The Steepest Roads

[Morningrider]

I’ve been scratching my head trying to think of one special number that everyone understands and most riders agree captures in one number the “steepness” of a route so it can be compared with other routes measured the same way. Having a cutoff for steepness, the way I did it above, is easily understood but different cutoffs give different results. Also, if we say “steep” means over 15% grade, then a 14.9% grade counts for nothing and a 15.1% grade counts the same as a 35% grade. I think for reducing “the steepest road in Thailand” to one simple number which reflects (only) the steepness of the route that can be calculated from actual GPS tracks, we need a number that gives more weight to more time spent on steeper grades and more weight to steeper grades and does not require any arbitrary cutoff at all. How about the time-weighted slope of the route? The sum of the products of the time between each trackpoint and the grade of each trackpoint, divided by the moving time of the route. The number means the time-weighted average slope of the total route, in percent grade. It seems to work well. Big Dipper is still #1. What do you think?

 

[DavidFL]

We could also add in / compare these.
R4001 the Rak Thai Road.
The Lao U Road - Rom Pho Sai road, Thoeng.
R4029 the Phua An Ma Road, Chiang Kham.
Singapore Road, Wiang Kaen.
R1334 the Pha Bur Road, Doi Tung.
R4029 the Pha Tang Road, WIang Kaen.
R4030 Doi Phachi / Santisuk, Pong, Phayao.
R1249 Doi Ang Khang, Fang.
The Nor Lae ascent / descent, from Doi Ang Khang, but only 6 kms.
R1333 Nan the Huay Lom / Huay Chanin Road, Nan.
R1130 - R1234 the Doi Mae Salong Road, Mae Chan.
R4054 the Huai Lang Road, Wiang Kaen.
R1149 Doi Tung to Mae Sai.

But for me it should still be the Big Dipper?

 

[Morningrider]

OK, will have a look. Fun to go back to the maps.

 

[Moor66]

3004 SW of Mae Sariang have some steep sections near the refugee camp
Yesterday these fellas had a good trek 555

 

[DavidFL]

3004 SW of Mae Sariang have some steep sections near the refugee camp
Yesterday these fellas had a good trek 555
View attachment 153597

How long is the road & is it all dirt?

 

[Moor66]

The 3004 section west of 105 is around 80 km, from Sop Moei and down SW and then up NW on Kloselo mountain, for to meet 1194 in Mae Sam Laep at the river.
Have dirt sections for sure, let me guess not more than 20 km. One sudden 100 meter long muddy slope with rocks where I just barely made it with my little 100 kilo baby bike. Have a little bit riverbed riding too.
But the first 20-30 km are very good. At Ban Sue Mue they have done a shortcut westwards towards Kloselo, bypassing the nasty southern end and refugee camp.

 

[DavidFL]

The 3004 section west of 105 is around 80 km, from Sop Moei and down SW and then up NW on Kloselo mountain, for to meet 1194 in Mae Sam Laep at the river.
Have dirt sections for sure, let me guess not more than 20 km. One sudden 100 meter long muddy slope with rocks where I just barely made it with my little 100 kilo baby bike. Have a little bit riverbed riding too.
But the first 20-30 km are very good. At Ban Sue Mue they have done a shortcut westwards towards Kloselo, bypassing the nasty southern end and refugee camp.

Thanks for the update, if you've got any more pics you're welcome to share them & make it a little report "the Sop Moei - Mae Sam Laep loop" if you want. Just a few pics & a couple of paragraphs is fine.

 

[DavidFL]

A final report from Morningrider

The steepest three roads in Thailand are:
1. R1249 Nor Lae to Ang Khang, 13.3%, 6 km
2. R4018 Big Dipper, 13.1%, 11 km
3. R4009 West Segment, 12.1%, 12 km
The steepest 12 km of the much-boasted-about 3054 is tied for 8th place with the 12 km Singapore Road, both at 10.2%. (The whole 43 km 3054 route is in the 16th place on the list.)

