Big Pic Warning - Hoover Dam Bypass Bridge

Vaughn McMillan

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Rob, here are the pics I mentioned in the Tour de Wood thread. This is from an e-mail that's been forwarded around multiple times around engineering offices, so I don't know who to credit for the pics or the text. I got it from my dad the civil engineer.

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Creeping closer inch by inch, 900 feet above the mighty Colorado River, the two sides of a $160 million bridge at the Hoover Dam slowly take shape. The bridge will carry a new section of US Route 93 past the bottleneck of the old road which can be seen twisting and winding around and across the dam itself.

When complete, it will provide a new link between the states of Nevada and Arizona. In an incredible feat of engineering, the road will be supported on the two massive concrete arches which jut out of the rock face.

The arches are made up of 53 individual sections each 24 feet long which have been cast on-site and are being lifted into place using an improvised high-wire crane strung between temporary steel pylons.

The arches will eventually measure more than 1,000 feet across. At the moment, the structure looks like a traditional suspension bridge. But once the arches are complete, the suspending cables on each side will be removed. Extra vertical columns will then be installed on the arches to carry the road. The bridge has become known as the Hoover Dam bypass, although it is officially called the Mike O'Callaghan-Pat Tillman Memorial Bridge, after a former governor of Nevada and an American Football player from Arizona who joined the US Army and was killed in Afghanistan. Work on the bridge started in 2005 and should finish next year. An estimated 17,000 cars and trucks will cross it every day.

The dam was started in 1931 and used enough concrete to build a road from New York to San Francisco. The stretch of water it created, Lake Mead , is 110 miles long and took six years to fill. The original road was opened at the same time as the famous dam in 1936.

An extra note: The top of the white band of rock in Lake Mead is the old waterline prior to the drought and development in the Las Vegas area. It is over 100 feet above the current water level.

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I'll bet it is mighty impressive in person, Don. I found a few more pics...these were taken at the end of January 2010 after the suspension cables had been removed. I believe these were taken by Frank Kozeliski, a consulting engineer in Gallup, NM.

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I can relate to what Steve said. With my fear of heights, I wouldn't be able to work on a project like this one, although I think I'd be willing to drive on it. I'm fascinated by the process and logistics of building something like this, though.
 
I wonder how strong the wind are coming down the river valley, walking across the bridge might be a terror
 
Vaughn thats fantastic. I have been to Hoover but of course it was before this bridge started. Its a real site for sore eyes. Great feet of civil engineering. I aint no civil engineer but i would love to work on a project like this and drive over it i definitely will some day.

It sure is gonna help the security of the Hoover Dam. I have always been worried about that one being on the "targets" list by the bad boys. Vegas needs that dam or it will die of thirst.

When i was there once i stopped on the Arizona side and looked down there used to be a small gift.caffeteria on the side of the road just up from the dam. Walked to the edge and we could hundreds of catfish hanging about the surface of the water waiting for something to fall in the water. Seems they been attracted to things people through over the edge.

The water was very very low that year.

Thanks for the pictures Vaughn very interesting project. :thumb:

Thinking allowed they must have used some technology to get the concrete to set at the temps that exist around that area.

Back in the day i know of a dam in Norther Natal (SA) where they actually built an ice making factory in order to build the dam. They floated huge blocks like icebergs in the coffer dams in order to get ambiet temps down sufficient to set the concrete with the heat and humidity that one gets in this specific area.

I wonder how things have changed and how they dealt with that issue on this bridge with casting those blocks in locale.
 
the bridge is almost as amazing as the surroundings its in.
I hope I get to make my trip out there soon, Im very dissapointed I never was able to travel there last sept/oct as planned.
 
...Thinking allowed they must have used some technology to get the concrete to set at the temps that exist around that area...

I know in the case of the dam itself, they cast pipes into the concrete, then ran river water through them to cool the concrete as it cured. Heat is generated when concrete cures, and excessive heat will cause problems, so for any big monolithic pour it can become an issue. The heat from the concrete itself can be more of a problem than the outside air temps. Here's more info on the dam concrete.

For the bridge, the panels that were cast on site and the rest of the structural concrete aren't really all that thick, so I suspect they were able to control the temps using fairly standard "Las Vegas building" practices...things like adding ice to the mix water and using other additives like fly ash that can help keep the temps down.
 
I've always said that if someone ever says I fell to my death that I was murdered. I'll never be high enough to fall and kill myself!:) Those pics are amazing! I do get sweaty palms just looking at them though.:eek:
 
Thanks Vaughn for the info. Explains a lot to me. Quiet amazing these projects. Sorta demonstrates the positive side of us humans being able to achieve such projects when we put our minds to it. Amazing that we still aint solved many of the other issues that plague our world. But as a physics prof once said, things would be different if engineers ran the whole show. Things would get done and properly.:D;):thumb:
 
John Daugherty;212464...Those pics are amazing! I do get sweaty palms just looking at them though.:eek:[/QUOTE said:
Ditto! amazing pics and amazing that people are crazy enough to build that too!
 
Hi Vaughn, Great pictures!! Some time back I was watching the National Geographic Channel. They were having a one hour program about the Dam and they said that some of the concrete is still not cured in the Dam. It would be interesting to know how they know or verify that statement. Thanks Vaughn, Joe
 
Those are impressive. The build process amazes me too. We have a new suspension bridge going up here in KC. It has a center support for the cables and they put in one half of the deck with supports underneath.

I was wondering how they were going to install the other half of the deck without stopping river traffic. Turns out they are installing section by section from the center out with the matching pair of cables on other side of the center support to counter balance the weight of the section as they add them.

Pretty neat to watch.
 
Nope me either. You couldn't pay me to drive over it.

I've always said that if someone ever says I fell to my death that I was murdered. I'll never be high enough to fall and kill myself!:) Those pics are amazing! I do get sweaty palms just looking at them though.:eek:

The bridge walls are always high enough to take the "fun" out of it... I remember walking on the Golden Gate bridge waayyyy back in '89 and thinking that.

I cross the Blue Water bridge (Link to picture I found) that connects Sarnia to Port Huron,MI all the time. It's also wayyyy up there, but you can't really look straight down when you're driving, so it just seems like a long hill.
 
If they ever make another James Bond movie, it would be a good back drop.

Now for the heights thing. I can go up on most anything I build. Back when I bow hunted, I would generally be at the 25 foot mark. House roofs, no problem either. St. Louis Arch and flying are not a problem either. Something about that bridge says no way.
 
....they said that some of the concrete is still not cured in the Dam. It would be interesting to know how they know or verify that statement...

My guess is that they can take temperature readings deep inside the concrete. If the temps are higher than the surrounding concrete/air/water, then the cement in the mix is still hydrating (curing). Also, the parts that are exposed to water will be gaining additional strength for a long, long time. Concrete gains strength the longer it is kept moist.
 
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