Federal officials turned down Arlington County’s application for a national transportation program that could have expedited approval for a much-sought streetcar project because authorities doubted the system could be built for the estimated $250 million.

But Arlington officials said that will not stop them from moving forward with the project, and it may allow them to apply for another federal program that could provide even more funding for the streetcar line.

In an April 12 report, the Federal Transit Administration denied Arlington’s application for the Small Starts program saying that the almost five-mile-long streetcar line likely would cost closer to $310.1 million, and could rise as high as $402.4 million including $71.8 million in contingency funds — double what county officials had predicted.

The FTA also suggested that Arlington consider larger streetcars, add staff members and further develop the plans.

On Tuesday, Arlington officials said that while they were disappointed they didn’t qualify for the transit administration’s program, that decision frees them to apply for another federal program that could bring more than the $75 million they sought. In fact, the decision provides a road map for how to apply for the New Starts program, which serves as the primary financial resource for local transit programs.

“This will help us rethink how we’re doing or add to how we’re thinking. This puts us in a much better place to be ready,” County Manager Barbara Donnellan said. “The key for us is: keep working, keep plugging along, get it done, keep moving forward.”

The long-planned streetcar line, from the Skyline area of Fairfax County to the Pentagon area of Arlington, does not rely solely on federal funds. The project foresees using at least $35 million in state funds and $35 million from Fairfax County. Arlington’s $104 million contribution would come from a commercial and industrial real-estate tax that can only be used for transportation needs.

Donnellan, Arlington transportation chief Dennis Leach and Steve Del Giudice, the county’s transit services bureau chief, said in an interview Tuesday that even if the FTA had accepted the streetcar project, they would have had to apply in about two years for money because acceptance doesn’t guarantee funding.

Arlington officials said the FTA’s denial won’t slow the county’s progress on planning, which is about 90 percent done, or the construction, which has yet to begin.

Donnellan, Leach and Del Giudice also said that the new Virginia transportation bill could bring more money for transit to Arlington and other Northern Virginia jurisdictions, although it’s not certain how much or when.

“The [County] Board has been pretty clear it’s not their intention to raise local taxes on residents to build this, and that’s the direction at this point in time and so I will follow it,” Donnellan said.

One option for funding the streetcar project might be tax-increment financing. That method usually allows a government to borrow money against expected future gains in taxes; that money subsidizes current improvements in infrastructure. Donnellan said that the county’s “Triple Triple A” bond rating, in which three major rating agencies gave Arlington their highest endorsement for its financial management, allows the inner suburb to get financing not always available to others.

The complexity of the Columbia Pike streetcar project in some ways has worked against the county, Donnellan said, because it’s “not conducive to sound bites.”

“This will make a difference in the quality of life for people in Arlington for years to come, and we’re moving forward,” she said.

The streetcar project continues to be controversial. Despite 15 years of planning and discussion, and the support of many business owners and nearby residents, as well as longtime elected officials such as former state senator Mary Margaret Whipple (D), building a streetcar line in lanes of traffic along the heavily used Columbia Pike has prompted opposition from County Board member Libby Garvey and others.

More than 16,000 people each day ride buses along Columbia Pike now, making it the most heavily used bus route in Virginia. Arlington County plans to add 14,000 apartments, condos and homes to the 16,400 there now, and if all those new residents choose to drive, the result would be gridlock.

Proponents say streetcars have the capacity to handle that extra demand, and they are attractive to the new, young residents that the county, employers and businesses hope to lure to the area. The streetcars would share the road with buses and other vehicles.

Opponents of the streetcar project say modern rapid-transit buses can move almost as many people for significantly less cost, and they are not locked into a single route, which could cause problems during accidents, weather or sudden high demand elsewhere.

The Arlington County Board and the Fairfax County Board of Supervisors have twice endorsed the construction of the streetcar line, as part of their overall redevelopment of the region.