[Tagging] Feature Proposal - RFC - More Consistency in Railway Tagging

Sat Apr 13 20:06:28 UTC 2013

David Fisher <djfisher81 at gmail.com> wrote:

> > Croydon Tramlink is one counter-example, and I'd concede that
> someone has
> done great work in accurately mapping the path of it that I wouldn't
> want
> > to destroy, but it is sadly completely disconnected from the highway
> network, and that is what I'd like to address.
> 
> As a Croydon mapper myself who has made changes to the tramlink
> network...
> firstly thanks for noticing that it looks OK!  It's by no means all my
> own
> work, but I like to think I've done my bit :)   There's actually only
> one
> stretch which is relevant to this debate: the Addiscombe Road section
> between East Croydon and Sandilands (I presume it is this section you
> refer
> to when you say "completely disconnected from the highway network"?). 
> All
> the other on-highway parts are only single-track, so are easily
> represented
> by a single way with nodes merged with the highway.
> 
> Anyway.  My two cents, for what it's worth:  I am strongly in favour
> of
> mapping highways and railways differently (one way per separated piece
> of
> tarmac for roads; one way per rail for railways).  One form of
> compromise,
> however, could be to treat specifically on-highway rail systems with
> the
> "highway" protocol.  Or, maybe for multi-rail on-highway sections, map
> them
> as separate ways (cf Addiscombe Road tramlink) and use a relation just
> to
> cover these sections?  I realise this is not ideal for cities with a
> large
> proportion of such sections, but long-term it may be a way to maintain
> detail whilst limiting complexity (since relations would not be needed
> for
> *every* section, just shared sections).
> 
> Cheers,
> 
> David Fisher.
> 
> 
> 
> 
> On Sat, Apr 13, 2013 at 7:11 PM, Martin Atkins
> <mart at degeneration.co.uk>wrote:
> 
> > On 04/13/2013 10:18 AM, Rovastar wrote:
> >
> >> Martin,
> >>
> >> The example you gave for tunnels and bridges are the same for roads
> as
> >> well.
> >> If you have a bridge or tunnel with 2 roads (one for each one-way)
> and a
> >> train line(s) and footpath each will be a tagged with a separate
> bridge.
> >> So
> >> in that regard rail is actually are consistent with the road
> network.
> >>
> >
> > Point taken: it is a general problem with bridge tagging, not one
> with
> > railway tagging. I found some discussions on the wiki about
> modelling
> > bridges as areas that would address this, but I don't really have
> any
> > interest in mapping bridges in particular, so example retracted for
> the
> > purpose of this discussion.
> >
> >
> >  Also you say you want it better for simple mapping and other can do
> more
> >> detailed mapping if they want to. I see no part of your proposal to
> add
> >> additional tracks like is now yet you imply in the posts here that
> it is.
> >> If
> >> you do think this then it doesn't not help the crossing example you
> gave
> >> as
> >> we will have the same problem again.
> >>
> >
> > I have not described a way to describe the actual routes of tracks;
> I lack
> > the expertise (or interest, frankly) to describe that next level of
> detail,
> > I just propose that we separate that next level of detail from this
> simpler
> > level of detail, rather than using the same tags for both.
> >
> > I've seen the area:highway proposal for mapping the detailed shape
> of
> > streets, sidewalks and footways. My assumption was that this
> proposal could
> > be extrapolated to include a similar model for railways, modeling
> the
> > precise shapes of the trackbed the rails run along, the positions of
> the
> > individual tracks within that trackbed, etc.
> >
> > If I were trying to define such a thing my first thought would be to
> > define a new way tag to mean "the exact path of a track" and use
> separate
> > ways from the simple route network. e.g. railway:track=rail . I've
> not
> > spent nearly as much time pulling that idea apart as I have my
> simple
> > route-oriented proposal, so I'm sure someone who knows more about
> railways
> > than I do could find examples where that doesn't apply, but it's a
> strawman
> > to start with.
> >
> > I could also compromise on making the schematic network be the thing
> that
> > gets new tags, but I think it's tough to say whether it's better to
> suggest
> > re-tagging detail work in dense areas where there are evidently lots
> of
> > avid mappers at work (and the re-tagging could thus happen
> relatively
> > quickly), or to suggest re-tagging the basic network in areas where
> there
> > is less detail and there are fewer (or no) active mappers.
> >
> >
> >  Do you propose that we change *all* the currently mapped multi
> track rails
> >> to conform to your new standard?
> >> e.g. here there are hundreds of tracks/railways which IMHO
> accurately
> >> reflects what is on the ground.
> >> http://www.openstreetmap.org/?**lat=51.47119&lon=-0.14847&**
> >>
> zoom=15&layers=M<http://www.openstreetmap.org/?lat=51.47119&lon=-0.14847&zoom=15&layers=M>
> >>
> >
> > Under my proposal it wouldn't do any harm to leave existing detailed
> > tagging in place where the railway doesn't cross the highway, since
> a
> > railway way represents "one or more tracks", and that holds for the
> example
> > you showed. Optionally one could add tracks=1 to the existing ways
> to make
> > it very clear.
> >
> > The converse is not true: if you define that a railway way
> represents
> > exactly one track, then there's lots of work to do to turn miles of
> > existing one-way-per-railway tagging into one-way-per-track.
> >
> > When it comes to tramways and level crossings, whichever approach we
> take
> > there are many counter-examples to be corrected, of course.
> >
> > I would note that if we *did* adopt a separate tagging scheme for
> detailed
> > mapping of tracks then at least one could simply re-tag the existing
> > railway=rail as (e.g.) railway:track=rail and not destroy the
> existing
> > detailed geometry. Of course, someone would have to draw in the
> basic route
> > network too; I bet the data for that is somewhere buried in the OSM
> > historical record, since a schematic view of the UK railway network
> was
> > imported into OSM as a starting point many years ago and is still
> the basis
> > of simple mapping in many rural areas, but admittedly I have no idea
> how or
> > whether it could easily be recovered for situations like your
> Battersea
> > example.
> >
> >
> >  However what I do agree with you is that the rail guidelines should
> be
> >> more
> >> detailed but I would go the other way with saying that all tracks
> should
> >> be
> >> mapped not less for complete mapping. That is a common way of doing
> things
> >> and going forward especially as we get more detailed mapping (it's
> slowly
> >> coming to the US ;))
> >>
> >>
> > I'd be fine with that as long as the result includes details about
> how to
> > connect the road and rail networks in a clear, unambiguous way at
> all
> > levels of detail. It is the lack of definition around these
> interactions
> > that causes the most difficulty, I think.
> >
> > London isn't a great example of the problem since it has many, many
> > railways but very few situations where railways connect with
> highways at
> > grade.
> >
> > Croydon Tramlink is one counter-example, and I'd concede that
> someone has
> > done great work in accurately mapping the path of it that I wouldn't
> want
> > to destroy, but it is sadly completely disconnected from the highway
> > network, and that is what I'd like to address.
> >
> >
> >
> >
> > ______________________________**_________________
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> > Tagging at openstreetmap.org
> >
> http://lists.openstreetmap.**org/listinfo/tagging<http://lists.openstreetmap.org/listinfo/tagging>
> >
> 
> 
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Did you intentionally write "one way per rail", or did you intend to say "one way per track"?  I had not seen anyone in the discussion, up until now, propose mapping each rail as a separate way.  This would mean that a single-track right-of-way would require two ways, unless you were mapping a monorail.

-- 
John F. Eldredge -- john at jfeldredge.com
"Reserve your right to think, for it is better to think wrongly than not to think at all." -- Hypatia of Alexandria
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