The cost of a five-mile Columbia Pike streetcar line has jumped as much as $100 million since 2007, officials for the initiative said Friday, pushing the cost of the transit system to as high as $261 million.

Inflation accounted for about $20 million of the increase, said Arlington County Board Chairman Chris Zimmerman (D). Federal requirements for higher-contingency funding added $34 million to the cost, and an increase in the number of vehicles and higher engineering costs boosted the price another $20 million. Zimmerman said the jump in cost was not surprising or unexpected because the last estimate was done four years ago.

The increase is “actually fairly slight,” Zimmerman said. “These numbers are always a moving target in transportation projects. . . . We build high schools that cost $150 million.”

The revised cost estimate came because Columbia Pike Transit Initiative Policy Committee officials are preparing to apply for federal funds that would cover 30 percent of the project’s cost from the Federal Transit Administration’s New Starts and Small Starts program. If that money comes through, the state is expected to contribute about 14 percent of the cost. Arlington taxpayers would have to shoulder $112 million, and Fairfax County taxpayers would cover $28 million. The cost for the line, at $50 million per mile, is comparable to similar projects across the nation, Arlington officials said.

The first phase of the line, which will connect Pentagon City in Arlington to the Skyline area of Fairfax, is planned to open in 2016 if construction starts in 2013. A second leg running south through Crystal City to the Alexandria line could follow, with the potential to fan out through the eastern part of Northern Virginia.

“Of course, we’re early in the planning and design process, and it’s important we have as realistic as possible figures to deal with,” said Sharon Bulova (D), chairman of the Fairfax Board of Supervisors.

The project has been planned for years and is one part of a massive redevelopment plan for Columbia Pike to revitalize housing, land use and streets along the corridor. County officials believe that by 2040, 3,900 residences and 2.2 million square feet of commercial development, with 7,000 new jobs, will be added.

“This is a project that has the most potential to help us achieve our environmental goals and livability goals,” Zimmerman said. “We think it will have a very high return.”