Like most other plans for ameliorating heavy traffic, it is somewhat effective for a short time, but it soon just causes that many more cars to try to drive through the area.
I've hit gridlock at 3am on the 101 before. The whole city feels like it was designed to be some elaborate torture device for commuters.
I guess any system of transportation would feel like torture for commuters if that system is overloaded and operating beyond its reasonable capacity.
One data point: As bad as it can be at times, especially on/near The Strip, Las Vegas still seems less congested than LA.
http://articles.latimes.com/1985-06-07/local/me-16088_1_traf...
as for the 3am traffic, that was probably night time caltrans work, or a drunk driving accident :(
I think that LA takes pride in its traffic, like some kind of shared struggle.
It is the only city I have lived in that has an implied 30 minute allowance for traffic delays. Everyone understands and you can use the excuse anytime or day of the week.
In a dense area like Manhattan, transport is not so bad because walking, cabs, or the subway are all viable alternatives in many cases.
In a lower density sprawl area like Los Angeles, cabs are prohibitively expensive for most trips, the subway usually doesn't go anywhere near where you are or where you want to go, the buses are stuck in traffic like any other vehicle, and walking is dangerous (due to the lack of pedestrian-friendly sidewalks in many areas) and would take many hours for each trip.
I think the best way to fix LA traffic would be to greatly increase the density and start building upwards so that walking and public transport become viable options for many more cases, but that seems very unlikely to happen anytime soon. It'd take decades to do anyway. So for now, it looks like LA is just stuck with its insane traffic status quo.