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Opened 3 months ago

Closed 3 months ago

Last modified 3 months ago

#18508 closed enhancement (wontfix)

Warn about unusually long footway crossings

Reported by: gaben Owned by: team
Priority: minor Milestone:
Component: Core validator Version:
Keywords: Cc:

Description

If a way tagged with footway=crossing + highway=footway and it's longer than around 30-40m it is highly likely an error. The validator should warn about these ways.

The longest crossing in the world is probably in Shibuya, Tokio, which is about 44m long according to this source.

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Change History (13)

comment:1 Changed 3 months ago by Klumbumbus

Is this a common error in the database? Can you count the objects with overpass?

comment:2 in reply to:  1 Changed 3 months ago by gaben

Ah, that's not how it works, unfortunately. If a whole crossing is drawn as a single way around eg. a 4-way intersection, it creates too many false-positive results. But with increasing the length it doesn't detect shorter ways which are wrong, just checked on overpass.

Replying to Klumbumbus:

Is this a common error in the database? Can you count the objects with overpass?

Yes, a moment. The global query timed out with 180s.

comment:3 Changed 3 months ago by Klumbumbus

Yes, I noticed this too, did some analysis in Germany.

With a threshold of 150m these are 57 out of 23017 footway=crossing ways in Germany.

comment:5 Changed 3 months ago by gaben

Priority: normalminor

I see, thanks for the analysis. My global query timed out once again now I'm rate limited.

Maybe configurable info level check possible? The threshold would be up to the user.

comment:6 in reply to:  5 Changed 3 months ago by Klumbumbus

Replying to gaben:

Maybe configurable info level check possible? The threshold would be up to the user.

That doesn't help to separate the right from the false positives

comment:7 Changed 3 months ago by GerdP

I think this would require a lot of logic. You have to detect parts going into one direction and measure the length. If one part is longer than x meters create a warning. Can be done with java but I don't see why.

comment:8 Changed 3 months ago by gaben

Yeah, that's the only thing I come up with. Too much work for a little benefit. Wontfix?

comment:9 in reply to:  8 Changed 3 months ago by Klumbumbus

Resolution: wontfix
Status: newclosed
Version: latest

Replying to gaben:

Wontfix?

Yes except someone comes up with a new idea.

comment:10 Changed 3 months ago by gaben

I have a new idea. The length check + if a footway shares a node with a higher importance way (residential and up) between the ends. If not, the rule can be applied. What do you think?

comment:11 Changed 3 months ago by GerdP

Yes, would reduce the false positives. On the other hand, if no such shared node exists even a short way might be flagged. Thinking about it maybe someone may split a footway=crossing to map a different surface on a crossing island.

comment:12 Changed 3 months ago by skyper

Just for the record, do not forget other values for highway like path and cycleway:
highway={0} + {0}=crossing

comment:13 in reply to:  12 Changed 3 months ago by gaben

Replying to GerdP:

Yes, would reduce the false positives. On the other hand, if no such shared node exists even a short way might be flagged. Thinking about it maybe someone may split a footway=crossing to map a different surface on a crossing island.

That's true, but those ways are short, at least shorter than the suggested length (30-40m).

Now I see a different problem. If a footway is parallel to another highway and long (crosses multiple minor roads), the check wouldn't work. Meh :/

Edit: But checking the distance with a different threshold between shared nodes maybe could work. It's going to be very complex again...

Last edited 3 months ago by gaben (previous) (diff)

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