The Lake Ponchartrain Causeway is the world's second or third longest elevated span over water. It is listed by Guiness as the longest bridge. At 23.6 miles it stretches all the way from Metairie to Mandeville. thecauseway.com is the official website of this bridge.

Go ahead and click on the Satellite view now. Scroll northward a few time to get a sense of this bridge. Then zoom out until you can see how long it is.

Normally traffic flows north on the eastern span, south on the western. A $3 toll is collected at the North plaza only. The speed limit was recent raised to 65 and is rumored to be vigorously enforced.

Marine traffic is prohibited from entering a zone one mile to each side of the causeway in order to prevent collisions.  In the past there were incidents in which barges rammed the causeway when their operators fell asleep. At least one of these resulted in automotive fatalaties.

During the Katrina evacuation the contraflow plan reversed traffic on the western span. This provided four northbound lanes and helped empty the city smoothly.  Unlike much else in Katrina, the evacuation of 1.5 million people went smoothly. Some believe this was because the of the lessons learned from Ivan one year earlier.

Undamaged by the storm, the causeway was jammed with traffic for two months after the storm because of the damage to the I-10 Twin Spans.