I just spent the last five hours out in it. Here are my observations:
All freeways are jammed and bumper-to-bumper, like the very worst of rush-hour, except that it doesn't end, not even in the middle of the night, and *all* sections of freeway are that bad, including the parts that are normally still pretty clear during normal rush-hours. The only exception are lanes heading *towards* the coast, which are about as empty as they can be -- I made record time heading down towards the NASA are. It's getting *back* that was grueling.
The feeder roads are actually better than the freeways most of the time, and at times can zip along pretty quickly, up to 50mph.
Just a block or two off the freeways, the surface roads ARE CLEAR SAILING. I found this to be consistently true all over town. If you know your way around town, AVOID THE FREEWAYS and drive the surface streets. You'll make *much* better time, even taking into consideration the traffic lights and lower speed limits. Not only are the evacuees all on the freeways and not on the surface streets, but the regular city traffic isn't out as usual either, since the whole city is battening down the hatches.