[Tagging] Tunnels and bridges

[Martin Koppenhoefer]

2013/2/1 Pieren <pieren3 at gmail.com>:
> On Fri, Feb 1, 2013 at 11:06 AM, Tobias Knerr <osm at tobias-knerr.de> wrote:
>> - ways must be split at the beginning and end of the bridge
> Not necessarily. "layer" can be set on the highway before and after
> the bridge (if it is done carefully and not interfer with other
> crossings). What I like in this modeling is that we could avoid
> splitting if no attribute of the road is affected by the bridge (or
> tunnel).


IMHO we shouldn't "avoid" splitting as it will tend to make our data
less consistent. Think about ways under the bridge. Also we are
already splitting the ways for lots of reasons (routes and
turn_restrictions, changing attributes like maxspeed, surface, width,
lanes, oneway, lit, etc.), there is really no point in not splitting
at bridges (IMHO). It would require everyone to do expensive ST_Within
queries to determine simple stuff like where on the road is a bridge
and which object is above which.

cheers,
Martin