specify the notion of regions

[derhuerst]

When @juliuste migrated meinfernbus to FPTF, we noticed that there is the concept of regions/cities/hubs.

Berlin for example has several long-distance train & bus stations, all distinct but well-connected through local public transport. I makes sense to keep them as stations, because they may still have individual stops, but clustering them would enable more advanced routing information.

Now questions arise:

• what is the relationship between regions/cities/hubs? 1:n or m:n?
• what name is the best? often these clusters are cities, but not always. sometimes they may be more fine-grained (airport broader area) or less (a Bundesland). "cluster" and "hub" seem very generic.
• where to specify them? should a region/city/hub have a stations field or the opposite? or both?

[derhuerst]

@juliuste argued that there's actual value in clusters being able to overlap each other, which indicates a m:n relationship with stations.

[juliuste]

As @derhuerst already mentioned, I'd strongly advocate a m:n relationship in order to support - or at least to not disable by default - the possibility of assigning multiple clusters to one station. For instance: This could be useful when clustering stations into both geographical regions and cities. The station Nice-Ville could then be included in the clusters named Cote d'Azur and Nice which - at least to me - really makes sense.

[juliuste]

Regarding the naming issue, I'd personally choose between cluster and region. cluster is the more general term while region would probably be more easily understandable for people who didn't read the specification when using one of our modules - at least I'd know what do do with a regions method while I might not be so sure what a method called cluster does. This isn't the strongest or most important argument, still not completely irrelevant though.

Anyway, I wouldn't call the new type hub, since this sounds more like an important interchange station than an actual cluster. I'd even call big stations like Frankfurt Hbf or - even bigger - Frankfurt Flughafen a hub on their own since they serve as an interchange point for quite a decent amount of connections.

[juliuste]

On where to specify the relations: As @derhuerst already mentioned in a private discussion, there is no way to reverse engineer the station-cluster-relation starting at a cluster in a lot of cases. Therefore, I'd propose to at least include a regions key in station object. For practical reasons though, I'd also like to have an additional optional stations key in region objects to enhance the workflow in some situations.

[juliuste]

Bump 🔨

[derhuerst]

Therefore, I'd propose to at least include a regions key in station object. For practical reasons though, I'd also like to have an additional optional stations key in region objects to enhance the workflow in some situations.

Sounds reasonable to me. However, we should clearly stress what's the preferred direction if only one direction can be specified.

[derhuerst]

This might be interesting:

https://wiki.openstreetmap.org/wiki/Proposed_features/Metro_Mapping#Voting https://wiki.openstreetmap.org/wiki/Talk:Proposed_features/Metro_Mapping