Conceding that Interstate Rte. 66 was the price exacted by Virginia Gov. Mills E. Godwin for the completion for the Metro subway system in Virginia. Secretary of Transportation Brock Adams reaffirmed yesterday the decision of his predeccessor to build the highway.

"My commitment is to the Metro system," Adams said. "If (Construction of I-66 from the Capital Beltway to the Potomac River) produces a Virginia commitment to Metro, then we should demonstrate our willingness to meet them halfway."

Although he said that Godwin had made no additional commitments to financial support of Metro in virginia, Adams said that he was "personally convinced of a change" in Godwin's attitude toward the subway system. Godwin, who once called Metro a "boondoglle," had "indicated to me his full support and continuing cooperation in completing the Metrorail system in Virginia," Adams said.

In additional, Adams said, Godwin has reaffirmed his agreement to the conditions to which former Transportation Secretary WIlliam T. Coleman Jr. tied his recent approval of I-66.

Calling the decision a "very difficult" one, Adams said that if it had been his decision to make "from the beginning, I might have decided it differently." But, he said, "it's been a very long process, it's gone on too long, and I think that's wrong in government decision-making."

The $170 million highway was first proposed in 1956.

Despite a number of pleas for an audience from groups on both sides of the I-66 issue, Adams said he had not consulted with any of the citizen groups or local governing bodies that have taken an active interest in the highway's fate over the years.

Such outside consultation, he said, "would taint the decision," making it necessary to reopen the long process of public hearings and documentation that has kept the highway a continuing controversy. Nevertheless, Adams said in an interview at The Washington Post, he would not be surprised to see his reaffirmation of Coleman's decision be contested in court.

James Govan, leader of the Arlington Coalition on Transportation (ACT), the group that stopped an eight-lane version of I-66 with a court suit nearly three years ago, was quick to confirm Adams' prediction. Govan said he had not expected a decision by Adams so quickly but he said he expects ACT's lawyers to file suit to stop the highway within the next two weeks.

"Mr. Adams has approved a bad project that will cost the paypayers more than just the Metro system would," Govan said. "It's very unfair to the citizens. They voted for Metro, they voted to pay for it, but they didn't vote for this highway."

Fairfax County Board Chairman John F. Herrity, who has been one of the most ardent advocates of I-66, praised Adams' decision."It's an absolutely fantastic victory for the people of Fairfax and Northern Virginia," Herritty said.

Virginia state highway authorities estimate that construction of te 9.7-mile highway extending from the Beltway in Fairfax through Arlington County, could begin as early as April.

Among the conditions on the highways construction that Adams reaffirmed are the inclusion of Metro in the I-66 median strip and virginia's preparation of the median strip to the extent that the only cost to Metro is the laying of the subway rails. In addition, Godwin agreed to transfer funds from the abandoned Three Sister Bridge over the Potomac River to Metro. These conditions will provide an additional $70 million to the Metro system.