The United States became the country it is because of people with vision and big ideas. Indeed, John F. Kennedy captured the essence of this spirit when he said, “We choose to go to the moon in this decade and do the other things, not because they are easy, but because they are hard.” Daniel Burnham, the visionary Chicago planner, exhorted the people of his time to “make no little plans. They have no magic to stir men’s blood.”

Undoubtedly, great dreams will shape the American future. But the Washington Metropolitan Area Transit Authority’s recently revealed plan to create an underground Metro line encircling the city’s core is so far beyond dream as to enter the realm of fantasy. It’s a setup for a disappointment comparable to the forlorn soul in that 2000 television commercial who asked where the flying cars were that he had been promised in his youth.

It’s like a sojourn from one parallel universe to another to read on one day stories of the decay and financial crisis of the system, only to be whiplashed the next by promises of a whole new line — one that, it should be noted, is estimated to cost $26 billion at first blush. The one thing that experience has shown us is that when it comes to building this system, $26 billion will become $30 billion or more before the first construction permit is pulled. Kennedy would have found the moon launch to be comparatively easy.

The Post’s article on the proposal made no mention of the incredibly complex politics associated with advancing such a vision or of the challenges involved in financing, much less operating, such a new line under the Metro compact. New stations and tracks are funded by the jurisdictions in which they exist, and 12 of 14 new or greatly expanded stations identified in the plan would be in the District. It would be interesting indeed to see how the District would pay for a construction project of that scale. The entire Silver Line to Dulles International Airport has but 11 stations, most of them above ground, and the turmoil over its funding is well documented. The remaining two stations proposed by Metro are in Arlington, which could feasibly fund them, were they connected in some way to reality.

What possible benefit of this project would inure to the people of Maryland, particularly those who dwell beyond Montgomery and Prince George’s counties? While they would be spared the capital construction cost, the state would still be zapped with an increase in operating costs into eternity for the privilege of watching more of its residents spend entertainment dollars in the District.

Even now, many Montgomery County riders suffer the indignity of being tossed from every other homebound train at Grosvenor-Strathmore station during rush hour, thanks to Metro’s lack of enough dollars — and a supportive vote from the District — to fund the full ride out to Shady Grove.

The people at Harry Weese’s architectural firm created a monumental system for our monumental city, but that system lacks the engineering simplicity to do the basic job of getting people where they want to go.

If we’re going to start dreaming really big, though, why not go back to where it all began? When I was chair of the WMATA board in 2004, Stanley Allen, one of Harry Weese’s project architects for the original design, came to me with a grand idea. What you should do, he said, was build a line that effectively paralleled the Beltway and circled the city. He even presented me with a laminated card with the whole thing drawn and laid out like a stone’s ripple emanating from the city. The number for that one was $24 billion.

Allen is a big-ideas man, integral to the design of the Metro we know, and a class act. The Washington region, though, is a transportation basket case that needs to focus on reality. Why don’t we finance to maintain and efficiently operate what we already have before leaping through the looking glass to embrace a project that has no practical hope of ever getting off the drawing board?

The writer was a member of the WMATA board from 2003 to 2006, serving as chairman in 2004.