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After Sept. 11


Terror-proofing America

Architects want safe structures without creating a fortress mentality

By Anthony Flint, Globe Staff, 7/30/2002

A series of occasional articles about security, buildings and cities after Sept. 11.

Part 1
Safeguards in cities could get new look

Part 2
Architects want safe structures without creating a fortress mentality

Part 3
Sept. 11 pushes firms to suburbs

Rigidity and resilience: Engineers are designing new buildings to block a terrorist's destructive mission, while providing easy escape for occupants in an emergency.


The Security Infrastructure Partnership

American Society of Civil Engineers

National Fire Protection Association

Federal Emergency Management Agency

The National Institutes of Standards and Technology

Institute of Structural Engineers

American Society for Industrial Security

American Institute of Architects

American Association of Engineering Companies

Building Owners and Management Association

horter, stronger, more resilient. Less apt to break into shrapnel in an explosion. Harder to get into, but easier to get out of.

In the future, buildings seen as at risk for terrorist attacks will be designed with those guiding principles in mind, according to architects, engineers, security professionals and fire-safety officials, all currently immersed in the complex business of terror-proofing the built environment.

Garden walls and park benches can be ''hardened'' to stop an explosive-laden delivery van in its tracks. Shatterproof glass and rubber coating on concrete walls minimize the flying debris that injures as many occupants as any initial blast. Columns and beams can be designed so buildings stay standing even if one piece of the structure collapses. And fireproofed elevators and wider stairwells help move large numbers of people in a hurry.

The task of making buildings stronger and safer has been around as long as there have been earthquakes and fires, and was given new urgency after the bombing in Beirut in 1983 and Oklahoma City 12 years later. But, after the attacks on the Pentagon and the World Trade Center nearly a year ago, the goal for potential terrorist targets has never been clearer: Protect them, stave off a total collapse in the event of an attack, and allow large numbers of people to get out all at once.

The fortifying of the nation is seen as a kind of last line of defense in homeland security - a rethinking of the design of physical structures, in contrast to procedural changes within existing systems, such as immigrant screening or examining airline baggage. The families of victims of Sept. 11 are calling for structural changes to complement new evacuation procedures in major buildings, in anticipation of another attack.

Yet the effort is anything but simple, rife with concerns about a fortress mentality that will diminish the vibrancy of urban areas, as well as basic questions about the cost-effectiveness of design changes that could cost billions, with no guarantees and perhaps only limited protections.

''We need to make the right changes, and give it careful thought,'' said Jonathan Barnett, a professor at the Center for Fire Safety Studies at Worcester Polytechnic Institute.

David Dixon, architect at Goody, Clancy in Boston and president of the Boston Society of Architects, said caution is also warranted because security measures could end up hurting cities, if business and government functions retreat behind a new kind of gated community.

''It's a bit like the windowless schools that were built in the '70s as a response to the energy crisis. There's no point in going overboard, or being one-dimensional in our thinking,'' Dixon said.

The design changes being discussed by architects, engineers and fire-safety and security professionals are not for every building, but rather for government facilities and other high-profile, high-occupancy buildings that have been identified as possible terrorist targets, said John Roberts, past president of the Institution of Structural Engineers, based in the United Kingdom, which this month published 20 ways to make tall buildings safer.

Nor is the discussion limited to how buildings like the World Trade Center could possibly survive the impact of fuel-laden jets, Roberts said. The basic issue, he said, is preventing ''progressive collapse'' - when an entire structure fails after a portion of it is destroyed, however the explosive device is delivered. This can be done by making the structural framework flexible enough so huge amounts of energy can be absorbed if necessary, and by designing ''alternate load paths,'' which redirect sudden changes in the load or weight of a building, from the top to the bottom.

Engineers are already making changes in the designs of tall buildings in Asia to anticipate these sudden, extraordinary shifts in loads. ''It's not that we can't do these things; it's just that no one ever thought it was necessary,'' Roberts said.

Small changes in structural components can make a huge difference, said Barnett, an investigator for a report on the collapse of the World Trade Center released in May by the Federal Emergency Management Agency and the American Society of Civil Engineers. A diesel pipe near a key vertical-to-horizontal transfer of load on the fifth floor of 7 World Trade Center apparently worsened the inferno there and eventual collapse, he said. The solution: Don't put fuel pipes near critical structural junctures.

Minimizing destruction in the event of an explosion can be achieved in numerous low-cost ways, said Norman Glover, who represents a group called The Infrastructure Security Partnership and has done extensive antiterrorism work. Shatterproof or laminated glass, as well as window frames that don't hurl through the air in one deadly piece, can reduce casualties enormously, Glover said. Also worth changing, he said - the materials in dropped ceilings, duct hardware, and Venetian blinds, which turn into flying razor blades in a blast. Heavy-fabric ''blast curtains'' and rubber coating on concrete walls can also catch and contain debris before it has a chance to get airborne.

