The Steepest Hills

Morningrider

Ol'Timer
May 19, 2023
54
41
18
As a rainy-day exercise I tried to answer the question: where are the three steepest hills in Thailand, according to Google Earth? My nominations are:

#1: 59 degrees at 19.85063,99.06698 on the 1249 from Nor Lae to Ang Khang. The winner.
#2: 57 degrees at 19.21699,98.03487 on the 5035 Elephant Trail The first-runner up.
#3: 56 degrees at 19.85568,99.05691 on the 1249 from Nor Lae to Ang Khang

56 degrees at 19.85568,99.05691 on the 1249 from Nor Lae to Ang Khang.jpg


57 degrees at 19.21699,98.03487 on the 5035 Elephant Trail.jpg


59 degrees at 19.85063,99.06698 on the 1249 from Nor Lae to Ang Khang.jpg


These could be the steepest three hills in Thailand, but there may be others that are steeper that my prospecting did not uncover. There are many hills over 40 degrees, and over 30 degrees is routine, but there are very few hills over 50 degrees, let alone almost 60 degrees. I used to have a Willys M38A1 jeep and its maximum rated slope in low-low 4WD mode was only 70 degrees.

Let’s try to perfect the top-three list. You can use Google Earth to plot the elevation profile of a challenging road to measure its steepest slope (plotting more than about ten km at a time reduces the peak grades, probably due to averaging, so you need to check less than 10 km at a time). Enter the start and end coordinates in the Directions boxes, then right click on the resulting route and click on Show Elevation Profile to see the peak and actual grades. If the resulting route isn’t what you expect, then you have to use Google Maps together with Google Earth. Or you can PM the coordinates of a suspected steep hill to me and I’ll help plot. It’s much easier the second time!

This is just the measurement of the grade of one hill and doesn’t indicate how steep the rest of the road is or how difficult the hill climb is considering the surface, curvature, width, and visibility. For that, you can look at the “Steepest Roads” thread.
 
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Morningrider

Ol'Timer
May 19, 2023
54
41
18
Surprisingly, not even close to the top three:
1. Big Dipper switchbacks, 40%
2. Singapore Road, 35% (they seem steeper because they are so narrow and dangerous)
3. The R1149 Doi Tung switchbacks, 44%

The are all steep roads but as it happens don't contain one really, really steep hill, according to the Google Earth elevation profile. I am not sure how accurate Google Earth is, or their minimum length for a slope calculation, but it probably is more accurate than a consumer-level GPS for elevation.

I checked these before, because my starting point for the Steepest Hills was prospecting in the Steepest Roads list. But there may be a really, really Steep Hill which is not on the Steepest Roads list because there isn't enough of it to count as a road. (For the Steepest Roads I didn't count any road shorter than 5 km.) Maybe around Chiang Dao near the Treehouse. I will have a look tomorrow.