CN/IC & US-51 & I-55 bridges over Pass Manchac at Akers, LA

(Bridge Hunter broke on Mar 22, 2023; no Historic Bridges; Satellite)

It is hard to tell from the street views, but I'm guessing the US-51 bridge uses steel girders and the I-55 bridge uses concrete girders.

Google Map puts the label "The Manchac Swamp Bridge" halfway between the two road bridges.

Street View, Feb 2021

Street View, Feb 2021

 

Street View, Jan 2019

Street View, Apr 2023

Some comments on a post asking about the remote operations of the Lake Pontchartrain Bridge.

The photo in the above comment.

reduper
[I-55 is a twin trestle over the swamps, but a single bridge over the open water.]

The interstate bridge was finished in 1979, and it is the "third longest water bridge in the world" at 22.8 miles (36.69km). [atlasobscura]

It is the longest bridge on the Interstate Highway System. Some claim it is the longest toll-fee road bridge in the world. "Its piles were driven 250 feet (76 m) beneath the swamp and with the cost of the span being $7 million per mile ($4.3 million/km) (equivalent to $20.5 million per mile ($13 million/km) in 2020) to complete." [DBpedia]

On sep 14, 1976, a barge allided with the US-51 bridge and a huge section "collapsed amid a shower of concrete and vehicles... That destruction caused three vehicles to fall into the water, and only two survivors were found." [HearldGuide, paycount 2? This article is about how to escape from your car, not about the allision. You may not want to spend a "paycount" on it.]

3:15 drone video