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 <j...@jfeldredge.com>wrote: > David Fisher <djfishe...@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 >> <m...@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. >>> >>> >>> >>> >>> ______________________________**_________________ >>> Tagging mailing list >>> Tagging@openstreetmap.org >>> http://lists.openstreetmap.**org/listinfo/tagging<http://lists.openstreetmap.org/listinfo/tagging> >>> >> >> ------------------------------ >> >> Tagging mailing list >> Tagging@openstreetmap.org >> http://lists.openstreetmap.org/listinfo/tagging >> >> > 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 -- j...@jfeldredge.com > "Reserve your right to think, for it is better to think wrongly than not > to think at all." -- Hypatia of Alexandria > > _______________________________________________ > Tagging mailing list > Tagging@openstreetmap.org > http://lists.openstreetmap.org/listinfo/tagging > >
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