Hi Martin, Your proposal makes a lot of sense.
bridge:structure (or type) seems the logical place to put it, along with bridge:name, bridge:clearance (or whatever min/max clearance tags we have for tidal situations), etc... The principal should also be extended to tunnels. eg tunnel:structure, using values like - "excavated" (shallow cut and cover tunnels), "bored" (deeper tunnels), and "covered" (ground-level tunnels enclosed by a building/structure). BJ On 17/01/2012, at 3:32, Martin Koppenhoefer <dieterdre...@gmail.com> wrote: > Currently the documented values for "bridge" don't seem to follow any > (single) classification system. > http://wiki.openstreetmap.org/wiki/Key:bridge > > Fortunately 98.49% of all actually used values don't have this problem > (they are "yes"), but the rest seems a mess: > > 1. There is a first classification system using the kind of way going > over it for distinction: > > 1.1 A road (or railway): "viaduct" (a term that is not really well > defined, especially the distinction between a "bridge" and a "viaduct" > doesn't seem to be clear). This is a bit mixed because besides the > road this seems to be a bridge with several abutments in "small" > distances, whatever "small" is, and "viaduct" seems to be used also in > conjunction with railroads. Not sure but I feel as "viaduct" might > also be a bridge typology (see 3). > > 1.2 Water: "aqueduct" (suitable for the parts of aqueducts that span > over a void). The definition seems to extend the use to all kind of > aqueducts ("A longer structure for carrying a canal or fresh water.") > while many aqueducts are not spanning over something (they are tubes, > have a solid support like a wall without openings or even are > underground) so they clearly aren't bridges. > > This first system doesn't make much sense IMHO, because you can > already see by other tags which kind of way is on top (waterway, > highway, railway), but it is currently the most used. > > > 2. Another classification system on the page is one according to the > structural system employed: > 2.1 arch > 2.2 pontoon > 2.3 suspension > > 3. And even another system is that of typology: > 3.1 bascule > 3.2 drawbridge > 3.3 humpback > 3.4 lift > 3.5 swing > > > "so why is this bad?" one might argue. Well, the problem is that with > this chaos you won't be able to tag all properties (typology, > structural system, carried way) of a bridge, you will instead have to > decide which one to focus on (might also lead to tagging wars). > Another problem is that the lack of systematics makes it difficult to > extent this system with new values, because it is not clear where the > focus is. > > > I propose to use distinct tags for these properties instead: > > 1. is not needed IMHO (see above). If the interesting fact for > viaducts are the several "small" spans I'd put this into typology. > 2. could be tagged with bridge:structure (or structure or structural_system) > 3. could be tagged with bridge:type (or type). > > > > Last but not least I'd like to ask you for comments on 3 new values: > N1. a bridge made of few ropes where you walk on a rope: > http://bauwiki.tugraz.at/pub/Baulexikon/HaengeSeilBrueckeB/Kaiserschild_1.jpg > http://www.gruppenstunden-freizeit-programme.de/ferienlager-freizeiten-erlebnisse/freizeit-bilder/seilbruecke/Piratenlager-05-262.JPG > http://www.bergsteigen.at/pic/d6025434-21f9-4d93-9ce9-42aba5cf00db.jpg > > additionally we could tag the amount of ropes (or even more precisely > the amount of "upper" and "lower" ropes) > > are these described in English with the term "zip-line"? > http://en.wikipedia.org/wiki/Zip-line > > > N2. a similar bridge made of ropes, but you walk on planks: > http://bauwiki.tugraz.at/pub/Baulexikon/HaengeSeilBrueckeB/Trift_Bruecke_1.jpg > http://bauwiki.tugraz.at/pub/Baulexikon/HaengeSeilBrueckeB/Tripsdrill.jpg > > I guess this would be a "simple_suspension_bridge" > > > N3. A "Cable-stayed_bridge" (the absence of this value makes it > probable that most of these might currently be tagged as suspension > bridges or not classified at all). The difference from a suspension > bridge is that the cables are directly attached to the towers / pylons > instead of to another cable, see here: > http://en.wikipedia.org/wiki/Cable_stayed_bridge > > cheers, > Martin > > _______________________________________________ > Tagging mailing list > Tagging@openstreetmap.org > http://lists.openstreetmap.org/listinfo/tagging _______________________________________________ Tagging mailing list Tagging@openstreetmap.org http://lists.openstreetmap.org/listinfo/tagging
