Local governments caught off guard by Elon Musk's Hyperloop

Musk didn't say who gave him the approval, and he acknowledged that the deal is far from finalized.

President Donald Trump in March met with Musk, who raised the Boring Company idea then, White House officials said.

In its own statement, The Boring Co. said feedback on the proposal has been positive and it has "received verbal support from key government decision-makers for tunneling plans".

Musk runs electric auto company Tesla Inc. and rocket maker Space Exploration Technologies Corp., among other ventures.

It envisages slashing the three-hour train journey between NY and Washington to 29 minutes. His tunnel-digging operation, "The Boring Company" (pun intended), has already broken ground on an underground shaft near his rocket company in California to circumvent gridlock in Los Angeles. Drawing heavily from Goddard's vactrain, a Hyperloop comprises a sealed tube or series of tubes through which a pod may travel free of air resistance or friction conveying people or objects at optimal speed and acceleration. The 225 mile journey now takes around three hours by train. The system would also have stops in Philadelphia and Baltimore, Musk said.

Musk also tweeted that a first set of tunnels would be to "alleviate greater LA (Los Angeles) urban congestion", adding that the company would also "probably" do a loop from Los Angeles to San Francisco, and another in Texas.

"Elon Musk has had no contact with Philadelphia officials and we do not know what he means when he says he has received government approval".

Last month, Musk tweeted that he had "promising conversations" about a tunnel network with Los Angeles Mayor Eric Garcetti. He urged supporters to contact their representatives to speed that process.

Running from "city centre to city centre", the tunnel would have "up to a dozen" more entry and exit points along the route, Musk said in a series of tweets about the project.

Philadelphia spokesman Mike Dunn released a statement saying, "There are numerous hurdles for this unproven "hyperloop" technology before it can become reality". The U.S. Department of Transportation referred ABC News' inquiry to the White House. But Musk quit both councils last month after Trump announced he would withdraw the USA from the Paris climate accords.