AT Actual Walking Length

[Lilred]

Cool hands: where did you get that elevation change number? I once heard the A.T. is equivalent of ascending and descending Mount Everest 7 times, but according to your number it's actually a bit over 8.

I had always heard it was 8 times...

[chief]

And don't forget the curvature of the earth. The further north you go, the shorter a mile is.

I call BS on that one!

[walkin' wally]

When a maintaining club does a relo the difference in distance from the old to to the new is recorded and sent to the ATC. Thats why the total distance changes nearly every year.

[Driver8]

I'm pretty sure the distances account for elevation changes because I'm very attuned to how fast I'm moving and how long it takes me to cover a certain distance on all types of terrain.

That's not to say that AT mileage signs are accurate +-/ 10' or anything but they're close enough for government work IMO.

Because a hiker inevitably will weave somewhat from side to side in the trail corridor - avoiding puddles, icy patches, walking around boulders, etc., the "wheel method" probably ends up giving the minimum distance one might ever hike on the trail. I think a couple percent additional distance above the wheel figure would be a fair estimate.

[Driver8]

... the vertical component (475,200 feet of elevation change).

Cool hands: where did you get that elevation change number? I once heard the A.T. is equivalent of ascending and descending Mount Everest 7 times, but according to your number it's actually a bit over 8.

For the record, Everest's base to peak stature is about 12300 feet. Base camp west of the summit (for Hillary and Norgay's ascent, the most common route) is at 17,700', and the summit is at 29,029'. So 475.2K would be just over 19 Everest round trips of elevation change. Just saw a superb British documentary of the initial successful ascent, The Conquest of Everest. Great film - highly recommend it. Got a hold of it from the local library as part of this set: http://www.amazon.com/Into-Thin-Air-.../dp/B00000IML4 .

[Awol2003]

Ham Bone, the distance that you see published in guidebooks is intended to account for ups and downs and twists and turns. There is no such thing as a "true" distance of the trail, only good approximations. For such a long trail, even the word "approximation" implies more accuracy than is possible. The published distance is more like a consensus.
GPS will usually measure too short. Wheels will usually measure too long (they travel more like an ant than a person), and wheels return useless values if not carefully calibrated and maintained. I plan to include a little about trail measurement in my talk at Trail Days this year.

[Jim Adams]

There was one stretch (I can't remember exactly where it was... northern part of the trail somewhere) where the mileage signs were WAY off. They were all about 30% short of actual mileage.

I think this is the stretch before South Kinsman in N.H. Seems like you walked for ever for about 11 miles when the signs said 6.6 miles.

Cool hands: where did you get that elevation change number? I once heard the A.T. is equivalent of ascending and descending Mount Everest 7 times, but according to your number it's actually a bit over 8.

I remember someone adding all of the elevation gains going NOBO and it totaled around 68 vertical miles.

I belive distances are still measured by wheel, which is the only way to get a pretty accurate measurment. GPS hasn't been around long enough to be used for trail signage mileage.

I remember DellDoc measured the trail via GPS...2002? The GPS would also read elevation gains and loses if it had a barometer or barametric altimeter in it and would adjust the distances on the readout.


geek

[Captain Blue]

And don't forget the curvature of the earth. The further north you go, the shorter a mile is.

I call BS on this too!

10-K: Support this claim with some facts.

[Jim Adams]

I call BS on this too!

10-K: Support this claim with some facts.

I don't think that it would be shorter but should be closer to level.

geek

[BobTheBuilder]

I call BS on this too!

10-K: Support this claim with some facts.

Just look at Greenland on a map. It's way north, and looks like it's the size of Texas, but it's really the size of Rhode Island. You can walk across it in a couple of hours! Another lie - it's not really very green!

[Ham-Bone]

Ham Bone, the distance that you see published in guidebooks is intended to account for ups and downs and twists and turns. There is no such thing as a "true" distance of the trail, only good approximations. For such a long trail, even the word "approximation" implies more accuracy than is possible. The published distance is more like a consensus.
GPS will usually measure too short. Wheels will usually measure too long (they travel more like an ant than a person), and wheels return useless values if not carefully calibrated and maintained. I plan to include a little about trail measurement in my talk at Trail Days this year.

Thanks....I wasn't too wrapped up in an exact measurement....I only thought that the mile markers were flat measurements. But now I know.