More data to come.

 

[Moor66]

But how should we define what is a steep road?
One with a short steep stretch of just 1 km?
Or one that have many steep up and down stretches, like 3054?
Or a road that have a long steep-in-one-go stretch of say at least 5 km,
i.e. a brake fluid boiler going downwards?

Which roads climb more than 1000 meter in less than 10 km of riding?

While the 3054 has many steep up and down sections, it doesn't have a long continuous steep section, right?
I mean like the steepest part of 4009, the 8-9 km long stretch where the road climbs 800 meter in one go, near the western end. (a part of the 12 km west segment)

If we think of roads that climbs high in one long exhausting go, the Wat Ko Pha Doh road (doi paper road) that takes off northeast from 105 some 30 km north of
Mae Ramat surely is a top candidate I believe.
(this road is one of a few entry stretches from 105 towards Omkoi area)

From 105 to the junction next to temple high up on mountain ridge where the gravel/dirt starts it's 18,5 km of asphalt and concrete, mostly quite good.

The steepest 9 km long stretch of this road climbs 1050 meter in one go,
so definitely steeper than the steepest 8-9 km stretch of 4009.

On 1249, if I pick the steepest 5.5 km of the 6 km mentioned in before post, the road climbs 780 meter in one go.
(I have never been there, now surely high up on my list of soon-must-to-go roads)

On 4018, if I pick the steep 5 km of the western stretch, the road climbs 730 meter in one go.
(this road I have been to on a rental 500X, quite scary as a super newbie to thai roads. Super smokey too, so no pics worth seeing)

Concrete under the dust. Part of the steep long brake cooking stretch where you descend 1050 meter in just 9 km

At around 1400 meters up, after the steepest part.

 

[Moor66]

I wonder how many roads in Thailand that gains altitude more than 1000 meter in less than 10 km of driving?
The steepest stretch of 1009 Inthanon road takes 11 km to climb 1000 meter.
The Wat Ko Pha Doh road does it in 8.5 km.

 

[DavidFL]

This is how our resident expert Morning rider sees it

Some notes received from Morning rider
Of the roads I analyzed—and please point me to any others that should be in the top ten—the steepest road in Thailand is the “1249 Nor Lae to Ang Khang,” as you expected, but it’s only 6 km long. Of the roads over, say 10 km long, the steepest is the “4018 Big Dipper.” #2 is the “4009 West Segment, and #3 is the “1345 Phu Anma Viewpoint.”

That’s only considering the steepness. But if there are two roads of the same steepness where one is straight and smooth and the other has many tight turns and bad pavement, the latter would be more of a trophy ride. That’s why I added a calculation of “Effort,” which is the steepness divided by the speed to take the road condition into account. Maybe “Terror” would be a better word! If Road A is twice as steep as Road B but one can only ride at half the speed of Road A, which on backroads is due to hairpin turns, loose gravel, rough surface, and/or narrow tracks, then the roads would be tied for “Effort,” even though Road A wins the steepness competition. If Road B is widened and repaved, then the Effort ranking go down. But the steepness ranking will always be the same.

Sorted by “Effort” the toughest road in Thailand is the 4009 West Segment. It is not the Big Dipper, because the Big Dipper is 9% steeper (13.1/12.1) than the 4009 West Segment but it is also 20% faster (40/33) and thus easier to ride. By Effort, #2 is the 1345 Phu Anma Viewpoint and #3 is the Singapore Road. Then the Elephant Pass Viewpoint at #4 and the Big Dipper at #5.


Note there maybe some changes to this list as we double check data.
I see some that need to be double checked.

 

[Moor66]

That's an interesting take for sure! Then the Ko Pha Doh road easily tops 4009, it's longer and steeper than 4009's steep western stretch, not to mention the thick bulldust (on top of concrete) in some of the hairpins and slopes! The 4009 was almost dust free two weeks ago.

