[OSM-talk] Layer defaults for bridge and tunnel

[sergio sevillano]

Robin Paulson escribió:
> 2008/6/15 Susanna Björverud <susanna.bjorverud at telia.com>:
>   
>> Hi,
>>
>> AFAICT the keys bridge and tunnel do currently not assume any default value
>> for layer apart from the normal layer=0 that holds for all objects. While it
>> of course is necessary to be able to specify the layer for both of these
>> keys, it also seems to me that the "normal" case is that bridge should imply
>> layer=1 and tunnel layer=-1. The wiki pages for bridge already states "In
>> the easiest case the bridge gets the tag layer=1" and the one for tunnel "In
>> the easiest case the tunnel gets the tag layer=-1"
>>
>> When looking at a new area in JOSM, I as a rule run the validator, and one
>> of the most frequent (in my totally unscientific, with no statistics to back
>> it up gut-feeling) "mistakes" that it warns about (crossing ways) is bridges
>> and tunnels without an accompanying layer tag. If I knew how I would try to
>> verify this against the database... but alas I do not.
>>
>> I would therefore like to suggest that if it is possible bridge=yes should
>> in the absence of a layer tag be interpreted as layer=1 and that tunnel=yes
>> in the absence of a layer tag should be interpreted as layer=-1, in the same
>> way as a junction=roundabout implies oneway=yes etc.
>>     
>
> personally, i would prefer if this were implemented at the editor
> level - i.e. when i add a 'bridge = yes' tag, it also adds a 'layer=1'
> tag as well, so i can either accept, or occasionally change it. where
> possible, and appropriate, i would prefer things like this be in the
> open
>
>   
i personally back Robin Paulson opinion, if something is to change is 
that when you put the brige=yes tag automatically the layer=1 tag 
appears and then manually change the value if it´s not the case, same 
for tunnel and layer -1. this can be implemented as a preset setting tag 
in potlach and JOSM.

if it´s assumed  that abscence of layer is other than 0 wich is default 
(and a simple rule). then is going to be some confussion because 
different values of layer are going to be defined with no feedback to know.

sergio

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