[OSM-talk] tagging roads

[Blaž Lorger]

Hi,

I have noticed intense discussion about changing how roads should be tagged. 
It seems that some people devised their own way how to apply different values 
for highway tag and now attempt to force this on everybody.

On the other hand some people are attempting to introduce new values for 
highway tag 
(http://wiki.openstreetmap.org/wiki/Proposed_features/residential_narrow and 
http://wiki.openstreetmap.org/wiki/Proposed_features/residential_narrow/old).

Both approaches seem wrong. Changing how roads should be classified will break 
existing OSM data. Introducing new values will only add to confusion choosing 
road classification.

It seems that both issues are caused by desire to achieve certain rendering in 
mapnik or TAH. I guess best way to solve such problems would be to render 
streets differently based on value of tag width. This would encourage use of 
tag width. This way we would also gain useful data that can be used by routing 
software.

Another tag that is currently not supported by rendering engines is surface. I 
think renderers should make distinction between paved and unpaved roads. 
Otherwise you are risking that people will classify unpaved road as track just 
to achieve desired rendering effect. I am aware that highway=unsurfaced is 
rendered differently. But this value is supposed to be deprecated. Besides, 
unsurfaced roads can have different classifications 
(http://wiki.openstreetmap.org/wiki/Highway#Exceptions_to_physical_attributes).

I also propose extending instructions for road classification to use width tag 
when road is narrow. Instructions should also suggest what is considered 
narrow. For instance less than 4 meters for residential and unclassified roads, 
less than 6 meters for tertiary roads, less than 8 meters for secondary and 
primary roads. For trunks and motorways this limit should probably apply to 
lane width. Proposed limits on when certain type of road is considered narrow 
should match rendering rules.


 Blaž