Before they built the dam a couple of miles downstream from here, this stretch of the river must have been a rapids. That means the river scoured the bottom down to bedrock. So they are buildings piers keyed into the bedrock that can withstand the lateral forces of a true arch. Since it is a true arch rather than a tied arch, they don't have the option of building the arch near a shore and floating it into place like they did, for example, the Eggner Ferry Bridge. To keep the navigation channel open, they are using back stays to build the arches with 35' to 65' steel segments.
Beginning this fall or early winter [2018], crews will begin lifting the 35- to 65-foot steel segments into place. Currently, the steel segments are being fabricated at a plant in Gary, Ind., after which they will be trucked to the Quad-Cities, said Danielle Alvarez, the I-74 project manager with the Iowa Department of Transportation....Cable stays will be used to hold the segments into place, while the rest of the segments are raised and fitted together. There will actually be two arches in each direction on the new bridge, angling inward to form a pair of basket handles....Alvarez said the tied-arch design at Talbot Memorial Bridge (Centennial) between Davenport and Rock Island is more of typical of Mississippi River crossings, but the relatively shallow water depth and rock elevations under I-74 allowed for the new bridge to be a true-arch design. The cost of the steel fabrication, as well as putting the segments into place, is $17 million for both spans, according to the Iowa DOT. [ArchIsNextStep]
I have not been able to find construction photos of the arch construction.
The "Y" part of the piers looked like they could be precast "trophies" similar to the ones used for the new Pensacola Bay Bridge. But these photos shows they built the piers in place.
( Bridge Hunter , 3D Satellite ) I don't normally do yet another steel tied-arch bridge, but when you get a view as unique as this, I went for it. This is "reverse railfan." Specifically, it is a photo from a train instead of a train. And at the bottom is some photos of the cantilever truss that it replaced. William A. Shaffer posted The Jefferson Barracks Bridge at St. Louis, MO (Shot through the window of Amtrak #22 en route to St. Louis) (Photo by William A. Shaffer) By Service Depicted: Other ServiceCamera Operator: SSGT PAUL GRIFFIN - ID:DFST9500065 , Public Domain, Link Roads and farmland in St. Louis area are hard hit by floodwaters. Location: SAINT LOUIS, ILLINOIS (IL) UNITED STATES OF AMERICA (USA) 1993 Westbound bridge built 1984; eastbound bridge built 1990, The navigation channel span is 910'. Missouri State Archives from Flickr The eastbound span of the Jefferson Barracks (I-255) bridge was opened in December 1990, not 1986. It was opened right around the...
( Bridge Hunter , Historic Bridges , HAER , Satellite ) P&LE = Pittsburgh & Lake Erie Railroad Photo from HAER PA,4-BEAV,1--1 from pa3716 One of 26 images posted by Mike Brady [Many of the images show the stresses calculated for each member of the truss.] Pictures are of the original Stress sheet of the P&LE cantilever bridge at Monaca - Beaver PA . Appears to be drawn on vellum type paper using a ink well pen. All of the math about the bridge is here. Live load,dead load, impact load and wind load Date is Jan. 31, 1908. Bought this on eBay around 20 years ago. Was unaware at the time of purchase of what I was getting. Wow, when I actually received it. Total calculated design load on one of the main bearings is 11,994.000 or 12 million pounds or ( 6 thousand tons). One of 26 images posted by Mike Brady Photo taken by Bob Harris in May 2012 from Bridge Hunter ( new window ) Mark Arnold posted five photos with the comment: " CSX's Ohio River cross...
I've noticed that NYC and Los Angeles have to pay a lot for water supply whereas Chicago has to pay a lot for water removal. I knew NYC dammed rivers in the mountains that are north of the city and then used tunnels (aqueducts) to transport the water into the city. What I did not know, until I studied the Cannonsville Dam , is that they also get water from the Delaware River watershed, which is a lot further away. Since I found this overview map, I'm writing this post to record it. Project Description , page 6 from nyc.gov A NY Times article about a leak in the Cannonsville Dam focuses on the people aspect of the dam. If you look at the map, Deposit, NY is downstream of the Cannonsville Dam. The residents are still bitter that 1000 people, including entire towns, were displaced over a half-century ago when the dam was built. Now they are bitter that they have to worry about the risk of living downstream of a dam. Since a big river flows right through them, they question why N...
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