Wyoming’s Teton Pass Road Collapses, Governor Declares Emergency

[roamer_1]

@rustynail  Thank you.

That guy is too engineery. It ain't no damn piano.
The vid was enlightening though. They've already pushed the top soil off the uphill side, and you can bet money there will be 2 lanes of gravel there, toot-sweet. It'll be 20' lower than the original road, using the original road to bolster the temporary one. Meanwhile, the original road will be pushed into the cut to provide material for the fix.

I still think it was a water issue. And to fix it proper, a big culvert (3' anyway, maybe a 5' squashpipe) would need to be installed at the bottom of the fill - That will take longer than anything to do it proper - So I bet they won't do it.

[DB]

@rustynail  Thank you.

That guy is too engineery. It ain't no damn piano.
The vid was enlightening though. They've already pushed the top soil off the uphill side, and you can bet money there will be 2 lanes of gravel there, toot-sweet. It'll be 20' lower than the original road, using the original road to bolster the temporary one. Meanwhile, the original road will be pushed into the cut to provide material for the fix.

I still think it was a water issue. And to fix it proper, a big culvert (3' anyway, maybe a 5' squashpipe) would need to be installed at the bottom of the fill - That will take longer than anything to do it proper - So I bet they won't do it.

There's no obvious seepage of water coming out of the sidewalls of where it failed. So it isn't clear there was any underground source of water moving through it. Most likely cause is poor engineering with the soils used.

[roamer_1]

There's no obvious seepage of water coming out of the sidewalls of where it failed. So it isn't clear there was any underground source of water moving through it. Most likely cause is poor engineering with the soils used.

There's a cavern on the leftward face of the slide. Zoom way in on that.

[DB]

There's a cavern on the leftward face of the slide. Zoom way in on that.

Yes, the soil was less compacted there. But I don't see any signs of water seeping out of any of it.

[roamer_1]

Yes, the soil was less compacted there. But I don't see any signs of water seeping out of any of it.

Look below it on the natural ground. And look deep inside it... Wtf is that? something white-ish...

Doesn't matter. there's 10-20 year old trees on the downhill sluff edge... That dirt stayed put a long time before it gave. To write off water in an extraordinarily wet spring, on a big fill with no drainage is a mistake, I think.

And they'll use the fill they have. It's  a mountain road. You have to mess with it all the time.

[DB]

Look below it on the natural ground. And look deep inside it... Wtf is that? something white-ish...

Doesn't matter. there's 10-20 year old trees on the downhill sluff edge... That dirt stayed put a long time before it gave. To write off water in an extraordinarily wet spring, on a big fill with no drainage is a mistake, I think.

And they'll use the fill they have. It's  a mountain road. You have to mess with it all the time.

That is probably layers of fill. The fill likely came from different locations with different soil composition.

[rustynail]

A curved suspension bridge would look nice.

[DB]

Look below it on the natural ground. And look deep inside it... Wtf is that? something white-ish...

Doesn't matter. there's 10-20 year old trees on the downhill sluff edge... That dirt stayed put a long time before it gave. To write off water in an extraordinarily wet spring, on a big fill with no drainage is a mistake, I think.

And they'll use the fill they have. It's  a mountain road. You have to mess with it all the time.

There still could have been water, but it would have to be below what we can see. Maybe even a sink hole. On what you can see, if it were saturated with water it would be seeping out at the edge of the failure. That isn't obvious in the photo.

[roamer_1]

There still could have been water, but it would have to be below what we can see. Maybe even a sink hole. On what you can see, if it were saturated with water it would be seeping out at the edge of the failure. That isn't obvious in the photo.

I think that cavern fell into the failure.

[roamer_1]

A curved suspension bridge would look nice.

Bridges cost lots and lots of money. There's a reason why there ain't a bridge there already.

[roamer_1]

Where is the sluff? where did it go?

[roamer_1]

Here it is. The road did not fail... the natural land beneath it went. The sluff, with its trees intact...

[Sighlass]

Every 10 years we have a nice wipeout on our mountain roads up the mountain.... 2 years later they have them up and running again at full capacity. Fortunately there is several means of getting up the mountain within a few miles of each other. But it does put a strain on the truckers at times.

Good news is this slide can be temp fixed with a few 2X4s and duct tape. /s

[Smokin Joe]

Here it is. The road did not fail... the natural land beneath it went. The sluff, with its trees intact...

It isn't done. Note the crack in the pavement on the right side. There is another slice there that looks primed to follow the original slide.

[unite for individuality]

Here it is. The road did not fail... the natural land beneath it went. The sluff, with its trees intact...

It's hard to build a stable road on unstable land.

The land immediately below the embankment that failed
is just as steep as the embankment - for several hundred feet of elevation.
It's a long, steep hill down to the bottom of that valley.

The land also slopes away from the inside of that curve, too.
Water intrusion had to come through the ground under the uphill side of that curve.

[roamer_1]

It's hard to build a stable road on unstable land.

The land immediately below the embankment that failed
is just as steep as the embankment - for several hundred feet of elevation.
It's a long, steep hill down to the bottom of that valley.

The land also slopes away from the inside of that curve, too.
Water intrusion had to come through the ground under the uphill side of that curve.

Welcome to the mountains.
This is just normal.

