[Talk-ca] Problem with overpasses in NB??

berniejconnors berniejconnors at gmail.com
Wed Dec 4 00:07:26 UTC 2013


      That's great info and very helpful. 


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-------- Original message --------
From: Harald Kliems <kliems at gmail.com> 
Date:12/03/2013  7:04 PM  (GMT-04:00) 
To: berniejconnors <berniejconnors at gmail.com> 
Cc: talk-ca at openstreetmap.org 
Subject: Re: [Talk-ca] Problem with overpasses in NB?? 

Okay, so I've done some digging. Unfortunately, the Overpass API does not have a function to identify intersecting ways with a shared node. The only way to find those would be do do an Overpass query for all the bridges and then use javascript to identify the ways that share nodes. I lack the skills to do the latter. 

Identifying bridges which lack the layer tag, however, is easy: http://overpass-turbo.eu/s/1FZ

Once all the missing layer tags will have been added, we can then use keepright's (http://keepright.ipax.at/) layer conflicts function. Based on the description of that function it actually seems like it should already be able to find the problematic junctions:

"Connected ways should be on the same layer. Crossings on intermediate nodes of ways on different layers are obviously wrong. Junctions on end-nodes of ways on different layers are also deprecated, but common practice. So you may ignore this part of the check and switch them off separately. Please note that bridges are set to layer +1, and tunnels to -1, anything else to layer 0 implicitly if no layer tag is present."


On Tue, Dec 3, 2013 at 9:21 AM, berniejconnors <berniejconnors at gmail.com> wrote:
Here is another sample of the problem since Richard corrected my other example ;-)


As I see it there are 2 problems with these bridges:
1) they intersect with the roads that pass beneath them
2) the layer value is not set so the default value of layer=0 (ground) is assumed. Typically a bridge should have layer=1.

I would like to have an overpass api query that selects bridges that meet either of these conditions.


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