[OSM-talk] Key:layer update

Frank Little frankosm at xs4all.nl
Wed Mar 12 14:22:49 UTC 2014

Richard Z wrote
>> >In practice this rule is broken more often than you would think: Hamburg
>> >is full
>> >of waterways connected with roads on bridges through a tag obstacle.
>> >France is
>> >full of bridges sharing a node with the waterway bellow.
> http://www.openstreetmap.org/node/1522876252

I would say this is an example of incorrect mapping and I would correct it if
I came across it on survey. It is either a culvert or a bridge, or a ford. A
layer tag should not be necessary in any of these three cases.

As mapped, the waterway=stream (Way #138911739) runs underground (layer=-1),
probably through a culvert given the way the stream left and right are
separately outlined as waterway=riverbank (and without layer=*). The way
(stream) should be tagged as a culvert.

Perhaps there is in reality a bridge not a culvert, in which case the road
needs splitting and the appropriate new road segment tagged as bridge=yes.

In either case, a layer tag is not needed for rendering.

Given the layer tag, it is unlikely that the mapper thought it was a ford. (I
don't know whether the cadastre data distinguishes between these features).
Fords do not need layer tag, by definition.

The solution will be to find and remap such examples.

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