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."

One of the architecture firms most savvy at designing urban streetscapes that are both comfortable and secure is Rogers Marvel Architects of New York City. Their designs for the New York Financial District have raised security to an art form.

The Stock Exchange and Wall Street (potential terrorist targets) are areas of dense foot traffic in lower Manhattan. After 9/11 (and temporarily again during the "Occupy Wall Street" protests), security barriers sealed off the street. The firm's task in 2004 was to restore public space while minimizing the risk of a potential incident. Their elegant, bronze-clad sculptural bollards (called "NoGos") are not only appealing but also muscular, able to stop a 15,000-pound truck traveling 50 miles per hour. For approved vehicular access, the firm designed perforated bollards that glow red or green to signal "stop" or "go" atop a turntable inlaid in the pavement. "Like your aunt's Lazy Susan," Robert Rogers says, the turntable and bollards rotate to grant passage when desired or impede it when necessary.

Another clever intervention is a "Tiger Trap" made of collapsible concrete installed near the World Financial Center. Adapted from arrestor beds used at the end of short runways in airports, the concrete is engineered to fail under the weight of a truck bomb but is invisible to pedestrians walking atop it on planting beds or plazas.

"The most interesting things are not what's been done before," Mr. Rogers says. "What they teach in architecture school is problem solving. That's the adventure of being an architect – where the intrigue and excitement lie."

The plan for a new US Embassy in London illustrates how a standoff zone does not mean standoffish design. The KieranTimberlake architectural firm of Philadelphia recently won the commission with their design for what James Tim­ber­lake calls "an urban building in an urban park." The building itself will be a see-through cube atop a colonnade, surrounded by curving paths, trees, berms, gardens, and a pond that acts as a moat. Instead of being foreboding, the blast-resistant glass and polymer skin of the building creates, Mr. Timberlake says, a welcoming, crystalline "beacon," an "open, transparent, sustainable icon of democracy." Timberlake calls the security requirement not a "constraint but an opportunity." By incorporating it in the design process rather than as an add-on or afterthought, he hopes their approach "will have a transformative effect on the expression and presence of barrier design."

Although the aesthetic appeal of buildings with these new design parameters isn't always impaired, public access is, which diminishes social cohesion and inclusiveness. Carol Willis, director of New York's Skyscraper Museum, laments how the flow of foot traffic has been reduced to funneling people single file to a checkpoint.

Destroying civilization to save it?

"Buildings are safer," Ms. Willis admits, "but against what? Airplanes crashing into them? That shouldn't be an engineer's problem." She would like to see – ideally – a return to fully free, public space open at all times to everyone.

"What's the point of protecting your civilization if you're going to destroy it in order to save it?" Mr. Kamin, the critic, asks. "We're talking about the effects buildings have, not just on their functions but on the spirit of people who encounter them every day. If they're dour and fortresslike, it casts a cloud over urban life, and that hands a victory to the terrorists."

"The design message you send," Hop­per says, "should not be totally contradictory with the architecture of the building, or the space and the democratic ideals we're looking to promote." More and more, architects are integrating physical security into holistic designs that are not off-putting but graceful and inviting.

"Security is not the most desirable thing, but it's become a fundamental thing," Rogers says. "We must engage it and make it an exercise that improves the public realm."