It took us 12 hours to drive from Houston to New Orleans 3 years ago, a normal 6 hour trip. It was road construction combined with regular Fri afternoon traffic.
there were people that didn't make it from 610 loop and 290 to the beltway in 12 hours...much less 500 miles to new orleans...there is simply no way to evacuate that many people given the present highways...the traffic jams were over 100 miles long. people sat still idling until they ran out of gas. i think next time they should evacuate the northern portions of the city earlier in the week or only allow cars with no empty seats access to the evacuation routes to cut down on traffic...it was really amazing to watch...maybe a light system like florida has where people can be warned when all lanes are heading out of town during emergencies instead of having to wait for the police to set up all the road blocks.