Darrin Smith <[EMAIL PROTECTED]> wrote:
> When I read one part of the OSM wiki I see it talking about classifying
> highways purely by their physical characteristics
..
> The majority of pages talk about classifying roads by their state
> funding designation and or highway reference which is fine because
> these are pretty easy to explicitly define.
There is little doubt that the original highway definitions corresponded to
the classification system in the UK. The
primary/secondary/tertiary/unclassified correspond pretty closely to the
road classifications there.
The arguments over physical or administrative classifications lie around
the edges of the discussion in the UK. Some people thinking an 'A' road in
certain sections, may be secondary, or some such.
Anyway, rest assured this is a "live debate". Check out
http://wiki.openstreetmap.org/index.php/Proposed_features/Highway_administrative/physical_descriptions
>
In some urban areas in Australia, the reference definition can work quite
well. In Sydney, Motorways correspond to motorways, trunk roads correspond
to metroads, and residential/unclassified to surburban correspond to
streets going nowhere. This only leaves primary/secondary etc to be
subjective to a certain extent.
However, in rural areas of NSW, the system doesn't work so well. If you
use the reference method, you will find that there are a handful of state
highways, a couple of auslink roads, and that leaves 99% of all the roads
without a reference classification. This would dramatically reduce the
usefulness of the resulting map to use a reference classification. Most
roads would look the same. Many main routes between towns have no
reference classification at all.
It would be nice if Australia had a reference system that would work
comprehensively. It doesn't, and that leaves us always requiring a certain
element of subjectivity.
I would say - if there is a workable reference system for a particular
area, then it is best to use the reference system, and make a
correspondence to the OSM types. Document the area and the reference
system on the wiki, and coordinate a discussion to ensure there is a
consensus for that area.
Where there isn't a workable reference system - where that would leave far
to many roads unclassified, or through roads not indicated as through
roads, then some subjectivity has to be used. Not just the physical
propoerties of the road, but also whether it is the main linking road
between centres, etc. The current wiki guidelines for Australian Road
Tagging are the result of previous discussions to try and pin this down,
and try and standardise as much as possible where no reference system will
work.
If you can come up with a practical, yet unambiguous and objective, system
for all of Australia, that would be great. Short of laying seige to the
roads departments and councils, I don't think that is going to happen. I'm
sure if you have ideas for improvement, or a workable reference system for
Adelaide, then you just need to convince people of the benefits, and update
the doco.
Ian.
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