[OSM-talk] Bridges / viaducts for railways

[matthew-osm at newtoncomputing.co.uk]

On Mon, Jan 28, 2008 at 05:57:24PM +0000, Tom Chance wrote:
> I'm a bit confused about these tags:
> 
> railway=viaduct
> bridge=yes
> cutting=yes
> embankment=yes
> 
> Why is it not a property like bridge, cutting etc. and will it render
> correctly? Should it be changed to viaduct=yes?

Ewww, yuck... boolean flags.

Personally I would tag as:

  railway=rail
  bridge=viaduct

for cutting I would have thought more like (this is a suggestion, there
is probably a better way):

  railway_level=-1  or  railway_level=cutting

and for embankment

  railway_level=1  or  railway_level=embankment

Map features has the really odd (IMO):

  railway=viaduct (node)
  highway=viaduct (node)

with the comment of something like "A high or long bridge...". "long"
and "node" don't go together as far as I am concerned ;-). You also don't
know what type of railway goes over the viaduct, as you lose the railway=
information.

A possible, but slightly odd, example would be an underground train going
above ground and over a viaduct - it would be railway=subway, bridge=viaduct.
If memory is correct, I think the DLR does that in some places in London
(railway=light_rail, bridge=viaduct)?

Not sure what others do, though...

Cheers,

-- 
Matthew