[OSM-talk-ie] Newbie!

Andrew McCarthy me at andrewmccarthy.ie
Tue Mar 18 11:39:15 GMT 2008


Hi again,

On Mon, Mar 17, 2008 at 01:29:53AM +0000, Dermot McNally wrote:
> This may depend a little on what you understand a tertiary road to be.
> If you haven't already seen it, you may wish to refer to the tagging
> guidelines for Irish roads:
> 
> http://wiki.openstreetmap.org/index.php/WikiProject_Ireland#Highway

Aye, I've been getting reading up on that, and following through the
other pages on features and metadata.

> (disclosure: I wrote this, it has, like all other OSM documentation,
> no official standing, but it ties in closely to what the UK mappers
> are doing and it makes for reasonable rendered output).
> 
> There has been a lot of confusion in the community about what tertiary
> is supposed to mean, but I've generally used it to represent a road
> that you'd cheerfully use on a route to somewhere even if your
> destination wasn't actually on that road.
>
> To return to your question, therefore, I'd imagine that overly narrow
> roads wouldn't be ones you would use by choice as a route to somewhere
> and for that reason I'd tag them as unclassified, not tertiary.

So at this level it's a bit more subjective than any official
designation by the council, then. I think I've a feeling how to go about
it now.

Side question: Does every public road have an "L...." number, or only
some? I noticed a while ago that there are some pretty small roads in
Wicklow that have very prominent signs indicating "L1234" or whatever.
And by prominent, I mean two poles per sign, one sign on each side of
the road entrance. If only the whole country had such thorough
signage...

> It can be. JOSM has a plugin that can do this for you, based on an
> "aggressiveness threshold" that you can customise yourself. So if
> you're going to do it, you'd probably be foolish to do it laboriously
> by hand. But you should probably take pains to ensure you're not
> discarding any good information. A rippled road can mean too many data
> points (if it's rippled at very high zoom level) or it could mean far
> too few points (if rippled at lower zoom - in this case, the points
> you have are useful, but insufficient to convey the true detail of the
> bends). You should probably refer to a good-quality GPS trace during
> any cleanup you undertake to avoid junking useful detail.

Okay, I'll be driving one particular road twice tomorrow myself, so
between that and the existing map I'll have a pretty good idea what
should be kept and not. There are some multi-kilometre stretches which
are absolutely straight, as far as the eye can see.

Many thanks,

Andrew




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