The 101/405 Interchange

Ranked the most congested interchange in the nation — the gateway where the climb into the pass begins.

Key facts

The US-101 (Ventura Freeway) / I-405 interchange was ranked the No. 1 most congested interchange in the nation in the American Highway Users Alliance's 2004 "Unclogging America's Arteries" study.
It is routinely reported to carry on the order of ~450,000 vehicles a day and is commonly called the busiest/most-congested interchange in the country.
The US-101 here is the Ventura Freeway; the I-405 is the San Diego Freeway. South of this knot the 405 begins its climb into the Sepulveda Pass (summit ~1,130 ft).

Narration transcript

The freeway crossing over your head right now is the 101, the Ventura Freeway, and the tangle where it meets the four-oh-five has a dubious crown: in a landmark national study of traffic bottlenecks, this interchange came in first — the single most congested freeway interchange in America. Something like half a million vehicles try to thread this one spot every single day. If you're moving right now, savour it. If you're not — well, you're in historic company.

This is the hinge of the whole trip. Behind you is the flat, tamed San Fernando Valley. Ahead, the roadway tips upward and starts to climb, because you're entering the Sepulveda Pass in earnest now — up over the spine of the Santa Monica Mountains and then down the far side into West LA. From here on, the land does the talking, and the buildings start.