Lessons from Hurricauine Katrina

The great hidden lesson of Katrina is the value of the bicycle. Supposedly people got stuck in the city because they didn't have cars, but I was told by someone who evacuated New Orleans by car that traffic moved only 3-5 miles per hour. You could go that fast on foot (though you still need a place to go) and two or three times that fast on a bike. Bicycles can carry more people per hour over a bridge of a given size than any other technology, with much more energy efficiency, and without any gasoline or electricity. This will become obvious if the large bike-riding populations of Minneapolis or Seattle ever need to flee a disaster. For some people that message will come too late.
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http://www.ranprieur.com/essays/katrina.html

would be good. The are less than a 1000.00 and really good on gas.
You can't take much, but you can sure get around easily and they are faster then bikes and easier on the legs.

The Lake Pontchartrain Causeway used to be ,until recently, the world's longest bridge (24 miles long). It is also a major evacuation route out of the city and not to mention that the Causeway doesn't have much in terms of a shoulder to ride your bike on safely.

Getting out of town to safety is just too far away for a bicycle to be practical even if you took an alternate route. New Orleans is tricky to evacuate because of the geography of the city. Bussing or putting evacuees on a train are the best solutions I can think of.