Fairfax County formally agreed Tuesday to help fund the second phase of the Dulles Rail Project despite serious concerns supervisors still have about state funding, labor agreements and neighboring Loudoun County’s increasingly shaky commitment to the $2.7 billion project.

“A long time ago we started discussion about rail in the Dulles corridor and — as the Grateful Dead said — what a long, strange trip it’s been,” said Supervisor Michael Frey, R-Sully. “I can come up with far more reasons why we shouldn’t than why we should. We still don’t know how we’re going to pay for it. We continue to have discussions with the state and whether they’re in it or not. We continue to fight with [the Metropolitan Washington Airports Authority] board. We don’t know if Loudoun’s going to be in it or not.”