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rickb
09-18-2006, 06:49
Not that it matters much, but I was wondering...

Would the AT be shorter if the miles were measured by a GPS or as plotted on a flat map, rather than by a wheel?

Seems to me that you walk farther between two points when there is a mountain between them, rather than a flat plane.

Or to put it another way, is a mile in the Whites longer than a mile in SNP?

Just wondering.

LIhikers
09-18-2006, 07:07
The AT has been measured by GPS. A number of years back I met Doc Del (or was it Del Doc?) who walked the entire AT with a pack full of sophisticted GPS equipment that took and recorded it's position every few seconds. He walked the center of the trail, as it appeared to him, and shut the equipment off every time he went off trail. Then when he'd come back to the trail he'd switch the equipment back on at the same place he left the trail. As I understand it he had done that 2 or maybe 3 times before he died a few years ago. I don't know for sure what ever happened to that info but he had told me it was to make the maps more acurate.

celt
09-18-2006, 07:32
I too met Del Doc (died 5/20/04 age 79) in 1999 in the Smokies and 2003 at the ATC biennial meeting in NH. ATC volunteers were finishing up his GPS project last summer in The Whites. I met one measuring the paths of the Garfield Ridge Campsite and he asked me the dimensions of the tent platforms for his data. I think a good GPS unit can measure accurate distances because it plots points and determines elevation. The data is available on the ATCs website:

http://www.appalachiantrail.org/site/c.jkLXJ8MQKtH/b.851255/k.4226/Appalachian_Trail_GIS_and_GPS_Data.htm

celt
09-18-2006, 07:37
Del Doc's obit in the AT news had some interesting info on the GPS data

http://www.appalachiantrail.org/atf/cf/%7BD25B4747-42A3-4302-8D48-EF35C0B0D9F1%7D/ATN04Jul.pdf#search=%22Del%20Doc%20GPS%20appalachi an%20trail%22

Alligator
09-18-2006, 17:06
GPS can determine elevation. A GPS will record however many points you ask of it. This would be subject to memory (not really a problem with an $ unit.) The distance between points will be straight lines. So I think you might lose distance any time there is curvature between recorded points on the GPS. It is also possible though to locally smooth the data or utilize some other algorithm to add back the curvature. If the data is processed it might not be different.

Brushy Sage
09-18-2006, 22:25
All these measurements are dependent on the device(s) used, and the skill of the operator. Also, the results are valid only at the time of measurement. The AT is such a dynamic path that it changes year by year. Every relocation, every bog that is bypassed, every stream crossing that is shifted, changes the total length of the trail. Some of these differences are feet; others are miles. GPS and other technology provides data that can contribute to an accurate record of the changes through the years.

Nean
09-19-2006, 01:18
If I had to bet, (longest/ most accurate) I'd go w/ the wheel.;) :)

Kerosene
09-19-2006, 12:25
I can just see some guy trying to push a wheel up the rock scramble of South Kinsman. Somehow I don't think that I'd trust the accuracy in these sections!