[Talk-us] Rural US: Correcting Original TIGER Imported Ways
Martijn van Exel
m at rtijn.org
Mon Feb 12 22:39:01 UTC 2018
I am very happy to see this rekindled interest in TIGER cleanup!
Having done a fair amount of backcountry exploring, I know that there is a
wide range of road grades and aerial imagery alone is not enough to decide
how navigable a roads is for a particular type of vehicle. Or, for that
matter, what its access limitations are. I do agree with Clifford that
leaving them as poorly aligned 'residential' roads is the worst possible
situation. Yes, worse than deleting the road altogether. What I usually do
is mark the road as track without a track grade tag. This seems to me to be
the most acceptable generic solution for a remote mapper: acknowledging
that something that could potentially be navigated by a 4 wheeled vehicle
exists, without being more specific. Local knowledge can then come to the
rescue to upgrade to unclassified if appropriate.
Another note on the MapRoulette side of things: I would very much
appreciate your feedback on the new MapRoulette version Clifford linked to.
Just email me, join #maproulette on slack, or file an issue at
On Mon, Feb 12, 2018 at 3:08 PM, Kevin Kenny <kevin.b.kenny+osm at gmail.com>
> On Mon, Feb 12, 2018 at 12:55 PM, Kevin Broderick <ktb at kevinbroderick.com>
>> Please, please, please don't convert rural roads to tracks based on
>> imagery alone unless it's incredibly clear (and that would exclude anything
>> with forest cover).
>> While many of them should definitely be unclassified, not residential,
>> downgrading the main rural routes to tracks doesn't match local usage nor
>> the functional topology of the road network in such places. There are a lot
>> of USFS and BLM roads around here that are the only way to access
>> significant areas, that commonly see normal passenger-car traffic and that
>> can be traveled at reasonable speed in a sedan (or at 30+ MPH with a little
>> ground clearance and driving skill),. Having these differentiated from true
>> tracks (where even a stock 4x4 is likely going to be operating at 15 MPH or
>> less) is incredibly helpful for routing and visual use of the map, and it's
>> a lot easier to recognize what I'd call "areas of questionable data" when
>> they haven't been aggressively armchair-mapped. Also, the smoothness key is
>> really helpful for tracks and impossible to map from orthoimagery.
> Yes, yes, yes.
> In the rural areas that I can travel to readily, TIGER is downright
> hallucinatory (and there are few enough mappers that cleanup has been
> agonizingly slow). TIGER has roads in places where no road is, ever was, or
> even ever could be. (I've seen one going up a series of cliffs totalling
> about 2000 feet of ascent!) But even in 'leaves down' images, it's nearly
> impossible to see the forest roads, much less trace them, and there is
> definitely a wide variation in quality. Some of them are well-compacted
> sand and shale, that once they've been rolled in the spring, support
> driving at 30+ MPH. Others, I wouldn't bring my Subaru on. (Although I've
> been on a few of those in the ancient Ford Explorrer that the Subaru
> replaced.) Some are gated, some, you simply have to decide for yourself
> that they're not drivable.
> The 'dirt roads' range from 'highway=path abandoned:highway=track
> smoothness=impassable' to 'highway=tertiary surface=compacted
> smoothness=intermediate', with no way for an armchair mapper to tell among
> The old road maps that they used to give out at gas stations had, on many
> of these roads, "inquire locally for conditions," which is still good
> advice. The signage may say, "LIMITED PURPOSE SEASONAL-USE ROAD: No
> maintenance November 1-April 15" - but in practice, they'll keep it open
> later in the Autumn unless the snow comes early, and when they open it in
> the spring depends on when the crews can get it clear - it could be weeks
> late if there's been a bad washout or rock slide. There's absolutely no way
> to tag and encode that sort of thing. Inquire locally for conditions.
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