[Talk-us] Rural US: Correcting Original TIGER Imported Ways

Kevin Broderick ktb at kevinbroderick.com
Mon Feb 12 23:02:01 UTC 2018

If you can cover an entire area (which I'd define as a swath between the
nearest state highways), I agree that downgrading to track absent other
clues is one reasonable solution. One of my key points is that anyone who's
spent a fair bit of time trying to use GPS maps (of any origin) in
poorly-mapped areas will quickly recognize an area that is clearly an
unverified TIGER import, which signals both (a) that the data is clearly
questionable and (b) that it might be an interesting place to explore to
find out if the roads do go through or not. The questionable map data can
be very useful, especially in conjunction with other data sources, in
attempting to piece together a route through an area that lacks fully
maintained roadways. If a track doesn't actually exist, yes, then it should
certainly be deleted, but I've ridden right-of-ways that were damn near
impossible to see with leaf-on imagery and also found other routes that
looked more road-like via the same imagery impassable, so I definitely
wouldn't delete anything unless you can get there in person and look for
evidence of a roadway, perhaps one that hasn't been maintained in decades
(e.g. Class IV roads in Vermont and Class VI roads in New Hampshire).

Downgrading some ways to tracks without doing so to a whole localized
network creates the appearance of a higher level of data accuracy than
actually exists, which IMO is more likely to bite someone in the ass than
having a localized network of roads that are mislabeled. I know it would
make some of the exploring I've done via on/off-road motorcycle more

I'd also suggest that leaving tiger:reviewed at no is appropriate if you
haven't been able to travel the road/track in question and determine
whether it is really an unclassified road or a track, so it remains flagged
for further review if someone has the time and proximity to do so.

On Mon, Feb 12, 2018 at 3:39 PM, Martijn van Exel <m at rtijn.org> wrote:

> 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
> https://github.com/maproulette/maproulette3/issues.
> Martijn
> On Mon, Feb 12, 2018 at 3:08 PM, Kevin Kenny <kevin.b.kenny+osm at gmail.com>
> wrote:
>> On Mon, Feb 12, 2018 at 12:55 PM, Kevin Broderick <ktb at kevinbroderick.com
>> > wrote:
>>> 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
>> them.
>> 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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Kevin Broderick
ktb at kevinbroderick.com
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