While Arlington County awaits word on whether it will receive federal transit funds for the planned Columbia Pike streetcar, elected officials have been weighing their options on who will manage the project and the size and type of streetcars they prefer.

No sooner had Chairman Mary Hynes declared Tuesday night’s workshop a “learning journey,” then board member Libby Garvey called for an independent cost-benefit analysis of a streetcar system versus a bus rapid transit alternative. “There’s never been an informed and public conversation about this,” Garvey said.

Except, several supporters pointed out, there have been many conversations about the streetcar.

“We’ve had a very robust public discussion not once, but twice,” retorted county board member Chris Zimmerman.

Zimmerman, who has been on the board since 1996 and has been a longtime backer of the streetcars added: “One may not agree with the decision the board made, but there was a very robust public discussion, and we did it twice.”

Garvey, who joined the board in March, had abstained in July when the board last endorsed the idea of building a streetcar system along Columbia Pike. She said at the time that she needed more time to study the idea.

The streetcar system, which is a joint effort between Arlington and Fairfax counties, is estimated to cost about $250 million, with the hope that the federal government would pick up about one-third of the cost. The decision on funding by the Federal Transit Administration could come as soon as this month, officials said.

State transportation funds are expected to cover another 14 percent of the construction costs. Taxpayers in Arlington and Fairfax counties would split the remaining 56 percent, with Arlington picking up most of the cost because 80 percent of the streetcar line would be in its jurisdiction. Operating costs would come from general county funds.

A single streetcar costs between $3.5 and $4 million, county staff members said. A new bus would cost $700,000 to $800,000. However, county transportation planners expect so much job and residential growth in the corridor over the next 20 years that they predict buses could not handle the demand. Advocates point out that those predictions were based on conservative federal guidelines, and in most other American cities that built streetcars, ridership was 12 to 72 percent higher than projected.

Details such as the width of the streetcar tracks are important because once set, they can’t be changed without major cost and effort, staff members told the board. Three weeks ago, the board heard presentations from representatives of Canadian and U.S. cities about how to structure the management of construction and operation of the transit system.