A federal appeals court has refused to block the use of toll revenues to complete the construction of a commuter rail linking the Washington, D.C., suburbs and Dulles International Airport.

A three-judge panel of the U.S. Court of Appeals for the Fourth Circuit on Monday affirmed a decision by U.S. District Judge James Cacheris of the Eastern District of Virginia to dismiss on summary judgment a putative class action challenging the project.

The Metropolitan Washington Airports Authority is currently extending what is locally known as the Silver Line to Dulles, which is located in Loudon County, Virginia, about 26 miles from Washington. Dulles is the region's major international airport, and is primarily accessed by a toll road.

The named plaintiffs in the lawsuit have claimed that the interstate compact that created the MWAA decades ago provided that revenues from the toll road were to be used for airport improvement projects only, and that the construction of a commuter rail line does not fall within that definition.

Cacheris, and the Fourth Circuit, disagreed. A train line, the courts said, is vital to the airport's operations, especially given the area's serious traffic woes.

“Excessive congestion can effectively strangle airport operations and require citizens to spend an even longer portion of each day making a flight or returning from one,” wrote Fourth Circuit Judge J. Harvie Wilkinson.

Judges Allyson Duncan and Barbara Keenan joined in the ruling.

The MWAA's attorney, Stuart Raphael of the Washington office of Hunton Andrews Kurth, said this is the fourth unsuccessful lawsuit challenging the construction of the Silver Line project.

“The Fourth Circuit thoroughly addressed the legal  issues,” Raphael said.

The plaintiffs' lawyer, Gene Schaerr of Schaerr Duncan in Washington, did not return a call seeking comment on the decision.

Wilkinson, in the Fourth Circuit opinion, wrote that the completion of the Silver Line was vital for the area.

“Efforts to alleviate congestion and expand access to the facilities in major metropolitan areas often and understandably meet with challenges from those whose lives and properties may be affected by any given project proposal,” Wilkinson said. “But some improvements need to be made lest growth overwhelm the ability of the metropolis to deal with it.

“There is no basis in law for finding that the dedicated funding mechanism here was impermissible,” Wilkinson said. “To find otherwise would throw longstanding airport expansion arrangements into turmoil. We decline to take that step.”