AT Actual Walking Length

[Ham-Bone]

Went out on my first hike of the year last weekend. Buddy and I had an interesting conversation. Has anyone ever calculated the actual lenth of the trail taking slopes into account? If 2,170+ is the flat distance on a 2D map, then the actual length that you walk is ________ if it were stretched flat.

[rickb]

For a very long time the distances were measured by a wheel.

[LoneRidgeRunner]

Went out on my first hike of the year last weekend. Buddy and I had an interesting conversation. Has anyone ever calculated the actual lenth of the trail taking slopes into account? If 2,170+ is the flat distance on a 2D map, then the actual length that you walk is ________ if it were stretched flat.

I've often wondered that myself on other trails also..Having seen signs with distances marked from place to place and then seemingly walked much farther than that does tend to make one wonder it it's flat map distances and not taking slope error or the fact that every little curve and crook in the trails aren't shown on maps. Or could it be distances calculated by GPS routes, again not accounting for all the crooks and curves between the different way points or the slope error?
Someone said for a long time the distances were measured with a wheel. I suppose that would be the most accurate method possible.
You asked a good question that I would like to know the answer too also. Not that it REALLY matters because the distance we actually walk be the same regardless of whether or not we know the accurate distances.

[10-K]

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.

[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.

[Jim Adams]

It has been measured with a wheel and I also believe a GPS. Mileages are for the exact walking distance. I remember a year when Warren Doyle was pushing a wheel, 1990 I think and the mileage that year was 2,168.

geek

[LoneRidgeRunner]

It has been measured with a wheel and I also believe a GPS. Mileages are for the exact walking distance. I remember a year when Warren Doyle was pushing a wheel, 1990 I think and the mileage that year was 2,168.

geek

WOW..That had to be tedious pushing a wheel that far..also measuring with a GPS and taking measurements at every turn would have been tedious also. Of course the GPS couldn't measure the slope error. I suppose the operator of the GPS could have counted contour lines and figured the slope error. There is a mathematical formula to do that. Again, a very tedious task for over 2100 miles.

[Slo-go'en]

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.

Distance shown on trail signs is rounded to the nearist .1 mile and sometimes aren't updated if there was a reroute. And we all know that at times there are short 3/10ths of a mile and sometimes there are looong 3/10ths of a mile (usually at the end of a long day when that 3/10ths is up hill to a shelter!)

[Ham-Bone]

Good to know....I didn't expect that answer. This means that the elevation profiles that I look at can't be extremely accurate since they are plotted on a grid with equal 1 mile increments that correlate with AT mile markers. Since the AT mile markers are wheel-measured (thus actual length including slopes), then the grid marks should...............Ah nevermind, this is giving me a headache!

[10-K]

Good to know....I didn't expect that answer. This means that the elevation profiles that I look at can't be extremely accurate since they are plotted on a grid with equal 1 mile increments that correlate with AT mile markers. Since the AT mile markers are wheel-measured (thus actual length including slopes), then the grid marks should...............Ah nevermind, this is giving me a headache!

Also, read up on vertical exaggeration as it relates to the elevation profiles on your maps.

The distances listed (by and large) account for elevation changes.

If you think about it, it'd be easier to push a wheel than it would be to figure out flat line distances through the mountains.

[Ham-Bone]

Also, read up on vertical exaggeration as it relates to the elevation profiles on your maps.

The distances listed (by and large) account for elevation changes.

If you think about it, it'd be easier to push a wheel than it would be to figure out flat line distances through the mountains.

I see your location is Erwin. That is where I hiked this weekend (to and fro Erwin).

[Cool Hands]

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.)

[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!

[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.

[jersey joe]

Yes, he did his GPS survey in 2002...his rig cost him about $50,000 and as he was doing the survey

I met Delldoc on my 2002 thru hike coming out of a town. He had a large backpack on with the gps unit, it was bigger than I would have wanted to carry. He was an older fella, I wished him luck in making it to the end of the trail.

This thread is very interesting to me. I was recently asked if the trail included elevation gain. I thought it did since the I knew the trail was measured by a wheel, but I wasn't sure...this thread confirms that.

[Uncas10]

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 wonder if some industrious trail maintainer replaced all the exiting signs with GPS mileage that did not account for elevation changes. It wasn't a big deal, but it was a full day of "God dammit. I know I have walked [X] miles by now!" Anyone recall that? Vermont maybe?

[Linesman]

If someone could measure the AT taking all bends and bumps into account then the measured length would be much higher, perhaps tens of thousands of miles. Measuring any kind of highly irregular path like a coast line is tricky because the more closely you measure the longer it gets.