Sometimes, in OpenStreetMap, two or more highways entering and exiting a roundabout are mistakenly connected to the same node on the roundabout itself.
Why is this a problem?
Routing, navigation and planning software relies on accurate OSM data to provide clear direction instructions. Incorrect roundabout connections can lead to confused drivers and potentially inefficient travel.
How can you help?
We’ve identified these leads through data analysis. Here’s how you can contribute:
Review the Leads: We’ve used queries to pinpoint potential issues based on the number of highways connected to a roundabout node. These leads exclude pedestrian paths, cycleways, and roads on different levels (bridges/tunnels).
Open the Task: If comfortable, use your preferred OSM editor to open the specific task. In some cases it might be necessary to open the task in JOSM in order to edit the task due to relations being involved. If you are not comfortable editing these tasks feel free to unlock the task and select a different one.
Fix the Connection: Separate the potential incorrectly connected highways by creating additional nodes along the roundabout’s perimeter. Ensure each highway connects to a distinct node if needed.
Advanced cases: Sometime, more complex edits involving relations might be needed. If you’re unsure, consider unlocking the task and letting another more experienced contributor handle it.
It looks like this challenge was built on the assumption that every node having more than one road was a problem. As a consequence, we have seen a large number of edits by user acting in good faith but “solving” non-issues.
IMHO, the challenge should be redone and only flag situations where you have roads going into the roundabout AND roads going away from the roundabout.
This is a router problem, not an OpenStreetMap problem. Making these corrections is “drawing for the renderer”. There are many places where the same situation occurs, but outside a roundabout (see for example Node: 314954167 | OpenStreetMap)
or better OpenStreetMap ). At this last place, TomTom reported 4 errors because the Chaussée du Sart-Tilman was tagged with “roundabout=yes”. By removing the roundabout tag everything becomes normal again and it is no longer just a simple crossroads.
Why can data consumers not handle the red node as-is? What is the benefit of splitting the red node into two nodes? Depending on the roundabout, splitting the node into two may unnecessarily distort the geometry of the roundabout, especially for multi-lane roundabouts.
Hello @JeroenvanderGun and @wwwouaiebe
We’ve reviewed many cases, and while some may seem a bit awkward or tricky, we’ve followed the guidelines, as outlined in the wiki, which advise against directly connecting approaching and departing roads.
Adding to that, we added detailed instruction on the challenge, that it may be that the roundabout tag is not needed, probably will need to be fixed and no action is to be done for/on the geometry itself.
Why can data consumers not handle the red node as-is? What is the benefit of splitting the red node into two nodes?
I think this comes from one paragraph in the OSM Wiki, claiming that data consumers need to route at least on one way having junction=roundabout to detect they were in the roundabout. Doing that in the situation of the red node requires more queries; I suppose this is the reason why people want to “fix” connecting roads everywhere they can. https://wiki.openstreetmap.org/wiki/Tag:junction%3Droundabout#Connecting_ways
But you have a point here: encouraging people to remap as many roundabouts as they can, just for the sake of fixing, can lead to careless mapping and broken data.
