Yes it was. Worked quite well too, for those that had cars.
Would have worked just as well for everyone else if Nagin and Blanco had bothered to implement their own evacuation plan and used the area's school buses and public transport buses to get the carless people out of town too.
contraflow did seem to work pretty well.
I think they said the last evacuation the flow was about 4000 people/hour with all kinds of problems. I didn't see it in print, but I heard a reporter say that 18000/hour were leaving at one point.