[OSM-dev] MAPNIK - proposal to drop rendering of underground railway lines

Abigail Brady morwen at evilmagic.org
Thu May 17 18:34:29 BST 2007

On 5/17/07, Robert (Jamie) Munro <rjmunro at arjam.net> wrote:
> I still think the problem is that it isn't clear if railway=subway
> implies that it is under the ground or not - we need to distinguish
> railways that are part of subway networks from railways that are under
> the ground. The two properties are independent of each other.

The way this is being used in London is that
*LUL lines are railway=subway
*DLR is railway=light_rail
*mainline is railway=rail
*shared LUK/mainline lines are railway=rail
*physically underground lines are tunnel=yes: all 3 types can be of this.

Central London has acquired ways representing the deep level tube
lines, which aren't geographically accurate, but the information is
out there enough to make good approximations (an awful lot of tube
lines run under major roads, for example, even though there was no
pressing construction need for this, legal issues made it worthwhile

Suggest to drop rendering of ways with both railway=subway and
tunnel=yes if this decision is made, this should take care of things.
railway=rail tunnel=yes are usually good in terms of position, and so
is railway=subway tunnel=no.

In the longerterm, we could maybe have a way property indicating
whether the way is a mere topological way, like the ones representing
LUL lines basically are, and renderers could decide not to render
topological ways.  I'd be loathe to delete these ways out of the
database though, as they can be useful for the reasons detailed above.

who admits to adding some of these (but not having started the practice)

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