[Tagging] New proposal: Obligatory tagging of oneway on motorway_link

[Paul Johnson]

On Fri, Sep 11, 2015 at 6:56 AM, Shawn K. Quinn <skquinn at rushpost.com>
wrote:

> On Thu, 2015-09-10 at 14:20 +0200, Joachim wrote:
> > I drafted up a proposal about oneway=* for highway=motorway_link.
> > Please comment.
> >
> http://wiki.openstreetmap.org/wiki/Proposed_features/Motorway_link_obligatory_oneway
> >
> > Proposal:
> > Define on the wiki page of highway=motorway_link that oneway=* must
> > also be tagged for every motorway_link. If not tagged, the oneway=*
> > status of this way is undefined.
>
> Though I agree in principle with the idea of making tagging more
> explicit, how big of a practical concern is this? i.e. how many times in
> the real world is motorway_link a two-way road?


It's enough of an edge case I'm in favor of there not being a reasonable
assumption.  Most are one-way, there's a considerable number that aren't.
Immediately coming to mind are multiple ramps joining US:OK:Turnpike to
surface highways, particularly when not within a major urban center (such a
configuration allows a single toll taker to provide information, receipts,
change and collect tolls from a single booth where mainline toll collection
is not feasible).

Ideally checking motorway_link for oneway=* and warning for values other
than yes or no would be be handled by validators (something I also support
for motorway and motorway_link for foot=* and bicycle=* since there's a
very wide mix of both in North America, making blanket assumptions
generally bad on this continent).

> - For routing purposes it is recommended to not route over ways with
> > undefined oneway since any assumption may be wrong and it would be
> > best to correct the data.
>
> This I don't. In a lot of cases the likely direction of a motorway_link
> can be inferred by the angle of the junction, even if not explicitly
> tagged.


Agreed.


> > - In map editors undefined oneway should be displayed as tagging
> > error.
>
> This makes sense, but will cause a fair amount of grief while the
> existing data is fixed.
>

This is a band aid that needs to be ripped off, and sooner is better than
later.  Just look at the fun we're having killing route refs on ways (as
opposed to route=road relations) dinosaur...
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