MARTA won’t be the operator of the soon-to-be-completed Atlanta Streetcar, according to a top official in Mayor Kasim Reed’s administration.

“It’s been over the last year that we pretty much determined that the best way to go about this is using a mechanism other than MARTA,” said Tom Weyandt, Reed’s senior transportation policy advisor.

He cited cost as the reason, saying the city would have had to pay for a pricey insurance policy that MARTA wasn’t going to cover.

“It has to do with a whole set of cost structures…insurance that we would have to assume for a new service that MARTA could not accommodate under their existing rapid rail operation,” said Weyandt.

He added the job of operating the streetcar system was put out to bid earlier this year. He said a private contractor would be selected in a matter of weeks.

Some transit advocates wonder why MARTA couldn’t offer a more competitive proposal to operate the Streetcar, and attempt to gain a greater foothold in a system that the city and the Beltline clearly have ambitions to expand.

MARTA spokesman Lyle Harris declined comment on the subject. In an emailed statement, he said only the transit agency continues to work closely with the city “to ensure that every aspect of the Atlanta Streetcar project is a success.”

MARTA so far has been heavily involved in the project’s engineering and design, and acted as a pass-through for the city to apply for federal funds. The city won a $47 million federal Tiger II grant in 2010 for the project.

In addition, Streetcar officials say MARTA has been helping review the companies hoping to win the contract to operate the system.

David Emory, president of Citizens for Progressive Transit, said whether it’s MARTA or a private contractor, the city is right in trying to get the best deal possible.

“That way more money hopefully can be spent on improving the Streetcar and the frequency of service,” said Emory.

The city has purchased four streetcars, but current plans call for operating only two of them during service hours, with expected wait times between vehicles of 15 minutes. Transit advocates are hoping the city can locate additional funds to operate more than two cars at a time and lower headways to below 10 minutes.

The streetcar project was originally supposed to be completed earlier this year, at a total cost of $93 million. But construction issues have delayed the project and caused the budget to swell by millions. City officials now say the Streetcar is set for operation in May.