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

David Fisher djfisher81 at gmail.com
Sat Apr 13 20:12:42 UTC 2013


Sorry, yes, "one way per track", of course.  Was writing hurriedly.
Thanks,
David.


On Sat, Apr 13, 2013 at 9:06 PM, John F. Eldredge <john at jfeldredge.com>wrote:

> 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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>>>
>>
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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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