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| 20150730 3368, upstream side from Illinois river bank |
According to Bridge Hunter, the tied-arch spans are 730 (south) and 630 (north) feet. The eight spans between the arches are considered "approach spans." I can't tell from the pictures if they have concrete or steel girders. Either way, they are big! Each span must be about 400 feet and the depth of the span is comparable to the height of a semi-truck trailer.
Bridge Hunter indicates the bridge was built in 1973. In the tradition of incompetent Midwest concrete contractors, according to a comment found while researching the Blue Hummer bridge posting, the bridge was closed for a year around 1980 to repair cracks in the concrete, and then it had another major overhaul in the early 1990's. Even with all of this repair work, the Super- and Sub-structure rating went from Good to Fair between 2008 and 2010 and the Sufficiency Rating went from 82.8 to 71.8. (UglyBridges)
During the 2011 Flood: overview, closeup.
Update:
While studying the cracks in two other tied-arch bridges: the I-64 bridge over the Ohio and the I-40 bridge over the Mississippi, I came across some information about the cracks in this bridge.
The plan noted some similarities between the I-40 bridge and the Interstate 24 bridge over the Ohio River between Kentucky and Illinois. In 1979, the latter bridge was closed because of cracks found in the main members and tie girders of the tied arch span, according to the document.According to published reports, structural problems on the Ohio River Bridge included 119 cracks as a result of defective welding, and the bridge was closed from August 1979 through October 1980. It was closed to truck traffic until the summer of 1981."An electro slag welding process was used during construction of this bridge," the plan said. "The I-40 Mississippi River bridge was constructed with the same process."The Federal Highway Administration banned that welding process in 1977 for many applications under its jurisdiction, including bridge fabrication. The ban was lifted in 2000 after research from universities and industry produced a replacement called "Narrow Gap Improved Electro Slag Welding."
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| B&T, one of 13 photos |
But the new Paducah Bridge was not without its issues caused by defective welding. Before it even opened to motorists, cracks were identified in hanger bars that connected steel cables to the top of the arch. They were replaced with hanger bars that were bolted in place. In 1977, cracks were discovered in force bars under the bridge deck. They were repaired by bolting reinforcements atop the cracks. In 1979, 119 cracks were discovered during a routine inspection in welds in the tie girders, or the main supports of the arches over the river channel which required the interstate crossing to be closed to traffic for two years. And in 1984, additional cracks were discovered during a routine inspection in at least ten floor beams near porthole openings. The cracks were repaired by bolting plates around the openings to remove stress from the area and work was completed within a week. In short, cost-cutting measures that allowed the superstructure contractor to win the $11.5 million low bid construction contract came back to haunt the state over the ensuing decades as it had to shell out over $5 million in repairs. In all of the repairs, the defective welds were fixed with hardier (and more expensive) plates and bolts. [Blog]
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| 20171230 9399rc, Approaching the south arch from the south. |
Approaching and under the north arch.
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| First of three photos in C Hanchey's Illinois Flickr Album, cropped, License: Creative Commons Attribution (CC BY-NC) |
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| Screenshot I would have been sweating that one. Boat southbound above I24. Al Slidell: Hard to swing with that hip barge along side. David Gulden shared Calvin Galbraith: somebody was day dreaming, easy bridge to make |
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