[Tagging] new access value

ajt1047 at gmail.com ajt1047 at gmail.com
Fri Oct 9 21:42:36 UTC 2015

On 09/10/2015 19:54, Friedrich Volkmann wrote:
> On 09.10.2015 13:39, Richard Fairhurst wrote:
>> localised meaning does not always have to be parsed into universal
>> tags.
>> Here in the UK we have very specific access legislation for paths. On a
>> bridleway, for example, cycling is permitted, but cycle racing is forbidden,
>> and cannot be authorised (whereas it can be authorised on other rights of
>> way). Then we have "restricted byways". And "byways open to all traffic".
>> And "unclassified county roads". And so on.
> Sounds more like a road type issue than an access tags issue.

It's not a road type issue.  It's not especially uncommon to have a 
"legal right of access" that legally allows vehicles that physically 
won't fit.

> Strange
> regulations for certain road types exist in most if not all countries,
> including mine. These regulations should be documented at
> http://wiki.openstreetmap.org/wiki/OSM_tags_for_routing/Access-Restrictions#United_Kingdom.
>> It's madly complex. It would be inappropriate to ask the rest of the world
>> to accept special tag values just for this specific use, but on the other
>> hand, it's not realistic for UK mappers to break this down into 30 'atomic'
>> tags per path. (Especially because the permissions for each path type do
>> occasionally get redefined, as per
>> http://www.legislation.gov.uk/ukpga/2000/37/contents.)
> We should avoid explicit tagging of access restrictions that are defined by
> law. By declaring implicit defaults on the aforementioned page, we only need
> to change one line on that page instead of myriads of ways whenever a law
> changes.
>> So we use the standard OSM broad-brush duck tagging (highway=track,
>> highway=footway, highway=cycleway etc.) and add a UK-specific value to
>> record the legal status of the path (designation=public_bridleway,
>> designation=restricted_byway, designation=byway_open_to_all_traffic etc.).
>> That way, it's easy to map, easy to parse in outline, possible to parse in
>> detail, and doesn't impose a burden on the 95% of non-UK mappers or the 99%
>> of data consumers who don't care.
> However, the data consumers who do care have a hard time.

I do care (I create maps that incorporate these rights of way), and 
don't have a hard time.

> You deliver them
> non-standard tags they either miss completely or don't understand. The
> designation=* proposal was voted down long ago. International usage of
> designation=* is a mess, see taginfo. There's no way applications can use
> this. OSM is an international project, don't use proprietary tags.

"creating a proprietary tag" is effectively exactly what you're 
proposing (the first line of the first message in this thread was "I 
intend to write a proposal for a new access=* value, but I don't know a 
reasonable tag name.").

You're entirely within your rights to use a new "access" value, and 
everyone else (router developers included) is entirely within their 
rights (and very likely) to ignore it.  This does a worse job of 
communicating the access rights to the intended audience than 
"access=destination with some sort of caveat" would.

There are routers out there that don't understand that bicycle access on 
trunk roads is country dependant, or that it might be possible to route 
_through_ gates on tracks; do you really think that they'll cope well 
with an access value that they've never heard of?



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