User:Segubi/draft proposal basic network revisited

draft proposal basic network revisited
Proposal status:	Draft (under way)
Proposed by:	Segubi
Draft started:	2022-10-11

Proposal

It is proposed to mark routes that belong to an official (mainly cycling) network that is operated by the state and follows distinct rules and uses specific signs to distinguish them from other routes, usually operated by private associations. These routes can be destination orientated without names or route orientated as named routes. A special concern are the parts of the network consisting of unnamed routes.

At the moment there are many different ways to represent these routes in osm, mainly by collecting ways in sometimes nested relations. The tagging and naming schemes vary strongly between districts or even between neighbouring towns.

Proposed is to mark these basic routes of the network with the tag network:type=basic_network. The usage of ways in such a basic route does not exclude that a named route leads over these ways as the named routes sometimes change quickly just by adding route inserts in guideposts. It wouldn't be feasible to delete underlying basic routes if they change the function.

Rationale

This proposal is based on two germ cells: On the one hand, the need to map the official cycling network in Germany, which has been developing more and more clearly since the 1980s, with a specific signposting system. On the other hand, the desire to systematically name unnamed routes of a route network (independent of the chosen means of transport). The latter approach led to the idea of extending the already existing and accepted key network_type, which has so far been used exclusively for node networks, by another value basic_network to characterize routes within a network that share the essential features of the network (operator, signposting etc., route markings) but do not have their own name and offer additional connections.

The advantage of the new tag is to have the possibility to add the information about the network type without destroying existent information that may be interesting for other data users. E.g. there would have been the possibility to use the tag cycle_network=* to indicate the official network, but the different districts and states in Germany use sometimes special names for their implementation of the network and these are now in use as tags for cycle_network=* (see taginfo [1]). It seems to be impossible to harmonize the existing naming schemes.

Another idea was to use a tag network=bcn in analogy to the tags lcn/rcn/icn etc. But this also results in conflicts with existing taggings. (See a quite extensive description and discussion of different possibilities in Germany by Jochen: User:JochenB/Wegweisungsnetz-Alternativen).

It seemed useful to recur to an existing key that is used in the official cycling networks, network:type=*, that was so far used only with the tag network:type=node_network. As the routes marked with network:type=node_network are also part of the official cycling networks the additional marking is not necessary and one doesn't get conflicts.

The tag is in use as an temporary flag to keep the discriminating information in newly introduced route-relations since summer 2021 but got adopted after a few months by other mappers with now over 7000 occurances (as of October 14th, 2022), so it seems necessary to collect usage, find common rules, discuss them to create a helpful wiki to the key.

Rendering

An aim of the tagging would be to create maps that represent the official network.

External discussions

There have been abundant discussions about the topic of tagging routes, whether unnamed routes can be routes in the "sense of osm" and so on.

I'd love to say: read the official guidelines by the state first before joining any discussion (e.g. https://www.radverkehrsnetz.nrw.de/downloads/HBR_NRW_Kap03_Jul2019.pdf) but unfortunately they are available only in German. (But who is capable of reading that should do that first...)

There are some discussions that could not be resolved in the forums and mailing lists:

"A route without name is not a route in the sense of osm" (https://forum.openstreetmap.org/viewtopic.php?id=66366, DE:Bicycle/Weg oder Route). There have also been defined critera to check that. There is said, that only routes that have a distinct reference are routes and so on.	Further explanations below, but: a route is in osm primarily a relation with the tag type=route. Of course, this relation makes only sense if filled with ways. Everything else is a matter of convention and usefulness and not a question of truth.
2. "No need to introduce new keys or values", no need for relations: Use cycle_network=* at the ways, that's sufficient.	Problems: This is not verifiable at the single way as the belonging of a way is only visible in the context of the guideposts and route markers. They ways can be extremely different: They can be waterways (ferries!), paths, tracks, streets, even stairs (rarely, and then usually with a ramp for pushing the bicycles. Next difficulty: How to maintain? Searching for all ways in an area with cycle_network=*, but how to find out, when this tag was really been verified and by what source. If ways are split, one is created newly, even with an analysis of the changesets you will have difficulties to check whether the tag has been introduced voluntarily or by chance, and relying on what source. In doubt you keep the tag and won't delete it. (And you can expect a big amount of doubt.)

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