[Tagging] layer=-1, rivers, bridges and tunnels

André Pirard A.Pirard.Papou at gmail.com
Sat Mar 15 12:25:16 UTC 2014


I wonder why we make bridges split and split and split the roads.
In reality, bridges are pieces of concrete or stonework at level -1
under an uninterrupted foil of tarmac at level 0.
Or at level 0 if it's understood that the renderer knows what's a bridge.
And the renderer knows, as it draws two thin stripes beside the road.
So, a bridge can be a little way segment overlaying the road.
This lets the routing software ignore the unnecessary complication of
having to account for bridges as part of the route.
This lets the bridge having its own attributes, unrelated to the road,
for example a different name.
This makes obsolete discussions wondering if the bridge must be split in
two because the road changes in the middle.
Etc. etc., all pieces clutch in very neatly.
And BTW, this is similar to tunnel=culvert which is an optional feature
of a bridge and that surprises no one at layer -1.
And now, if we put bridges and culverts at -1, the rivers or streams are
normally at -2.
Tunnels (inside which the road runs) should be segments too, at level +1
or 0.

I have tagged a number of streams and rivers at -2 -1 0 and I find it
appreciable to have an instant view of where the complete main stream
is, if not exaggeratedly long, as well as less prone to errors.



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