CHICAGO (CBS) — Could billionaire Elon Musk’s proposed tunnel from downtown to O’Hare International Airport be nothing more than riding a Tesla underground? In recent tweets, Musk said that’s “pretty much” the idea.

“This is simple and just works,” he tweeted last month.

Musk might be tweaking his plan for a high-speed underground transit system to O’Hare with a significant downgrade in technology.

His original plan was to use his so-called hyperloop transportation technology to send autonomous electric vehicles known as skates to carry up to 16 people and their luggage on the 18-mile trip between Block 37 and O’Hare.

“This is something that’s new and exciting. It’s not just the same old thing. America is about trying bold new things and finding technologies for the future,” Musk said last year, after former Mayor Rahm Emanuel selected his Boring Company to build a high-speed transit system to O’Hare.

The announcement was made to much fanfare from Emanuel.

“It’s easy to be a critic or a cynic. What jobs do they produce? What economic growth do they produce?” the former mayor said at the time.

Musk promised to f oot the $1 billion bill for a futuristic tunnel where self-driving pods would whisk travelers between the Loop and O’Hare in just 12 minutes.

Critics raised plenty of doubts about Musk’s plan, while acknowledging the need for faster transportation to O’Hare. Experts noted Musk’s tunneling and hyperloop technology have not yet been proven to work.

“We really need to have a fast express train to O’Hare. All of our competing cities have it,” said Rick Harnish, executive director of the Midwest High Speed Rail Association. “Musk has a concept with lots of questions.”

Though the Boring Company showed off its California test track last December, there are signs there might be no light at the end of the tunnel.

Concept illustrations showed the self-driving 12-passenger pods would be hurled forward at 150 mph on a futuristic “skate.”

However, the latest video from Boring indicated the plan now might be nothing more than sending Musk’s electric Tesla Model X electric sedans – seating five – on autopilot through the tunnels.

“I think it’s absolutely viable,” said Northwestern University civil engineering professor James Hambleton

Civil engineers have said the underground construction and transportation technology aren’t as unbelievable as they sound.

“We can do it, it’s just a matter of how much is it going to cost,” Hambleton said.

Chicago’s new mayor could put the brakes on the project.

Lightfoot has cast serious doubt on the ability to build Musk’s tunnel without public funds, and made no mention of the tunnel in her mass transit proposals while running for office. She also questioned the transparency of the bidding process.

In a statement, the mayor’s office would only say she’s “evaluating several major transit projects.”

“There is Metra service to the airport. It’s not very good, but it’s something we can build on,” Harnish said.

Metra operates a sparsely used O’Hare Transfer station along the North Central Service line.

The station is located at the airport’s new rental car center, two miles away from the terminals, meaning riders must also use a shuttle bus and the airport’s People Mover to actually get from the Metra station to the airport. Also, only 9 inbound and 10 outbound trains stop at the O’Hare Transfer station on weekdays, with no weekend service at all.

Metra has estimated it could upgrade the line and provide reliable frequent service for $500 million.

However, state lawmakers have not provided enough funding for the project in the new capital construction plan.

“We need to have Springfield step up and invest in the trains,” Harnish said.

That might prove as challenging as a $1 billion privately-funded tunnel to O’Hare.

Musk and the Boring Company have not responded to repeated requests for comment.

Vince Gerasole