2013/6/5 Martin Koppenhöfer <dieterdre...@gmail.com>: > yes, but you can easily see whether it is one tube with both directions going through, or if there is one tube per direction (more usual case due to security reasons). Then you still have to define what is one "tunnel", maybe also 2 (or more) distinct tubes could qualify as one tunnel?
"Tunnels" can have even more complex topologies than only 1 or 2 tubes going through, it depends on the purpose. Regarding power lines, technical facilities can follow surface streets but it's not mandatory. They can have different heights, different levels with links between them, manhole access, etc... We still call them "tunnels" here but there's really nothing common with road tunnels. It's out of question to map such restricted access facilties with details, but it's important to show if several features share the same infrastructure or not even if it's difficult to represent whata tunnel is in that particular situation. > Yes, you could either use a relation for the bridge (with name, ref, wikipedia and other tags, describing the bridge) and add the highways to the relation with a role running over the bridge, or draw distinct geometry for the bridge perimeter (and eventually geometry for the supports, pylons, etc.). The latter could also be done additionally and added to the relation). The same applies for tunnels besides that we often don't know exactly the shape of the tunnel. The problem is such features (like power lines or ways of a highway) are always redundant with components of tunnels or bridges themselves. We don't need to create dedicated geometry for an highway tunnel since the geometry of the road gives the path followed by this tunnel. So we can precise it in the "role" attribute of the tunnel/bridge relation member which tube the road way represent. Since OSM doesn't manage relation member attributes at all, it will be difficult. => A relation for each tube or gallery ? François Lacombe francois dot lacombe At telecom-bretagne dot eu http://www.infos-reseaux.com
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