[Tagging] New key proposal - paved=yes/no

Richard Fairhurst richard at systemed.net
Mon Sep 22 08:13:10 UTC 2014


Tomasz Ka┼║mierczak wrote:
> I would like to suggest making the paved key for highways 
> (and probably other types of elements) official.

First of all, this is OSM: there are no "official" or "unofficial" tags. Use
what you like as long as it accords with core OSM tagging principles such as
verifiability.

Secondly, however, as someone who parses surface tagging for both routing
and rendering at http://cycle.travel/map, this proposal is unnecessary.
(cycle.travel renders paved cycleways, firm unpaved and rough unpaved
tracks/cycleways differently, and applies different routing penalties based
on surface.)

Your use case is that the new tag would make it easier for data consumers to
tell whether a road is paved or not. It wouldn't. It's already very easy.
You simply have a list of the surface= values that your application counts
as paved (and this isn't as universal as you might think: are cobblestones
"paved"? They're fine if slow in a car, but torture on a thin-tyred road
bike).

This is literally just two lines of code in an osm2pgsql Lua tag transform
script, and thus available to anyone using the standard rendering toolchain.
If you don't want to do it this way, you can run a Postgres query
post-import, or just some extra conditions in your Mapnik/Carto .mml file.
It's really not hard.

Please, please, please don't fall into the trap of trying to optimise for
data consumers when you're not a data consumer. OSM has far too much of this
and it's resulted in a lot of nonsense tags over the years. Since you'd
never reach 100% coverage for paved=, the data consumer would need to
continue to parse the surface= tag. So the main effect would be to make life
_harder_ for data consumers, who would now have to check not just three
surface-type tags (surface=, tracktype=, smoothness=) but four. Or in other
words:

http://xkcd.com/927/

cheers
Richard





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