Not the whole story

The LA Times Bottleneck Blog posted these LA employment and population density maps. (Click on the link above to go to the post with the map legends.) The red areas in the employment map shows a high density of jobs downtown, Westwood and Century City areas. Yellow areas are the next highest density employment areas followed by green.
The darkest green areas have the highest night-time population density, followed by medium and light green. My neighborhood is medium green, 8,934 to 10,178 people per square mile (though I calculated slightly over 11,000 for my block).
Transportation folks use these maps to argue for more public transit in the Westside. Builders use these maps to argue that they should be allowed to build more dense urban infill projects in the Westside.

There is some truth to both arguments, but both views distort reality. Traffic will increase when you build housing near jobs unless the people who work in a neighborhood can afford to live in that neighborhood.

While the night-time population of Beverly Hills is largely very affluent and white, the daytime population is primarily brown. In fact, Spanish is the dominant language in Beverly Hills during the day time. Do Beverly Hills workers live anywhere near Beverly Hills? No, they take a two hour bus ride from dense Eastside neighborhoods. (The best Mexican food in Los Angeles comes from taco trucks that service the residential neighborhoods of Beverly Hills.)

Do you think the servers at Jamba Juice or the Cheesecake Factory at the Americana at Brand in Glendale will be renting the $5000/month apartments or buying the $700,000 condos above their workplaces?

Housing people near their workplaces is a good start, but it won't magically cure LA traffic. The 800 pound gorilla is international trade. We, the denizens of LA, are not fully responsible for our own traffic. The collective American public, and our insatiable appetite for cheap imports and cheap air travel, is also largely responsible for LA traffic and pollution.

"The twin ports of Long Beach and Los Angeles handle 43 percent of the container cargo entering the United States, clogging the surrounding roads and rails." Those containers get loaded up onto trucks taking up 20-50% of the traffic lanes of our freeways. In fact, a coworker says he dreads Wednesday and Thursday, when the laden trucks head out of the harbor. Read Clogged Arteries for the story and to view the graphic below.
Moreover, LAX is one of the world's busiest airports. By day, airliners pack the twin runways continuously. By night, air freight land semi-continuously. The air freight terminal at LAX disgorges diesel trucks carrying air cargo onto the surface streets near LAX around the clock. Particulate levels near the airport are measurably higher during the holiday season due to the rise in air freight traffic. This is another reason to plan ahead and send your holiday presents by surface methods.

I live and work (and get my medical care) in the area bounded by LAX to the north, LA and LB ports to the south, the ocean to the west and I-405 (one of the busiest and most congested freeways in the USA) to the east. Did I mention that it takes 1.5 hours to travel the 17 miles to UCLA because it is on the other side of the busiest freeway interchange in the country (I-10 and I-4o5)? Hermitdom never looked so attractive.