Proximity’s Price

This April 19 marked the ninth anniversary of
the morning in 1995 when a truck parked at the curb a stone’s toss away
from the Alfred P. Murrah Federal Building in downtown Oklahoma City
erupted in a gigantic explosion. The blast was heard 20 miles away and
carved a crater eight feet deep and 30 feet wide. The 4,800 pound
fertilizer bomb in the truck destroyed one-third of the nine-story
building from the roof to the ground, killing 168 people and injuring
over 500.

Fourteen months later, on June 25, 1996,
another powerful bomb concealed in a truck exploded in front of Khobar
Towers apartment building 131 near Dhahran, Saudi Arabia. Parked 80
feet away from its intended target, it exploded with the force of
20,000 pounds of TNT, drilling a 50-foot wide by 16-foot deep crater
and peeling open the face of the building, which housed American,
Saudi, French, and British troops, killing 19 and injuring more than

Both bombs caused tremendous devastation and
loss of life and proved that bombs don’t have to be placed within their
targets—proximity is enough when it comes to wreaking havoc.

But while terrorists have learned that being
nearby is near enough, security professionals have also learned
something about the danger of proximity bombs and how to protect
vulnerable buildings from them. From the broadest perspective, both the
Department of Defense (DoD) and civilian authorities learned they
needed more money, more people, better intelligence and advanced
technology for protection and response to terrorist attacks against
important civil and governmental structures.

And they learned some very specific lessons as well.

Glass missiles

Looking at side-by-side photos of the
destroyed portions of the Murrah and Khobar Towers buildings, the
devastation is similar.

In both the Murrah and Khobar building
bombings, most fatal injuries were the result of the “progressive
collapse” of the buildings.

However,the Oklahoma City Health Department
concluded that the primary cause of most nonfatal injuries was caused
by blast-generated debris, mainly glass fragments. The new Oklahoma
City federal building, consequently, makes extensive use of safety
glass. At Khobar Towers, flying glass was the leading cause of nonfatal

Robert Newberry, Principal Deputy Assistant
Secretary of Defense for Special Operations and Low-Intensity Conflict
at the time of the Khobar Towers bombing, explained in testimony before
Congress that the Department of Defense, as well as the federal
government, must “look at structures that don’t fall apart when a bomb
goes off near them. You look at the glass, the windows. You look at the
design of the building. That doesn’t mean we redesigned every base
house or every building on the base, but we looked at those areas that
we thought were vulnerable where you could have mass casualties.”

The prevalence of injuries from flying glass
in the event of a terrorist bombing was recognized prior to the Khobar
Towers attack. In his July 1997 report on the bombing, then-Secretary
of Defense William S. Cohen pointed out that “the Command’s decision
not to install Mylar (a shatter-resistant coating) on the windows in
Khobar Towers” was “contrary to an express recommendation in a
vulnerability assessment on Khobar Towers prepared six months before
the bombing.”

While Mylar wouldn’t have prevented the vast
majority of the fatalities, which were caused by the building’s
collapse, it would have reduced the injuries from flying glass. DoD
subsequently issued two technical reports addressing the issue of
glass: “Blast Resistant Tempered Glass Windows,” and “Windows Retrofit
Using Fragment Retention Film with Catcher Bar System.”

“Glass is a major hazard in any blast,” says
Ed Conrath, a specialist in blast resistance at the U.S. Army Corps of
Engineers’ Protection Design Center (PDC) in Omaha, Nebraska. “If a
blast occurs, the majority of injuries occur because of glass…If we can
put in better glass and anchor it better at a nominal cost increase,
we’ve gone a long way toward solving the injury problem.”

Conrath brought the industry up to date at
the Protective Glazing Council’s (PGC) National Symposium, Protective
Glazing Solutions for Homeland Security, in 2002.

Although protective glazing is not an
especially exciting or glamorous industry, it is vitally necessary as
an integral component of the war on terrorism. Blast resistant windows
retrofitted prior to Sept. 11, 2001 in portions of the Pentagon helped
save lives that day. The use of protective glazing technology for the
building was originally intended to protect against an external blast.
Instead, the glazing protected against an internal explosion expanding
outward when American Airlines Flight 77 hit the building. The
retrofitted windows directly adjacent to the point of impact remained
intact while old windows in Wedge 2, approximately 150 feet away,
shattered from the force of the blast.

Installing windows constructed of tempered,
laminated, or other protective glass, or installingKevlar blast
curtains, are techniques that should be used in the design of new
buildings or to retrofit existing buildings, according to, “Lessons
from the Oklahoma City Bombing: Defensive Design Techniques,” published
by the American Society of Civil Engineers (ASCE).

Structural changes

The Oklahoma blast penetrated deep inside the
Murrah building, catastrophically damaging the main horizontal
load-bearing crossbeam between the second and third floors. This
crossbeam supported vertical pillars stretching from the third floor to
the top of the building. The blast also severed vertical columns
located deeper within the building. As these supports were destroyed,
the northern third of these floors collapsed.

The Murrah building bombing was intimately
re-scrutinized by the Federal Emergency Management Agency’s (FEMA)
Building Performance Assessment Team (BPAT), with the Khobar Towers
bombing in mind. The BPAT’s mission was to investigate commonalities in
the damage caused to both buildings by the explosions. The team
included engineers from FEMA, the U.S. Army Corps of Engineers, the
General Services Administration (GSA) and the National Institute of
Standards and Technology (NIST).

