Search code examples
openstreetmapqgis

Where is the traffic flow direction stored in OSM route data?

I downloaded OSM route data and opened it in QGIS in order to see if traffic flow direction could be displayed (and this is the case). To do so, I just changed the symbology by replacing the simple line symbol by the arrow.

So, I am wondering where this information is stored in the downloaded route data? How is QGIS able to display it?

Solution

  • Every way in OSM has a direction. A way can have a oneway tag. If oneway=yes is set then traffic can only flow in the direction of the way. If oneway=-1 is set then traffic can only flow against the direction of the way.