If you’re a bit confused about Elon Musk’s plans to tunnel his way out of terrible LA traffic, you are not alone. Last week, Musk and his Boring Company, a venture devoted to speeding up and bringing down the costs of tunnel boring, sat down for an hour-long public informational meeting in a Los Angeles synagogue. The company theoretically chose the location because it is close to the proposed site for a 2.7-mile test tunnel in the city's Sepulveda Pass, where the Boring Company will test out (and maybe innovate) its new tunneling tech.

The location had a strategic purpose, too: The meeting, held in the darkest moments of an LA rush hour, was a pain in the ass to attend. “Wouldn’t it be better,” a quiet South African–accented voice might have whispered, “if you could jump inside a pod and go?”

Musk’s vision, if realized, would do just that, allowing future Angelenos to evade the city’s infamous traffic by hopping aboard 16-passenger pods, waiting at hundreds, if not thousands, of small parking-spot-sized stations throughout the city. Elevators would lower the pods down into a subterranean highway system, where they could reach speeds of 150 mph. “For tunnels, you can have hundreds of lanes,” Musk said. “There's no real limit." (The system would also be able to carry personal cars, like Teslas, though for a higher price.) He calls the system the Loop.

To get to this techno future, Musk wants to speed up the process of tunnel boring by a factor of 15 and reduce its costs by a factor of 10. He’ll do this, he says, not by reinventing the cutter head but by making smaller tweaks to tunnel-boring machines, the process of excavation, and muck removal. “A lot these things are really simple,” he said. “It’s not rocket science.”

Some people in LA disagree. Two neighborhood groups, the Brentwood Residents Coalition and the Sunset Coalition, have already filed a lawsuit against the city for attempting to exempt the Sepulveda test tunnel from a formal environmental review.

Thus far, experts say, the ideas Musk has articulated aren’t exactly new. But they could have potential to speed up tunneling, which has seen little research-and-development enthusiasm in the US. (Europe, China, and Japan, by contrast, are great at tunneling.)

But even after last week’s hour of explanation and a smattering of written audience queries (selected by a Boring Company employee based on how many people voted for each), WIRED still has some questions about the Boring Company’s proposed test tunnel and the company’s grander vision for a cross-city transportation scheme. Let’s dig in on a few of Musk’s ideas.1

1. Make Tunnels Narrower to Reduce Cost

This could work, says Marte Gutierrez, a professor of civil and environmental engineering who studies underground tunneling for transportation at the Colorado School of Mines. “The cost of the tunnel goes up almost exponentially by diameter,” he says. “By making the tunnel smaller, you not only reduce the cost, you make it faster.”

2. Automate Tunnel Boring and Tunnel Support Construction

Gutierrez also buys this. “If you could do it as an automated production line system, like when you assemble cars, there is a lot of ground for improvement,” he says. He notes tunnelers should allow the ground to sit or “relax” before they build supports.

But the idea of automation in tunneling is far from new. “Automated segment technology now is extremely well-established,” says Gary Brierley, a civil engineer who has worked on tunneling projects for 50 years. Brierley doesn’t think it’s possible for anyone to get the sort of speed or efficiency gains Musk has targeted. “There’s no way to streamline that process,” he says.

3. Turn Muck Into Bricks, Right at the Tunnel’s Mouth

Brierley is skeptical. Muck removal usually doesn’t account for a significant portion of the price of a tunnel bore. What’s more, selling bricks—Musk suggests they could go for 10 cents per—ain’t easy.