The Alexandria City Council yesterday agreed unanimously to sign a pact that will allow construction of Metro's planned rail station at Van Dorn Street in the city's West End.

In signing the agreement, city officials abandoned their earlier demands for some kind of written assurance from the Metro board and Fairfax County that the Van Dorn station, scheduled to be completed in 1990, would not be opened as the terminus of the Yellow Line.

Alexandria Mayor Charles E. Beatley and other city officials have expressed concern that as an end-of-the-line station, Van Dorn would become a center for traffic congestion and unwanted commercial development.

Instead, they wanted assurances that funds would be available to extend the line to the Franconia-Springfield stop, scheduled for completion in 1994.

Beatley had threatened that the city would not pay its share of the Metro funding agreement until he received such assurances.

But Metro and Fairfax County officials were reluctant to make such an agreement with Alexandria that might leave the Van Dorn station built but unused for several years.

Before voting yesterday, Beatley said he was taking the action "in a spirit of reasonable cooperation," adding that "all of us have only one thing in mind and that is the long-term building of the line all the way to Springfield."

Council member Donald C. Casey, who is Alexandria's representative on the Metro board, said yesterday that it was still possible for some kind of compromise to be worked out on the Van Dorn opening.

"We do have six years before that station opens," he said.

"I feel we can work out a compromise if given time to do it."

He added that it could be done only "if we stop throwing grenades at each other in the press."

Beatley's threats had angered Fairfax County Board of Supervisors Chairman John F. Herrity, who at one point called Alexandria officials "bandits."

City Council member Robert L. Calhoun yesterday told the council that signing the interim capital contributions agreement, which will allow construction to proceed on an 89.5-mile Metro system, was urgent.

He said signing it would facilitate Alexandria's requests to Northern Virginia congressional representatives to push for a speedy authorization of federal funds needed to extend the rapid rail system beyond those 89.5 miles to its originally planned 101 miles.

Calhoun said that signing the pact also would make it easier for Alexandria to lobby state legislators for funds to help the city with its $11 million contribution to the Metro construction.

"That's something the state legislature ought to help us out with," Calhoun said.