Elon Musk first envisioned double-decker 405 before tunnel idea

Elon Musk shed some light Thursday on how he arrived at the idea to build privatized, high-speed tunnels for cars and 18-passenger “pods” beneath Los Angeles.

Musk said previously that he used his commute to brainstorm ways to address the traffic congestion he experienced going from his Bel Air home to work at SpaceX’s headquarters in Hawthorne. But before he conjured up the tunneling scheme, Musk had a different idea: Turn the 405 into a double-decker freeway.

“I had a very well thought-out design,” the entrepreneur told Los Angeles Mayor Eric Garcetti at a “fireside chat”—there was no fire, not even a flamethrower—to open the National League of Cities conference, held in Downtown LA.

Multi-level freeway interchanges are a familiar sight in Los Angeles, including an elevated high-occupancy platform of the 110 Freeway. Double-decker freeways have historically presented a seismic risk in other cities like San Francisco. A stacked section of a Bay Bridge on-ramp collapsed in the Loma Prieta earthquake, killing 42 people.

Musk said his double-decker would have been “seismically safe,” made of steel and built in pre-fabricated sections.

Extra lanes were added to the 405 freeway—although not in a separate level—when it was widened in a five-year construction project. (Musk was so frustrated with the project’s progress in 2013 he offered to put up money to speed the process.)

But the expansion of the freeway actually made travel times one minute longer as more cars crowded the new routes, a phenomenon transportation planners call “induced demand.”

Musk came to his own realization that adding extra tiers to the 405 was a bad idea after puzzling over how to build off-ramps that wouldn’t get gridlocked.

“The corner pieces were getting tricky,” he said, reasoning that people would have become frustrated exiting the freeway’s multi-leveled lanes.

Tunnels, Musk said, were a better option.

“You have to go 3D,” he said Thursday.

Garcetti asked Musk why he didn't explore the possibility of flying cars (known as “vertical takeoff and landing” vehicles, or VTOLs), but Musk said these vehicles were too loud, dangerous, and vulnerable to weather conditions.

Musk unveiled the tunneling idea in a December 2016 tweet, saying: “Traffic is driving me nuts. Am going to build a tunnel boring machine and just start digging...”

As the idea gained traction on social media, Garcetti said he received a text from Musk the next day asking if he needed any permits to start digging.

“[He] texted me the next day saying, ‘Do I need permits for this?’ And I said ‘yes, there are probably going to be some permits that you need,’” Garcetti revealed Thursday, laughing.

Musk reported having “promising conversations” with Garcetti, whose office endorsed the idea in a statement.

Since Musk was building his experimental test tunnel in the city of Hawthorne, where SpaceX is located, he did not need permits from Los Angeles. But Musk’s tunneling venture, which he named the Boring Company, did require approval from Hawthorne’s City Council, which it received in August 2017.

Courtesy the Boring Company

Three months later, in November, the Boring Company applied for permits to start digging a 6.5-mile tunnel parallel to the 405 freeway in the city of Los Angeles. A second phase of the project would add more tunnels close to major destinations such as LA Live, USC, and the NFL stadium in Inglewood.

The Los Angeles City Council voted to consider exempting the project from environmental review. Two neighborhood groups opposed the motion by filing suit against the city.

Experts have been skeptical of Musk’s tunnel idea, noting that the project faces outsize hurdles when it comes to environmental laws and community approval, and is not likely alleviate traffic congestion. Renderings show cars and pods entering and using the tunnels one at a time, much like a freeway on-ramp.

In August, the Boring Company submitted a proposal to the city of Los Angeles to pursue a tunnel from either Los Feliz or East Hollywood to Dodger Stadium, offering fans 4-minute rides to games for $1. A public meeting in August meant to start gathering community input was sparsely attended.

Musk said the Boring Company’s tunnel-boring machine has been digging at a rate of one mile every three months—about the same speed as Metro’s TBMs, although Musk’s tunnel is a smaller diameter. The test tunnel is now 6,000 feet long—a little over a mile—and will open to the public for rides in December.