Proposal:Deprecate railway:narrow gauge

Deprecate railway:narrow_gauge tag
Proposal status:	Draft (under way)
Proposed by:	UnniMan
Tagging:	railway=narrow_gauge Data item
Applies to:
Definition:	I suggest deprecating this tag
Statistics:
Draft started:	2025-11-28

Problem Statement

The narrow_gauge tag is ambiguously defined and it does not fit in the rest of the tags of that key. First, it appeals to gauges narrower than the typical in the area, which is ambiguous. But most importantly, the railway= key defines whether a railway has heavy rail (=rail) nature, tram nature, subway nature, funicular nature... It is totally independent of the gauge. Narrow gauge thus does not belong in there, since any funicular, subway or heavy rail also fits in the narrow_gauge definition, thus losing that information.

The gauge is listed in the gauge= key, and the railway= tag should not depend on it.

Proposal

I propose to deprecate that rag and to redefine the railway:rail tag include heavy rail of any gauge. I do not think an automatic change of all of them to rail is necessary, but it should be a policy to stop using it.

Rationale

I am not sure why this tag was created in the first place. More so, considering that there is no tag for broad_gauge. If it existed, Japan, that uses 1067mm as its major gauge but 1435mm for high-speed, would have its high-speed railway not be rail and not render correctly (see Impact on Data Consumers), which is to all views incorrect. Spain also uses a different gauge for high speed (in this case, Spanish is 1668mm), and at no point has anyone every thought of classifying high-speed 1435mm railways as narrow_gauge, because they are just as rail as the others. "narrow_gauge" was perhaps intended for touristic, mountainous railways, but it has been used for a mishmash of different-nature railways and affected renderings. gauge= includes all needed information about gauge and usage= can be used to clarify whether it is touristic. But similarly, a touristic standard-gauge rail and a touristic narrow-gauge rail should not have any difference other than their gauge= tag. If there is any narrow-gauge rail that does not fit in any other railway= tag, a new one should be created (peoplemover? heritage?) instead of keeping this one.

In India, in the context of Project Unigauge, the rails that were broadened have had their gauge= tag changed but also the railway= one. The change made apparent some other issues, like missing tags, that simply did not show up when it was narrow_gauge, so it went unnoticed.

Tagging

This is a short list of railway= tags, taken from OpenRailwayMap/Tagging. The separation of narrow_gauge, in my opinion, does not fit in here.

rail	(active) track	A track that is used on a regular basis.
proposed	Planned track	A planned track, still in the design phase (no construction yet).
construction	Track under construction	construction=* can be used for a more precise description. It obtains the value usually given to railway=*, such as railway=construction and construction=narrow_gauge.
disused	Disused track	The track is preserved (can still be seen) but is no longer in use and possibly overgrown.
abandoned	Abandoned track	While the track no longer holds any rails or signals, the former line (or even a trackbed) can still be seen. These remains might include embankments, trenches, bridges and tunnels.
razed	Overbuilt track	A former track that has been built upon. While some remains might still be seen, the former route is subject to educated guesses for the most part. Note that mapping demolished railways without traces should be done in OpenHistoricalMap - not in OpenStreetMap.
narrow_gauge	Narrow-gauge track	A track with a gauge (width) narrower than typical to this country. A gauge might be defined by the tag gauge=* using the unit of millimeters. For tracks with three rails, the tag railway=rail can be used, specifying both gauges by gauge=*, separated by a semicolon (such as 1435;1000).
light_rail	City railway, sometimes "Suburban"	City railway and tramlike underground trains, sometimes "suburban." These can be heavy trains, differ in power system (usually electric, occasionally diesel), have their own signals and are a distinct vehicle fleet. These usually are in a dedicated right-of-way, rarely having level crossings with road traffic. However, in denser urban areas these can be street-running like a tram, even while remaining tagged railway=light_rail. North American examples include San Diego Trolley, San Francisco Muni, Portland MAX, Calgary CTrain, Dallas DART, Cleveland Blue and Green Lines, The Tide in Norfolk, Baltimore Light Rail and Buffalo Metro Rail where passenger=urban might be found more frequently (instead of passenger=suburban, which are considered more "commuter" railways using full-sized "heavy rail" railcars).
subway	Subway/Metro	Underground railway in larger cities, powered mostly by third rail. It has its own vehicles and signal system. Sometimes it also comes to the surface or is on an aerial causeway for a segment. Do not map ordinary railway, which goes partially underground, with this tag! (Instead, use layer=-1 or a "deeper" negative value and tunnel=yes). Subway/Metro is usually considered "heavy rail" and is always distinct from "light rail."
tram	Tram	Mostly overground on-street laid tracks ("street-running"). It is common that vehicles like motorcars can share traffic lanes with trams. Some special railways similar to trams might be also mapped using this tag. Larger parts of tram tracks can also go underground (use layer=-1 or a "deeper" negative value and/or tunnel=yes). Some tram routes also use ordinary railway tracks. These should me mapped as ordinary railway tracks (railway=rail).
miniature	Miniature railway	Small railways in parks for entertainment or as a tourist attraction, mostly narrow gauge (up to 600mm). These are often a "scale" of a "standard" railroad size, for example "1/4 scale miniature railroad."

Impact on Data Consumers

In the case of Spain, whose narrow_gauges were recently changed to rail, a main northern railway (that had usage=main) was not showing up in OpenStreetRailway until it was zoomed in to the same level as railway=subway. Branches of railway=rail were appearing at a zoom level worse than

In this rendering of a Swiss area, the rails that are usage=branch and usage=industrial show up, even those that have state=proposed. But there are some missing railways: narrow gauge ones. No narrow gauge, regardless of their usage or state, will appear until you further zoom in to here. It has little explanation. A possible fix would be to fix ORM, but it shows that narrow_gauge simply doesn't make sense. All heavy railways, regardless of whether their gauge is broader or narrower than usual, should be rail.

External discussions

Talk:Tag:railway=narrow gauge

Talk:Tag:railway=narrow gauge/Proposal

Comments

Please comment on the discussion page.