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LPL, HPL, Section difficulty in data book pages

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LPL, HPL, Section difficulty in data book pages

Postby Catnapper » Sun Nov 06, 2016 7:21 pm

I hiked the AT in 2015, and I'm thinking of hiking again in 17. The postholer data book and planner for the AT have been very interesting to me as I think about various options. I've got a couple of questions I can't seem to find answers to on the site, and I'm hoping to find answers here.
1) In the detailed data book pages, there are two columns following the elevation column: LPL and then HPL. They are obviously related to elevation, but I can't tell what exactly the relationship is.
2) In the planner, there is a section rating. How is this rating calculated?
3) Most of the planner section ratings match my recollections of the difficulty of the trail, but some seem unusual. For instance, the section from Big Island, VA to Buena Vista is rated with a difficulty of 9.4. I just don't recall anything in that section that was so difficult. I wondered about The Priest, but that is in another section. Again, I'm curious how the ratings are determined, and if there is a human input into the final difficulty rating, for instance, that might have made this section rating so difficult.
Thanks for any input.
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Re: LPL, HPL, Section difficulty in data book pages

Postby postholer » Mon Nov 07, 2016 4:35 pm

Catnapper wrote:1) In the detailed data book pages, there are two columns following the elevation column: LPL and then HPL. They are obviously related to elevation, but I can't tell what exactly the relationship is.
2) In the planner, there is a section rating. How is this rating calculated?
3) Most of the planner section ratings match my recollections of the difficulty of the trail, but some seem unusual. For instance, the section from Big Island, VA to Buena Vista is rated with a difficulty of 9.4. I just don't recall anything in that section that was so difficult.


Hey Catnapper, here are some answers to your questions:

1. LPL is "Low Point from Last" and HPL is "High Point from Last". You're just automatically supposed to know that! :wink:

2, 3. The rating is calculated using length of climb, elevation change and percent grade. The algorithm sometimes has difficulty with shorter mileages (< 40 miles). There are other factors that contribute to unexpected results. The longer the section, the more accurate the results. Take this rating with a 'grain of salt'.

The AT data book has never made it into PDF format. Laziness on my behalf!

Hope that helps!

-postholer
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Re: LPL, HPL, Section difficulty in data book pages

Postby Catnapper » Mon Nov 07, 2016 6:43 pm

Postholer,
Thanks for the info. I do find both the online data book and the phone app useful. I use a formula set I've refined over the years to help predict my hiking times which uses distance, elevation increases and decreases, and indirectly considers grade. It's always interesting to me to see how others estimate trail difficulty. With my poor knees, I lend more weight in my calculations to elevation loses than do most calculators. By the way, I appreciate all the other info on this site. I'll be getting a printed copy of your high resolution AT map soon to put up on the wall.
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