<div dir="ltr"><div>Apologies for the long email below, but I'll summarize my position as:</div><div>a) TIGER data, while imperfect, is very useful and not particularly harmful when considered against other generally available map data.</div>
<div>b) The distinction between unpaved roads and tracks is important</div><div>c) It's often virtually impossible in forested areas to distinguish a minor gravel road from a track by orthoimages, particularly if the imagery was taken while trees had their full complement of leaves, so either alternate imagery or ground surveys are necessary to correctly tag these ways.</div>
<div><br></div>While I can't speak to the U.S. as a whole, I can vouch for the TIGER import data around me (and in Vermont generally) as being far from perfect but also far better than no data at all. Based on a completely unscientific survey of the road history that I've examined while editing, the vast majority of ways in Vermont are TIGER imports that have been edited only by a couple of metadata-adjustment bots. The TIGER data in Vermont includes a lot of Vermont's "ancient" roads—legal right-of-way that vary from privately maintained but publicly accessible gravel roadway to rough woods roads and even to roadways that have returned to forest and are difficult or impossible to locate on the ground.<div>
<div><br></div><div>With that said, OSM is not unique in including many of these "roads" in its database; Google, Garmin, and other mapping provider share many of the same errors, and even the venerable Delorme Gazetteer—by far the best indication in Vermont of whether a road goes or not—has errors. Blithely following any set of GPS directions in this state, particularly with routing set to "shortest distance," is likely to put you on at least one "road" that isn't passenger-car friendly; I, and most other folks in Vermont, I'd wager, have a habit of reviewing Garmin's suggestions for roads named "Unpaved Road", "Alley", or "Town Highway #33" (the last being a side-effect of all town roads in Vermont being numbered as well as named, and the class-four roads often not having proper names).<br>
<br>With that said, we also have thousands of miles of well-maintained gravel roads that are passenger-car passable well over 95% of the time (and some very near 100%). Treating all unpaved roads as tracks would actually create a more-dangerous situation in the "boy who cried wolf" scenario—drivers might get accustomed to easily passable "tracks" and be a bit surprised when they find one that isn't. There is statewide data available from the Vermont AOT which provides better information than the TIGER data, in terms of both completeness and of accuracy, but I lack the time to figure out how to create an automated process to compare the AOT data to OSM to more quickly identify "roads" that are likely to be tracks. The state-provided shapefiles do have data that is rather good at distinguishing proper roadways from tracks, but the gradations of not-town-maintained road aren't applied consistently from town-to-town (what one town calls "Impassable or untravelled" may be "primitive and unimproved" in another town), and most freely available imagery from commercial sources is virtually useless for these ways—one may be able to readily pick out a few spots where there's indication of a woods road but not have any luck at all with tracing the entire way. The state has imagery from spring and fall overflights that is more helpful than Bing imagery (which seems to be consistently captured while all the trees have their full complement of leaves), but until it finished its LIDAR overflights and releases that data, most of these ways will require on-the-ground surveying to distinguish both exact route and whether or not they are passable by vehicle or foot.</div>
<div><br></div><div>Updating these is one of my priorities, and I think most of the unmaintained right-of-ways in my area are now correctly tagged in OSM (and I've added many of the missing track sections that are right-of-way but not passenger-car-friendly), but that's a very small part of the country as a whole.</div>
<div><br></div><div>I'd also argue that a fair number of people are misusing "dirt" as as surface type when "gravel" is more correct, both in conversation and in tagging, but that's probably a battle I'd not win. In my mind, "gravel" should be used for any maintained roadway where gravel has been added, while "dirt" would be used for roads whose surfaces are comprised of the material that happened to be there before the road was created.</div>
</div></div><div class="gmail_extra"><br><br><div class="gmail_quote">On Tue, Sep 2, 2014 at 8:05 AM, Martijn van Exel <span dir="ltr"><<a href="mailto:m@rtijn.org" target="_blank">m@rtijn.org</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div style="word-wrap:break-word"><div style="font-family:Helvetica,Arial;font-size:13px;color:rgba(0,0,0,1.0);margin:0px;line-height:auto">
