It’s a visionary idea for beautifying Chicago and lifting a community’s property values whose time has never come.

But might it come at last? There’s still an allure here for making no little plans, even if they are arguably unwise.

The idea is the Kennedy Expressway cap, a green oasis that could be built on a deck over the highway as it cuts its swath west of downtown. It would cover that unsightly traffic, diminish its roar and provide open space for a West Loop region that teems with new residents, offices, hotels and restaurants. Think of it as Millennium Park replicated about a mile and a half west.

Capping the Kennedy is a notion that’s been out there for years, always with a dream-like quality to it. It was included in the city’s 2003 Central Area Plan, its first comprehensive look at the downtown region since 1958, and it also was featured in a 2009 “action plan” update that cheerily set a goal of completing it by 2020.

I wrote about it 2012 and 2013, when the cap acquired an advocate in Steven Fifield, a developer who pioneered the push into the Near West Side and has since focused on other areas. Fifield enlisted Scott Sarver, now a principal at RATIO Architects, to draw the schematics and consider the costs.

What brings this up now? I was at a meeting last week called by Ald. Walter Burnett Jr. (27th) and the West Loop Community Organization where residents offered comments about a new hotel and apartment tower connected to an office building on the block just west of the Kennedy between Washington and Randolph streets. People liked the project overall, but talk inevitably turned to traffic management and lack of park space for an area that now has many young families. Residents said the closest parks, Mary Bartelme and Skinner, can be overrun.

That’s when Burnett brought up capping the Kennedy. I asked him about it later. He said the project could tap into funds in his ward’s tax increment financing districts that may be close to expiring. “If we don’t use it, we lose it,” he said. “That money has to be distributed back to all the taxing bodies, so let’s use it while we can.’’

Burnett noted Fifield has been an ardent supporter and developers could come up with money on their own. I asked if he thinks the proposal would pass muster with Mayor Lori Lightfoot, who wants more public investments in underserved areas, and Burnett deflected the question to her planning commissioner, Maurice Cox. “This planning commissioner is for green space and open space,” he said. Some area residents also have said the idea could work for the Eisenhower Expressway near the medical district.

Sarver said he still believes in the cap. If the experience of Millennium Park is a guide, the Kennedy cap “would generate billions in tax revenue for the city. It would be wonderful. That stretch of roadway is a real fissure in our city.’’ He said other cities, such as Dallas, have done well by relegating a highway to a tunnel and creating attractive public space above it.

“I think this really would be the kind of project that TIF dollars were intended for,” Sarver said.

The cost? Sarver estimates it at $50 million per block. If you did the stretch between Randolph and Adams streets, that would get you to $200 million. Others may suggest capping only two or three blocks. He said there was an opportunity to do this when the Jane Byrne Interchange was reconstructed a few years ago, but nobody pushed the idea. That was before Gov. J.B. Pritzker and “thinking big.’’

Cox was unavailable for comment last week and the mayor’s office had no immediate response.

If this is to happen, it will take a public-private partnership and serious fundraising. Advocates will have to inoculate themselves against the criticism that this is a rich neighborhood being favored by the public largesse. But who knows? In a city where a developer can secure a potential $1.3 billion in public assistance to build a wealthy enclave on the North Side riverfront, anything is possible.

Besides, parkland is a worthy cause. On the Near West Side, it might keep some of the young tech workers in town after they have babies and start thinking about a bigger space, maybe a backyard, of all things.

If the Kennedy cap goes forward, it might also set the open space crowd against the anti-TIF social justice warriors. That might be fun to watch.