Huey P. Long Bridge (Jefferson Parish)

From Wikipedia, the free encyclopedia

Huey P. Long Bridge

Carries	4 lanes of US 90 2 tracks of the NOPB
Crosses	Mississippi River
Locale	Jefferson Parish, Louisiana
Maintained by	New Orleans Public Belt Railroad
ID number	022600060100001
Design	Cantilever truss bridge
Longest span	790 feet (241 m)
Total length	8,076 feet (2,462 m) (road) 22,996 feet (7,009 m) (rail)
Clearance below	153 feet (47 m)
AADT	50,500
Opening date	December 1935
Coordinates	29°56′39″N, 90°10′08″W

USS New Orleans passes under the bridge, March 2007

This article is about a bridge in Jefferson Parish, Louisiana; a second Huey P. Long Bridge is in Baton Rouge.

The Huey P. Long Bridge in Jefferson Parish, Louisiana, is a cantilevered steel through truss bridge that carries a two-track railroad line over the Mississippi River at mile 106.1 with two lanes of US 90 on each side of the central tracks.

Opened in December 1935 to replace the Walnut Street Ferry, the bridge was named for an extremely popular and notorious governor, Huey P. Long, who had just been assassinated on September 8 of that year. The bridge was the first Mississippi River span built in Louisiana and the 29th along the length of the river.

1 Structure
2 History
3 Expansion
4 See also
5 References and external links

[edit] Structure

The widest clean span is 790 feet long and sits 135 feet above the water. There are three navigation channels below the bridge, the widest being 750 feet. The distinctive rail structure is 22,996 feet long and extends as a rail viaduct well into the city. The highway structure is 8,076 feet long with extremely steep grades on both sides. Each roadway deck is a precarious 18 feet wide, with 2 9-foot lanes, but because of the railroad component, is unusually flat for a bridge of this height. Normally, bridges this high have a hump to accommodate the height but this bridge is flat to accommodate rail traffic. [1]

The bridge is a favorite railfan location, and is the longest railroad bridge in the U.S. The bridge is owned by the New Orleans Public Belt Railroad (AAR reporting marks NOPB), which is owned by the City of New Orleans and managed by the Public Belt Railroad Commission. The bridge is hated by many drivers in the New Orleans area due to the narrow 9-foot (2.7 m) wide lanes without shoulders. Also, as the East Bank approach meets the superstructure of the bridge, the two vehicular roadways "jog" or shift inwards towards the bridge centerline about 1 1/2 feet (0.45 m) since the through-truss portion of the superstructure is 3 feet wider than the deck truss portion of the east approach.

The foundation of the bridge is also unique. The land in and around New Orleans was formed by silt deposits brought down the Mississippi River. The clay topsoil (locally called "gumbo" and notorious for its role in the Hurricane Katrina levee failures) is compressible and unsuitable for foundation loads. However, bedrock is around 1,000 feet below the surface, making it too deep for normal bridge foundation construction. So, the main piers are seated on a layer of fine sand 160 to 170 feet below Mean Gulf Level and rely on their massive weight and girth to hold them in place.

The bridge dates from an era when the construction of large works presented significant engineering challenges and the needs of rail and auto travel were more matched than they are today. Large bridges mixing rail tracks and highways were common, as typified by the MacArthur Bridge and McKinley Bridge in St. Louis, Missouri and the Harahan Bridge in Memphis, Tennessee. A second Huey P. Long Bridge, which is very similar in design was built further upstream in 1940 in Baton Rouge, Louisiana and was pretty much the last of its kind. While both of the Long bridges still carry both types of traffic, most of the others have been converted either to entirely rail use (Harahan in 1949, MacArthur in 1981) or entirely auto use (McKinley from 1978-2001, with pedestrian use added when it reopens in September 2007), and new large bridges are always devoted exclusively to meeting increasing vehicular traffic needs. Current rail demands are well met by existing bridges that are a testament to the care and craftsmanship of early 20th century bridge builders.

[edit] History

The history of the Huey P. Long bridge is almost as complex as the bridge structure itself. As early as 1892 the Southern Pacific Railway proposed a high level bridge, but a depression that year prevented further work on a project that would have been an overwhelming challenge for the engineers of the time due to soil conditions and extremely high clearances needed to clear river navigation. With the development of the Public Belt Railroad System, interest in a river rail crossing grew and lead to passage of a constitutional amendment in 1916 granting the city exclusive power to build and operate a crossing. Three general ideas emerged from the planning process: a low-level drawbridge, a tunnel and a high-level bridge. The tunnel idea died first because it would have provided limited capacity and the War Department (after years of wrangling) ultimately rejected the idea of a drawbridge as too problematic for such a significant concentration of vital transportation infrastructure.

Work on the design of the bridge began in earnest in 1925 by the engineering firm of Modjeski and Masters. Some pilings were actually driven that year to prevent expiration of congressional authority and provide further information for the design. As the magnitude of the project became apparent and projected costs ballooned, financing difficulties compounded by the Great Depression delayed the project. Finally, on November 5, 1932, the bonds of the Public Belt Railroad Commission were guaranteed by a complex agreement between the Southern Pacific Railroad, the City of New Orleans and the State of Louisiana. Main construction contracts were signed on December 30, 1932 and work formally started the following day. Construction of the bridge proceeded smoothly over a three-year period with only minor interruptions due to high water and a one-month strike in September of 1933.

[edit] Expansion

The bridge is slated for expansion by the Louisiana Department of Transportation and Development beginning in 2006. The project will expand the bridge from the current configuration of two 9-foot lanes in each direction, to three 11-foot lanes, with a 2-foot left shoulder and 8-foot right shoulder in each direction. Additionally, the approaches to the bridge will be rebuilt, including the replacement of the traffic circles at Jefferson Highway and Bridge City Avenue with overpasses and standard signalized intersections. In April 2006, the Louisiana DOTD opened an office in the nearby Jefferson Business Center to serve as a public information center on the reconstruction project. [2]. The first of four construction phases is underway with a widening of the main piers, reconstruction of the approaches in 2008, and completion in 2012 with the widening of the main river trusses. The original schedule was delayed by Hurricane Katrina, but completion is still planned for 2013.