[Tagging] Tunnels and bridges

Pieren pieren3 at gmail.com
Fri Feb 1 12:21:29 GMT 2013

On Fri, Feb 1, 2013 at 12:46 PM, Martin Vonwald <imagic.osm at gmail.com> wrote:

> are split so that bridge=yes and layer=1 can be tagged. So we reuse
> those nodes and connect them to the new outline. We do NOT have to
> change any existing tagging!

By "consumer", we all think about "renderer" (which is in my knowledge
the only consumer looking for bridges in OSM atm). If you keep the
"bridge" tag on the multiple highways, it is duplicating the
information. And you don't fix the rendering issue because Mapnik will
continue to draw one bridge per highway.
To avoid the duplicate rendering, we need the "bridge" tag only on the
polygon. But then, the rendering software will have to decide to draw
the polygon itself. Or like today, draw some symbols along the line.
In both cases, if you want a correct rendering (draw only one bridge)
wihtout simply drawing the bridge polygon, the software will need some
spatial requests anyway (to determin the group of highway segments
that belong to the same bridge).


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