The last concrete stretch close to the temple junction is not that old

 

[Morningrider]

You’re right. I have that track, from four years ago. Of the routes I checked, Wat Pha Doh Road is in the top five for average steepness (11%) but is—by far—#1 for grade/speed (36) because the road is terrible. These photos are taken from the easy spots, where I could safely stop. The surface was poor for street tires, slip-sliding away with long dried ruts a foot deep from 4WD tracks. My hands were shaking at the end of it.

 

[Morningrider]

To try to find the steepest paved road anywhere in Thailand, I ran the Garmin tracks of my Thailand rides from 2017 to 2023, 72,000 km, 2 million trackpoints, through GPS Visualizer and then a monster spreadsheet in Excel to identify the steepest 5, 6, 7, 8, 9, 10, 12, 14, 16, 18, 20, 30, 40, 50, 60, and 70 km (16 specific distances) of each of the twenty routes I had taken. I had to use several filters, such as disallowing U-turns because otherwise the steepest routes often turned out to be up and down the same route, thus counting the steepest bits twice. And disallowing ferry crossings when I discovered that walking upstairs from the car deck to the roof with my Garmin Oregon in my pocket was computed as a steep hill in the sea! My ThinkPad took about four hours to process each of the twenty routes, by far the slowest Excel spreadsheets I ever made. Then I manually sorted the steepest of the sixteen distances for the twenty rides to get the steepest of the steepest.

I didn’t include my older tracks because the GPS system elevation accuracy was poor in years past, and anyway my later rides often included the most interesting parts of previous rides. Based on comparing multiple rides over the same routes, and based on comparison of my tracks with tracks GT Rider sent me, I estimate the accuracy of the steepness calculations to be within about half a percentage point.

Steepest means the highest time-averaged absolute value of the grades between trackpoints (measured over at least 3 meters while moving) along the route. I did a second analysis to identify the routes with the steepest grade divided by the lowest speed, time-averaged from trackpoint to trackpoint. “Grade/Speed” is of course subjective, being based on one rider’s speed on one day’s weather and road conditions, but it helps to compare two routes of similar steepness—a faster route usually takes less effort than a slower one (better surface, fewer hairpins, wider track).

These were the twenty rides the computer analyzed, by following the routes that I happened to take on each of these rides and segmenting them into all possible overlapping routes of the sixteen lengths mentioned above (tens of thousands of routes were calculated for each ride):

Here is a summary of the results, sorted together with longer routes that I selected manually for comparison:

The steepest roads I could find are the 5035 Elephant Pass, 4018 Big Dipper, 1345 Phu Anma, 5080 Mae Kampong, 1249 Nor Lae to Ang Khang, 4010 Ban Wiang, the Ko Pha Doh Road, 4009 West Segment, 1333 Phu Fa, 3037 Doi Pha Luang. The most intense roads (Grade/Speed) I could find are Ko Pha Doh Road, 1345 Phu Anma, 3037 Doi Pha Luang, 5035 Elephant Pass, 5080 Mae Kampong, 4010 Ban Wiang, 4018 Big Dipper, 4009 West Segment.

Of course, long and short rides can’t be compared with each other but only with other rides of similar length, like marathons and sprints. Almost any ride can be made steep, if you make it short enough.

If anyone has a correction or addition, please PM me a recent GPS track (coordinates, elevations, and timestamps) that should be on this list. I’ll gladly run it through the analyzer and add it. It doesn’t take long.

