The long-dreamed-of Second Avenue subway will take another important step toward becoming a real thing of concrete and steel today, as the federal government plans to announce that it has formally approved $1.3 billion in financing for the project's first phase.

Transportation Secretary Mary E. Peters said in an interview that the money would be paid out over the next seven years as construction progresses on the subway's first leg, which will have stops on Second Avenue at 92nd, 86th and 72nd Streets and at 63rd Street and Lexington Avenue.

The Metropolitan Transportation Authority began preliminary work on the line after Gov. Eliot Spitzer held a ceremonial groundbreaking in April.

Ms. Peters said the federal money would pay for about one-third of the work on the first phase, which is expected to cost more than $4 billion. The first leg is scheduled to open in 2014, and it will run as an extension of the Q line.