Three U.S. Appeals Court judges appeared baffled and incredulous today at suggestion that they should, for a second time, block construction of Rte. I-66 across the Virginia suburbs toward Washington.

"You think they ought to close off all entrances to the city?" asked Circuit Court Judge Donald S. Russell, a former South Caroline governor, who seemed to be puzzled by the dispute.

He wasn't alone. "Something's wrong here," snapped Judge H. Emory Widener Jr., the only Virginian on the foree-judge panel. What was wrong, Widener made clear, was not the state's proposal to build the four-lane, limited access road from the Capital Beltway in Fairfax County to near the Theodore Roosevelt Bridge across the Potomac.

What was wrong he said, was the suggestion by the road's opponents that Virginia not build the road and turn over the highway construction costs, about $200 million, to the Washington Metro subway system. "They don't build Metro with highway funds, you know that," he told Gary D. Wilson, lawyer for four civic groups fighting the highway. (In fact, millions of dollars of federal highway funds have been transferred to Metro construction.)

Today before the fourth U.S. Court of Appeals Wilson's argument found little, if any sympathy from the three judges who had been hurriedly assigned to the case late yesterday. Although the judges did not issue a formal opinion today, their comments and critical questions left little doubt that the state will be free to continue building the road until at least October.

Assuming the same judges are assigned to review the entire I-66 case then, it would also appear that the opponents will have great difficulty getting the court to disapprove the highway. There were times today when the judges seemed already convinced of the road's benefits, as Russell told Wilson at one point: "Why do you not want more people to have easier accress to your city?"

Wilson refused to concede the case after the 90-minute hearing, but his remarks made clear his concern. "I hope on reflection they will change their opinion," Wilson said. He said the opponents will not appeal an adverse ruling that allows the present construction to continue.

Even with the "expedited hearing" the judges agreed to grant the I-66 opponents, the highway department should be well along with construction of the first 1.5-mile segment of the road and have advertised for bids for a second 1.75-mile section of the highway by the time of the next court hearing, probably in October.

Wilson's case seemingly boiled down to an issue between trees and money. To claims that 100-year-old trees were being toppled, an assistant state attorney general Valentine W. Southall Jr., argued the state faced sharply escalating construction costs if work on the highway were delayed again.

Judge Widener, who comes from the town of Abingdon in Virginia's rural southwest corner, clearly was impressed by those arguments and the state's claims that it had purchased some of the unused right of way for the road 17 to 18 years ago. "Somebody's got to be paying the interest on that money . . ." he sharply toldWilson at one point.