I'm interested in the way "Motorways" are described in OSM.
For instance that one :
describes a motorway between 2 cities : Paris and Lille (North of France).
However the members of the relation are for both driving directions : Paris -> Lille AND Lille->Paris .
Is there an "easy" way to know which ways are part of the Paris->Lille driving direction and which ones are only relevant for the other driving direction (=split the relation in two parts, one for each driving direction) ?
Any hint or idea is welcome to extract such information from the relation !

asked 19 Feb '11, 20:35

y0n3l's gravatar image

accept rate: 0%

edited 19 Feb '11, 20:43

The best solution would be to split the relation into two parts, one for each driving direction. In the US, directional roles have been used: north/south/east/west, but this does not seem to be the convention in France.

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answered 21 Feb '11, 12:40

Mike%20N's gravatar image

Mike N
accept rate: 17%

I would include the two new relations in a super relatin, too

(28 Feb '11, 20:56) Baloo Uriza

I'm not that an easy solution exists. Maybe you can code (for example with python and DOM) an analyser on the data that, starting from a node, build the set of ways that are connected.

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answered 22 Feb '11, 09:26

NicolasDumoulin's gravatar image

accept rate: 13%

Hello Nicolas, Yes this is what I ended up with : I split the relation in x parts on my side by finding which ways have common nodes.

(27 Feb '11, 14:20) y0n3l

Good. Maybe you can flag your question as answered :-) And it will be nice to post your script if it is possible.

(28 Feb '11, 10:42) NicolasDumoulin

Yes, I'll flag the question as answered, but I was waiting for a little while to see different answers (actually I think that Mike's answer is the right one, after a more in depth look , I saw that some french highways were using this tag, but only a few of them). For the scripts , humpf, it's written in ObjectiveC so unless you're in the Mac / iOS I think it's useless :/ Are you the guy from http://pld.dumoulin63.net ? I'm also on open street map fr ;)

(28 Feb '11, 20:31) y0n3l

Ok, ObjectiveC will be useless for me. Yes, it's the same dumoulin ;-)

(01 Mar '11, 08:43) NicolasDumoulin

You could try ignoring relations, and extracting "WayChains". A chain of ways that are connected end-to-end.

My WayChains TIGER fixup analysis does this kind of thing (on motorways as it happens, although it would work for other kinds of end-to-end connected ways)

The logic to join together ways into "waychains" can be found in waychainsummary.rb.

I'm running it with a pre-processing step using my osmosis simplify plugin, which reduces ways down to just their start node and end node.

Note however that I was deliberately designing this to help find problems in the U.S. motorways data. For extracting OpenStreetMap data for practical use, you may find this approach a little fragile. e.g. if a mapper tags an onramp with highway=motorway instead of highway=motorway_link, then it may not chain the ways correctly at that point. You'd have to fix it before trying again.

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answered 01 Mar '11, 11:32

Harry%20Wood's gravatar image

Harry Wood
accept rate: 14%

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question asked: 19 Feb '11, 20:35

question was seen: 4,357 times

last updated: 01 Mar '11, 11:32

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