapped and no junction details have been added yet. You might be able to check this by looking at junctions you know or have photos of to see if correct tagging is used. In some countries roundabouts are rare.

There are also separate tags for
highway=mini_roundabout https://wiki.openstreetmap.org/wiki/Tag:highway%3Dmini_roundabout
highway=turning_loop https://wiki.openstreetmap.org/wiki/Tag:highway%3Dturning_loop

  • If there are space characters, put that side of the tag in double quotation marks, e.g. name=“Main Street”.