Lake Pontchartrain Causeway

Infobox_Bridge
bridge_name= Lake Pontchartrain Causeway


caption= The southern end of the causeway at Metairie
official_name=
also_known_as=
carries= 4 lanes of Causeway Blvd
crosses= Lake Pontchartrain
locale= Metairie, Louisiana and Mandeville, Louisiana
maint= Greater New Orleans Expressway Commission
id=
design= Low-level trestle with mid-span bascule
mainspan=
length=
width=
clearance=
below=
traffic= 43,000cite web|url=http://www.nola.com/newslogs/tpupdates/index.ssf?/mtlogs/nola_tpupdates/archives/2006_11_20.html#206890|title=Causeway lighting project cost double expectations|accessdate=2007-02-22|author=Christine Harvey, New Orleans Times-Picayune]
open= August 30, 1956 (southbound)
May 10, 1969 (northbound)
closed=
toll= $3.00 (southbound)
map_cue=
map_

map_text=
map_width=
coordinates= coord|30|11|59|N|90|07|22|W|region:US_type:county
lat=
long= The Lake Pontchartrain Causeway, or the Causeway, consists of two parallel bridges crossing Lake Pontchartrain in southern Louisiana. The longer of the two bridges is the longest in the world over water, measuring at convert|23.87|mi|km|2 long. The bridges are supported by over 9,000 concrete pilings. The two bridges feature bascule spans over the navigation channel convert|8|mi|km|0 south of the north shore. The southern terminus of the Causeway is in Metairie, Louisiana, a suburb of New Orleans. The northern terminus is at Mandeville, Louisiana.

History

The idea of a bridge spanning Lake Pontchartrain dates back to the early 19th Century and Bernard de Marigny, the founder of Mandeville. He started a ferry service that continued to operate into the mid-1930s. In the 1920s, a proposal called for the creation of artificial islands that would then be linked by a series of bridges. The financing for this plan would come from selling homesites on the islands. The modern Causeway started to take form in 1948 when the Louisiana Legislature created what is now the Causeway Commission.

The original Causeway was a two-lane span that opened in 1956 at a cost of $30.7 million. A parallel two-lane span, 1/100th of a mile (15 m) longer than the original, opened on May 10, 1969 at a cost of $26 million. The Causeway has always been a toll bridge. Until 1999, tolls were collected from traffic going in each direction. To alleviate congestion on the south shore, toll collections were eliminated on the northbound span. The standard tolls for cars changed from $1.50 in each direction to a $3.00 toll collected on the North Shore for southbound traffic only.

The opening of the Causeway boosted the fortunes of small North Shore communities by reducing drive time into New Orleans by up to 50 minutes, bringing the North Shore into the New Orleans metropolitan area. Prior to the Causeway, residents of St. Tammany Parish had to go around the lake, either the east side via the Rigolets Bridge on U.S. Route 90 near Slidell, Louisiana or on the west side via U.S. Route 51 through Manchac, Louisiana.

After Hurricane Katrina on August 29th, 2005, videos collected showed damage to the bridge, but the damage was mostly on the unused turnaround on the older southbound span; the structural foundations remained intact. The Causeways have never sustained major damage of any sort due to hurricanes and other natural occurrences, a rarity in the causeway community. The existing fiber optic cable plant was blown out of the tray but remained intact per optical time domain reflectometer (OTDR) analysis. With the I-10 Twin Span Bridge severely damaged, the Causeway was used as a major route for recovery teams staying in highlands to the North to get into New Orleans. The Causeway reopened first to emergency traffic and then to the general public, with tolls suspended, on September 19, 2005. Tolls were reinstated by mid-October.

Major barge accidents

The Causeway has been struck by barges on three occasions that have caused structural damage resulting in the collapse of portions of the roadway. [ [http://blog.nola.com/graphics/2007/08/download_file.html Hazardous crossings - Graphics - "Times-Picayune" - NOLA.com ] ]

* January 17, 1960, an empty barge struck the bridge in heavy fog in the morning. Two of the Causeway's 52-foot spans collapsed and a third was damaged. There were no fatalities.
* June 16, 1964, a tugboat pushing two barges collided with the bridge in the early morning causing four spans to collapse into the lake. A Continental Trailways bus fell into the lake killing six people.
* August 1, 1974, several barges collided with the new northbound span collapsing several spans and sending several vehicles into the water, killing three people.

Regulations

* Currently Both spans have a 65-mph speed limit during the day barring fog, rain or high wind. This was increased from 55 mph in 2004 in order to increase safety on the span and reduce travel time by 4 minutes. However, the southbound span has night time sight line issues at the span's rises, requiring a speed limit of 55 mph over the humps. The Causeway Commission is studying the expense of lighting the rises on the southbound and possibly the northbound span. [http://www.nola.com/newslogs/tpsttammany/ "Nighttime speed limit going up on southbound Lake Pontchartrain Causeway" NOLA.com]

Third span plans

In 2002, the Causeway Commission discussed the construction of a third span, before ultimately deciding to renovate the existing spans as studies showed traffic growth leveling off. The third span was estimated to have cost $400 million, which by 2006 had risen to $800-900 million. In the aftermath of Hurricane Katrina, traffic has grown to 40,000 vehicles per day as the population of Northshore parishes have rapidly increased. A 1992 traffic study predicted the traffic capacity of the current spans would be exceeded in 2007; an estimate that was later revised to an earlier date and rendered useless by Katrina related population shifts. In early March 2006, General Manager Robert Lambert acknowledged that the Commission may revisit the plan for a third span. Lambert cited the increase in traffic and the need for better evacuations routes to the north as the leading reasons for reexamining the need for a new span. The proposed third span would be east of the current northbound span and include two travel lanes and a full right-hand shoulder. The current southbound span would also be fitted with a full shoulder. The current northbound span would then be used as a one lane with full shoulder reversible roadway to correspond with peak travel hours. [cite web|url=http://www.southeastroads.com/lpc.html|title=Lake Pontchartrain Causeway|accessdate=2007-02-22|author=SouthEast Roads]

See also

*List of bridges in the United States
*List of bridges by length
*Megaproject
*Prestressed concrete
*Orders of magnitude (length)

References

External links

* [http://www.thecauseway.com/ The Causeway website]
* [http://maps.google.com/maps?t=k&hl=en/&ll=30.102366,-90.124283&spn=0.856593,1.277161&t=k Google Maps satellite image]