Here is the same list as a text file, in case anyone wants to cut and past the coordinates into Google Maps to see the (approximate) routes.
19.192119,098.063456 to 19.219267,098.031105 > 5035 Elephant Pass 06 km
19.871104,100.356972 to 19.880315,100.307487 > 4018 Big Dipper 07 km
19.463951,100.511164 to 19.461167,100.530289 > 1345 Phu Anma 06 km
18.863648,099.356208 to 18.840115,099.374842 > 5080 Mae Kampong
19.850795,099.067989 to 19.869779,099.053002 > 1249 Nor Lae to Ang Khang
18.197692,100.435386 to 18.183008,100.487318 > 4010 Ban Wiang
19.884056,100.292859 to 19.860756,100.367548 > 4018 Big Dipper 11 km
17.236142,098.341312 to 17.280666,098.372167 > Ko Pha Doh Road 14 km
19.208824,098.076024 to 19.244495,097.996111 > 5035 Elephant Pass 20 km
19.007785,097.978359 to 18.997637,098.047005 > 4009 West Segment
18.970210,101.105007 to 18.989009,101.191410 > 1333 Phu Fa
20.079278,099.185297 to 20.059926,099.169558 > 3037 Doi Pha Luang 05 km
17.288621,098.356489 to 17.296685,098.393055 > Ko Pha Doh Road 07 km
17.210460,098.331498 to 17.355516,098.477927 > Ko Pha Doh Road to Mae Tuen
20.062013,099.208988 to 20.041619,099.163970 > 3037 Doi Pha Luang 12 km
19.495665,100.458612 to 19.453175,100.528421 > 1345 Phu Anma 14 km
18.1578120,100.36719 to 18.181743,100.490415 > 1024, 1342, 4010 Nam Gon
19.790236,100.341187 to 19.784439,100.401651 > Lao U (Rom Pho Sai) Road
17.9660770,097.92928 to 17.979350,097.977980 > 3004 Eng Neo Microwave
20.0020440,100.48522 to 19.947709,100.510123 > 4029 Singapore Road
17.088599,098.513192 to 17.151985,098.475324 > 3054 Steepest Segment
19.095506,100.412406 to 19.078973,100.499420 > 4330 Doi Pha Chi Santisuk
16.3697130,099.01101 to 16.229190,098.928276 > 1090 to Umphang 40 km
19.181050,100.984336 to 19.148827,101.155546 > 1256 Doi Phu Kha
16.460658,098.909929 to 16.229190,098.928276 > 1090 to Umphang 90 km
16.876672,101.171961 to 16.896666,101.105754 > 2331 Phu Thap Boek
19.988136,100.467104 to 19.933865,100.508378 > 4029 Doi Pha Tang Road
17.018803,098.523733 to 17.404135,098.456724 > 3054 to Mae Tuen
19.806480,099.132890 to 19.940880,099.042265 > 1249 to Ban Nor Lae
20.180510,099.771193 to 20.104088,099.615590 > 1130, 1234 Mae Salong
19.851354,100.380501 to 19.850039,100.438944 > 1155 to Phu Chi Fa
19.008597,097.974443 to 18.827524,098.036903 > 4009 Past Sunflowers
20.311914,099.820177 to 20.293884,099.769852 > 1334 Pha Bur
18.229392,100.411231 to 18.179997,100.657349 > 4010 to Na Muen
16.724886,098.595953 to 16.018195,098.862176 > 1090 to Umphang 163 km
19.481578,097.963383 to 19.587518,097.943319 > 4001 Ban Rak Thai Road
19.279550,098.604750 to 19.558010,098.637140 > 4030 to Wiang Haeng
18.376637,097.942922 to 18.355165,098.133765 > 4006 Mae La Noi to La Up
20.434787,099.877948 to 20.180518,099.771209 > 1149, 1338 Doi Tung
18.317150,100.611485 to 18.345283,100.443168 > 1216 to Wang Pung
19.0209560,098.85334 to 19.017451,098.763295 > Buddha Footprint Temple
18.909811,100.950202 to 18.986114,101.056527 > 1257 Khun Nam Nae
19.569811,100.926206 to 19.518395,101.222232 > 1081, 101 Khun Nan
19.136400,100.790745 to 19.115163,100.649514 > 4022 to Sop Khun
20.166211,099.711967 to 20.330070,099.634890 > 4052 Yaek,Thoed Thai,Mae Moh
19.413847,098.915385 to 19.384120,098.717131 > 3024 Mueang Khong
18.490877,098.672954 to 18.589250,098.487274 > 1009 to Doi Inthanon
18.6732420,100.99196 to 18.747971,101.195998 > 1168 to Viewpoint
19.134115,098.704083 to 19.284313,098.485364 > 1095 to Hua Kaeo
19.359495,100.702797 to 19.406461,100.397685 > 1148 Past Biker Cafe
19.506664,098.957969 to 19.681574,098.626384 > 1322 Doi Mae Salong
13.850862,100.639559 to 14.023118,099.532149 > 346 to Kanchanaburi

