User:Rurseekatze/Station Importance Draft
Renderers can't display on a map in each zoom level, so they have to make a selection. The more important an object is, the earlier (in zooming in) the object should be rendered. For highway=* as an example you see motorways starting in zoom level 3 and residential roads starting in zoom level 12 and much smaller.
The importance of a station is also necessary for the decision which label is rendered in cases of collision. This information is also helpful for ranking search results.
For roads the value of highway can be used for such categories and rankings. But a system like this is missing for railways.
Background
Currently we use the tag railway:station_category=1-7 for mapping the German railway station category, but this is very german-specific. We need a way to tag the importance of a station using generic definitions that are independent from any country-specific categories.
Numeric values are not user-friendly, human-readable terms are preferred.
Looking at route relations associated to a stations could be a possible solution, but is very complex to implement and would require preprocessing. This would also just work for passenger stations, but not for e.g. freight yards.
Looking at the number of platforms is also complex to implement and does not produce useful results (Example).
Inspired by importance=*, I propose a tagging schema using station_importance=* with the following values:
Proposed tagging
The following proposal is more a characterization than a definition due to the situation that the boundaries between these categories are fluid, similar to road tagging.
The following definitions and examples are currently focussed on passenger stations, but this tagging can also be used for non-passenger stations such as freight stations, yards, employee stations, service stations, spur junctions and sidings.
station_importance=continental
Stations that are located in big cities (often capitals). These stations are large traffic hubs and important nodes in the long-distance network within a continent. Most of the national long-distance traffic runs via these stations and the station can be used to interchange between highest category trains. Trains of all categories stop here, especially highspeed trains, long-distance trains and night trains. The station is usually the most important one of several railway stops in a city.
In Germany, this category would correspond to "Bahnhofskategorie" 1.
Examples:
- Frankfurt (Main)
- Munich
- Stuttgart
- Hannover
- Vienna
- Salzburg
- Moscow Yaroslavskaya
- Grand Central Terminal, New York
- Milano Central
station_importance=interregional
Typically located in larger cities with national importance. These stations are part of the long-distance network, but less important than stations from the highest category. These stations are commonly used for interchanging between long-distance and regional trains. Trains of all categories stop here. The station is usually the most important one of several railway stops in a city.
In Germany, this category would correspond to "Bahnhofskategorie" 2-3.
Examples:
station_importance=regional
Stations that are typically located in cities and larger towns with regional importance. These stations are typically located at junctions of railroad lines from different directions. Passenger use this station to intersect between different regional trains to different directions. All regional and commuter trains stop at this station (in Germany all S-Bahnen, RB, RE), but long-distance traffic is restricted to single trains (in Germany e.g. single IC or EC). The station is usually the most important one of several railway stops in a city.
In Germany, this category would correspond to "Bahnhofskategorie" 3-4.
Examples:
station_importance=urban
Stations that are typically located in towns and larger villages with local importance. Typically these stations are not served by more that two lines and are not used by passengers to intersect between trains. Most of the regional trains stop at these stations (in Germany RB and S-Bahn, some RE), but there is typically no long-distance traffic.
In Germany, this category would correspond to "Bahnhofskategorie" 3-5.
Examples:
station_importance=suburban
Stations that are typically located in suburbs of metropolitan areas. Only commuter trains (S-Bahnen in Germany, sometimes RB), light rails and subways (U- oder Stadtbahnen in Germany) stop here. Typically these stations are not served by more that two lines.
In Germany, this category would correspond to "Bahnhofskategorie" 4-5.
Examples:
station_importance=local
Stations that are typically located in villages and hamlets of rural areas. These stations have importance for just a few surrounding villages, hamlets or e.g. a touristic site. Only regional trains stop here (RB in Germany), but there may be also some regional who do not stop here or just stop on demand (German "Bedarfshalt"). Typically these stations are served just by one line. Stations which are just served sometimes (e.g. by historic and touristic trains or for special events) also belong to this category.
In Germany, this category would correspond to "Bahnhofskategorie" 6-7.
Examples:
Previous tagging
I propose to keep the existing railway:station_category=* for mapping country-specific categories like the German railway station categories. It is necessary to discuss if these country-specific values should have a country- and/or operator-prefix (such as signals).