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<div class="moz-cite-prefix">On 2014-03-20 15:29, Martin
Koppenhoefer wrote :<br>
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<div class="gmail_quote">2014-03-20 15:02 GMT+01:00 André
Pirard <span dir="ltr"><<a moz-do-not-send="true"
href="mailto:A.Pirard.Papou@gmail.com" target="_blank">A.Pirard.Papou@gmail.com</a>></span>:<br>
<blockquote class="gmail_quote" style="margin:0 0 0
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<div text="#000000" bgcolor="#FFFFFF">Following a gentle
dispute on OSM-talk-be about the class of a particular
road, I pointed out without any follow-up that road
classification (primary ... tertiary, as well as
national ... local on IGN maps) is very subjective but
that the road width is very objective.</div>
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<div>yes, the highway classification is slightly subjective
but as osm shows, the cloud can usually find a commonly
accepted values, so this doesn't seem to be a real problem
(also because it doesn't really matter if a road is
classified as secondary rather than primary, and more than
one class up or down is usually not the range up to
discussion). <br>
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The problem comes with <a
href="http://www.openstreetmap.org/way/72502906#map=17/50.53927/5.64976">such
roads as Belgian N674</a> which is uniformly classified as
national on IGN official maps. On the eastern part, it's worth the
primary status for through, heavy traffic. On the center part, it's
certainly only secondary. But on the part going NW it's a dangerous
road. And, despite its official status, only its 5 m width and bends
can show that : 2.5 m wide lorries can't cross each other and they
step on the verge. The road once crumbled down into the meadow below
and is waiting for the next turn. Even cars must break and make a
brisk turn. It would be nice that OSM routing avoided that road.<br>
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<div>Of course everybody is free to add a road width as
well, there is the tag "width" for this, and also the tag
"lanes". Unfortunately until now, only 5% of all
highway-elements (admittedly not only roads) have the tag
lanes and 1% has the tag width.<br>
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The width would come as a complementary information: avoid it
despite a gentle official classification apparency.<br>
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<div text="#000000" bgcolor="#FFFFFF"> Moreover, the
width can be very easily measured with JOSM on Bing.<br>
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<div>you should be careful with the spherical mercator
projection though, you might end up with different widths
for the same width due to different latitudes, I am not
sure how precise those measurements in JOSM actually are
(some time ago they weren't but maybe this is fixed now).<br>
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Good point that would have to be analyzed. Especially if there's a
difference between NS and EW measurements!<br>
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<div text="#000000" bgcolor="#FFFFFF"> Of course, the
closely related parameter is speed.<br>
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<div>related to width? I do not think there is a close
relation, at least not a reliable one.<br>
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Speed (to drive safely) is not intrinsic but in fact a consequence
of other factors, including narrow width. Or it can be enforced.<br>
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<div text="#000000" bgcolor="#FFFFFF"> While reading your
texts, I've had a crazy idea: measuring vibration in
the car. There are Android vibration measuring programs
like Vibration Monitoring. Alas, car vibration is very
much dependent on car suspension. But would some of us
experiment this or another idea and come up with a
solution?<br>
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<div>this sounds interesting indeed, while I agree that it
mostly depends on the car suspension. With (unsuspended)
bicycles this would be more reliable I guess, but still
the ability of the driver / rider to avoid holes in the
surface might make a huge difference (e.g. in Rome there
are some very bad roads with profund holes that get tapped
every now and then but later reopen due to the heavy
traffic. If you are on roads that you drive often you
almost automatically get the habit of avoiding them, also
at higher speeds, because you know their exact locations
by mind).<br>
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Yes, dodging the suspension would be the idea, see next.<br>
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<div class="moz-cite-prefix">On 2014-03-20 23:18, David Bannon wrote
:<br>
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<blockquote cite="mid:1395353898.1037.40.camel@davos-LT" type="cite">
<pre wrap="">If we wanted to measure vibration I guess we could have a process to
calibrate individual car's suspension. Maybe something like driving over
a set of steel pipes of defined size a defined distance apart ?</pre>
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Yes, I also thought of calibration, but the dynamics of suspension
(spring + damper) is rather complex.<br>
The safest bet would be to stick 2€ accelerometers directly on the
car axis.<br>
They're readily available for a cheap micro-controller called <a
href="http://www.arduino.cc/">Arduino</a>.<br>
This needs some software development compared to a ready made
Android but it would be a fine project.<br>
<br>
<div class="moz-cite-prefix">On 2014-03-20 21:15, Fernando Trebien
wrote :<br>
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<pre wrap="">Even so, we would still have to presume things about the driver's
personality (an adventurous person would not care much about rougher
surfaces, while a precaucious one would probably rather avoid them).
We can pick a "standard" personality (we don't even know that very
well without some statistics, do we?) or we can probe other people and
then apply statistics on the results.</pre>
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There would of course be a protocol such as driving at a 40 km/h
constant speed and in straight line, unless, of course, it would
break something, a fact that should of course intervene in the
classification.<br>
<br>
<div class="moz-cite-prefix">On 2014-03-20 23:18, David Bannon wrote
:<br>
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<blockquote cite="mid:1395353898.1037.40.camel@davos-LT" type="cite">
<pre wrap="">However, I doubt if we'd achieve anything useful, the sort of roads we
are talking about are usually quite erratic, smooth sections then
substantial holes or what ever. You slow down for the holes or you break
something ! But interesting idea....</pre>
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Please note that, although it could also be used for local hazard
warnings, my idea is to provide to routing software additional data
with which it could favor one itinerary over another.<br>
<blockquote cite="mid:1395353898.1037.40.camel@davos-LT" type="cite">
<pre wrap="">Andre, I guess we can measure the width of a road to a reasonable
accuracy via sat images. But I am not sure what that tells us. We cannot
assume a relationship between width and quality of the road can we ? Not
here in Australia anyway, many of the outback roads that are typical of
the subject of this discussion are quite wide, wider than some of our
fancy freeways closer to population centers.</pre>
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The width is only meaningful when the road is narrow and one must
drive accordingly.<br>
You have plenty more room than we have.<br>
Here, the roads must at least pass between the people (and they're
not hopping away) ;-)<br>
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Cheers,<br>
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