Lake Pontchartrain Causeway
Coordinates: 30 ° 9 '53 " N , 90 ° 7' 44" W.
| Lake Pontchartrain Causeway | ||
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| use | Road bridge | |
| Crossing of | Lake Pontchartrain | |
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Mandeville (Louisiana) Metairie near New Orleans |
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| construction | Yoke bridges with slab superstructure in prestressed concrete | |
| overall length | Causeway I: 38.39 km. Causeway II: 38.42 km |
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| start of building | Causeway I: 1955 Causeway II: 1967 |
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| completion | Causeway I: 1956 Causeway II: 1969 |
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The Lake Pontchartrain Causeway ( Lake Pontchartrain Bridge , actually named after the dam ) is a bridge that consists of two parallel road bridges that cross Pontchartrain Lake , north of New Orleans , Louisiana , and Metairie , a suburb of New Orleans Joining Orleans in Jefferson Parish , with Mandeville on the north shore of the lake in St. Tammany Parish .
The Lake Pontchartrain Causeway was the longest bridge in the world when it opened.
description
The first, western bridge was built between 1955 and 1956 and is 38.388 km long.
The second, eastern bridge was built between 1967 and 1969 and is 38.422 km long.
The slightly different lengths are due to the different ramps built into the lake. The bridges are so long that the shores of the lake are only visible for just under 13 km (8 miles).
The two two -lane bridges are 24 m apart. They are guided separately in one-way traffic. On the older bridge, traffic is heading south, on the newer one heading north. There is a connection ( crossover ) at seven points , on which you can switch from one bridge to the other in an emergency.
Both bridges are 10 m (33 ft ) wide. Your road surface is only 4.5 to 4.9 m (15 to 16 ft) above the water. Just under 8 miles (12.7 km) from the banks, the lanes for a 44 m (145 ft) wide ship passage rise to a clear height of 15 m (50 ft), with the northern passage for taller ships through a steel passage Bascule bridge can be opened.
Both bridges are Jochbrücken with plate superstructure , consisting of pre-stressed concrete - prefabricated parts were built.
Original bridge (1956)
The first Lake Pontchartrain Causeway was designed by Palmer & Baker Inc. in 1954. Jean Muller , who at the time was head of Eugène Freyssinet's New York office, was also involved in the planning .
The Causeway was not only the first major prestressed concrete bridge in the USA after the Walnut Lane Memorial Bridge in Philadelphia , Pennsylvania, completed in 1951 . He also planned and implemented the mass production of prefabricated bridge parts on land and their assembly in a very large bridge project for the first time. In addition, for the first time on land, round, hollow prestressed concrete piles with a diameter of 1.37 m (54 inches ) were used.
All concrete parts were produced in a temporary precast concrete plant near the north end of the bridge in Mandeville.
Construction began on May 23, 1955 with the installation of the first piles.
The Jochbrücke consists of 2232 bridge fields, each 17 m long (and the ship passageways that were converted when the second bridge was built). Two of the round piles each support a crossbeam on which the 16.46 m (54 ft) long and 10 m (33 ft) wide prestressed concrete deck slabs are supported.
The piles were constructed in uniform lengths of 4.88 m (16 ft) and were stacked until they reached the intended depth at 27 m (88 ft).
The industrial series production made it possible to manufacture bridges up to 100 m in length per day.
The bridge was completed four months ahead of the agreed date and inaugurated on August 30, 1956.
The Lake Pontchartrain Causeway was included in the List of Historic Civil Engineering Landmarks by the American Society of Civil Engineers in 2013 , less as an example of prestressed concrete technology, but because of the first use of industrial mass production.
Second Bridge (1969)
The traffic on the bridge had risen to 3000 vehicles per day within a few years, so that a second bridge was necessary. Construction began in September 1967. Due to technical progress, this time deck slabs with a length of 25.60 m (84 ft) were used, which were supported on yokes with three piles each, which also had thicker walls. With improved production and construction methods, bridges up to 487 m in length were built per day. The new bridge was opened on May 10, 1969 after a construction period of 25 months.
traffic
From 1956 to 1995 a crossing cost a constant $ 1 toll , then $ 1.50, currently (2016) $ 3 is only collected on the north bank for the trip south.
Since 2004 it has been allowed to drive on the causeway (except on the bascule bridge) at 65 mph (105 km / h).
The bridges were damaged (less than feared) by Hurricane Katrina , so they had to be closed from August 29 to October 14, 2005.
Traffic increased from 3,000 vehicles per day in 1960 to 30,000 on weekdays and up to 3,500 vehicles per hour at peak times. The traffic is expected to reach the capacity limits of the bridges in 2018, which is why the construction of a third bridge is being discussed.
See also
literature
- Judith Dupré: Bridges , New York 1997, ISBN 1-884822-75-4 .
Web links
- Lake Pontchartrin Causeway on Bridgemeister with numerous photos
- Lake Pontchartrain Causeway. In: Structurae
- Video of a car crossing
Individual evidence
- ↑ The different lengths of the ramps may be the reason for the different lengths of the bridges mentioned in the sources; the dimensions given here are based on Google Earth.
- ↑ a b c d e f g h i Lake Pontchartrain Causeway on the AARoads website
- ↑ a b c Bernard Marrey: Les Ponts Modernes; 20 e siècle. Picard éditeur, Paris 1995, ISBN 2-7084-0484-9 , p. 190
- ^ Robert Rhoden: Lake Pontchartrain Causeway named National Historic Civil Engineering Landmark. Article dated November 8, 2013 on nola.com -The Times-Picayune
- ^ Toll on the bridge website