[roamer_1]

The land also slopes away from the inside of that curve, too.
Water intrusion had to come through the ground under the uphill side of that curve.[/size]

BTW, That's right. I think the uphill side was holding water...It's a big bowl that apparently did not have a culvert installed. I think that sitting water percolated down till it hit rock, and then headed for the valley floor, sluffing the whole 9 yards.

Not necessarily true, but probable to me.

[Smokin Joe]

BTW, That's right. I think the uphill side was holding water...It's a big bowl that apparently did not have a culvert installed. I think that sitting water percolated down till it hit rock, and then headed for the valley floor, sluffing the whole 9 yards.

Not necessarily true, but probable to me.

Adding more material at the head of a slide just pushes harder on the toe. The deep fill was an addition.

(They had a hell of a time trying to stabilize US 85 past the Theodore Roosevelt National Park North Unit because the slope was unstable, for much the same reasons. Cut away the toe of the slump, and it slumps more, add more to the head, same result. It is only when the two are in balance that it is stable. Lubricate it with standing water on the uphill side, and all bets are off.)

[roamer_1]

Adding more material at the head of a slide just pushes harder on the toe. The deep fill was an addition.

And the road is all bentonite... Clay. Might as well be a pond dam without a culvert.

(They had a hell of a time trying to stabilize US 85 past the Theodore Roosevelt National Park North Unit because the slope was unstable, for much the same reasons. Cut away the toe of the slump, and it slumps more, add more to the head, same result. It is only when the two are in balance that it is stable. Lubricate it with standing water on the uphill side, and all bets are off.)

That's right. Note that I don't know it didn't have a culvert - I just see no evidence of it. In a big slide, it cn suck the culvert right out of the road never to be found again - There's a weirdo sideways liquifaction at work in landslides... It does strange things.

The reason I say this is specifically from experience. One of our culvert lays did exactly that... Wound up 300 ft down hill and more than 50 ft downstream - I was accused of never having laid it, so they were trying to pin the road failure on me. I barely found the thing - Nobody thought it would go that far subsurface.

Landslides do weird things.

[Smokin Joe]

And the road is all bentonite... Clay. Might as well be a pond dam without a culvert.

That's right. Note that I don't know it didn't have a culvert - I just see no evidence of it. In a big slide, it cn suck the culvert right out of the road never to be found again - There's a weirdo sideways liquifaction at work in landslides... It does strange things.

The reason I say this is specifically from experience. One of our culvert lays did exactly that... Wound up 300 ft down hill and more than 50 ft downstream - I was accused of never having laid it, so they were trying to pin the road failure on me. I barely found the thing - Nobody thought it would go that far subsurface.

Landslides do weird things.

Bentonite is incredibly slippery when wet. Driving on it (in the badlands) when it's wet is a real white knuckle deal, with a road surface like trying to drive on vaseline.
And it fractures when dry (it's a high shrink/swell clay).

While if kept wet it can be a good seal, dry it and fracture it and then wet the fractures, it might get permeated before it swells shut. It should not be the layer anything sits on unless it is used as a barrier layer for a pond, landfill, or other impoundment on a very flat landscape, but can be be layered on the uphill slope (with adequate drainage for that side provided for).
In general, clays formed by weathering of feldspar (like kaolinite) are more stable, and those derived from volcanic ash are the least so.

Among the worst, straight bentonite can swell as much as 15 times it's dry volume (and get slicker than cat crap doing so, because the hydration happens between the plate like clay lattices).
I didn't see any such drainage provisions either, but the view of all that may be obscured by the failure.

That drainage can be blocked by accumulated vegetable material, tree branches and the like, even rocks moving downslope, and must be carefully designed and maintained to keep the water from backing up.

It just doesn't look like that was done.

[rustynail]

https://www.youtube.com/watch?v=PFqRa-fp-us

[DB]

Has there been an official report of what caused the failure? Don't you need that before you build a replacement and put people on it?

[roamer_1]

Has there been an official report of what caused the failure? Don't you need that before you build a replacement and put people on it?

Nah. This is a temporary fix - That's all it is - Made to stand for a year or two while they go to fixing on the real thing.

The engineer guy in the vid above is being to nitpicky (a nitpicky engineer, go figger)... This is just to get it open so they can use it through the summer, and not lose all their tourist dough.

And it's a good job- You'll note they did almost exactly what I said they'd do, according to the earlier reports.

And I still don't see a culvert. Like I said, that'd be the hard part. The long part... Getting all the way down to grade to install it would take a whole lot of time... And they didn't do it.

Hopefully they do on the finished product.

[DB]

Nah. This is a temporary fix - That's all it is - Made to stand for a year or two while they go to fixing on the real thing.

The engineer guy in the vid above is being to nitpicky (a nitpicky engineer, go figger)... This is just to get it open so they can use it through the summer, and not lose all their tourist dough.

And it's a good job- You'll note they did almost exactly what I said they'd do, according to the earlier reports.

And I still don't see a culvert. Like I said, that'd be the hard part. The long part... Getting all the way down to grade to install it would take a whole lot of time... And they didn't do it.

Hopefully they do on the finished product.

Three weeks is impressive. It apparently took about 3,000 dump truck full loads of dirt to fill.

[roamer_1]

Three weeks is impressive. It apparently took about 3,000 dump truck full loads of dirt to fill.

Yeah, but the lion's share of that came off the old road... The old road is gone, or significantly reduced at least. So I'd bet that was done with belly dumps till they got up to building the roadbed. THEN it was proper dump trucks.