This proposal aims to deprecate the tag railway:narrow_gauge. The railway key has many tags depending on the type of infrastructure (train, tram, subway, monorrail, disused…) and also one for narrow gauge railways. While it arose because, in some areas, narrow gauge railways have per se a special nature and operation, this is not true for all countries, and the tag has become a way to tag all narrow gauge railways, even though there already exists another key to enter the gauge. Those “countries with special narrow gauges” should instead use other keys like usage, and deprecate this narrow_gauge tag that does not fit in with the rest of tags of the railway key.
This is a tag that is widely used in OSM (60k uses). gauge is tagged on 52k of the 60k uses, so someone needs to get busy updating the remaining 8k before we can even think of moving forward with this.
This tag is documented as being supported by a relatively large number of projects (about 30). Once you’ve updated the data so that gauge can in fact be used, please submit PRs to the projects whose representation of OSM data you would otherwise break (four of those are mine, and the PRs for those are actually straightforward - let me know if you need help).
Actually, I’d suggest here is probably the better place for all sorts of reasons (wider OSM audience, automatic translation, less horrible UI, etc.).
To avoid confusion, could you change “railway:narrow_gauge” in the thread topic to “railway=narrow_gauge” - otherwise people might think that you want to deprecate some arcane sub-tag named railway:narrow_gauge rather than deprecating the well-established narrow_gauge value of the railway tag.
I did this. (As a country category moderator, I have the ability to rename topics regardless of location. That’s probably a bug rather than feature, but it’s useful. @woodpeck, can you?)
I will add my reply to the Wiki discussion page here also:
I mostly agree with your proposal, as the tag is very ambiguous, and the data it can provide can be covered by almost every sort of other tag, such as the exact gauge, and whether it is a tourist or miniature railway (though where I live we have a miniature railway that is 600mm gauge :D ).
Japan, South Africa, and New Zealand are all perfect examples where “railway:broad gauge” is a “missing” tag, when in reality it adds weight to the Narrow Gauge tag being a little bit redundant. E.g. this section of 2140mm track in the UK is not tagged as “broad gauge”, Yet this section of 610mm is tagged with Narrow Gauge.
My only concerns are the Tag already has widespread and almost universal use, and many rendering tools for OSM use this tag to to distinct between what should be rendered as one way, and what as another. Because the tag is specifically for “narrower than the countries standard gauge” it covers those “blind-spots” like with the examples of countries who use Metre gauge, “Cape” gauges. This is a very easy way to distinct these tracks, and for a very long time maps have differentiated between what is and isn’t standard gauge railways.
I think we will need to hear a bit from people who run these rendering services, and how easy it would be to change. This change could be a bit of a “pulling the Jenga block out” moment.
Maybe there should be a proposal for switching the “narrow gauge” to “non-standard” or “alternative” gauge, as that can work both ways for bigger or smaller, and then for examples of lines like Maglevs or Shinkansen they could lean more on the “highspeed” tag, or the actual gauge as a number to solve in the render what sort of line to display.
Actually, a closer look at the data suggests that it’s not so simple. This overpass query looks for railway=rail with an unexpected gauge (n the UK and IE). While some are genuine, most of those appear mistagged - there are a lot of miniature railways in there. Things like this “wide siding” are just wrong. Going through this data would require examination on a case-by-case basis.
Determining the gauge for some narrow gauge might be tricky. If I tried to measure this one I’d likely get arrested and shot, and not necessarily in that order.
I can understand what you’re saying (in some places narrow_gauge is functionally the same as rail) but just “deprecating values” is not an answer.
Oh, I agree, that is just what the proposal template requires.
For sure, and I wouldn’t just recommend mass changing all worldwide narrow_gauge to rail. But deprecating it would allow/entitle each region’s mappers to start the switch process, instead of keeping/adding narrow_gauge and leaving the problem for the next mapper. We could perhaps include a note in the proposal (and later on in the tag website) that the removal of narrow_gauge from a line should ensure that there is a listed gauge?
gauge=narrow is still an option, to preserve mappers’ life.
I don’t think that would help much, since the main underlying issue is that railway=weird_gauge overrides any other infrastructure consideration (heavy rail, tram, monorrail, miniature…). A weird-gauge heavy train rarely has the same rendering needs as a weird-gauge miniature train.
I understand the missing gauge tag issue, but it’s worth noting that railway=rail also has 9% of missing gauges (which represents 200k ways). So hypothetically, putting gauge=narrow and railway=rail wouldn’t really be a loss of information.
But many narrow_gauges are miniatures too, whose gauge is not really relevant. I understand that deprecating it might tempt someone to just change everything to rail, but if they do so, are we really losing any information? It is just as misrepresented as it is now.
Well that’s taking it to an extreme. I don’t understand how subway fits in here. A subway is a suburban line, exclusively for passengers and usually with high frequencies. In general the community does a pretty good job in distinguishing between “fake metros“ like through-running high frequency heavy rail that goes underground and actual metros, even against the branding of the local authority (looking at you, Melbourne Metro).
