[Tagging] Chaos and uncertainty in "bridge"

LM_1 flukas.robot+osm at gmail.com
Mon Jan 16 18:06:04 GMT 2012


I agree that what you describe is bad. I agree that your first point
can be inferred from what is on the bridge (sometimes there can be
more).
After a short research:
All values that you mention in 2 (together with bascule) are structure types .
Number 3 (without bascule) is mode of operation for moving bridges.

So my suggestion would be:

bridge=[arch;suspension;cable_stayed;bascule;beam...] just like
http://en.wikipedia.org/wiki/Bridge#Types_of_bridges

The third would indeed deserve a separate tag, I suggest
bridge:movable=[drawbridge;swing;lift;yes (moves in an unspecified
way)]

For your photos:
N1 - if it can be considered a bridge at all it should have separate
value, eg. bridge=zip_line
N2 - suspended bridge, if it should be more specifiic something like
bridge=suspension:[simple; underspaned; stressed _ribbon;
suspended_deck; self_anchored...] could be used


Lukas (LM_1)


2012/1/16 Martin Koppenhoefer <dieterdreist at gmail.com>:
> 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
>
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