jm at liotier.org
Thu Feb 18 14:44:17 UTC 2016
On 2016-02-17 15:18, Malcolm Herring wrote:
> From the IHO Hydrographic dictionary:
> breakwater. A structure protecting a shore area, HARBOUR, ANCHORAGE, or BASIN from WAVES. See also FLOATING BREAKWATER.
> jetty. In U.S. terminology, a structure, such as a WHARF or PIER, so located as to influence CURRENT or protect the ENTRANCE to a HARBOUR or RIVER.
> In British terminology, a PIER, usually of solid construction, intended as a berthing place for vessels. See DOCK, LANDING, WHARF.
> mole. A massive structure of masonry or large stones serving as a PIER or BREAKWATER, or both.
> pier. A long, narrow structure extending into the water to afford a berthing place for vessels, to serve as a promenade, etc. See also JETTY.
> quay. A WHARF approximately parallel to the SHORELINE and accommodating ships on one side only, the other side being attached to the SHORE. It is usually of solid construction, as contrasted with the open pile construction usually used for PIERS
> wharf. A structure serving as a berthing place for vessels.
Thanks - that is quite authoritative !
It seems that the orientation related to the shore (natural=coastline,
waterway=riverbank etc.) is quite unambiguous:
- Orthogonal: pier- Alongside: quay
Then we have a second dimension related to how the object is built:
- concrete pile
- wood pile
- metal pile
Though the main dichotomy is masonry vs. pile.
And then a third dimension that expresses whether or not mooring is
possible - which is nicely expressed by the well-used mooring=* tag
which can be applied to all the objects concerned.
We can already drop the Openstreetmap use of wharf, mole and jetty which
are ambiguous and/or redundant. Also, dock is a specific concept
(enclosed+varying water height) that is very adequately expressed by
waterway=dock - so let's get that one out of the way too.
Orthogonal, masonry and no docking is the special case of
man_made=breakwater, an already well-used tag - mooring=no is implicit
here, though the external boundary structure of a harbour may be a
breakwater with a quay on its internal side... No problem for
Openstreetmap - tag a man_made=quay on the internal side.
man_made=pier is quite good as it is now - except that it is often
assumed to be supported by piles... We learned that, while piles are the
most common case, other cases exist such as masonry. I believe it would
be perfect if we could complement man_made=pier with a tag for that.
man_made=quay looks fine too and might also in some (rarer) cases
benefit from such a tag.
Together with a few special cases such as man_made=breakwater and
waterway=dock, I believe that man_made=pier and man_made=quay,
complemented with mooring=* unambiguously cover all cases where a few
ambiguous and somewhat synonym tags are currently used.
So, how should Openstreetmap express how the object is built ? I would
argue towards using the well-used material=* tag... I specifies only the
material and not the sort of construction, but material=wood,
material=masonry, material=metal etc. are common values that feel quite
fitting to how we want to describe piers and quays.
And then once set on that path, we'll one day be able to sunset
man_made=mole, man_made=wharf and man_made=jetty.
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