[Tagging] Status of oneway=cw oneway=ccw

Sarah Hoffmann lonvia at denofr.de
Thu Mar 14 10:43:04 UTC 2019


Hi,

I was pointed to the discussion from the waymarkedtrails issue
tracker. I haven't followed the whole discussion. Here's just my
two cents as somebody how processes route data.

On Wed, Mar 13, 2019 at 04:37:19PM +0100, s8evq wrote:
> > If you want to indicate the preferred direction of a walking route that is
> > basically loop-shaped, a concept that is different from the legally binding
> > oneway, then some kind of clockwise / anticlockwise tagging should be used.
> 
> Yes Volcker, this is what I'm after. It's about loop-shaped walking/hiking/cycling routes, that should only by done in one direction, because of way-marking and signposts.  (Most of the bicycle routes in this overpass query fall in that category https://overpass-turbo.eu/s/GWB, quite a lot!)
> I'm not talking about individual ways that are oneway restricted for pedestrians.
> 
> 
> How to properly indicate the preferred direction of this kind of relation? 
> 
> method (1) With proper forward / backward roles on the members of the relation? (as stated in the route=bicycle wiki page https://wiki.openstreetmap.org/wiki/Tag:route%3Dbicycle and mentioned by Volcker Schmidt and Kevin Kenny)

That's for the case where a route forks and follows different
ways for forwards and backward directions of the route. I'd still
expect both directions to be present.

> method (2) By using the tag oneway=yes, (as stated on the route=hiking and route=foot wiki page  https://wiki.openstreetmap.org/wiki/Tag:route%3Dhiking https://wiki.openstreetmap.org/wiki/Tag:route%3Dfoot but it causing a lot of confusion here)
> 
> I have not seen anybody on this mailing list defend the usage of method (2). Can I ask the question: why it is in the wiki?

Then let me defend the method. I like the simple oneway=yes
(or oneway=signed if you think it clashes with the legal
 restriction tags). It is the least hassle for a mapper.
In addition to using the tag  you need to make sure that
your members are correctly ordered in the direction where the
route is signed. Then it is also really easy to determine which
the recommended direction is, if you look at the entire
relation.

NB: There is a bit of a conflict though here between those who
just want to paint the routes on a map and those who want to
process entire routes. For the map creators the forward/backward
solution is much nicer because the role is relative to the way.
It makes it easier to simply add a couple of arrows to indicate
direction. The 'oneway=yes' is a pain because you first need to
determine if the way is forwards or backwards in the relation.
When assembling routes from the relation exactly the opposite
holds. Forward/backwards doesn't give any information about the
direction of the route the way belongs to.

So disclaimer here: I like oneway=yes because waymarkedtrails
fully processes relations.

oneway=cw/ccw might be useful for mappers to verify that the route
is correct but rather difficult for processing.

Sarah




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