Update on the treehouse bridge in the redwoods of the Santa Cruz mountains

[Danny D.]

Just to give you an update, the bridge was repaired after the last section fell down in the earlier Pineapple Express:

Those earlier storms took down a few nearby Monterey Pines, which decapitated the Internet access to the bridge & the temporary power:

We had to restring the Internet access in addition to the electrical lines running for hundreds of feet along the forest floor:

We also had to detach the bridge from the support at the smaller redwood trees (which are, themselves, at least 100 feet tall), but we added a swinging cable, to take some of the load off the cables:

Now the bridge is almost at the large redwood tree, almost 100 feet from the starting point, and now 16 feet wide, instead of the original

10 feet wide for most of the length of the cable bridge:

Here is an underside view of the bridge (I can't fit the whole thing into a single picture because it's too long from the ground looking up):

Here's a side view (again, the hillside being what it is, I can't get the whole thing into a single picture):

Each section is 16 feet long, by 10 feet wide, and hung on the 3/8" steel cable for support, and I'd say we're about 30 to 40 feet up:

We still use the cargo net, slung between the trees, in order to go back and forth to the big anchoring tree at the far end:

We only have about 8 feet to go, and we'll be at the big tree, and ready to start building the two-story treehouse, which, in the end, will include running water, electricity, Internet, etc.

[jloomis]

Lots of work. I live in the redwoods in Fort Bragg. I have had thoughts of one special tree, and getting to the height where I can see the ocean.... It is still a dream though. John

Just to give you an update, the bridge was repaired after the last section fell down in the earlier Pineapple Express:

Those earlier storms took down a few nearby Monterey Pines, which decapitated the Internet access to the bridge & the temporary power:

We had to restring the Internet access in addition to the electrical lines running for hundreds of feet along the forest floor:

We also had to detach the bridge from the support at the smaller redwood trees (which are, themselves, at least 100 feet tall), but we added a swinging cable, to take some of the load off the cables:

Now the bridge is almost at the large redwood tree, almost 100 feet from the starting point, and now 16 feet wide, instead of the original

10 feet wide for most of the length of the cable bridge:

Here is an underside view of the bridge (I can't fit the whole thing into a single picture because it's too long from the ground looking up):

Here's a side view (again, the hillside being what it is, I can't get the whole thing into a single picture):

Each section is 16 feet long, by 10 feet wide, and hung on the 3/8" steel cable for support, and I'd say we're about 30 to 40 feet up:

We still use the cargo net, slung between the trees, in order to go back and forth to the big anchoring tree at the far end:

We only have about 8 feet to go, and we'll be at the big tree, and ready to start building the two-story treehouse, which, in the end, will include running water, electricity, Internet, etc.

[Vic Smith]

Is all of this subject to local building codes? Seems to me somebody is going to end up dead from a long fall.

[Danny D.]

Vic Smith wrote, on Sun, 08 Feb 2015 08:49:38 -0600:

It's my understanding that the local building codes do not pertain to tree houses.

[Pico Rico]

does your insurance cover it. Like when your buddy takes a header?

[Roy]

Danny, I don't wish you any bad luck and you certainly are determined to co mplete your project BUT it will be for naught. Mother nature will get you a gain. You really need some consulting engineers to finish the "project" bef ore it goes down again. If your trees never moved it would be a different s tory but the variables are against you.

[John Larkin]

Don't all those trees sway (asynchronously!) in the wind?

You could occasionally get the equivalent of a rogue wave, a big spike of acceleration.

[Danny D.]

Pico Rico wrote, on Sun, 08 Feb 2015 08:01:33 -0800:

You'll notice our "insurance" consists of lots of safety lines.

[Danny D.]

Oren wrote, on Sun, 08 Feb 2015 08:21:15 -0800:

That's a good idea, to get 'em off the payroll, before they hit the ground.

Most of the neighbors have been pitching in, so, that's a large payroll to downsize quickly.

Here's a view of the way down from the end closest to the big redwood:

[Danny D.]

Roy wrote, on Sun, 08 Feb 2015 09:22:32 -0800:

What? You're not our consulting engineers? I have proof that we consulted you, and everyone here! :)

To your point, the trees did move in the last Pineapple Express which caused the last slung section to crumple to the ground:

It also caused the wood to split in a couple of places:

We determined it was, as you said, because the small trees moved, so, we detached the bridge from the small redwoods in the middle:

Now the bridge is no longer attached in the center, to the small redwoods to either side of the 10-foot-wide section:

One other problem is that the bridge "bent" in the middle; but we'll plan to resolve that when we do the final leveling:

We only have about 8 feet to go, and then we can walk from ground level, to something like 30 or 40 feet up, over about

75 feet of length, and be flat and level the entire distance:

[Danny D.]

