The "President's Square" -- that section of Pennsylvania Avenue in front of the White House -- should have been closed to private autos, but not to buses, long ago for reasons that have nothing to do with security. Since the end of World War I, we gradually have abandoned the L'Enfant avenues to the private automobile, with devastating consequences for the quality and efficiency of the city. If citizens could have known the consequences of that action in advance, it never would have been permitted. This practice should be reversed. That will take time; the Pennsylvania Avenue closing is a good place to start.

But the Secret Service deserves the harshest criticism for arrogating to itself dominion over a piece of the nation's capital city. Bureaucratic agencies such as the Corps of Engineers, the Federal Highway Administration and many others have left a record of destruction by assuming that complex design problems can be addressed by single-objective solutions.

For instance, removing buses from this section of the avenue is particularly damaging to city functions. Knowing that and viewing the problem in its natural complexity, the managing agency put buses in a separate security category from private autos and trucks. The suicide bombers in Israel demonstrate that buses provide individual terrorists with access to crowds. But total security is not possible. A terrorist might pack on his person enough explosive energy to destroy himself and a crowded bus. But to damage a building more than 200 feet away may require a magnitude of explosives that can be carried only in a vehicle.

The National Park Service and the National Capital Planning Commission, both agencies that should know better, deserve similar criticism. For the Park Service to treat the problem as the decoration of a strip of avenue violates what should be its commitment of design in the large. Ignoring half the traffic problem is a case in point: The westbound movement on E Street south of the White House can be reconstructed easily without danger to the president.

This is an urban design problem (which means it is complex by definition), a traffic problem, a security problem and, above all, a problem in national symbolism.

JOSEPH PASSONNEAU

Washington