Elon Musk, the billionaire tech entrepreneur, announced Thursday on Twitter that he has received "verbal" government approval to build a high-speed underground transportation system from New York to Washington, with stops in Philadelphia and Baltimore.

The 46-year-old behind the automaker Tesla and commercial launch company SpaceX said his tunneling company, The Boring Co., wants to shorten the trip from New York to Washington to less than a half-hour — by taking on what would be the biggest U.S. infrastructure project in decades.


"Just received verbal govt approval for The Boring Company to build an underground NY-Phil-Balt-DC Hyperloop," he wrote on Twitter. "NY-DC in 29 mins."

"City center to city center in each case, with up to a dozen or more entry/exit elevators in each city," he added in another tweet.

"Still a lot of work needed to receive formal approval, but am optimistic that will occur rapidly," he said in a third.

Musk did not elaborate on which government agency or official gave him the verbal approval. He also did not offer a cost estimate.

Such a project would cost billions of dollars and require approvals — and likely funding — from federal, state and local governments to move forward.

While he did not say when such a project might begin or end, he said it would be built concurrently with one he has teased similarly in Los Angeles.

The Maryland and Baltimore departments of transportation said they were looking into Musk's statement and did not otherwise comment.

The U.S. Department of Transportation referred questions to a White House spokesman, who sent a statement but did not provide any additional details.

"We have had promising conversations to date, are committed to transformative infrastructure projects, and believe our greatest solutions have often come from the ingenuity and drive of the private sector," the White House statement said.

President Donald J. Trump made a campaign promise to launch a trillion-dollar reinvestment in U.S. infrastructure, a plan he has largely expected to rely on the private sector to spearhead. Musk had a falling-out with the Trump administration in June, quitting a pair of business advisory councils after Trump said he would withdraw the United States from the Paris climate agreement.

The high-speed transportation system Musk wants to bring to the East Coast is known as Hyperloop — a high-speed train that runs inside a de-pressurized tube using an electric motor and an arrangement of magnets to levitate above a track — similar to the maglev proposals that have been floated for years.

The technology required to build such a system has been developed already, said Dirk Ahlborn, CEO of Hyperloop Transportation Technologies.

Ahlborn's company began researching and developing Hyperloop in 2013, when Musk debuted the idea, he said. It is working with governments in the United Arab Emirates, South Korea and elsewhere to build Hyperloops in those countries.

"The technology is there," he said. "The technology is not the issue."


A competitor known as Hyperloop One demonstrated the technology on a Nevada test track in May 2016.

Other hurdles are far likelier to hold up the process, Ahlborn said.

For one, Hyperloop costs $20 million per mile when it's built above ground, without the added expense of digging a tunnel, and it requires approvals from the various state and local governments where it's built, he said.

If the project gets state or federal funding, the construction work also likely will require a competitively bid procurement process, Ahlborn said.

Because a Hyperloop hasn't been built in the United States, it lacks regulations governing its construction and operation, he added.

"You're building something that doesn't exist," Ahlborn said. "You have to create all those new laws."

Baltimore Mayor Catherine E. Pugh, a Democrat, signaled that the city won't get in the way, praising Musk's idea in a statement Thursday.

"If his plan becomes a reality it has tremendous potential to create new opportunities for Baltimore and transform the way we link to neighboring cities," the mayor's statement said.

Baltimore County Executive Kevin Kamenetz called the project "exactly the type of long-term, innovative transit solutions we need in our state."

Kamenetz, a Democrat who is weighing a run against Gov. Larry Hogan in 2018, used the Hyperloop announcement to take a jab at the Republican governor's $135 million BaltimoreLink bus system overhaul last month, which opponents have criticized as an inadequate answer to Hogan's cancellation of the $2.9 billion Red Line east-west light rail project in 2015.

"The success of Baltimore — and our entire state — requires a return to a comprehensive integrated transportation system for the region, not only a color coded bus line realignment," Kamenetz wrote in a post on Facebook.

A spokeswoman for Hogan did not respond to a request for comment.

The project isn't the only high-speed transit option being pursued for the congested Interstate 95 corridor. If it moves forward, the Hyperloop proposal likely will compete for funding and public interest with the Northeast Maglev project.

Baltimore Washington Rapid Rail is studying track alignments for the 300 mph, Japanese-designed magnetic levitation train it says would shorten the trip between the two cities to 15 minutes. The idea is to use such a short line to demonstrate maglev's effectiveness to then extend it farther to New York.

Hogan gave that project his support — although he has made clear the roughly $10 billion to $12 billion cost would be covered by the Japanese government, federal money and the private sector. It is undergoing an environmental review, which is expected to be completed by February 2019.

Addressing the Northeast Corridor's transportation challenges will require "a variety of options, including high speed rail," Northeast Maglev CEO Wayne Rogers said in a statement Thursday that did not directly address Musk's announcement.

"The Northeast Maglev team remains focused on the engineering and environmental work currently underway to bring proven maglev technology to the Northeast corridor," Rogers said. "We look forward to results of environmental impact study and continuing to hear from local residents and communities as the project continues to evolve."

Musk's tweets quickly went viral and drew a slew of responses from reporters and other interested followers, seeking more details on the proposal.

Asked whether a below-ground Hyperloop could ever be built in Texas, through Dallas, Houston, San Antonio and Austin, Musk replied: "For sure."


"First set of tunnels are to alleviate greater LA urban congestion," he tweeted. "Will start NY-DC in parallel. Then prob LA-SF and a TX loop."

A BBC tech reporter tweeted at Musk, asking why he announced the verbal approval instead of waiting for an official agreement. "Seems premature to announce … unless you're drumming up support for the project?"

"Support would be much appreciated!" Musk replied.

In a follow-up tweet, the billionaire entrepreneur doubled down, asking his 10.4 million followers to contact their elected officials if they want it to happen fast.

"Makes a big difference if they hear from you," he wrote.