[Openstreetmap] key/values for tunnels and bridges

[Simon Hewison]

I found myself using JOSM to add key/values to a set of roads I know well.

since according to Nick, we have class=(motorway|primary|secondary|path) 
which would affect how his viewer renders the lines, do we have a way of 
defining how to define key/value pairs that would denote a tunneled 
section of a motorway, or other road?

If nobody else has already started on this labeling, might I suggest
this could be used to determine z=order when rendering things like 
multi-level motorway interchanges correctly.

elevated=-1 (tunnel or underpass, below the level of surrounding ground)
elevated=0 (default)
elevated=1 (a bridge)
elevated=2 (a bridge over a bridge)
elevated=3 (a bridge over a bridge over a bridge)
elevated=4 (some civil engineer is having a joke)
and so on

you may want to have something like elevated=-0.5 for things like 
cuttings, which is sometimes rendered differently

Tunnels are normally depicted on road maps by some sort of a dashed 
edged line, with the weight of the line being the same for the type of 
road it represents.

Likewise, bridges are often rendered with bridge arches either side of 
the track.

Ordnance Survey Landranger symbols:

http://62.25.96.205/products_new/landranger/symbols/viewsymb.cfm

If nobody has any objection, I'll wikify this later in the day.
-- 
Simon Hewison