 

[Morningrider]

And here are summary sheets of the steepest roads. The area of the pink blobs shows the Grade/Speed at each interval of the route relative to the rest of that particular route—the bigger the blob, the tougher that spot relative to that route. The histograms are interesting, especially the Big Dipper and Elephant Pass, where almost none of those roads is level.

 

[Moor66]

17.236142,098.341312 to 17.280666,098.372167 > Ko Pha Doh Road 14 km

To me something is very wrong here... these cordinates includes the long supersteep section of the Ko Pha Doh road that goes up north, but then turn right at the high elevation junction, downwards another steep dirt gravel road that heading eastwards

And within those cordinates, some steep downwards riding is included, before the supersteep 9 km long climbing section starts.
Then the other rocky bumpy dirt road that descends a few km eastwards is included.
Confused 55

 

[mikerust]

East of Mae Chai I have a candidate. 6040 rises from around 400m to 1000m in about 10kms passing through Si Thoi or colloquially called the coffee village. It then follows the ridgeline to Viewdoi Homestay the last 4kms being dirt.
The dirt then continues 5kms back down to the valley floor at Pa Faek. So the last bit is steeper but not asphalt so doesn't count?

But I don't have the tech to measure it precisely. Managed to get my phone to display elevation though.
Unless my handheld Magellan GPS will do it. (if I can get it to switch on). I do have an inclinometer I could put on the road.

 

[Dodraugen]

55555 - Its nerdy beyond description, but I love it!

 

[Morningrider]

17.236142,098.341312 to 17.280666,098.372167 > Ko Pha Doh Road 14 km

To me something is very wrong here... these cordinates includes the long supersteep section of the Ko Pha Doh road that goes up north, but then turn right at the high elevation junction, downwards another steep dirt gravel road that heading eastwards

And within those cordinates, some steep downwards riding is included, before the supersteep 9 km long climbing section starts.
Then the other rocky bumpy dirt road that descends a few km eastwards is included.
Confused 55

Sorry for the confusion. Back in 2019 I had ridden what I thought was the Koh Pha Doh Road from the 105 to Mae Tuen, 39 km. stopping at the temple on the way, hence the slight detour in the GPS track. When I scanned my tracks for the steepest and

7 and 14 km rides, those segments appeared. In other words, that 14 km (out of the whole 39 km) was the steepest continuous 14 km of the Koh Pha Doh Road, or more properly, route, since it is more than one road. In the list above that road appears as one of the steepest (and hard work considering the slow speed) at 7, 14, and 39 km. Here is the plot of the whote route to Mae Tuen. The last part of it is part of the 3054 now.

 

[Morningrider]

East of Mae Chai I have a candidate. 6040 rises from around 400m to 1000m in about 10kms passing through Si Thoi or colloquially called the coffee village. It then follows the ridgeline to Viewdoi Homestay the last 4kms being dirt.
The dirt then continues 5kms back down to the valley floor at Pa Faek. So the last bit is steeper but not asphalt so doesn't count?

But I don't have the tech to measure it precisely. Managed to get my phone to display elevation though.
Unless my handheld Magellan GPS will do it. (if I can get it to switch on). I do have an inclinometer I could put on the road.

Can you let us know the coordinates at the start and end and any junctions along the way, or put them in Google Maps and send a link or a screenshot?

