Nine months after vowing to forge ahead with a high-speed rail line between downtown and O’Hare Airport in his second term, Mayor Rahm Emanuel is finally taking his first concrete step to make that elusive dream a reality.

The mayor and his slow-starting Chicago Infrastructure Trust are issuing a request for qualifications aimed at identifying teams interested in designing, building, financing, operating and maintaining an express train to O’Hare in partnership with the city.

The goal is to deliver express service that would whisk travelers between downtown and O’Hare in “20 minutes or less,” cutting travel times in half.

The city and the trust will consider “potential corridors above or below surface level” to deliver express service “at least every 15 minutes for the majority of the day” for fares “less than” the cost of a taxicab or Uber ride to O’Hare.

“A taxi ride from downtown to O’Hare could be $60. Ubers run around $40. There’s a lot of room between the price of the CTA or parking to price a service in a way that you can make a lot of revenue,” said Deputy Mayor Bob Rivkin.

Update: Elon Musk says he’ll enter competition for O’Hare express train

The RFQ identifies three potential routes while remaining open to other options.

Rivkin identified those routes as: the CTA Blue Line that runs along the median of the Kennedy Expy.; the Metra North Central line that comes into downtown just north of Union Station and freight railroad rights-of-way that would run west to Forest Park and north to O’Hare.

The Blue Line option could be “a structure built above or below ground,” the deputy mayor said. The North Central option could terminate at “its own place” or at Union Station, Rivkin said.

The request for qualifications follows an analysis conducted by a working group created by the mayor last year to determine the feasibility of a project that has eluded Chicago mayors for decades.

The group studied “demand for ridership, potential terminal locations as well as possible routes and alignments.”

The next step is to determine “private sector interest in construction and operation,” officials said.

Interested bidders must include a downtown station, an O’Hare station and one maintenance facility and determine ways to avoid or minimize “potential conflicts or impacts on existing transportation systems and the environment.”

The overall price tag for the system is not yet known, but taxpayer support is off-limits. The RFQ stipulates that O’Hare express service will be bankrolled “entirely by the concessionaire” and funded “solely by project-specific revenues” including fares or advertising.

Responses are due on Jan. 24. The city and the trust then intend to select one or more “most qualified” respondents to proceed to the request-for-proposal phase.

Absent from the city’s press release about the RFQ is any mention of the trip top mayoral aides took to Los Angeles a few months ago to talk to visionary billionaire Elon Musk about Musk’s Jetsons-like plan to build tunnels to house high-speed rail.

But Rivkin said he hopes and expects that Musk will be among the bidders vying to build and operate the new service.

“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.

Rivkin was asked whether he believes Musk’s jaw-dropping technology could work in a cold-weather climate like Chicago.

“We think it could be feasible at no cost to the taxpayers and this is the right format to use to find out formally if that is the case. We’ll know as soon as we get responses,” Rivkin said.

Earlier this year, Emanuel appeared gung-ho on the Musk technology and said Musk was “very interested.”

The O’Hare express project has been a dream of Chicago mayors for decades.

Former Mayor Richard M. Daley once hoped to convince Chinese investors to build a high-speed rail system to O’Hare that would originate from the $200 million Block 37 super-station.

It never happened, leaving the underground station looking like little more than an unfinished basement.

Aviation Commissioner Ginger Evans once vowed to steer clear of the Block 37 station, but Emanuel now considers it an option and plans to announce the RFQ inside that underground space.

Engineering and design giant WSP Parsons Brinckerhoff was chosen to identify potential routes, develop a cost estimate, and pinpoint the location of downtown and airport stations, under terms of a $2 million contract awarded last year.

City Hall also retained Rivkin, former general counsel at the U.S. Department of Transportation, to provide “legal expertise in identifying a clear path forward and working with potential partners.”

Rivkin was subsequently chosen to replace Steve Koch as deputy mayor.