With impressive unanimity so far, all sorts of federal and regional authorities have concluded that the Secret Service's thought of maybe banning traffic along Pennsylvania Avenue in front of the White House is a singularly bad idea. Even some of the most security-conscious authorities have concluded that as protections go, this one's a bomb; that it just might invite more terrorists than it would deter. Is there still anyone in the White House who thinks the idea has possibilities? Outside those gates, anyway, the rave notices are nowhere in evidence.

FBI Director William H. Webster, for one, noted that "sometimes excessive security actually invites trouble." Elaborate measures could be a victory for terrorists, Mr. Webster said, who might get the impression that the United States had been forced into "a siege mentality." This could produce "a sense of having achieved success without having to run any risks." Effective security measures should be as inconspicuous as possible, the director points out.

Officials from all around the region agree that, as security measures go, this one should be a goner. Virginia House of Delegates member Marian Van Landingham of Alexandria took a royal view of the plan, calling it "another step toward the imperial presidency." D.C. Council member H. R. Crawford, this year's chairman of the Metropolitan Washington Council of Governments, termed the idea "somewhat shocking," said it would be "extremely damaging" to downtown traffic and added that the plan reflects "a fortress mentality."

The Council of Governments -- representatives of every local government in the region -- then unanimously approved a resolution calling for consultation with the Secret Service, the White House and other agencies before making any move to curb traffic on Pennsylvania Avenue.

How serious is the Secret Service about this, anyway? A spokesman now says "there's no concrete plan yet." If one materializes, concrete wouldn't be a bad wrapping for it -- before it's deep-sixed over the side of the 14th Street Bridge.