I think I got unsubscribed from talk-us again on my work account (it’s not you, it’s me), reposting from my personal account:</div> <div><div style="font-family:helvetica,arial;font-size:13px">— <br>Martijn van Exel<br></div>
</div> <div style="color:black"><br>From: <span style="color:black">Martijn van Exel</span> <a href="mailto:martijnv@telenav.com" target="_blank"><martijnv@telenav.com></a><br>Reply: <span style="color:black">Martijn van Exel</span> <a href="mailto:martijnv@telenav.com" target="_blank"><martijnv@telenav.com>></a><br>
Date: <span style="color:black">September 1, 2014 at 9:46:36 PM</span><br>To: <span style="color:black">Nick Hocking</span> <a href="mailto:nick.hocking@gmail.com" target="_blank"><nick.hocking@gmail.com>></a>, <span style="color:black"><a href="mailto:talk-us@openstreetmap.org" target="_blank">talk-us@openstreetmap.org</a></span> <a href="mailto:talk-us@openstreetmap.org" target="_blank"><talk-us@openstreetmap.org>></a><div class="">
<br>Subject: <span style="color:black"> Re: [Talk-us] Dirt Roads (formerly: Abandoned railway) <br></span></div></div><br> <blockquote type="cite"><span><div style="word-wrap:break-word"><div></div><div>
<div style="font-family:Helvetica,Arial;font-size:13px;color:rgba(0,0,0,1.0);margin:0px;line-height:auto">
We have seen no major routing disasters because of the largely
fictional rural TIGER landscape, and I don’t feel an urgent need to
do something about it on this scale. The affected areas mostly have
no meaningful destinations anyway, and where they do, people will
get around to updating them. We can prioritize the more meaningful
areas using a TIGER ghost town analysis along the lines of the
TIGER desert analysis I did some time ago: <a href="http://oegeo.wordpress.com/2012/10/21/binders-full-of-tiger-deserts/" target="_blank">http://oegeo.wordpress.com/2012/10/21/binders-full-of-tiger-deserts/</a> (this
would actually be fun to do. Would people fix TIGER ghost towns if
I pointed them out?)</div>
<div style="font-family:Helvetica,Arial;font-size:13px;color:rgba(0,0,0,1.0);margin:0px;line-height:auto">
<br></div>
<div style="font-family:Helvetica,Arial;font-size:13px;color:rgba(0,0,0,1.0);margin:0px;line-height:auto">
highway=residential may be inappropriate, but it’s not as wrong as
marking all unedited TIGER residential ways with access=no - which
would make entire areas unreachable altogether. Also identifying
the ‘untouched TiGER’ ways is not super straightforward as several
bots have touched most ways in the US anyway, so you’d need to look
at the full history to make that call reliably.</div>
<div>
<div style="font-family:helvetica,arial;font-size:13px">
-- <br>
Martijn van Exel<br>
Telenav</div>
</div>
<div style="color:black"><br>
From: <span style="color:black">Nick Hocking</span> <a href="mailto:nick.hocking@gmail.com" target="_blank"><nick.hocking@gmail.com></a><br>
Reply: <span style="color:black">Nick Hocking</span> <a href="mailto:nick.hocking@gmail.com" target="_blank"><nick.hocking@gmail.com>></a><br>
Date: <span style="color:black">September 1, 2014 at 9:28:45
PM</span><br>
To: <span style="color:black"><a href="mailto:talk-us@openstreetmap.org" target="_blank">talk-us@openstreetmap.org</a></span>
<a href="mailto:talk-us@openstreetmap.org" target="_blank"><talk-us@openstreetmap.org>></a><div class=""><br>
Subject: <span style="color:black">Re: [Talk-us] Dirt Roads
(formerly: Abandoned railway)<br></span></div></div>
<br>
<blockquote type="cite">
<div>
<div>
<div dir="ltr"><div class="">
<p><span>While people work out how to remove the multitude of tiger
ways that don't actually exist, downgrade others from the incorrect
"residential" to "unclassified" or "track"<br>
depending on imagery or ground survey, and fix the geometry of all
unedited TIGER data, I beleive that it's absolutely essential (from
safety and useability perspectives) to immediately mark all these
uncertain ways as unroutable.</span></p>
<p><span>Whether to make them driveways or use access=no , I've no
idea.</span></p>
</div><p><span>I think thrse ways can easily be identified
by...</span></p><div class="">
<div><span>1) They are original TIGER data import<br>
2) They have not been edited since import<br>
3) They are "higway=residential"<br>
4) They are unnamed</span></div>
<div><span><br></span></div>
</div><div class=""><div><span>A bot could do this easily and then it really doesn't
matter how long it takes to find the best solution.</span></div>
</div></div><div class="">
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</blockquote>
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<br></blockquote></div><br><br clear="all"><div><br></div>-- <br><div dir="ltr"><div>Kevin Broderick</div><div><a href="mailto:ktb@kevinbroderick.com" target="_blank">ktb@kevinbroderick.com</a></div></div>
</div>