I have been reading about OSM Road from accepted answers here like,



and my question,


The answers fell short in explaining whether the segments in an OSM Road belong to a single road or grouped together from multiple roads. Since OSM Roads have intersections(answered in third link above), does it mean OSM Roads actually contain roads where travelling in multiple directions is possible.

To put it clearly,

  1. Is the road uni directional - one way or two way
  2. Does the OSM roads has structures like T-Joints (where the road has information(GPS points) on roads connected to an intersection.). Usually it is not possible for us to travel in both directions at the same time. So having OSM ID for GPS points in different road segments where you cannot travel, does not make sense to me.
  3. Where can I find the reference or documentation for these latent information for OSM.

Note: If the question seems too abstract, let me explain, I am trying to understand the OSM, since I'm using it for my research.


1 Answer 1


I think you didn't understood linked answers...

RAW OSM data doesn't contain strict information about crossings (intersections)... one road could be splitted in many places and for many reasons (4 eg. bridges or surface changes), also don't have to be splitted on every intersection.

Of course there is a tag highway=crossing in use but it's used only in specific cases (4 eg. crossing has it's name), so most crossings are not tagged this way.

As @underdark wrote in one of linked Q&A's to find crossings you have to convert RAW data into topology for routing - then every vertice of your graph is an intersection.

Also there is information about directions in roads both in RAW data (oneway=*) and in topology created by OSM2PO (cost, reverse_cost).

Last, but not least - please follow answers - as others said few times - open OSM editor (JOSM) and look at RAW data - there is nothing underneath, no hidden data - data is just like you see it in JOSM. Also OSM is open project - there is no such thing as top-secret-deep-web-osm-forum where you can find top-secret hidden information - everything is open

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