Elon Musk announced to his 15.6 million Twitter followers on Wednesday night that his Boring Co. tunneling endeavor will compete for a contract to connect Chicago’s O’Hare Airport to downtown, with a twist.

Musk said the Boring Co. will compete to build a “high-speed loop” which he later described in another tweet as a tube that doesn’t have the air sucked out with a vacuum, reasoning that you “don’t need to get rid of air friction for short routes.” It won’t be a vacuum-tubed “hyperloop” wherein a pod shoots through a tube at speeds of up to 700 mph, as described his “Hyperloop Alpha” whitepaper that started the hyperloop craze in 2013. “Electric pods for sure. Rails, maybe not,” Musk added later on Twitter.

Above-ground light-rail trains connect airports to downtowns of cities across America, and besides Musk’s underground Loop concept, several train proposals are expected.

In April, Musk revealed this animated video at the TED conference in Vancouver that showed how a car could be lowered via elevator into an underground tunnel, then drive onto what looked “skate” that would shoot it through the tube. Also in those tunnels would be tubes through which passenger pods travel.

His tweets on Wednesday were the first time that Musk has brought up a separate “Loop” concept which seems to be what he envisions for the Chicago proposal.

The Chicago Sun-Times reported in a story on Tuesday that the Chicago Infrastructure Trust had issued an open “request for qualifications” for projects to connect the central part of the city and its major airport, and that responses are due on January 24.

Musk has been in talks with Chicago leaders for nearly a year about the project.

Earlier this year, the Chicago Tribune reported that Musk was in talks with Chicago Mayor Rahm Emanuel about the very same project.

Back in January of this year, Emanuel — known nationally as a President Barack Obama’s chief of staff for most of the president’s first two years in office — told reporters that he invited Musk’s engineers to come to Chicago to “explore further what we are doing and planning, and to see if the tunnel approach is an alternative to the ones we’ve been discussing.”

It seems those meetings were fruitful, because this week, Emanuel’s deputy mayor, Bob Rivkin, told the Sun Times that the city hoped Musk would submit a proposal for the project.

The distance between downtown Chicago and O'Hare International Airport

“The RFQ is agnostic about whether this is a surface or sub-surface system. We hope Elon Musk and either builders of hyper-loops and other innovative technologies will respond,” Rivkin said.

Any respondents now must submit their qualifications to design, build, pay for, operate, and maintain the transportation system. The goal is to transport people from O’Hare to downtown in 20 minutes, which is about half of the typical time it takes to drive, details a press release issued by the city on Wednesday. Trains — or electric pods, if you’re Musk — need to leave at least every 15 minutes for most of the day and tickets should cost less than current taxi or Uber fares.

Interestingly, nowhere in the press release issued by the city of Chicago is there a mention of Musk or his Boring Co., but it seems as if the SpaceX and Tesla chief has received a sizable head-start.

Other Boring Company Projects in the Works

East Coast

In July, Musk said he had received “verbal approval” for a hyperloop that would connect New York City to Washington, D.C. “Just received verbal govt approval for the Boring Company to build an underground NY-Phil-Balt-DC Hyperloop,” Musk posted on his Twitter page Thursday. He added, “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.”

West Coast

Previously, Musk said he wanted to build an LA route from Los Angeles International Airport to Culver City, Santa Monica, Westwood, and Sherman Oaks.