Originally Posted by Cory W

The 405 has a bridge over it called the Muholland bridge. If you have ever heard of Muholland drive, that's the bridge. It goes over the 405. The 405 is being given an extra lane, this requires dynamite in much of the sepulveda pass (where the bridge is). If you have ever been to Los Angeles, this is just after the Getty Center / Sunset Blvd.

Los Angeles is a very unfriendly grid. The 405 runs north and south, as does the 5. The 101 and the 10, each run east and west (although the 101 is officially titled as north). This forms a "box" in the grid which surrounds Hollywood, West Hollywood, Beverly Hills and most of West LA, amongst others. There is no alternate freeway to slice this up. If you are at my place in West Hollywood, it takes a while to get to a freeway. Now, the other side of the 405 is Santa Monica, Brentwood, cut off by the beach.

The 405 is totally and completely abused on a daily basis. Without it functioning, it shuts down travel north and south (between the valley and West LA) and shuts down LAX travel which would be north bound. The 405 / 10 is the second busiest interchange in the world. The 405 / 101 is second (this stat is 10 years old, mind you). All the cars that would normally use the 405 for LAX to / fro, the Valley, Orange County, Santa Barbara will be diverted, much of which will divert into thoroughfares in West Hollywood, Beverly Hills and Santa Monica. None of which can closely fit this traffic. On a typical Saturday, the 5 freeway is at a standstill, and that's with a functioning 405.When President Obama had a piece of the 10 freeway shut down last summer for an hour, it created a 3 hour drive from Beverly Hills to Brentwood. That's typically done in 20 minutes. That was the 10.

The poor layout of Los Angeles is the key component here.

So, the typical commute from the Valley will be either three canyon roads or the 101 / 5 (both of which will already be at a stand still). Essentially, hundreds of thousands of drivers will be diverted into smaller streets in West LA (Bev Hills, West Hollywood) and Santa Monica (PCH). It will completely shut the greater Los Angeles city down, as well, potentially all the way up to central California and as far down as Mexico.

Have any of you ever flew into LAX? When the cab takes you out, the first freeway you likely get on is the 405. If you don't, you get on the 110. Now, imagine if you land on Saturday. Imagine all those cars you normally see, now being on a two lane road called La Cienega, or on the 110 (which is already being used).

The city planning crew is under fire to get this done in two days (before Monday). If they do not, heads will roll, public outcry will destroy reputations, and business will lose business and employees. So the city has launched an outreach program to encourage people from driving (hence, the drama). Its the best option they have, and they have done a great job.

I hope that explains it.