# Logs to shore up bench cut on steep slopes a durable solution?



## Schulze (Feb 21, 2007)

Yesterday I rode the trails in Cameron Park in Waco, TX. The Highlander trail was a lot of fun - it's a narrow bench cut on a steep slope with grades up to 40% (I measured!) and the soil moisture was perfect for grip.

The builders used Ash Juniper logs a lot to shore up the trail. The terrain doesn't have much available rock so I can see why they did this. Example:










Ash Juniper is a soft wood that is used a lot in fence posts. If you strip it of bark and sink it upright in the ground, it will last 50 years holding up barb wire.

I'm curious what the experts think the longevity on something like the above would give. With direct contact to the soil moisture I can't imagine it would be very long.


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## Schulze (Feb 21, 2007)

Since this was such an enjoyable trail, I stopped and took measurements on the best parts so I could build similar feeling trails on my land. I have a lot of steep hillsides where this type of trail fits well. 

I found that 27% was about the limit of an enjoyable climb, though 40% was rideable as long as the tread wasn't loose. 

Sadly, a lot of other trails in this park were poorly designed with significant sections of fall line trail that was eroding badly. It was also a maze in some sections.


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## Harold (Dec 23, 2003)

It won't hold up. But not for the reason you suspect. You can see what's going to cause the demise of this patch - undercutting. Water flows over the top of the log, falls over, and undercuts the back/bottom. Unless a more permanent solution is devised, this will continue and it'll just erode out.


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## Harryman (Jun 14, 2011)

Harold said:


> It won't hold up. But not for the reason you suspect. You can see what's going to cause the demise of this patch - undercutting. Water flows over the top of the log, falls over, and undercuts the back/bottom. Unless a more permanent solution is devised, this will continue and it'll just erode out.


This. It's a guaranteed failure at some point in the future. I'd never recommend using wood, since it has a limited life, but if there aren't any other options if you wanted to make a retaining wall/step, you'd bury the first course and stack on top of that. Since everyone is forced to step in the same place in front of it (especially horses), bikes will land in the same place, and water will waterfall off, the downslope will quickly erode deeper.

I'm not sure what you were using to measure, but 27% is far from enjoyable....


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## Schulze (Feb 21, 2007)

I have a slope app on the cell phone. For these short, punchy climbs, the steep stuff is really good, especially if you enjoy climbing. Yeah, I'm special....

I should have taken some better pictures, but much of this trail is on a steep sideslope, and when you start on it you're thinking, Man, no way I'm going up that! and the you just motor up it. And there's an effect of being "right on the edge" the whole time. 

The log in the picture is on a switchback, but most of the log use is shoring up bench cut on the sideslope. If it lasts ten years I'd be satisfied.


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## cerebroside (Jun 25, 2011)

Is that log cribbing on the outside of the switchback? Based on the age of similar stuff around here I would say 10+ years, but probably depends a lot on how wet the area gets.

I haven't seen any problems with undercutting of stuff locally. I expect for that to be an issue you would have to have a lot of water running down the trail?


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## Harryman (Jun 14, 2011)

If 10 years is durable enough for you, have at it. I try to design/build trails that won't need anything but superficial maintenance for 50-100 years. I'd rather be riding than maintaining.


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## Schulze (Feb 21, 2007)

I would too, but if I'm the only dude building a 7-8 mile trail, then I'd rather get it done in 2 years using methods that will last ten years instead of getting it done in 5 years using methods that will last 50 years. The I can spend a day a week upgrading the logs to rock work while riding it 3 days a week.

cerebroside, the cribbing is in the middle. The trail path goes to the left around that tree.


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## tbmaddux (May 22, 2012)

Here's some photos of a crib wall being built on Larison Rock, near Oakridge, OR, in the foothills of the Cascades mountain range. The trail network in this area is almost entirely very old-school forestry / logging / fire watch / fire break trail that has been adopted and maintained by mountain bikers in the past couple decades.

The trail can be shuttled easily using a paved road, and it gets ridden fast and hard. Here's a before shot from Greater Oakridge Area Trail Stewards (aka GOATS):









Here they are mid-work. They mined out the bench to insert pole tiebacks to hold the wall in place, then backfilled with imported rock and eventually covered with dirt from the upslope. Note that the poles are stripped of bark to improve their lifespan.









Last photo shows the completed project.









There are other trails in this zone where there are single logs used to line the outslope as riders roll into a tight switchback. There aren't any switchbacks on Larison Rock that I can recall (remember I said it was fast?), but here's an example of that from Lawler.









They never last. Inevitably they're hit by enough tires or erosion from beneath that they fail. Often it's when someone mistakenly places trust in their stability, resulting in a wreck.


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## DaveVt (Jun 13, 2005)

I've seen hemlock logs laid from tree to tree across a steep side hill from the CCC days in the 30s still holding up trail in a local state park. The entire mass has become stabilized as part of the forest floor. It's grown in to the side hill with a million little roots and some trees having sprouted right out of the decaying log. I don't see it going anywhere for a long long time...like ever. 

