Billionaire innovator Elon Musk claimed Thursday that he had received "verbal" government approval to build a futuristic underground rail system that would take riders from New York to Washington, D.C. in less than half an hour.

In a series of mysterious tweets that would not be taken seriously if it were practically any other corporate executive, Musk befuddled the transportation industry with claims that his latest venture is pursuing an ultra-high-speed rail network in the Northeast.

Transit experts say that gargantuan costs and prodigious bureaucratic hurdles make such a product extremely difficult to pull off.

Still, Musk's track record of building groundbreaking companies from scratch — including electric-car maker Tesla and space travel firm SpaceX — and plunging his own money into such ventures lends hope to travelers inconvenienced by highway congestion and rail breakdowns from New York City to Washington.

"Just received verbal govt approval for The Boring Company to build an underground NY-Phil-Balt-DC Hyperloop," Musk said.

He added that the system would ferry passengers from "city center to city center in each case, with up to a dozen or more entry/exit elevators in each city."

Madeline Brozen, associate director of the Institute of Transportation Studies at the University of California Los Angeles, said the potential costs are "incomprehensible."

An image released by Tesla Motors, is a conceptual design rendering of the Hyperloop passenger transport capsule.

A 120-mile above-ground stretch of the most comparable U.S. project, a high-speed rail project in California, will cost $7 billion to $10 billion, she said. But underground projects are more expensive, the hyperloop is unproven technology and Musk's system would travel five times faster than California's.

Moreover, winning approval for the project would likely require an arduous environmental assessment and authorization from numerous transportation authorities and other government agencies that are "territorial" and bureaucratic by nature, Brozen said.

"It’s quite easy to draw up enthusiasm for a project in 140 characters when you have 10 million followers on Twitter," she said. "It’s a very different ball game when you’re trying to bring a mega project to fruition."

It was not immediately clear what Musk meant by "verbal" government approval, which carries little weight in a world in which tunneling can require navigating a byzantine thicket of regulations.

But a White House spokesman said the Trump administration has had "promising conversations" with Musk and the Boring Co. and is "committed to transformative infrastructure projects" under the premise that "our greatest solutions have often come from the ingenuity and drive of the private sector."

A spokesperson for passenger rail company Amtrak, which controls much of the current rail corridor from New York to Washington, did not have an immediate comment.

A representative of the New York Metropolitan Transportation Authority pledged to look into whether the agency had had contact with Musk or The Boring Co.

A spokesman for The Boring Co. did not immediately respond to a request for details.

Musk's bold statements come a few months after he formed a venture called The Boring Co. to manufacture faster and more efficient tunnel-boring machines.

Having lost his patience with legendary California traffic, Musk recently pledged to build a short tunnel from his office to the Los Angeles airport before building a network of tunnels throughout the city. He has described a network of underground tunnels ferrying self-driving cars at high speeds as a solution to urban congestion.

But a hyperloop from New York to Washington would pair his dual ambitions for faster tunneling with hopes of a long-range rail system that travels several hundred miles an hour.

After New York-to-Washington, Musk said he would probably proceed with a hyperloop from Los Angeles to San Francisco and one in Texas.

The U.S. Transportation Department referred comment to the White House.

Contributing: Marco Della Cava

Follow USA TODAY reporter Nathan Bomey on Twitter @NathanBomey.