John Larkin wrote, on Sun, 08 Feb 2015 09:39:53 -0800:

I'm not sure how they sway in the wind, but, we decoupled the 75-foot long bridge from the middle trees after that last storm, and we're hoping to see the bridge still there after the one that is raging as we type.

One thing we noticed is that, in the wind, the bridge actually *rises* a few inches, like what happens with an airplane wing or a sailboat sail.

Since the bottom is dirtier, with respect to laminar flow, we suspect the air flows faster over the top than over the bottom:

The whole bridge is roughly the size of an airplane wing:

[Danny D.]

Bob F wrote, on Sun, 08 Feb 2015 13:02:33 -0800:

The Tacoma Narrows bridge is nothing like this, in length, anyway. But, your point is well taken.

[Joe Gwinn]

It's called flutter in aerodynamics. This is what happens when the frequency of the aeolian tone matches the deck-twist resonant frequency.

When it happens to an airplane wing, the airplane is usually lost. Look at some of the film clips.

One can greatly reduce the effect by spacing the boards apart by say an inch, which will equalize the pressure. The world is full of rope bridges over chasms, erected by people who never heard of aerodynamics.

The whole idea of rigid decks spanning flexible trees seems destined to fail.

Joe Gwinn

[jloomis]

I am still wondering about the overall width of such a bridge. I would think, that a smaller width would be stronger, and lighter, and still manage to carry one over with parts and pieces to the actual tree house. just a few thoughts.... john

Just to give you an update, the bridge was repaired after the last section fell down in the earlier Pineapple Express:

Those earlier storms took down a few nearby Monterey Pines, which decapitated the Internet access to the bridge & the temporary power:

We had to restring the Internet access in addition to the electrical lines running for hundreds of feet along the forest floor:

We also had to detach the bridge from the support at the smaller redwood trees (which are, themselves, at least 100 feet tall), but we added a swinging cable, to take some of the load off the cables:

Now the bridge is almost at the large redwood tree, almost 100 feet from the starting point, and now 16 feet wide, instead of the original

10 feet wide for most of the length of the cable bridge:

Here is an underside view of the bridge (I can't fit the whole thing into a single picture because it's too long from the ground looking up):

Here's a side view (again, the hillside being what it is, I can't get the whole thing into a single picture):

Each section is 16 feet long, by 10 feet wide, and hung on the 3/8" steel cable for support, and I'd say we're about 30 to 40 feet up:

We still use the cargo net, slung between the trees, in order to go back and forth to the big anchoring tree at the far end:

We only have about 8 feet to go, and we'll be at the big tree, and ready to start building the two-story treehouse, which, in the end, will include running water, electricity, Internet, etc.

[Danny D.]

Joe Gwinn wrote, on Sun, 08 Feb 2015 18:32:00 -0500:

We're currently using a Philips screwdriver blade as the spacer between boards.

Maybe we should use something thicker. This is a great idea, which I will share with the bridge owner.

Thanks!

[Martin Eastburn]

Sorry to see the work being done over - and such. We used to live on Hwy 9 off Glengary. Had about 100 of the sprouts that came up after the clear cut making lumber for SFO. Mine were between 100 and 130 feet When we left in 2006. Kinda miss the place. Now I have large oaks and tall pines.

Martin

[DecadentLinuxUserNumeroUno]

You mean a philips screwdriver shank?

Get a number three. Some of them are square shank, even more "precise". And they are certainly bigger.

[Danny D.]

DecadentLinuxUserNumeroUno wrote, on Mon, 09 Feb 2015 13:02:42 +0000:

Yes. Sorry. Shank.

Actually, truth be admitted, the first two sections were perfectly aligned, but, the next two "curved" a bit, due to the difficulties of getting every board lined up straight while being hung from the cables, so, at times, it's a screwdriver shank on the right side, but an inch (or so) on the left.

Looking up from below, you can see that these third and fourth 16-foot sections have a larger board-to-board spacing on the right than on the left:

[DecadentLinuxUserNumeroUno]

"We want to splay... just a little bit longer..." --Jackson Browne

snip

Arc of the Boardament. Just think of railroad tracks.

[Roy]

Believe me, Danny will be doing it over many, many times 'cause unless he i s a spider that walkway will not endure. Perhaps if he made a playhouse sus pended over the side of the mountain, it might work out for him. He could use a ladder or stairway down to the playhouse. Maybe even a cave in the si de of the mountain like the Indians of Arizona created. ==========