Designing for disaster

"Something there is that doesn't love a wall," a Robert Frost poem begins. As the glee greeting the downfall of the Berlin Wall proved, this feeling is especially true for public spaces. But in a post-9/11 era when security concerns dominate, walls are rising, not falling.

"We've gone from being America the beautiful to America the besieged," says Blair Kamin, architecture critic for the Chicago Tribune and author of "Terror and Wonder: Architecture in a Tumultuous Age."

The mission facing architects today is fusing aesthetics and armor. In the aftermath of attacks on US embassies abroad, the 1995 truck-bombing of the Murrah Federal Building in Oklahoma City, and the 2001 terrorist takedown of the World Trade Towers, guidelines for government buildings and other potential targets such as museums and monuments assumed a quasi-military character. Architects had to grasp new concepts like ballistic-resistant design, learn new terms like "hostile-vehicle mitigation," and employ new products like blast-resistant glass. No longer is it enough to protect against rain, snow, wind, and fire; the architect's brief now includes minimizing threats from at-tackers. The challenge is to design defensively without offending aesthetically.

Architectural first responders erred on the side of bulk, converting vulnerable public spaces into fortresses.

"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").

The National Museum of the American Indian on the Mall in Washington is a successful example. Cantilevered, curving bands of rough-cut limestone project 50 feet from the body of the building, protecting the east entrance from a crash attack. The sidewalk, which is elevated above the street, acts as another unobtrusive barrier, while nonlinear paths, pools, watercourses, and planted mini-grasslands and wetlands are a veiled – and beautiful – form of defense.

"Nothing is more important to security than people," says Hopper. The more that public amenities lure people to the street, the more this activity creates inherent security, something urban theorist Jane Jacobs called "eyes on the street."

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