[talk-au] maxheight/height

Roy Wallace waldo000000 at gmail.com
Mon Jul 27 23:11:21 BST 2009


On Mon, Jul 27, 2009 at 9:47 PM, John Smith<delta_foxtrot at yahoo.com> wrote:
> --- On Mon, 27/7/09, Roy Wallace <waldo000000 at gmail.com> wrote:
>
>> I think the bridge should be tagged.
>
> There was an overwhelming response on the main talk list that this be tagged as maxheight on the way that has the restriction, ie you can't go under the bridge unless you are under x metres.

There are two issues here: 1) what should be tagged and 2) what should
it be tagged with.

For 1), what should be tagged? Definitely the bridge. For two reasons:
firstly, clearance under a bridge is an attribute of the bridge.
Secondly, it is not possible to refer to "the section of the way that
is under the bridge", because the bridge is a way with zero width. The
only alternative is to tag "the entire length of any way that goes
under the bridge" or "some arbitrary length of any way that goes under
the bridge". I think these alternatives are undesirable at best -
misleading and messy at worst. For example, it's kind of like tagging
any house that's next to a park as "next_to_a_park=yes", rather than
tagging the big grassy area as "leisure=park" (yes, this is an
exaggeration, but the analogy is tagging the thing that is affected by
something rather than tagging the something itself).

For 2), what should it be tagged with? I concede that a bridge tagged
with "height" could be misinterpreted (as the actual height of the
bridge or bridge construction), as could "maxheight" (as referring to
a restriction involved with traveling on top of the bridge).

Therefore, I suggest a new tag, "clearance". A new tag should be
created when the current tags do not describe things adequately, which
I think is what has happened in this case.

Thoughts?




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