"Early reactions were crude and overbearing in how they tried to secure the perimeter," says Leonard Hopper, a past president of the American Society of Landscape Architects. Sidewalks bristled with bollards, concrete jersey barriers (used to define lanes on highways), and precast planters called "bunkerpots."
Necessity becomes opportunity
Gradually, architects and landscape designers are transforming necessity into opportunity. "Any good architect is going to make lemonade out of lemons," says Jeff Garriga, an architect specializing in courthouse design with Finegold Alexander & Associates of Boston.
One sweet result of the bitter reality is the recommended 100-foot "standoff zone" between a new building and the curb (to keep bomb-laden vehicles at bay). The setback creates new public spaces, planted plazas for pedestrians. And while buildings themselves may be "hardened" with concrete cores, thick masonry walls, and wide stairways as escape routes, softer measures on the outside effectively accomplish the three D's of defense: detect, deter, and delay.
Adding landscape elements, creating serpentine access routes to "calm" traffic (to diminish ramming speed or a full-frontal assault), and grading terrain to create varied levels are all part of defensive site design. Better than bollards (both as public amenities and at protecting the perimeter) are trees, bicycle racks, berms, water features, kiosks, bus shelters, planters, flagpoles, and benches.
"The best time [to thwart a threat] is before you get to the X-ray machine in the lobby," says Mr. Hopper, who wrote the book on using landscape for security ("Security and Site Design: A Landscape Architectural Approach to Analysis, Assessment, and Design Implementation").