City of Angels! City of Stars!

City of gridlocked freeway interchanges!

Getting trapped on Los Angeles' majestic, but traffic-jammed freeways, is such a routine local experience that filmmakers turned it into a rousing musical number, "Another Day of Sun," for the Oscar-winning movie La La Land.(I lived in LA for a decade and immediately recognized the gigantic 105-to-110 interchange, which provides an inspiring view of downtown LA for travelers coming in from LAX. Interestingly, I never got stuck in traffic there.)

The University of Southern California's

This will surprise no one who has regularly battled the LA freeways. Interstate 405 is the source of several major bottlenecks. "The 405," as it's called by Angelenos, opened in 1961 and is the nation's most congested stretch of road.

Fun fact: The 405 was the site of LA's "Carmageddon" in 2011, an expected monumental traffic jam that didn't actually materialize. Repairs were being done to a section that slices through the Sepulveda Pass, connecting LA's Westside with the San Fernando Valley.

The first appearance of the 405: where it connects to Interstate 10 — "the 10" — in this case allowing the easterly flow from the coast to turn north or south (Centinela to National is the backed up stretch of the surface streets).

"During evening rush hour, traffic drops to 11 mph at Centinela Ave. approaching the 405," the USC study reported.

You get the idea.

USC Viterbi has an a large-scale data platform for acquisition, storage, and analysis of LA-Metro's transportation with the Price School of Policy."

The Annenberg's role is to take the information and turn it into "data-driven journalism."

The traffic project entailed mining data from "17,000 street sensors on the main arteries and freeways across Los Angeles County and from transmitters on 2,000 buses," USC said. Then "undergraduate and graduate-level computer science students working ... cleaned, sorted and analyzed 11 terabytes of traffic data" before joining Annenberg students to crunch the numbers.

The 405 returns for more where it joins with the 105, an east-west freeway that provides access to LAX airport. At this interchange, traffic flows head north to Route 90, known as the Marina Freeway.

"Traffic just north of the 105 interchange used to zip along at almost 50 mph before slowing to approach the 90," USC noted. "Now average speeds there have fallen by more than half, and stay mostly in the teens until north of the 90."

Traffic on the 405 also gets messed up heading south, toward the I-10 interchange and the 90 interchange, during rush hour.

"The 10 and 90 interchanges make this stretch a challenging zone," USC said. "At their worst, average speeds at Venice Blvd. have declined 45%, from nearly 30 mph down to 15 mph. Traffic throughout this stretch stays in the high teens and low 20s."

Let's meet another freeway: the 101, referred to variously as the "Hollywood Freeway" and the "Ventura Freeway." Here's a point where the 101 meets the 405, with unpleasant effects.

Southbound 405 traffic runs into trouble around Sherman Way and Burbank Blvd., USC said.

"South of Burbank Blvd., average speeds slow to 10 mph approaching the 101 interchange. Further north, the worst drop-off occurs at Victory Blvd., where average speed plunged by two-thirds since 2012."

Already bored with the 101? Then meet the 110, a combined interstate highway and state route that's been around forever. Effectively, it connects the LA port with Downtown LA and Pasadena. Unfortunately for motorists, the 110 meets the 10 just south of Downtown.

"As morning commuters approach downtown at Florence, traffic drops to 16 mph and bottoms out at Vernon, at an average of 13 mph," USC said. "Between 51st and Vernon, average speed has declined by almost 40% since 2012."

I've personally experienced this living traffic hell on countless occasions.

In the evening, anyone headed south on the 110 gets hit at the same choke point. "Average speeds approaching the 101 and 10 interchanges are down almost 30% to 45% in five years," USC said. In one particularly gnarly section, the average speed hits as low as 18 miles per hour.

So there you have it — the LA freeway interchanges to avoid. Ain't nobody singing and dancing in those parts when it's bumper-to-bumper time.