CHICAGO, Feb. 7 (Xinhua) -- Elon Musk's Boring Company is among the four respondents that want to build and operate an express rail system from Chicago's O' Hare International Airport to downtown, Chicago mayor's office confirmed on Wednesday.

The high-profile entrepreneur has just sent his Tesla Roadster to space by SpaceX's brand new Falcon Heavy rocket on Tuesday.

Chicago Mayor Rahm Emanuel announced that Chicago Infrastructure Trust (CIT) has received four responses to the Request for Qualifications (RFQ) to design, build, finance, operate and maintain the O'Hare Express operating system.

The project aims to deliver express service that would take 20 minutes or less to travel from downtown Chicago to O'Hare International Airport, cutting more than 50 percent off current travel times.

"Four visionary groups have stepped forward because they see what we see - a connected Chicago is a stronger Chicago," Mayor Emanuel said in a statement.

"Strengthening connections between the economic engines of downtown Chicago and O'Hare airport will build on Chicago's legacy of innovation and pay dividends for generations to come."

According to the website of Musk's Boring Company, "To solve the problem of soul-destroying traffic, roads must go 3D, which means either flying cars or tunnels."

Musk claims his new drilling technology can trim costs on building a tunnel with high-speed pods to whisk riders to and from the airport.

The other three groups that show interest in the project are Oaktree Capital Management, O'Hare Express Train Partners (OHL Infrastructure, Kiewit, Amtrak) and O'Hare Xpress LLC (Meridiam, Antarctica Capital, JLC Infrastructure, Mott MacDonald and First Transit).

Chicago mayor's office did not mention in the statement when the city in the midwestern U.S. State of Illinois will start accepting specific bids on the project.