Elon Musk discussed his plan for hundreds of layers of tunnels in LA to ease traffic congestion on a Recode podcast published Friday.

Musk bemoaned the tremendous costs to bore tunnels currently.

If the construction can be made cheaper, Musk said, he could bore hundreds of layers of tunnels.

Among Elon Musk's sprawling business ventures, The Boring Company might be the most secretive.

The tunneling company is currently working on a project to ease traffic in Los Angeles — but Musk's comments on a Recode podcast published Friday seem to hint at ambitions well beyond a simple tunnel.

"We do expect to, over time, create a network of tunnels under greater LA," the SpaceX and Tesla CEO told journalist Kara Swisher. "And I think this is really the key to getting around the city very fast. You’ve got to go 3-D."

By 3-D, Musk means making more tunnels — tunnels that go deeper into the earth's crust, where they can crisscross, overlap, and do things traditional tunnels haven't done because of how expensive they are to bore.

"The cost of tunneling, historically, has been prohibitive," said Musk. "And they’ve also been incredibly slow."

His solution? A cheaper tunneling solution.

"You could certainly have a subway system which had many layers of tunnels," Musk said, "but the tunnels are so prohibitively expensive that they don’t do it. But you can go down 100 levels if you want to, you could have 100 layers of tunnels on top of each other … the key is a massive improvement in tunneling technology. That’s the linchpin, that’s fundamentally what it amounts to."

Read more: Elon Musk's tunneling company just unveiled a plan to transport people in Los Angeles to Dodgers Stadium in only four minutes — but the timing of the announcement is curious

The Boring Company says on its website that it can increase the efficiency of traditional Tunnel Boring Machines, or TBMs, which are incredibly large, slow, and expensive, through reducing runnel diameter by 50% and running the machine around the clock through automaton.

The company had previously posted photos of its progress on Instagram — along with the flamethrowers (er, *not* a flamethrower) it sold for fundraising — but as of Friday, the account was blank save for a few logos. That follows Musk deleting his personal Instagram account in August.

Then there's the question of capacity. Musk told Recode that he has never met a single person who uses the subway, a statement that echoes his previously-aired fears of public transport. This is likely behind Musk's vision for traveling "skates" or mini pods that will transport far fewer people per vehicle than a traditional subway train car. As many transportation experts have pointed out, this greatly reduces total capacity for the system.

Of course, hundreds of layers of tunnels could help with that capacity issue.

"Tunnels are really so underappreciated," Musk said.

Read Recode's full interview here.

More from Elon Musk's Recode appearance: