[Tagging] Tunnels and bridges

Kytömaa Lauri lauri.kytomaa at aalto.fi
Fri Feb 1 19:13:19 GMT 2013

>there and so on - so: keep them splitted and it's less work with more
>backwards compatibility.
>If they are not, it's up to you as a mapper if you want outdated
>renderers to use the old scheme or not.

Most renderers and conversion tools work internally without 
a database (even if they first fetch the data for the area
in question from a database) - many consumers of the data 
take an osm extract, and work on the ways one by one, 
one or multiple times, and draw them "as such" in appropriate 
order (say, mkgmap included).

There's work going on to have mapnik draw the road name
labels only once where a road has been split several times.
Not by me, but see the SOTM slides linked to on page
" Parking map – make and break stuff "

Mappers split ways a lot, for a lot of reasons, so avoiding the split
for a bridge and at the same time hiding the attribute in 
a) other, connected ways or b) a relation only or c) "the 
spatial data" seems ... making things unnecessary complex
for the consumers.


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