As a non-biker, I'd hate to end up clinching all the road mileage in a state but have my statistics show less than 100% because of bike routes I would never ride.
I'm not used to travel by bike or rail and I absolutely agree! Stats should be shows for each transportation system.
I think it was never proposed (by Jim or anyone else) to have one stats only but separate stats.
However, I like the idea that stats could optionally show all transportation systems one day. For that reason, I'm not sure if having separate data bases is a good idea. Having different servers for transportation systems (maybe even with different code versions) is definitely a no go if we wanna have this option one day...
Which transportation system should be added next? Rail, underground, bike, ferry or anything else?
I think it doesn't matter from a technical point of view. I guess adding an additional system is almost the same effort for a 2nd system only, 2nd+3rd or 2-4th system. The infrastructure must be implemented once and the front end is just design and text in the end of the day (which is some effort though).
I think the next system added depends on interested collaborators only who would start drafting routes.
And I think that's the way. First, we need routes drafted. Once there's a base of routes (like it already exists for rail), the implementation can start. That means, Quidditch33 should be added as collaborator so that he gets info of how to draft routes and work with GitHub. He's new, so one collaborator should check his first wpt files drafted, for instance about shaping points: Should bike routes be handled different to roads, e.g. should the "red limit lines" of the wpt editor be closer to the actual bike route?
I would only contribute for drafting (car) ferry routes but I've no idea how the routes should be drafted because only the start and end location are usually 100% clear, e.g. for connections in the Baltic Sea et cetera...