[OSM-talk-be] Docks (Antwerp port)

[Vincent Van Eyken]

Indeed many (most) docks in the Port of Antwerp are tagged twice / are represented by 2 entities in OSM: once as an area (with waterway=dock) and once as a linear way (waterway=canal). And I admit to be partly responsible for tagging those docks like that. 

Here is my take on the reason behind that scheme:
- those docks are relatively large bodies of water, hence the requirement for the area to be mapped, with the according waterway=dock tag.
- but they are also used as navigable waterways, similar to highways, and therefore (also) need a linear element, running along their centre line/thalweg, to easily enable (logical) route calculation; e.g. brouter already provides route calculation along waterway lines [1]
As a linear element, their function is imho more like that of a canal, hence the waterway=canal. Of course, this especially makes sense for an actual "Kanaaldok", but it might be disputable for a dock with only 1 entry/exit (like a "cul-de-sac")

So basically it is very similar to the tagging scheme for (large) natural rivers[2]: a linear, navigable way (waterway=river), combined with one or more closed areas (waterway=riverbank), or the "street/highway area" scheme for very detailed mapping of roads.

The messy rendering is of course a result of the fact that both line and area carry the same name, but I suppose that in itself is not a valid reason for change.

As to the types of docks on the wiki: certainly the description for dock=tidal does seem counterintuitive or even wrong... not sure what to make of it... 


[1] http://brouter.de/brouter-web/#zoom=12&lat=51.3012&lon=4.3286&layer=OpenStreetMap&lonlats=4.277115,51.346912|4.412899,51.254556&nogos=&profile=river&alternativeidx=0&format=geojson 
[2] http://wiki.openstreetmap.org/wiki/Rivers 



-----Oorspronkelijk bericht-----
Van: Michaël Dierick [mailto:michael at dierick.io] 
Verzonden: vrijdag 10 februari 2017 18:20
Aan: talk-be at openstreetmap.org
Onderwerp: [OSM-talk-be] Docks (Antwerp port)

Hi,

While looking around on the map at the port of Antwerp I noticed some docks are tagged as a waterway=dock as well as canals (waterway=canal) which results in a somewhat messy rendering ... any ideas on this? (do docks need to be tagged as canal as well)? 
(https://www.openstreetmap.org/#map=15/51.2551/4.3808)

Further when looking at the wiki the definitions of dock=tidal and dock=floating seem somewhat mixed up (see wikipedia @
https://en.wikipedia.org/wiki/Floating_dock_(impounded) and https://en.wikipedia.org/wiki/Dock_(maritime)#British_English ) ... 
could someone confirm this?

Thanks,

Michaël

PS: In maritime environments OSM is used quite a lot (indirectly) through www.marinetraffic.com

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