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 , 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...
( 3D Satellite ) I can't believe I drove right past this bridge when I went to the Hollywood Casino to get photos of Sam M. Fleming 's tow. Sydney Lane posted three photos with the comment: South of Joliet, Illinois just off Rt6 at the Johns Manville plant is this turn bridge that crosses the historic and now abandoned I & M canal. Though functional in the era of mule towed barges, it sets welded in place. It is still used today as an industrial spur line. It was Elgin Joliet and Eastern in my memory but I think it may be Canadian Northern now. The historic Illinois and Michigan canal linking Lake Michigan to the Mississippi River closed around 1930 when the current I&M opened to much larger barge traffic. Dennis DeBruler The industrial lead goes north to what was the Rock Island. This part of the Rock Island route is now controlled by CSX. 1 2 3 Sydney must have caught after some heavy rains. This satellite image is probably or more normal flow in the canal. 3D sat...
Because any remaining old style signals are going to soon be replaced to implement Positive Train Control, some railfans are taking pictures of the signals instead of trains. B&O and Pennsy were the two railroads that had their own unique design of signal heads. I have already covered Pennsy's yellow light positional design . This is looking south along the former B&O branch line (Cincinnati, Hamilton & Dayton) in Deshler, OH . The tracks just on the other side of the depot is the former B&O mainline to Chicago. Both of these routes are now CSX. 20151101 5338,cropped I cropped the above picture to make it a little easier to see that the horizontal red lights really are lit up. Also, you can see in the lower left corner that the signal head for southbound traffic on the southeast quadrant has a stop aspect. I stepped to the side for the closeup because I was trying to reduce the effect of the sun that was still rather high in the sky. What I inadvertently did was dem...
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