Does not route on (the edge of) multipolygon area highways.

[dreirund]

Issue

OSRM does route on simple polygon area highways (to be precise, on their edge). But if it is a multipolygon, it does not even route on their edge.

Steps to reproduce

1. Open ↗ this routing URL
2. Observe that, instead of snapping to the closest edge of a footway, the area highway defined as multipolygon (↗ this entity in OSM), it snaps to an area highway further away (↗ this entity in OSM) + resulting in a detour.
   Screenshot:
   

Further remarks

Similar issue for OpenRouteService and GraphHopper.

Regards!

[dreirund]

Addendum:

According to this comment, the area in question is a correctly defined multipolygon area and thus should be handled the same way as single-polygon area highways.

[mvl22]

According to this comment, the area in question is a correctly defined multipolygon area and thus should be handled the same way as single-polygon area highways.

No, the problem is that the Way has no data on it, so there is nothing to route over. Data about physical real-world objects does not go on a Relation. This is not a router bug: it is simply incorrect data. Just because an OSM editor allows you to write arbitrary tags into a Relation doesn't mean anything will be done with that data.

To fix this:

Edit this Way, which is the actual physical object:
https://www.openstreetmap.org/way/1085465662

Add the four infrastructure tags currently on the Relation:

highway=footway
lit=yes
smoothness=intermediate
surface=compacted

The remove those tags from the Relation.

[dreirund]

No, the problem is that the Way has no data on it, so there is nothing to route over. Data about physical real-world objects does not go on a Relation.

See this section in the OSM wiki:

An area (closed way or multipolygon) tagged with highway=pedestrian + area=yes is the most common way to map the pedestrian area of a square or plaza, where pedestrians can travel freely in all directions. […] If there are features or areas within the square or plaza which are not part of the walkable pedestrian area, these should be excluded by creating a multipolygon relation and making them inner members.

And that is exactly the case here: A multipolygon. In case of a multipolygon, the tags do not go directly on the way.

---

OK, maybe it is a "feature wish" and not an "issue" (I call it "inconsistency"), in case that the routing engine's routing on the edges of simple polygon area highways is not actually intentional, but just a side effect of just ignoring the area=yes tag.

My rationale so far was: Since simple polygons and multipolygons are to be treated similarly from the point of view how OSM defines them, if the routing engine routes along the edge of simple polygons, it also should do so on the edge of multipolygons.

Regards!

(And in the case that OSRM uses GraphHopper as backend, then I think this should be closed here and just be tracked here in the GraphHopper tracker.)

[DennisOSRM]

Closing the issue.

Graphhopper and OSRM are distinct efforts.

[dreirund]

This is a duplicate of #4176, I think.