[OSM-talk] Indiscrimate layering

Scott Atwood scott.roy.atwood at gmail.com
Sat Dec 20 17:25:39 GMT 2008

On Sat, Dec 20, 2008 at 8:50 AM, David Earl <david at frankieandshadow.com>wrote:

> - the layer tag is tagging for the renderer in 99% of cases with
> bridges. In nearly all cases a bridge/tunnel tag says "I am above/below"
> automatically and a layer tag should be unnecessary. There are a few
> exceptions, but they are very rare: primarily where a bridge crosses
> exactly over the top of another bridge, where there are more than two
> layers involved (e.g. - and this is the only one I have come across in
> 2.5 years mapping -
> http://www.openstreetmap.org/?lat=52.329684&lon=-0.192102&zoom=18&layers=B000FTFTTT
> where the A14 crosses the B1514 which in turn crosses the East Coast
> Main Line railway all at the same point). Had relations been invented
> earlier this case might have been better described using a relation.

I'm guessing you don't map in many heavily urbanized areas then, because
around where I live, freeway interchanges with two, there, four, or even
more layers are not uncommon, e.g:

And here is one nearby that hasn't been tagged with layers yet, and is
therefore difficult to visually parse:



Scott Atwood

Cycle tracks will abound in Utopia.  ~H.G. Wells
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