[Tagging] Tunnels and bridges
imagic.osm at gmail.com
Fri Feb 1 08:28:13 GMT 2013
First of all thanks to Steve for the good summary and I have to excuse
myself for bringing up the 3D subject. When thinking of multi-level
bridges I thought that it might be a good idea to reuse some existing
tagging scheme and the 3D scheme just sprung into my mind. But as it
was pointed out that this scheme doesn't fit for bridges lets forget
about it again. And if we can't use this scheme I would also not
suggest the key building as main key any more.
Concerning the main key I guess the best would be man_made which was
mentioned a few times. Currently I think of three different
1) One OSM-way, one level ----> tagged as usually with bridge=xxx on
2) Multiple OSM-ways, one level ----> additionally to the OSM-ways
(tagged according to 1) add the outline with man_made=bridge +
layer=<x> and optional bridge=<type>
3) Multiple levels ----> everything tagged with 1) and 2) and now
additionally the bridge-relation to combine the different levels of
the bridge and add the outline from 2) as outline-member to the
The more complex the bridge the more complex the tagging.
2013/2/1 Steve Bennett <stevagewp at gmail.com>:
> A few problems with the current approach:
> 1) When several things pass over the same bridge (eg,
> highway=secondary, highway=cycleway and highway=footway; or even just
> two independent lanes), renderers currently draw multiple bridges.
> 2) In areas where structures (buildings, paved areas, piers,
> riverbanks) are mapped precisely, bridges can't be - they're assumed
> to be the width of a standard road.
> 3) Bridges have distinct properties (name, height, etc) that can't be
> modelled properly because bridges don't actually exist. Tags like
> bridge_name are a kludge that don't work in cases like 1).
> These are all problems worth fixing.
> The solution seems to be:
> a) (Optional Create a relation that can group things together
> (type=bridge, or something more general if there's something good)
> b) (Optional) Create a closed way for the bridge itself, and tag it
> with a new tag (probably man_made=bridge would be best, because it
> would be better rendered by naive renderers than say building=bridge)
> c) (Optional) Add the bridge, if mapped, to the relation.
> It seems that every time this topic comes up, people want to go too
> far, and find general solutions (eg, solving both bridges and tunnels
> at once with "across" and "over" relation memberships), and start
> solving other problems too (eg, 3D buildings, not splitting ways when
> they pass over bridges...). It all gets complicated, and everyone
> gives up.
> But the solution above is pretty simple, and doesn't require breaking
> anything, and is totally optional. Map the way you do currently if you
> want, or also map the bridge separately if you want, or use a
> relation, or both.
> On Fri, Feb 1, 2013 at 10:01 AM, Michael Kugelmann <MichaelK_OSM at gmx.de> wrote:
>> On 31.01.2013 12:06, Martin Vonwald wrote:
>>> I'm looking for some alternatives to map tunnels and bridges that
>>> contain several ways. I'm not really happy with the proposed relation
>> The current method is used and well established since years and for my
>> point of view works fine. So I clearly dislike to change it.
>> Just my 2 cents,
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