Back on the California Zephyr traveling east from Denver. I took this photo while crossing the Mississippi River between Burlington, Iowa and Gulf Port, Illinois.
Although my photo (through a train window) isn't great, it does show an impressive looking bridge. I took it from the BNSF Railroad Bridge, a series of through trusses (with a swing span for the shipping channel) about a mile south of the Great River Bridge carrying I-34.
The I-34 bridge was built in the 1990s to replace a two lane steel structure that had been built in 1917 and was in terrible shape. Construction on the new bridge continued despite a series of floods (that destroyed the construction offices) and the bridge opened in 1993. Its a single tower cable-stayed bridge with a main span of 660 ft and a total length of 1245 ft. The cables are arranged in a fan and the two-legged, H-shaped tower stands about 300 ft above the Mississippi River. The bridge carries five traffic lanes and provides 60 ft of vertical clearance for ships traveling on the river.
The bridge is owned and maintained by the Iowa DOT. I wonder if it was designed by the Iowa DOT as well? I was hoping to find an entry in Structurae that would give some references to books and articles about the bridge but I wasn't successful. I did find some good information at John Weeks website
. I believe he's gathered information on all the bridges across the Mississippi River.
The tower foundations go through 90 feet of weak material before reaching bedrock. Although I couldn't find a reference to the construction material, it looks like a reinforced concrete tower (and a steel girder superstructure). The bridge has unequal spans, the tower is placed in the middle of the river, there are more cables on the west side and there are additional lifter cables to adjust for seasonal temperature changes; which must have made for a very challenging design project.