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

David Fisher djfisher81 at gmail.com
Sat Apr 13 19:52:55 UTC 2013


> 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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