[bigcranky]

Therefore, the length would be (2,181miles*5,280feetpermile)^2 + (475,200feet)^2 = 132,610,885,862,400 + 225,815,040,000 = 132,836,700,902,400. The square root of this is 11,525,480.51, and divided by 5,280 feetpermile gives us 2,182.9 miles. =

This is pretty accurate. I remember doing the math once and being surprised at how small the difference was in total length when taking into account large elevation changes.

[Roland]

Good old high school math comes to the rescue! Pythogorean Theorem, people. On wikipedia, the horizontal component of the trail is given (2,180 miles) along with the vertical component (475,200 feet of elevation change). So what do you do? Add the squares of each length, find that number's square root, and that is the actual distance, taking into account the rises! (If I'm wrong, someone correct me here...)

Therefore, the length would be (2,181miles*5,280feetpermile)^2 + (475,200feet)^2 = 132,610,885,862,400 + 225,815,040,000 = 132,836,700,902,400. The square root of this is 11,525,480.51, and divided by 5,280 feetpermile gives us 2,182.9 miles.

Only an extra two miles, but pretty interesting! (I realize after doing this that working with miles instead of feet would have been way easier... whoops.)

Your starting distance, 2180, was measured by a wheel, over ground. The wheel was rolled over the ups, downs, bumps and turns. Therefore your calculation to account for additional distance due to elevation change is totally unnecessary.

[weary]

Essentially by global standards, the AT is nearly flat. That's why Map people artificially increase the height drawings 5? fold. That exaggeration is needed to satisfy long distance hikers, who want to show profiles that suggest to folks at home how hard the trail is.

[SassyWindsor]

1117 miles = straight line from Springer to Katahdin. Not taking in earth curvature the difference between the actual wheel measurement and 1117 miles should be close to the distance caused by the the curves, zig-zags, and elevation or 1050 or so miles, which is close to half the total distance.

[SassyWindsor]

In other words, if one could walk in a straight line with no elevation change you could walk from Springer to Katahdin and back to Springer and have walked approximately 2234 miles, not far from the actual trail miles one way.

[bigcranky]

Look at it this way:

Take a single flat mile, 5280 feet.

Now add a 500 foot climb -- which is a pretty good grade for a hiker (500 feet per mile.)

If you are going uphill, how much longer than a flat mile do you end up hiking?

Well, use old Pythagoras. 5280*5280 + 500*500 = your answer (squared.) Do the math, take the square root, and you get....

5303 feet and change, or about 23 extra feet on a one mile climb. Not much difference.

Of course, the trail goes up and down a lot.

[Bronk]

I remember DellDoc measured the trail via GPS...2002? The GPS would also read elevation gains and loses if it had a barometer or barametric altimeter in it and would adjust the distances on the readout.


geek

Yes, he did his GPS survey in 2002...his rig cost him about $50,000 and as he was doing the survey he told me he didn't yet have a buyer for the data, though he was hoping the ATC would buy it, but there were no guarantees (perhaps they were waiting to see how good the data was before committing to buy it)...I think he said he was taking measurements every 3 meters, though watching him do it I would think this would be an approximation...probably doesn't matter because at the end you are just going to connect the dots of all the measured points. I have no idea if the data was ever used. He was essentially slackpacking the trail that year (it was his 4th thru-hike) with his wife meeting him at road crossings...a couple of times I met him on an upward climb and wondered if he'd make it the whole way without keeling over. He and his wife are good people, they were always shuttling people to and from town.

[johnnyblisters]

I see no reason why a wheeled measurement's data would be disputed, assuming the instrument was properly calibrated and utilized.

To answer the OP's question, the measurements you are given are not a linear measurement on a planar scale. When measuring with a physical instrument such as a measuring wheel, all geodesic variables are taken into account in that measurement.

And to 10-k, I think you forgot an emoticon at the end of this

And don't forget the curvature of the earth. The further north you go, the shorter a mile is.

[weary]

I see no reason why a wheeled measurement's data would be disputed, assuming the instrument was properly calibrated and utilized.
.....

Like most things in life, a measuring wheel measurement is only as accurate as the assumptions of the operator. Wheels work great on sidewalks and paved highways. They have variables when used on typical woodland trails, with scattered rocks and downed logs.

Do you roll the wheel up and over a big log or rock that a hiker would just step over? Or do you stop at the base of the obstruction and lift the wheel over?

What about measuring a rough trail? I find myself measuring from one side to the other of a trail, seeking the easiest route for pushing a wheel, but not necessarily the route I would walk without the hinderance of the mechanical device.