|Used to describe networks of various kinds.|
|Status: de facto|
|Tools for this tag|
This page aims to discribes the notion of a network-relation. In addition, it discusses mapping of networks in general.
A network-relation groups features as members of a network, marks them as being part of a certain network and represents this network itself. A route-relation with the network=* tag is therefore not a network-relation.
Goal of network relations
The goals of such relations varies depending on the subjects to be grouped. Common reasons to create and maintain them are noted below:
- Marking members for being part of a certain network, in cases where it would be difficult or even impossible to find information about membership using tools such as Overpass turbo.
- Increasing maintainability by applying tags used by all members to the relation, not the members themselves.
Good to know
Relations are not meant to model categories like "all tram stops in Frankfurt". It might be the case that such relations (still) exist. Before removing, get in touch with the last editors (if edits were recently) and the local community to assure that you did not misunderstand the notion of this relation.
- Network relations group their member regardless of a certain key or feature, as OpenStreetMap does not feature static IDs, the creation of network relations creates a "real" group.
- Each member can be described with a certain role, which is especially useful for network relations.
- Some network-relations may become huge as they represent huge network, this may become an issue.
- Especially new mappers repeatedly did not understand that/how they had to add parts of the network to the relation. Therefore, this was not always done properly and required additional maintenance.
Alternative to network relations
The use of network=xyz for all members of a network is the most common alternative. The drawback is that the value of the network is often not unique and the network=*-tag is already used differently for bicycle and hiking routes.
Outdoor sport networks
The concept of network-relations is used for node networks in particular. This enables grouping of nodes.
Public transportation networks
Network-relations are used in the contexts of a common fare system, a certain type of transportation and the (subsidized) concessions to operate a number of lines. There is a Category:Public transport by country listing specific information on public transport with regards to a certain country. This is far more than just network-relations. In general, network relations include all route-master relations of the network.
Network relations are used to mark the membership of a route to a public transport concession. This was motivated by the ease of maintenance in the light of constant changes in concession ownership.
The idea of network-relations for concessions or fare systems (German: Verkehrsverbunde) was doomed on the mailing list as they change regularly and have no relevance for the users. The current situation seems to be that everything is mapped in the route=* or route_master=* relations and network relations are abandoned and ignored (examples: missing underground line 4, with note=teilen, teilen, teilen, German for
divide, divide, divide).