I tought it was obvious, but let me spell it out: such restrictions represent a default which we should be recorded somewhere (not necessary inside OSM) once and observed by data consumers, not by creating potentially 100000’s of relations to again and again encode the default behaviour.
This is exactly the problem that exists in Brazil, where u-turns back onto the same way at intersections are generally prohibited without any explicit sign allowing them, so some mappers add 4 no_u_turn at every single intersection node. Please refer to: https://github.com/openstreetmap/iD/issues/2527 In fact, it is also reapet, IN BOLD, on the main relation:restriction page: https://wiki.openstreetmap.org/wiki/Relation:restriction * Don't map turn restrictions that are the default for a given jurisdiction and are not signed. It is much better to ensure that routing engines embody the regional rule rather than mapping every occurrence as a turn restriction. This applies particularly to unsigned U-turns in Brazil, where using turn restrictions will require hundreds or thousands of restrictions and micro-segmentation of all roads which in turn make editing data hard. Cheers, Thorsten From: Paul Johnson <ba...@ursamundi.org> Sent: Friday, 6 April 2018 07:50 To: Tag discussion, strategy and related tools <tagging@openstreetmap.org> Subject: Re: [Tagging] no_u_turn restrictions for every entry/exit into a roundabout when the way is split because of physical separation? Rather than mindlessly barfing back "But the wiki says…", how about a critical argument? Best practices aren't set in stone and necessarily should evolve as better approaches become apparent. In many jurisdictions (esp in North America), such rules are quite readily available and under government copyright online already. It's no less verifiable than ground truth, and just as applicable to navigation. On Thu, Apr 5, 2018, 16:34 <osm.tagg...@thorsten.engler.id.au <mailto:osm.tagg...@thorsten.engler.id.au> > wrote: https://wiki.openstreetmap.org/wiki/Good_practice#Don.27t_map_your_local_legislation.2C_if_not_bound_to_objects_in_reality From: Paul Johnson <ba...@ursamundi.org <mailto:ba...@ursamundi.org> > Sent: Thursday, 5 April 2018 23:38 To: Tag discussion, strategy and related tools <tagging@openstreetmap.org <mailto:tagging@openstreetmap.org> > Subject: Re: [Tagging] no_u_turn restrictions for every entry/exit into a roundabout when the way is split because of physical separation? I don't think that's particularly harmful. I'm not against extending the criteria to published laws, particularly when those laws are documented in an official source. On Wed, Apr 4, 2018, 23:10 <osm.tagg...@thorsten.engler.id.au <mailto:osm.tagg...@thorsten.engler.id.au> > wrote: Actually, it’s not just relatively harmless “noise”. Because such no_u_turn restrictions are indistinguishable from e.g. this one: https://www.openstreetmap.org/relation/8182004 (which I just created), that actually has a sign “on the ground”: https://www.google.com.au/maps/@-27.2141567,153.0014115,3a,75y,100.42h,82.68t/data=!3m6!1e1!3m4!1s-vnw60jwbq7XyR_-zZfreg!2e0!7i13312!8i6656 (excuse the streetview link, don’t have another photo of it right now, but I’m driving past it almost every day and am well aware of it). From: Tod Fitch <t...@fitchdesign.com <mailto:t...@fitchdesign.com> > Sent: Thursday, 5 April 2018 09:50 To: Tag discussion, strategy and related tools <tagging@openstreetmap.org <mailto:tagging@openstreetmap.org> > Subject: Re: [Tagging] no_u_turn restrictions for every entry/exit into a roundabout when the way is split because of physical separation? Seems like tagging “noise” to me. I’d expect a router to use the roundabout itself because exiting, making a U turn and then re-entering the roundabout will be longer and thus slower. Since the no U turn relations are there to make routing work and a reasonable router won’t need them, I’d say they are “noise”. If I were to go in to fix something on that intersection, I’d probably remove the no U turn restriction(s). But I don’t think I’d go out of my way to find them. Cheers! On Apr 4, 2018, at 4:36 PM, osm.tagg...@thorsten.engler.id.au <mailto:osm.tagg...@thorsten.engler.id.au> wrote: I’ve noticed that someone from the Microsoft Open Map team is very busy adding turn restrictions all over the place ( <https://www.openstreetmap.org/user/shawat94/> https://www.openstreetmap.org/user/shawat94/ ). In my local neighbourhood, I noticed that he added no_u_turn restrictions to all the nodes where a road into in/out of a roundabout is splitting (because of physical separation). Which basically amounts to 4 no_u_turn restrictions for every single roundabout. e.g. here: <https://www.openstreetmap.org/changeset/57747093> https://www.openstreetmap.org/changeset/57747093 <https://www.openstreetmap.org/changeset/57674063> https://www.openstreetmap.org/changeset/57674063 There is no actual no_u_turn sign in any of these locations, it’s just (mostly) physically a bad idea to attempt a u-turn here. Just a few weeks ago I discussed exactly this in #osm and the conclusion was that it was neither necessary nor desirable to do this. I made a comment about that to the first of the two changesets linked above, but haven’t gotten a reply. So, what is the general opinion about this here? Should these turn restrictions be created or not? Cheers, Thorsten _______________________________________________ Tagging mailing list <mailto:Tagging@openstreetmap.org> Tagging@openstreetmap.org <https://lists.openstreetmap.org/listinfo/tagging> https://lists.openstreetmap.org/listinfo/tagging _______________________________________________ Tagging mailing list Tagging@openstreetmap.org <mailto:Tagging@openstreetmap.org> https://lists.openstreetmap.org/listinfo/tagging _______________________________________________ Tagging mailing list Tagging@openstreetmap.org <mailto:Tagging@openstreetmap.org> https://lists.openstreetmap.org/listinfo/tagging
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