THE PANEL of 14 top architects, historians, planners and sculptors meeting this week on the design of that closed section of Pennsylvania Avenue in front of the White House can do the nation a great favor. Instead of producing plans to transform the strip in front of the White House permanently, they should consider only design ideas that will allow the avenue and the perimeter of Lafayette Park to be reopened and restored to their traditional and historic role as a grand street of the nation's capital. "America's Main Street," as Pennsylvania Avenue is known, has been converted to a sidewalk by fear. That is a concession to terrorism that should not be made permanent.

Two world wars did not close Pennsylvania Avenue. Neither did the Civil War or past attempts on presidents' lives, as the White House itself has noted. The avenue stayed open despite a British invasion, and despite street riots in the 1960s. But now, because of the devastation in Oklahoma City, the history of Pennsylvania Avenue may be erased by bulldozers. Sections of asphalt in front of the White House would be ripped up and replaced with grass, concrete planters and guard stations would proliferate, and the president's ever-expanding protective cocoon would grow beyond the White House fence. Some federal officials believe that a $1 million face lift with movable steel barricades will soften the harshness of what they intend to do. It will not. Do as administration planners want, and the president goes from living on a street connected by a broad avenue to the Capitol to living in a fortress surrounded by a huge park. Where will the line be drawn?

No one argues that the security of the president is not a paramount concern. But there is a question as to whether this kind of cordoning off of the White House in perpetuity is a proper or proportionate precaution to take. Closing off Pennsylvania Avenue for good would be an expression of defeat. The space that the government's planners would convert forever to a secure park is a street. It should remain one.