[Talk-GB] Conflicting tagging of london undergound stations

Abigail Brady morwen at evilmagic.org
Thu Sep 20 18:55:19 BST 2007

On 9/20/07, Alex Mauer <hawke at hawkesnest.net> wrote:
> I don't consider subways to be "in a tunnel"

Well, tell that to the tunnelling engineers!

> I consider them to be
> simply below (most) everything else.  Besides that, the roads as you say
> are on bridges; the subways aren't in tunnels.

Alex, I'm not sure whether you've much knowledge of the London Underground
network, so please forgive me if you knew any of this.  However, it is
necessary background for understanding the tagging system.

The London Underground is a large electric standard-guage railway network
that covers most of Greater London.  There are on this network several
different sections of track

*mainly in the outer suburbs, there are sections are at ground level, and
look pretty much like any other commuter rail system
*in a few places, there are sections which are elevated on embankments, well
above ground level (ie layer 1), and here the Underground goes on bridges
over various roads (bridge=1 for short sections)
*in a few places, there are sections in cuttings (ie layer -1), which
nontheless can see the sky for large parts.  A few roads will cross these on
bridges.  Here, we can have the road bridges be layer=0, bridge=yes
*in a few places, there are sections in tunnels of various depths.  these
sections cannot see the sky, roads that happen to cross the path of the deep
level tubes certainly aren't considered bridges.  this could be represented
as tunnel=yes, layer=-1

The tube network is all interlinked and most lines use a combination of
these different types of rail setting.  We tag all of it railway=subway,
whether or not it is actually underground or not, because it is all the same

What you are suggesting would lose the subtlety of the distinctions,
especially between subway in an uncovered cutting - which will be visible
from roads - and subway in an actual tunnel.  Now do you understand?

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