[Tagging] no_u_turn restrictions for every entry/exit into a roundabout when the way is split because of physical separation?

osm.tagging at thorsten.engler.id.au osm.tagging at thorsten.engler.id.au
Fri Apr 6 08:03:20 UTC 2018

Yes, that's from https://wiki.openstreetmap.org/wiki/Proposed_features/Defaults which André Pirard linked to just recently here.

Personally, I'm not a huge fan of the syntax. I would prefer the use of sub-relations.

You would then have a type=defaults relation, with apply_to members that specify the areas where the rules apply and match:(condition) members that refer to type=default relations which can simply contain a set of plain key=value tags (and don't need to have any members, they are just containers for tags).

If the same bunch of default values applies to different things with different matching rules, you can just refer to the same sub-relation multiple times.

One issue with all this is that while you can encode a lot of useful information this way, it doesn't help cases like the "it's not legal by default to make u-turns at signal controlled intersections" in Queensland. As such things can not be expressed with just a tag or two as default values on existing objects. They require specific coded support in router engines.

For that I would suggest something like

rule:no_u_turn_at_signals=yes on the defaults relation, and the router engines need to know what these mean then.


> -----Original Message-----
> From: Frederik Ramm <frederik at remote.org>
> Sent: Friday, 6 April 2018 16:39
> To: tagging at 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?
> Hi,
> On 04/06/2018 05:26 AM, osm.tagging at thorsten.engler.id.au wrote:
> > Putting information about the legal default into OSM is not the
> problem.
> > It’s just that nobody has developed a schema for it yet.
> The French have invented something: Check the "Part of..." listing
> here
> https://www.openstreetmap.org/relation/11980
> It seems that a couple more of these exist, e.g.
> https://www.openstreetmap.org/relation/1124248
> I don't know if anyone actually uses them.
> Bye
> Frederik
> --
> Frederik Ramm  ##  eMail frederik at remote.org  ##  N49°00'09"
> E008°23'33"
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