[OSM-talk] highway=track and motorcar=yes/no

[Ben Laenen]

On Friday 07 November 2008, Nic Roets wrote:
> On Fri, Nov 7, 2008 at 2:21 PM, Ben Laenen <benlaenen at gmail.com> 
wrote:
> > On Thursday 06 November 2008, Rainer Dorsch wrote:
> > > I like this idea of having country specific presets in the
> > > editors instead of having renderers to be country sprecific.
> >
> > It's way too late for that for tags like highway=track.
>
> It most definitely is not. There are only 8000 odd tracks in the UK
> that will need to be changed. But even if we decide to change all the
> 300,000 odd tracks in Germany, it's a small project compared to
> things like dropping the segments, getting rid of the 'class' tag and
> updating the TIGER data. Of the same scale as bots fixing spelling
> mistakes and tags.

"only"... does that mean you're going to revisit all 300000 tracks in 
Germany to check whether they allow cars or not? The project of 
dropping segments didn't have to introduce new information out of 
nowhere.

World-wide only defaults and no country defaults will simply not work:
* certain highways types have certain access rules that are different in 
each country, and they can always change later on (and as said before 
you won't be able to automagically correct those explicit tags)
* not all countries share the same vehicle types, world-wide defaults 
cannot handle that
* different countries, different implicit rules on tags like 
access=destination
* if you'd add motorcar=yes by default for each track, then where does 
it stop? bicycle=yes, foot=yes, moped=yes, motorcycle=yes... And then 
that complete set of tags for each highway in the world for each 
vehicle type there might be on this planet. Just the problem with this 
is that by having all this data, you actually *lose* information or 
you'd have to introduce foot=implicit_yes when it's a road that 
implicitly allows pedestrians. But in that case, you can observe the 
fact that implicit rules can be extracted from the highway type and 
perhaps some additional tags, so you don't need any implicit_yes or 
implicit_destination or implicit_whatever. You only need a set of rules 
for each country (the set of country defaults that in your model were 
in JOSM, but much more powerful).

Ben