I have a question - these evacuations discussed above all deal with hurricanes or major hurricane-like storms (Sandy). Those are all but unknown in Los Angeles - there is a record of one storm reaching the LA area in 1924 or so, but it was a puny little thing.

In Southern California, the disasters of choice are wildfires and earthquakes. I suspect evacuation in the aftermath of a really major earthquake (8.0 or so) would be very difficult with broken freeways, landslides etc. My general strategy is to shelter in place, essentially camping out where the backyard used to be. Obviously evacuation of an urban the size of LA will be a huge undertaking, if indeed it would be the best strategy.

The Southern California area has a long record of wildfire prompted evacuations. The problems with them are fairly trivial.