Manchac Swamp Bridge | |
|---|---|
 | |
| Coordinates | 30°18′11″N 90°24′21″W / 30.302946°N 90.405807°W |
| Carries |   I-55 / US 51 |
| Crosses | Manchac Swamp |
| Locale | St. John the Baptist Parish / Tangipahoa Parish, Louisiana, USA |
| Other name(s) | I-55 Manchac Swamp Crossing |
| Maintained by | LA DOTD |
| Characteristics | |
| Total length | 22.8 miles (36.7 km) |
| Width | 312 feet (95 m) |
| History | |
| Opened | 1979[1] |
| Location | |
 | |
The Manchac Swamp Bridge is a twin concrete trestle bridge near Manchac in the U.S. state of Louisiana.[1] It carries Interstate 55 and U.S. Route 51 over the Manchac Swamp in Louisiana and represents a third of the highway's approximately 66 miles (106 km) in Louisiana.
With a total length of 22.80 miles (36.69 km),[2][3] it is one of the longest bridges in the world over water, and is the longest bridge on the Interstate Highway System, and some claim it is the longest toll-free road bridge in the world.[4]
Opened in 1979,[1] with piles driven 250 feet (76 m) beneath the swamp, it cost $7 million per mile ($4.3 million/km), equivalent to $23.7 million per mile ($15 million/km) in 2023,[5] to construct.[6]
- ^ a b c Melaragno, Michele G. (1998). Preliminary Design of Bridges for Architects and Engineers. CRC Press. p. 377. ISBN 978-0-8247-0184-0. Retrieved June 20, 2010.
- ^ "Manchac Swamp Bridge". Atlas Obscura. Retrieved May 2, 2019.
- ^ "Manchac Swamp Bridge, one of the longest bridges in the world over water". www.dangerousroads.org. Retrieved March 7, 2022.
- ^ "Longest Bridges in North America". WorldAtlas. August 1, 2017. Retrieved March 7, 2022.
- ^ Johnston, Louis; Williamson, Samuel H. (2023). "What Was the U.S. GDP Then?". MeasuringWorth. Retrieved November 30, 2023. United States Gross Domestic Product deflator figures follow the MeasuringWorth series.
- ^ Loh, Jules (June 8, 1977). "Louisiana 'oasis' is cypress-paneled". The Tuscaloosa News. Tuscaloosa, Alabama. p. 6. Retrieved July 20, 2010.