High-risk Buildings Placed In a Class All Their Own
In response to a heightened public awareness about terrorism, biohazards and other crimes since Sept. 11, building owners, in consultation with design professionals, are seriously considering and often providing more security for real and potential threats. They do this through design, technology and operation.
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| FUNCTIONAL DECORATION Instead of bollards around this pedestrian plaza, the designer integrated decorative yet protective obelisks into the Stevens Institute of Technology building in Hoboken, N.J., across the Hudson River from Manhattan. (Rendering courtesy of ©ECOPLAN) |
Security design extends well beyond the front door and the property line of a facility, as many potential threats can cover entire neighborhoods and, in the worst possible case, could involve a city. From unsecured manhole covers and underground water mains to grade-level air intakes and unauthorized loading dock vehicles, secure-building design anticipates potential loss and damage by protecting the site perimeter, building envelope, people and property.
Achieving an appropriate balance between the need for security, and the privileges that have accompanied relatively open access in society has been widely debated among design professionals and public officials even before the 1995 bombing of the Alfred P. Murrah Building in Oklahoma City. After the Sept. 11 terrorist attacks, acceptable levels of risk have been reevaluated, especially in New York City and Washington, D.C., where previously unimaginable security measures have become the norm.
As a result of Sept. 11, things previously not considered are getting scrutinized. For example, many institutions have removed "sensitive" material from their Websites to prevent it from being accessed and misused. In other cases, architects and engineers are utilizing tried-and-true methods for securing buildings in places never before considered.
SITE PLANNING 101
Building setbacks, or standoff distances, create protective building perimeters by restricting vehicular access. Distance between an explosion and its target allows the strength of the blast to be dispersed. Standoff distances vary by facility, location, risk and threat. They may be reduced in some situations if the site perimeter can be secured in other ways. Clear zones, free of traffic, are also desirable to optimize surveillance capability. Typically, a site analysis and threat assessment will determine how to maximize standoff distances. In suburban areas, 100 ft is considered a desirable standoff distance, although this is often unrealistic in urban settings. The standoff zone can also be combined with other devices such as bollards, plaza setbacks, landscaping, trees and boulders to restrict vehicular access.
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| SAFER HEAVEN For best protection, lobby and its structural and air systems should be independent of other building systems. (Drawing courtesy of ©RM Kliment & Frances Halsband Architects) |
"Motorcycles and small all-terrain vehicles can deliver explosives, but rock terracing or concrete retaining walls can be effective deterrents," says David Dixon, an architect with Goody, Clancy & Associates, Boston. "Hardened street furniture, such as benches, lights and large trees, can protect building perimeters while potentially reducing the need for deep setbacks."
Trees can improve protection by obscuring assets and people, but they also screen perpetrators from view. Cameras, for instance, can be discretely located in landscaping and are not incompatible with trees. "We see many creative security design opportunities for innovative public art, sculpture, security screens and vehicular barriers," says Frances Halsband, a partner at R. M. Kliment & Frances Halsband Architects, New York City.
Perimeter fencing is assessed as anti-climb and "anti-ram," depending on the nature of the threats, says Halsband, who advises the U.S. State Dept. and the Federal Reserve Bank on security issues. "We must be able to determine if a 10-ft fence will stop a high-speed vehicle," she says.
Providing a secure appearance can cause attackers to look for an easier target. "Locking manhole covers and monitoring tunnels and areaways regularly will protect exterior utilities, which are crucial when communications systems are among protected assets," says Denis I. Goeser, associate and senior project manager, Leo A Daly Co., Omaha. "With many clients dependent on computers and data to remain operational, protecting these systems, and redundant critical utilities, is essential."
After the Sept. 11 attacks, Stevens Institute of Technology, across the Hudson River from Manhattan in Hoboken, N.J., integrated site planning, design, technology and operational measures into its new Technology Management Building, says Martin G. Santini, president of Ecoplan, Englewood Cliffs, N.J. Santini added protective obelisks that limited access to all but emergency vehicles, as well as a street setback. He also enhanced the visibility of adjacent pedestrian paths, installed an entry card access system, and added a full-time lobby guard position.
All building penetrations are possible points for security breaches. Urban high-rises lacking standoff distances, and any other high-occupancy buildings vulnerable to threats, pose unique design challenges.
Protecting building services is a big problem. As a general rule, life safety services, such as gas, fuel, power and water supplies, should be remote from all high-risk zones or encased in blast-resistant coverings to maintain service.
Electrical transformers are also vulnerable. Sidewalk-mounted transformers may be damaged by vehicles, disrupting service. These transformers can be located inside buildings, eliminating the possibility that they will be accessed by those who are unauthorized. However, loss of rentable tenant space and associated revenue may not appeal to building owners, says Andy Hlushko, senior vice president of Flack + Kurtz, a New York City-based consulting engineer.
ENERGY OPTIONS
Alternate energy sources may be considered. In areas where steam and gas are available, owners might consider chillers that can be powered by different energy sources, although more space is also required. If one source of power is lost, a second type may be substituted. Most landlords prefer smaller chillers and mechanical rooms to maximize rentable area. But these considerations must be balanced against potential threats and risks, not to mention construction costs and life-cycle operating costs that also vary by client and location. There also may be situations where backup emergency generators should be considered. These also should be located some distance from each other.
