Hawthorne leaders have signed off on construction of tech tycoon Elon Musk’s first test tunnel for electric vehicles extending west from SpaceX headquarters.

The City Council approved the two-mile underground track Tuesday night in a 4-1 vote, with only Councilman Nilo Michelin dissenting.

Digging the tunnel beyond the SpaceX property line, extending to beneath city streets, could begin any day. But don’t expect to see any dirt-covered construction workers or feel any underground rumbling along the route, which veers west under the northeast corner of Hawthorne Municipal Airport and along 120th Street.

“You don’t see it, don’t hear it, and certainly don’t feel it,” said Brett Horton, SpaceX’s senior director of facilities and construction, who also oversees Boring Co. work.

The company will aggressively monitor the impact of the tunneling and immediately stop work if the surface ground subsides by a half-inch above the tunnel, he said.

‘Everything happens underground’

The company already has built a shaft and a 160-foot-long tunnel entrance in SpaceX’s old parking lot, across the street from its 1 Rocket Road headquarters.

“Everything happens underground,” Horton said. “We won’t have construction crews walking down the street. We won’t have excavators.”

The tunnel depth will gradually slant down until it’s 44 feet, well beneath underground utilities.

The tunnel-boring machine that will do the bulk of the work was purchased after it was used to dig a sewer line in San Francisco, Horton said.

Musk has said he wants to vastly improve the efficiency of the machine to prepare for a series of Hyperloop mass-transit tunnel networks nationwide. But Horton said Tuesday that this test tunnel is relying on existing technology.

“We hired a structural designer from a large consulting firm to design the tunnel based on LA Metro specs,” he said. “We haven’t reinvented tunneling. We’re using proven technology and proven means and methods.”

Musk has said he eventually hopes to extend the Hawthorne tunnel into Los Angeles, ending at Los Angeles International Airport.

Nationwide tunnel networks planned

The Boring Co. also is testing a vehicle elevator it built in the parking lot that can deliver electric cars into the tunnel atop a specially designed “skate.” The skate is designed to also carry pods filled with pedestrians and bicycles through the tunnel.

While it isn’t officially expected to test high-speed electric Hyperloop trains, Musk hasn’t ruled out the possibility.

He introduced the Hyperloop concept in a 2013 white paper. The electric train would be buoyed by magnetic suspension technology that theoretically would allow it to get to speeds of about 700 mph. The trains would travel through depressurized tubes, allowing for such high speeds.

In July, White House officials announced that they had “promising conversations” with Musk about developing “transformative infrastructure projects” across the country.

President Donald Trump also has repeatedly said he intends to spur major infrastructure upgrades.

Getting up to speed

On Sunday, SpaceX will host its second annual university Hyperloop prototype competition in a vacuum-sealed, nearly milelong Hyperloop tube built on Jack Northrop Avenue.

The student engineering teams are working on a variety of Hyperloop technology systems, while Los Angeles-based Hyperloop One is in final testing phases of the first fully-built commercial Hyperloop system.

Musk reportedly has held onto the Hyperloop trademark, and could potentially start his own Hyperloop company. But that remains to be seen.

So far, Hyperloop One demonstrated the fastest system when its Hyperloop reached almost 200 mph this summer.

In the meantime, The Boring Co. is testing out new ways of reducing the cost of tunneling and making it more environmentally friendly. The company is experimenting with using the excavated dirt to make bricks or concrete blocks, rather than simply having it shipped elsewhere.

“These bricks can potentially be used as a portion of the tunnel lining itself, which is typically built from concrete,” according to a company statement. “Since concrete production accounts for 4.5% of the world’s greenhouse gas emissions, earth bricks would reduce both environmental impact and tunneling costs.”