Grand Canyon Skywalk

[JAE]

This project has been discussed previously somewhere in Eng-Tips, but this artlicle seems to describe some of the design features a bit more than before.

[blue]Grand Canyon Structure Soars 3,800 ft over the Colorado River[/blue]

Two questions -

They say in the article that this is a "spiritual place" - so why build an amusement-type tourist attraction there?

What is the long term structural behavior of glass laminates when exposed to constant thermal variations, sunlight, and small stress fluctuations.

 

[mapelCE]

JAE,

To your first question I can only say how sad. "Make the canyon more dramatic" and "make the experience like nothing else in the world". Wow! In a purely philosophical sense only a human could be that arrogant. If you haven't been to the canyon, go. It is one of the few places in the world I've visited that has actually struck me with a total sense of awe. I don't see how walking out on a catwalk could possible improve on the experience. What's next, a glass elevator up the face of half dome? The reason behind the project can be nothing other than financial. As you can see in the article, the village and even the center itself is being constructed with ammenities to attract tourists and then get them to spend money. From a financial standpoint its probably not an unreasonable idea given the number of people that go there every year. Improve on the Grand Canyon experience, I doubt it. Create additional revenues for the tribe that owns that land, absolutely. Notice how they didn't have to do an environmental impact study. Indian nations are not tied to most federal or state law. This project most likely wouldn't get built on Federal Land. Too many objections.

As far as long term performance of glass laminates, I don't have too much experience with that, but the Sundial Bridge up in Redding,California incorporates laminates in it's deck. They go through annual freeze/thaw cylces. Perhaps there is someone out there who can comment on the performance of that structure.

 

[MikeHalloran]

1. It's not like they're building a Ferris wheel cantilevered over the canyon. That's probably in Phase B.

2. Depends on the 'not yet designed' connection between the glass laminate and the box beams. I'm not convinced that the stress fluctuations will be small, either, given the certain presence of heavily laden stiletto heels and wheelchairs.

;--

I wonder what they'll do about:

- Abrasive scour of the upper glass surface from foot traffic carrying desert dust.

- Lawsuits from slip and fall injuries associated with a glass walking surface and spilled beer. Not to mention heart attacks, and the inevitable ultimate total failure of the laminate from deferred maintenance. [ Hey, there's five layers of glass; so what if one cracks? Hey, there's still three good layers of glass, etc... ]

;--

Ignoring the skywalk proper for the moment, the associated building/ counterpoise looks like a hydro plant; obtrustive, harmonious with neither skywalk nor desert nor canyon, and just plain butt- ugly. No doubt the Phase C casino will be equally charming.

;--

I really think the whole thing started as a ruse, intended to bluff the National Park Service into paying them _not_ to build it. Hey, I buy the Gov't. a new Lexus every year; a coupla snow tires wouldn't hurt as much as having the Europeans laugh at me more than they do now.

;--

Does the duty of an engineer to the general public extend to declining to participate in execution of a colossally bad idea?



Mike Halloran
Pembroke Pines, FL, USA

 

[archeng59]

gotta agree with mapelCE about the canyon. that's probably the most awesome place I've ever visited. The area around Grand Canyon Village is as commercialized as the whole place needs to get as far as I'm concerned. when someone starts doing stuff like that structure, it opens the door to a bunch of other stuff that ruins the beauty. Glen Canyon dam already messed it up some because of the water flow restrictions. Hopefully the Hualapai Nation will limit the commercial development of the area.

 

[JStephen]

"For an extra thrill, a trolley will be strung under the bridge for cleaning and possibly tours. It will be able to drop about 100 ft below the skywalk."

Sounds like the Ferris Wheel is not that far behind. But I predict bungee jumping would be the activity of choice there.

 

[astructurale]

I've never been to the grand canyon, but my spouse has and he liked the idea. Personally I am scared to death of heights, and idea of a structure like that cantileverd out gives me the willies!! I doubt I'd venture out onto it without much coaxing.

Another part that concerns me....

"There is no direction in the code for wind loading so we designed it to withstand winds of about 100 mph in all directions, particularly up, down and sideways, and we tamed the vibration with four tuned-mass dampers located inside the box beams at the center of the radius,"

I would think that a structure in a location like this would warrant a wind study. I would think the shape of the canyon would affect the wind, and that wind gusts would also be of particular concern.

Also, I think they should have already worked out those laminated glass connections by now. If I were them I would not have volunterred that information.

Thanks for posting this. I had not heard of it yet, and I look forward to learning about the projects progress.

 

[frogit22]

thanks for posting that. I hadn't seen that more technical article.

Is there going to be some kind of brace, or is this thing going to truly cantilever 60 feet?

 

[MikeHalloran]

No brace. Double cantilevered curved box beams with vibration dampers inside. The dynamics should be interesting.





Mike Halloran
Pembroke Pines, FL, USA