Security of air intake vents is important, especially for high-rises and large sports facilities. For high-rise construction, air intakes located 50 to 60 ft above grade effectively prevent hazardous materials released at ground level from entering heating, ventilating and air-conditioning systems. A 50-story building with all outside air coming in from the top of the building will also safely disperse biochemical contaminants released at grade. Placing rooftop air intakes away from the roof edge, and concealing them, if possible, will also make it harder for would-be terrorists to contaminate building air supplies.
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REDUNDANCIES
Where security is high, designers should plan to provide redundant standpipes for firefighting. These should not be adjacent to each other. It may also be necessary to build two separate fire pump rooms and redundant sprinkler systems. Owners must weigh the costs of redundancy against the likelihood that a single fire suppression system might be destroyed.
In certain buildings, redundant fire alarm systems may be appropriate and well worth the cost, say designers. An international mixed-use development skyscraper includes two duplicate fire command centers at remote locations, and a code-required firefighters' elevator, says Hlushko. Both the main and satellite centers are fully equipped with all components tied to a common system. Fire command centers should be staffed around the clock and located in highly visible areas, such as lobbies, to provide additional security layers, he says. Fire alarm devices, such as data-gathering panels located every third floor, ensure amplification and power supplies are maintained.
Some buildings present users with such complex circulation patterns that in an emergency, even those who use them regularly, may have trouble finding their way out. Graphics that aid navigation are often an important addition to exit signage required by code. Exit stairs should not end in the building lobby because smoke, blast or biochemical hazards may be present in an attack.
Maintaining fire alarm and public address systems, with built-in testing and redundancy, is critical, say experts. Use of multiple speaker currents ensures that coverage remains if a circuit is lost.
Closed-circuit television is generally one element of a security plan. Videos are helpful during investigations, provided they have been stored. With digital cameras gaining in popularity, hardening of digital video equipment storage rooms with fireproof materials is becoming essential.
Some international fire codes, especially in Britain, London, Hong Kong, Malaysia and Canada, call for separate elevators for firefighters. These consist of two small, dedicated high-speed elevators per floor, rising the full height of the building. Sized for three or four firefighters each, the elevators exit into pressurized vestibules adjacent to the fire stair enclosure containing hose rack and communication equipment. U.S. fire professionals have a different philosophy concerning these special elevators, says Carl Galioto, partner in charge of the technical group in the New York City office of architect-engineer Skidmore Owings & Merrill.
The New York City Fire Dept., for example, says that with a power loss, elevators and fire alarm system calls to the street are unreliable, and thus will not approve a firefighter's elevator code provision. However, service elevators in high-rises may be designated for a similar function. These elevators should ideally be protected by a pressurized vestibule from the elevator lobby or direct access to the stair from the elevator lobby if a vestibule is not feasible.
Ongoing security R&D will continue to improve communications, surveillance, engineering systems and building materials technologies. Curtains that can prevent flying glass shards from injuring people, and new sensors for detecting biohazards activity are among the newest developments.
'ACCEPTABLE RISK'
Security specialists have put forth several recommendations for buildings with symbolic value or tenants who may attract terrorists. Naturally, adoption of these concepts depends upon a determination of what the client or building owner deems as "acceptable risk."
Lobby security is getting lots of attention. The area between the front door and screening equipment, similar to metal dectectors used by airports, is at risk. Security is left in the hands of lobby guards. The lobby should be an isolated zone, hardened with reinforced walls to protect adjoining areas from blast.
HVAC systems should be designed to ensure that smoke doesn't migrate from the lobby to elevator shafts and the rest of the building. Dedicated lobby HVAC systems and separate supply and return air systems, to isolate the public space in terms of air circulation from the rest of the building, would minimize certain risks posed by biological and chemical hazards let loose in lobbies.
"Private developers are reviewing lobby security standards so they can attract government tenants for commercial buildings and private corporate tenants seeking to meet government standards," says Halsband. Lobbies require a minimum of 600 sq ft for circulation, equipment and screening, she adds.
Building a new 600-sq-ft lobby addition is an alternative for older buildings with limited interior space. The new structure can be a welcoming pavilion, providing a secure entry to a hardened facility beyond. This design concept is appropriate for embassies and international buildings. It was used at the U.S. Mission to the United Nations in Manhattan, designed by Gwathmey Siegel & Associates, New York City.
The new tower includes a "sacrificial facade," consisting of an exterior wall, vertical air pocket behind it and another structural wall inside. The facade is designed to absorb blast impact and contain damage. It is a first line of defense for the tower's structural integrity.
Loading docks are higher risk areas than the front entrance because they provide an easier entry opportunity for truck bombs that can contain greater amounts of explosives. For those concerned about attacks, loading docks should be hardened–their walls, floors and framing reinforced. And, they should have good ventilation in case of a blast. Transformer vaults, electrical service, emergency power lines and fuel oil pipes, as well as critical life safety systems such as fire command and emergency systems, should not be located below or adjacent to loading docks.
Mail rooms and receiving areas in high-risk buildings should be located off the street and away from loading docks, with blast hardening and dedicated ventilation. Additionally, mail rooms should be segregated, not grouped with other back-of-the-house functions. Separate buildings for mail rooms, receiving and loading docks, especially in high- security zones, are another increasingly popular option. However, the cost of these measures can be high.
For high-risk buildings, basement parking should be restricted to occupants with identification. Hardening structure against blasts and emergency ventilation is also prudent.
It is encumbent upon design professionals and those who own and develop buildings to remain alert to the vulnerabilities of the built environment, and continue to consider solutions for protecting public health, safety and welfare of the public.