Technology plays a big role in other measures. Sensors can be attached to key junctures in the structural framework of buildings to warn of an impending collapse. As a preventive measure, air-intake ducts in sensitive buildings can be equipped with monitors to detect the introduction of biological or chemical pollutants, triggering a shutdown of ventilation systems.

Engineers and security professionals are reluctant to elaborate on this and other tactics for fear of giving terrorists clues on the locations and workings of such systems.

Fire protection is also being scrutinized. The sprayed-on fireproofing in the World Trade Center was knocked off by the impact of the jets, leading to calls for tougher materials and more adhesive application - and, more generally, the use of reinforced concrete over steel. Water-supply systems for spinkler systems should be better protected with ''hardened'' and redundant ducts, engineers say, and the same goes for emergency communication and utility lines. Another step being considered is putting the emergency command center outside of major buildings, so it can't be taken out of action in a major event. But consensus is elusive, for example, on the issues of requiring both elaborate fireproofing and terror-proof sprinkler systems.

Designing buildings to accommodate new emergency evacuation procedures - currently the subject of radical rethinking - is also a priority, said Arthur E. Cote, executive vice president and chief engineer at the Quincy-based National Fire Protection Association.

Occupants of tall buildings have historically been told to remain on unaffected floors in fires, or move from one part of the building to another, a strategy known as ''defend in place.'' After Sept. 11, buildings may be designed for total evacuations all at once - requiring wider and more numerous stairwells, spaced well apart. The policy of not using elevators in an emergency also may be changed, if shafts and electrical systems can be built to withstand an explosion and fire.

Other means of egress are also being considered for tall buildings, whether through rooftop evacuations or the distribution of personal parachutes or escape chutes, which drop people down from upper floors slowly, like a mouse going through a snake.

And while buildings of the future will be designed to escape from quickly in an emergency, they must also be designed to serve an opposite function - making it harder for terrorists to approach and infiltrate in the first place. In the near future, park benches and drinking fountains reinforced with steel will replace Jersey barriers, all along the perimeter of the front yards of sensitive buildings. Landscaping such as raised, planted plinth walls will be another barrier to truck bombs, in 50-feet ''standoff'' zones between the building's front door and the street. Lobbies are increasingly being extended out as satellite pavilions, so entrants can be screened away from the main building - and suicide bombers can do less damage.

Several of these protective measures are already required in foreign embassies and new federal buildings, prompted originally by overseas bombings and Oklahoma City.

Somerville-based architect Moshe Safdie, who designed the new federal courthouse in Springfield, and the new Alcohol, Tobacco and Firearms headquarters in Washington, said the challenge in meeting the requirements was to build these places as strong as a fortress ''without making them look like a fortress.''

Safdie added that ''design will only get you so far,'' noting that at Ben Gurion Airport in Israel, which he redesigned, the trained personnel watching over everything are more important than any physical configuration.

Architects laboring under layers of fire and building codes and the Americans with Disabilities Act are generally wary of more restrictive requirements. Both the National Institute for Standards and Technology and the National Fire Protection Association are expected to issue recommendations on safety that could ultimately be adopted as codes. A better option is to evaluate each building on a case-by-case basis, which is known as performance-based design, said Robert Cizmadia, director of security at the engineering consultanting firm Gage-Babcock & Associates. Blending security and design, he said, will be '' a whole new ballgame, based on trial-and-error.''

Beyond the issue of codes, the most contentious area of the current debate is how ''safer'' buildings fit into the larger urban context, said Jeff Soule, policy director for the American Planning Association. If signature buildings in downtowns are all set back 50 feet from the street and have single checkpoint entrances that discourage free circulation, he said, ''we might as well put them out in a cornfield surrounded by razor wire.'' Soule is a founding member of the Security Design Coalition, which plans a major conference in September on how to blend safety and urbanism.

Architects and planners are worried about how security measures will affect cities because they are promoting cities as an alternative to new suburban developments that contribute to sprawl.

Still, while the ramifications of some protective security measures are studied, other immediate steps should be taken - to keep buildings standing in the event an explosion and subsequent fire, said Roberts, head of the engineering consulting firm, the Babtie Group.

''You can't fully protect any building, but we can do better - now we know what the game is,'' he said. ''If you can stop a building from fully collapsing, and secure the escape routes, that's the best we can do. We might as well do it, and I think we have a duty to do it.''

Anthony Flint can be reached at flint@globe.com.

This story ran on page C1 of the Boston Globe on 7/30/2002.
© Copyright 2002 Globe Newspaper Company.