I have done it where rocks are very few and far between. It takes a fraction of the time per foot than stone work and can be replaced as it fails, a 2 hour project at most every decade or two is a good solution IMO.


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## Harold (Dec 23, 2003)

IMO, you'd be lucky to get 5yrs out of single log cribs like that. I agree that being hit by tires or feet puts a lot of stress on these things. Based on info in the pic, I'm honestly doubting the need for any sort of crib wall in that specific spot.


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## aero901 (Apr 11, 2012)

Schulze said:


> I would too, but if I'm the only dude building a 7-8 mile trail, then I'd rather get it done in 2 years using methods that will last ten years instead of getting it done in 5 years using methods that will last 50 years. The I can spend a day a week upgrading the logs to rock work while riding it 3 days a week.


Get more dudes and build with the mentality of longevity. The next person who takes on maintenance of the trail will thank you. I was in your boat 7 years ago and now we're rebuilding all the retaining walls and features made from native "long lasting" woods. Using rock/dirt and treated wood products exclusively now.


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## WHALENARD (Feb 21, 2010)

tbmaddux said:


> Inevitably they're hit by enough tires or erosion from beneath that they fail. Often it's when someone mistakenly places trust in their stability, resulting in a wreck.


Wouldn't want to do that with the second to last berm on upper Dead Mountain. Might be a while before gravity rejoins you with terrafirma. That has got to be the biggest/tallest crib wall I've ever seen, it's impressive.


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## tbmaddux (May 22, 2012)

WHALENARD said:


> Wouldn't want to do that with the second to last berm on upper Dead Mountain. Might be a while before gravity rejoins you with terrafirma. That has got to be the biggest/tallest crib wall I've ever seen, it's impressive.


Yeah it definitely gets steep in there. Looks like they used a mix of wood cribbing:









... and rocks, cobbles, or boulders. This one they said was boulders:









You can find more from the build if you look for "Dead Mountain Trail" on Facebook; I picked those two photos from there. And the previous photos were from the GOATS group.


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## J.B. Weld (Aug 13, 2012)

Schulze said:


> I found that 27% was about the limit of an enjoyable climb, though 40% was rideable as long as the tread wasn't loose.


Dang, you are special. I like climbing too and 27% is about the very limit of what I can manage, and only if it's smooth and the grip is good. "Enjoyable" never comes to mind on those sort of grades, more like stars and vomit.


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## Harold (Dec 23, 2003)

Schulze said:


> I found that 27% was about the limit of an enjoyable climb, though 40% was rideable as long as the tread wasn't loose.





Schulze said:


> I have a slope app on the cell phone.





J.B. Weld said:


> Dang, you are special. I like climbing too and 27% is about the very limit of what I can manage, and only if it's smooth and the grip is good. "Enjoyable" never comes to mind on those sort of grades, more like stars and vomit.


I have no doubt that he needs to upgrade his measuring ability. First off, to learn how to measure slope in the first place. Second, to use something better than a phone app.


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## leeboh (Aug 5, 2011)

J.B. Weld said:


> Dang, you are special. I like climbing too and 27% is about the very limit of what I can manage, and only if it's smooth and the grip is good. "Enjoyable" never comes to mind on those sort of grades, more like stars and vomit.


 Stars and vomit. Thank you for an awesome quote of the day.


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## Schulze (Feb 21, 2007)

Harold said:


> I have no doubt that he needs to upgrade his measuring ability. First off, to learn how to measure slope in the first place. Second, to use something better than a phone app.


lol


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## roughster (Dec 18, 2017)

Can we get more of these posts on TBaA instead of more e-bike crap, please? Great conversation guys and it has me thinking of a few places I might be able to incorporate some of this strategy.


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## DaveVt (Jun 13, 2005)

To be clear, the picture used in this thread is what I would call sub par. We would use logs with a diameter of 10 to 12 inches or more, mostly buried and helded in place with at least one large stone on each end, mostly burried. We ised peeled hemlock for its batural resistance to rot and backfilled with smashed rock that we generated on site underneath mineral dirt. It a really high use area and we expect a long life. It has already outlasted rough cut hemlock dimensional lumber bridges we built the same year on the same trail a few hundred yards downstream.


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## GeePhroh (Jan 13, 2004)

leeboh said:


> Stars and vomit. Thank you for an awesome quote of the day.


Also sounds like a great trail name.


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## Schulze (Feb 21, 2007)

J.B. Weld said:


> Dang, you are special. I like climbing too and 27% is about the very limit of what I can manage, and only if it's smooth and the grip is good. "Enjoyable" never comes to mind on those sort of grades, more like stars and vomit.


They're not mile long efforts. 50-75 yards, then a sharp downhill and power up the next climb.

I think you're underestimating what grade you can do on a mountain bike.


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