 

[mikerust]

From 19.360956 99.751831 to approx 19.374388 99.706393

O Bo To Ban Si Noi-ban Pang Pu Lao Rd to พย.6040

Google maps directions are not 100% correct and will add about 3.7 kms on non-existent roads. Between 19.353337 99.714096 and 19.361055 99.711156
This bit ร้านค้า ของชำบ้านปางปูเลาะ to พย.6040 Whereas the actual road can be seen through the trees on Satelite view the right hand road

รà¹à¸²à¸à¸à¹à¸² à¸à¸à¸à¸à¸³à¸à¹à¸²à¸à¸à¸²à¸à¸à¸¹à¹à¸¥à¸²à¸° to à¸à¸¢.6040

maps.app.goo.gl

Then you can continue but the last 3km is dirt. พย.6040 to Viewdoi Homestay วิวดอยโฮมสเตย์ ป่าเมี่ยง Past the home stay the dirt road can be , again, seen through the trees.

 

[Moor66]

Aha that makes sense. Mee too did that NE route from the Koh Pha Doh junction, and looped back via the NW route entering at Mae Tuen hospital. The NW route is more scenic, you approach the temple junction/american football field on a mountain ridge dirt road

 

[Morningrider]

From 19.360956 99.751831 to approx 19.374388 99.706393

O Bo To Ban Si Noi-ban Pang Pu Lao Rd to พย.6040

Google maps directions are not 100% correct and will add about 3.7 kms on non-existent roads. Between 19.353337 99.714096 and 19.361055 99.711156
This bit ร้านค้า ของชำบ้านปางปูเลาะ to พย.6040 Whereas the actual road can be seen through the trees on Satelite view the right hand road

รà¹à¸²à¸à¸à¹à¸² à¸à¸à¸à¸à¸³à¸à¹à¸²à¸à¸à¸²à¸à¸à¸¹à¹à¸¥à¸²à¸° to à¸à¸¢.6040

maps.app.goo.gl

Then you can continue but the last 3km is dirt. พย.6040 to Viewdoi Homestay วิวดอยโฮมสเตย์ ป่าเมี่ยง Past the home stay the dirt road can be , again, seen through the trees.

I had a look at my GPS tracks, and unfortunately I haven't been there so I can't work the numbers. I've put it on my to-do list. Looks interesting!

 

[mikerust]

I had a look at my GPS tracks, and unfortunately I haven't been there so I can't work the numbers. I've put it on my to-do list. Looks interesting!

Give me a shout if you wish. I'll come with you.

 

[Morningrider]

I gave Mike a shout, he shouted back, and we met in Phayao for a ride up the 6040. He led his friend Roger and me to the start of the route and pointed the way at critical turns. The steepest section of the road starts as two lanes of asphalt at 500m and ends up as one lane of concrete soon after it passes the summit, at 1100m. It continues to a village where coffee beans are laid out to dry in the sun and enjoy a wonderful view—and big bikes are advised to turn around where they still can.

According to the GPS track, the steepest 9 km of the 6040 is tied with the 12 km long Singapore Road and with the steepest 12 km of the 3054, all with a mean grade of 10%. Yet the 6040 is hardly known outside the local area. A summary (the area of the pink blobs on the map shows the grade of that section divided by the speed, indicating the riding intensity):

My updated steep roads list (with R6040 in bold)

Also according to my GPS track, the curve at 19.36547,99.70733 has an 8m elevation gain over 18m (three segments between four trackpoints), which amounts to a whopping 45% grade. I scanned my 77,000 km of GPS trackpoints and could not find a steeper four-trackpoint hill. An 8m gain measured by GPS really means 8m +/- 1m, since the GPS rounds off to the nearest meter, so that curve is probably between a 40% and 50% grade. GPS measurements are not accurate over short distances. But there is no doubt that the whole route to the village at the top is good fun. Here are screenshots of the steepest curve from my traffic-cam: