It’s an alluring idea: An environmentally friendly electric train built at no cost to taxpayers that would fly above traffic, shuttling Braves fans from MARTA to Turner Field.

But there are reasons to doubt whether the $30-million floating train line discussed by the Atlanta Braves and Marietta-based American Maglev Technology will ever come to fruition.

Despite a string of attempts over 20 years in at least three states, American Maglev — short for magnetic levitation — has never launched a functional train.

Two governments - one of them Cobb County - concluded the firm’s technology is not ready for commercial use. The project’s purported financial backer, Spanish construction giant Grupo A.C.S., didn’t respond to requests for comment. MARTA, which would have to be involved to make the link to Turner Field work, declined to say anything about it.

Yet the Braves see promise in the proposal, which would effectively deliver customers to their doorstep at no upfront cost to the team.

Mike Plant, a Braves vice president, says the team has been talking to American Maglev president and pitchman Tony Morris for four years and sees his plan as a viable way to address the lack of a MARTA rail stop at The Ted.

Plant said the main reason people don’t go to Braves games is traffic and transportation challenges.

“For 20 years (Morris) has been trying to sell this technology that uses the equivalent of eight toasters to move a train,” Plant said. “Its new, and new is something that is always a challenge. But to us, it looks like a viable solution someone else is willing to pay for backed by some pretty reputable global companies.”

The proposed line would run between the Georgia State MARTA station and the stadium and would take 18 months to build, according to American Maglev. Each vehicle could carry about 250 people and make the trip in about 90 seconds.

Morris hopes to work a deal with MARTA to enable its riders to transfer seamlessly, with the maglev line capturing a share of revenue. When the Braves aren’t playing, the train would cater to Georgia State commuters who park near the stadium.

In the 60s, plans were made to run a dedicated bus way near Atlanta-Fulton County Stadium, but those plans were gradually changed due to opposition, said Georgia Tech Professor Harry West. A MARTA rail spur to the stadium has never been financially feasible and instead a game-day bus shuttles run from the Five Points hub.

The Braves bus shuttled 128,732 passengers to the stadium in 2012. At a basic $2.50 one-way fare, that equals about $321,830 a year. Plant said the Braves would commit $500,000 a year to subsidize operations.

According to Morris, Grupo A.C.S., the Madrid-based construction company, would pay all construction costs and operate the train at a profit. But Grupo did not respond to requests to discuss its commitment.

Transit advocates question whether the capacity of the train is sufficient for Braves games, as well as the wisdom of a link at the Georgia State MARTA station rather than Five Points, which would require fans from northern suburbs to transfer twice.

“There are some reasons to be a little concerned,” said David Emory, president of Citizens for Progressive Transit. “In general, maglev is relatively experimental untested technology. And there is a mixed track record with this particular company.”

Magnetic levitation technology uses magnets to float a train above a railway and propel it down the tracks. The technology has been used in Asia but not the United States. American Maglev says its technology is significantly cheaper to build than traditional rail.

Morris, a Georgia Tech-trained civil engineer, started talking up his technology almost two decades ago. In fact, his first pitch was for a similar line between MARTA and the 1996 Olympics stadium, which later became Turner Field. But that didn’t get off the ground and none of his proposals since has yielded a working system.

Morris in the mid 90s designed a train to connect Tampa, Orlando and Miami, according to reports at that time. He built a test track in Florida with government grant and county money, but abandoned the project when money ran out.

In Virginia, Morris promised to build a working system at Old Dominion University by 2002. But the technology never worked properly, several companies sued him for unpaid bills and federal funds fell through.

Morris insists he’s resolved technology issues and said the company no longer relies on government money.

“Birthing technology is not easy, but that doesn’t mean we shouldn’t do it,” Morris said. He said his current plant is “third generation,” adding “we could not have gotten here without the first two generations. This is the very nature of technology development, inventions and innovations.”

About two years ago Morris tried to interest Cobb County in a $441 million train that would run from Kennesaw to Smyrna and over to Dunwoody by 2015. An evaluation by the county concluded, “We believe AMT is a long way from approved commercial application and the costs are seriously underestimated …”

Morris said the evaluation was based on negative internet reports, and that Cobb officials didn’t visit the company’s test track in Powder Springs.

Morris’ company also is currently pitching a plan for a $315 million shuttle in South Orlando, which Morris also says would be financed by Grupo. The Orlando Sentinel reported that an engineering consultant to the state of Florida concluded last month the train needs much more testing and a better design.

The Braves project, which would span I-20, would need approvals by both the city and state. Duriya Farooqui, Atlanta’s chief operating officer, called it an innovative solution in the preliminary stages, and said it would be irresponsible not to consider a proposal backed by private investors.

The Georgia Department of Transportation says it is willing to work with all stakeholders.

“We think it’s a great idea to enhance and improve the way people get to and from Turner Field,” said spokeswoman Natalie Dale.