Re: [OSM-talk] smoothness

2008-11-27 Thread Robert Vollmert
This turned out rather long. Summary: smoothness is a useful tag,
though the wiki definition may be lacking. Thanks for reading.

On Nov 27, 2008, at 11:27, Dave Stubbs wrote:
 The table is full of such subjective assessments: can I roller blade
 on it. No, I can't. It doesn't help that I can't roller blade at all.
 So sure, if the tag was, is it possible to roller blade down this
 road assuming a skill level of a Grade III Roller Blading Proficiency
 Award? then it might have a point, but it's not.

How about: Would an average roller blader like to use this?

Personally, I couldn't care less for an absolutely precise and
objective definition for a tag. If the description gives a good
idea of how to use the tag in most situations, that's perfect.
There'll always be corner cases.

It's quite possible that people have tried too hard to define
smoothness objectively (and have claimed too strongly that
it's even possible to define it 100% precisely).

Here's how I see smoothness (on the smooth side of things, I don't
care about things beyond bad). If the people that formulated the
smoothness proposal disagree, I guess that proves your point.

excellent: this is what well paved new cycle ways tend to be like;
some fine type of asphalt; good for roller-skating, a pleasure on
a road bike

good: your typical road in good state; a cycleway like above but
with some small bumps from tree roots because they didn't care to
put a proper foundation (?) underneath; a high-quality non-paved
footway in a park

intermediate: a road the has been worn down and could use a new
cover, some unevenness from heavy traffic; motorway made of slabs
of concrete with annoying bumps when passing to a new slab (you'd
really want to use the fast lane exclusively if that's recently
been repaved); lots of tree root induced bumps on a cycleway; a
footway in a park with coarser gravel or uneven enough that
there'll be puddles when it rains; high-quality cobblestoned
road (small stones with flat surface, or perhaps some filling of
the gaps); the average motorist wouldn't mind, the average cyclist
wouldn't complain (at least not loudly), you wouldn't want to
skate here.

Anything worse, I'd tag bad for now and put a note/fixme in
so someone else can say how bad it really is.

I think smoothness fits the above distinctions quite well. Together
with surface=paved/unpaved, it should provide most information about
a way's surface that users of wheeled (on-road) vehicles would like
to have when deciding which road to choose.

Cheers
Robert


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Re: [OSM-talk] smoothness

2008-11-27 Thread DavidD
2008/11/27 Robert Vollmert [EMAIL PROTECTED]:

 How about: Would an average roller blader like to use this?

Take a cyclist with a racing bike. If they are training at high speed
they might find a road with irregularities and a few potholes
unusable. The next day the same rider and bike might be out on a ride
with the family and find the same road perfectly usable. On the family
ride the fact the road is low traffic and scenic is much more
important than on the training ride.

Clearly the cyclists objectives are playing a large part in
determining if a road is usable or not.

Is a road with potholes really smoothness=good? It must be because I
saw a racing bicycle use it.

I also use a city bike to map brideways and would happily use the
track pictured as smoothness=horrible if my objective is mapping.
http://wiki.openstreetmap.org/wiki/Image:Jena_Trackexample_profile.jpg
Since I used it on a city bike it must be surface=intermediate.

If you try to use the tag objectively it just does not work. If you
need to think about the average roller blader or average racing
cyclist then it is not objective. Trying to pretend it is subjective
when it isn't is just going to cause problems when people try and use
it objectively. Similar surfaces will end up with very different
smoothness values based on who they have seen use the road.

Collecting data to objectively classify smoothness is going to be a
lot of work. Physically measuring parts of the surface and the like. I
don't see the problem with admitting this and coming up with a decent
subjective scheme. I think you probably would get a lot of the benefit
of an objective scheme with a fraction of the effort.

-- 
DavidD

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