The lesson learned is that somehow, they need to figure out how to phase the evacuations so that they do it by area. Probably by staggering the times that roads are open and that certain areas only have a certain window to get out, then the next area is let out and so forth, so that not everybody tries to leave at the same time.
Logistically it would be difficult but still I think it's possible.
We had staggered ones here in FL...for hurricanes..and fires. It works. HOWEVER- with all the doubt about where it's actually going..it's hard to know when/where to tell people to leave. We thought Corpus, then Freemont, then Galveston/Houston..now a little further east. The logistics are tough.