[OSM-talk-ie] Updates to South Dublin

Dermot McNally dermotm at gmail.com
Sat Sep 8 12:45:35 BST 2007

On 07/09/2007, Robert Fitzsimons <robfitz at 273k.net> wrote:
> I've been doing a lot of extra cycling and covered most of the major
> roads around parts of South Dublin; the area includes Sandyford,
> Dundrum, Kilmacud, Clonskee, Milltown, Ternerure, Ballinteer, Marley
> Park, Rathfarnham, Sandyford Industrial Estate. I've still got a bit to
> fill in around Nutgrove, Churchtown, Ballinteer.  Next week I hope to do
> some of the roads new Dun Laoghaire.

Hi Rob,

Good work! I've just done some work on your
rathfarnham_ballyboden_marley.gpx trail. It relates mostly to roads
already present, but many, especially towards the start, were low
precision traces, so I was able to clean up a bunch of stuff. The
trails are coming out fairly clean, with the only tidyup being around
corners (which will always end up a bit rounded) and in those places
where it looks like you were stopped in traffic (a nebula of points).

> The tile server has picked up some of this already.  I wondering how to
> layout some junctions, two crossing main roads with traffic islands and
> filter lanes, and no right/left turns, bus/cycle only streets.  I'll
> try and take some time over the week to clear up these a proper
> questions.

This is somewhat a matter of taste - if a traffic island is only
present right at the junction, without forming any short dualled
stretch, I tend to simplify the island away. If you feel the division
is worth mapping, you can map as for dual-carriageway, and create a
one-way-way for each direction. In such cases, roads crossing at
junctions will join each "carriageway" at a node.

Turn restrictions have yet to find a satisfactory tagging, but a lot
of next-generation meta-information schemes are under discussion and
they aim to provide a framework within which to solve this problem.

Filter lanes as such need not be modelled - if separated from the rest
of the traffic flow by islands you could model them (and the turn they
make) as separate ways, but I'd tend not to unless doing so clarifies
the junction in some way for users or routing software. You may also
wish to use the lanes=? attribute to indicate areas where a road
becomes wider due to turning lanes.

Regarding usage restrictions, everything you need should be in here:

Have fun,

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