As for the other two, miniature is a whole different nature. A miniature will never ever transport anything. It’s purely for fun, like a toy. Railways, instead, transport stuff: even touristic ones can move you some kilometers, and mountain ones definitely do. Narrow-gauges, instead, have the capability to do just what normal railways do, even if a supposed majority of them is touristic.
As for monorails, sure, we could set gauge=0. We could also set rail_height=0 and call bus lanes (or any road) a railway. But here we have a consensus on what a monorail is. But it is not clear at all what a narrow gauge is, given that a lot of technically narrow gauges are not mapped as narrow_gauges precisely because it implies a “belittlement“ that is not so in many cases like mainlines and passenger roads.
On the topic of legislations: Even within the same country you can have narrow gauge railways be governed by different law even if you disregard trams. For example, Germany, which does have dedicated laws for narrow gauge railways (ESBO), also permits a non-standard gauge (if only limited to branch lined) on EBO branch lines (EBO being the main railway laws), meaning an narrow gauge railway can be governed by laws intended for standard gauge railways, and the most famous narrow gauge railway in Germany, the Harz Narrow Gauge Railway, actually is governed by EBO, not by ESBO.
To claim that railway=monorail should be deprecated because you can simply enter gauge=0 is ridiculous. For one, the width of the entire rail can be considered to be a gauge, for the other, monorails have fundamental differences to regular railways that they cannot be put in the same category (you could even argue that monorails shouldn’t even be railway=* but rather its own group) like how railways can cross with other ROWs, monorails can’t. That’s like saying highway=bus_guideway should be deprecated in favour of highway=busway because the latter is more general and both refer to bus infrastructure but both have different shapes to the point where highway=path is more like a subtype of highway=unclassified (and indeed, some highway=path originally were highway=unclassified).
No, because No matter where you are in the world, a Monorail is a monorail, a miniature railway is a miniature railway, a minimal railway is a minimal railway, and a subway is a subway.
Narrow gauge relies heavily on what the standard gauge of a country is. According to Russia, “Standard Gauge” is a narrow gauge.
gauge=0 is a model scale gauge, so would overlap tags.
However I do understand where you are coming from that other nonnumerical tags to exist to represent gauges that deviate from the expected gauge of a country.
And to add to that, where is the common use of “broad gauge” tags? (of which only 36 uses of the tag exists, yet countries like Japan have thousands of miles of “Broad Gauge” on their Shinkansen. These are already fulfilled by a numerical difference.
To make this a bit more concrete, and in line with the proposal’s direction of separating concerns, it might help to think in terms of independent dimensions:
This is where the formatting going all screwy!
Dimension
Example values
Current tagging
Infrastructure type
rail, tram, light_rail
railway=*
Physical property (gauge)
1435, 1000, 762
gauge=*
Operational usage
main, branch, industrial, tourism
usage=*
Service type
passenger, freight, mixed
service=*
Electrification
contact_line, rail, no
electrified=*
In this framing, the proposal is effectively suggesting a shift from:
railway=narrow_gauge
to something like:
railway=rail
gauge=*
possibly, usage=*
which makes sense conceptually, since gauge=* is already the explicit place for track width.
However, one open question is whether this decomposition is complete in practice:
railway=narrow_gauge has historically been used for a mix of cases (mainline, industrial, heritage, etc.)
gauge=* captures only the physical property
usage=* and similar tags are not always consistently applied or well-defined for all these cases
So the question becomes:
Does the combination of railway=rail + gauge=* (+ usage=* etc.) fully cover the semantics that are currently being encoded, even if inconsistently, by railway=narrow_gauge?
If yes, then a migration path could be defined quite clearly.
If not, then it might be worth identifying what additional tagging (or clearer definitions) would be needed before deprecating the existing tag.
I don’t think it does. I’d argue that when rail=narrow_gauge was invented, it was more in the sense of the layman’s definition of “the little brother of the big trains”. So that means it is a combination of narrower gauge, lighter built infrastructure and smaller stock. The exact definition will vary from country to country and there are, as always, corner cases. But at least in Germany and Switzerland, I’d argue that you get a pretty consistent response for many of the regional railway infrastructure, when you ask non-railway nerds, if this is a “rail” or “narrow gauge”. So it is well worth making that distinction. Things get a lot more fuzzy when you ask to distinguish between tram, subway and light rail (i.e urban rail infrastructure).
Why is a deprecation necessary at all? If you don’t care about the distinction between rail and narrow gauge, just handle the tags the same. If you prefer to make a distinction purely based on gauge, then use the gauge tag instead of the railway tag.
Another example is Ireland’s extensive network of peat bog railways, which is completely unrelated to the main rail network, and most map users would expect to be de-emphasised compared to “real” railways.
I understand the proposal would retag these from railway=narrow_gauge to railway=rail.The question is, is that a useful thing to do? They are already tagged as gauge=914, usage=industrial. So it won’t encourage mappers to add more information to tags - the information is already there. But it will mean that anyone rendering any kind of map, even a simple background map with no particular focus on railways, will have to parse multiple tags if they want to treat these differently. Is there a benefit that makes this worthwhile?
We also have some tracks in South East Queensland with triple tracks, so that both Qld narrow-gauge (1067mm) trains, & also NSW Standard-gauge (1435mm) can use the same tracks!
)