(
Bridge Hunter; no Historic Bridges;
Satellite)
This bridge was built as part of the
Shasta Dam project because the reservoir was going to bury the old road bridge that is in the foreground under 400' of water. One advantage of building bridges necessitated by a dam project is that the incredibly high piers can be built on dry land.
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CDOT, Image 1, cropped
The double-deck bridge is the world's highest double-deck bridge for both railroad and vehicular traffic. It also displays new concepts of earthquake effect and design methods. Important elements in the bridge's design include the record-breaking 350-foot main piers, introduction of earthquake resistance factors, cooling of the concrete in the main piers, and the use of perforated plates instead of laced members. Unique construction methods included reinforcing steel requirements of almost eleven million pounds of rebar in the abutments and piers, welding techniques used on the rebar, and the use of perforated plates on the truss members. Such innovations were shared with the engineering community through professional publications, such as "Civil Engineering" and Bureau of Reclamation Technical Memorandums. |
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| Steve Hand commented on his post |
Bridge Hunter is missing a zero for the length of the longest span. It is 630'.
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safe_image for Pit River Bridge
The highest combination road and rail bridge in the world, the Pit River bridge is also the highest rail bridge ever built in the United States.
The creation of Lake Shasta resulted in a dozen new rail tunnels and 4 towering trestles. |
The Southern Pacific used to hug the Sacrament River through this region. The new route had to cross multiple watersheds and go through some mountains between those watersheds.
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| 1958 Redding Quadrangle @ 1:250,000 |
Shasta Like is beginning to fill up.
Some of Eric's photos of this bridge catch traffic on top of the bridge. And it struck me that the 18-wheelers looked like toys on this bridge because it is not only long, the truss is deep. Then I saw this photo that caught a train on the truss. This confirms that the Warren trusses with verticals are DEEP.
I wonder if there are deeper straight trusses in America. There are certainly longer and deeper trusses. But every deep truss that I can think of has curved upper cords. Here is an example of the 517.5' Pennsylvania trusses of the
Merchants Bridge over the Mississippi at St. Louis.
The navigation span of
the railroad bridge across the Ohio River at Metropolis, IL, is 720' and the other four spans are 551'. But the trusses are not straight enough, and probably not strong enough, to support a bunch of truck traffic on top. (The reason the navigation span was so long in 1917 is that the steamboat interests convinced the federal government in a meeting in St. Louis to require that the span be over 700'. They thought that was ridiculously long enough that the railroads would not be able to build it.)
I found another photo with a train on the bridge so that we can again see how deep the truss is. Behind the text in this photo is another view of the road bridge that got submerged by the reservoir.
It is interesting that the shorter spans use the same deep truss design that was used for the 630' span. I would think they could have saved a lot of steel by making the two halves of the piers different heights and using more shallow trusses for the shorter spans.
When I accessed the satellite image for this bridge at 5:00am on Apr 24, 2020, I saw the "Temporarily closed" text shown at the right. In the sidebar, after I clicked the "Temporarily closed," I saw the following. But when I Googled "I-5 pit river closure today", all of the results were old news.
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City of Shasta Lake posted
And there's the old bridge in the background while building the new one......Apparently these fellows weren't afraid of heights Getting ready to erect Shasta Dam...... Photo Courtesy of the Shasta Lake Heritage & Historical Society Paul Jevert shared
New Shasta bridge (1945) |
The weight of interstate traffic plus railroad traffic has taken a toll on the 70-year old trusses. There is talk of moving the traffic to a new bridge. One advantage of the dual use is that they plan to retain the truss bridge as a railroad bridge. The Bureau of Reclamation wants to raise the
Shasta Dam 18.5'. But a lot of people are against it for a lot of reasons. HighestBridges indicates that if they raised it more than 20', they would have to raise this bridge.
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