“The purposes of the investigation were to
review damage caused by the blast, determine the failure mechanism for
the building and review engineering strategies for reducing such damage
to new and existing buildings in the future,” explained Dr. W. Gene
Corley, the leader of the BPAT team. “Specifically, mechanisms for
multi-hazard mitigation, including mitigation of wind and earthquake
effects, were considered” in the bombing investigation. “Among the
strategies evaluated were procedures and details provided in FEMA’s
1994 edition of, “National Earthquake Hazards Reduction Program
Recommended Provisions for Seismic Regulations for New Buildings.”

The BPAT investigation culminated with the
report, “The Oklahoma Bombing: Improving Building Performance through
Multi-Hazard Mitigation,” jointly published by FEMA and ASCE. This
report made specific recommendations concerning the design and
construction of new federal buildings, and provided mitigation
recommendations for existing federal buildings.

“One of the key findings from our team’s
report was that if the 1976 Murrah building had been built using
today’s seismic building design details, as much as 50 percent to 80
percent of the structural damage, and presumably the fatalities, could
have been prevented,” Corley said. “The resulting additional
construction costs would not have been millions, but a few thousand

“It is important to understand that the bomb
blast to the Murrah building was not devastating by itself—it just so
happened that it was located at a critical point which undermined the
whole structure of the building. What we discovered as a result of our
investigation was that most of the damage and a vast majority of the
fatalities were caused by the progressive collapse of the building.”

Corley explained that “the Murrah building
had what is called an Ordinary Moment Frame design, which is typical of
most office buildings not located in earthquake-prone areas. With this
design, if a critical element of a building fails, it may start a chain
reaction of successive failures that will take down the building. So
when the bomb blast destroyed three key columns supporting the Murrah
building, the floors progressively collapsed and stacked on top of each

“Analysis of the Murrah building showed that
it would have been impossible to design the building to remain standing
with one of its critical columns destroyed by the blast through the use
of brute strength alone. However, calculations show that if the
additional amounts and locations of reinforcing steel called for in a
Special Moment Frame had been used, the Murrah building would have had
enough toughness and ductility to prevent about half of the damage.
That is, even though the individual columns and slabs wouldhave been
damaged, the reinforcing steel would have held many of the building
elements in place, keeping large portions of the building erect—at
least sufficiently erect to allow the occupants to escape after the

By 1998, when Dr. Corley brought Congress up
to date on the lessons learned from structural bombings, there still
was “no single authoritative document…to provide definitive guidance to
an engineer on mitigating the effects of blasts,” he said. “Although
the body of knowledge is growing, it is only through the development,
adoption and use of a consensus standard will we be able to achieve a
uniform approach to mitigating the effects of blasts.”

The importance of planning

Nothing emerged more clearly from all of the
lessons learned in Oklahoma City than the degree to which contingency
planning contributes to an effective response. From clergy to
firefighters, from the schools to the Chamber of Commerce, everyone
agreed on the need for careful planning to be able to swiftly,
efficiently and effectively respond to terrorism.

“Successfully managing and exploiting the
flow of information is the key to managing any enterprise of the size
and complexity of the Oklahoma City bombing response, and the
information demands are heavy for both organizations and individuals,”
stated the Oklahoma Department of Civil Emergency Management’s After
Action Report. “Implementers need to know their respective roles and
responsibilities. Managers need to know what tasks are being undertaken
and who is undertaking them. They also need to know which tasks have
yet to be completed, and what assets are available to get critical jobs
done. They must also have the ability to direct available assets to
undertake assignments necessary to complete a specific task.”

Given the urgency of responding to a
terrorist incident swiftly and accurately, “Not only are the
information requirements demanding in this type of operation, the
requirements need to be met almost instantaneously,” the report noted.
“Successfully exploiting information and meeting communication
requirements not only facilitate the response to an act of terrorism,
but also serve critical roles in deterring future acts of terrorism and
facilitating planning and preparedness efforts should deterrence fail.”

Indeed, Jonathan H. Coffer, the Army
brigadier general who at the time of the Khobar Towers bombing was
Deputy Director for Operations [combating terrorism] on the Joint Staff
came to the same conclusion, telling the House Armed Services Special
Oversight Panel on Terrorism that “comprehensive response plans for
incident damage mitigation” and “Weapons of Mass Destruction (WMD)
response capabilities” are essential.

Both Oklahoma City and DoD stressed the need
for planning and training and pointed out its lack in both instances.
As Cohen pointed out in a 1997 report on Khobar Towers, “no model was
in place…to guide [anyone] in how to respond to and what to expect from
victims of terrorism… .”


Authorities interviewed agreed that the
extensive post-incident investigations of the Murrah and Khobar Towers
bombings, because of their unique similarities, present authoritative
lessons, from structural design to first responder preparedness, for
both civilian and military facilities that are attractive terrorist

Following the recommendations of these probes
will strengthen ongoing security and mitigation efforts. Unfortunately,
as congressional, civilian and other experts have noted, incorporation
of these lessons has not been as widespread as it should be. The newly
constructed federal building in Oklahoma City remains the only domestic
government structure that meets modern construction security protocols
learned from its predecessor and Khobar Towers’ destruction by bomb.

Until the Department of Homeland Security and
Pentagon act to more thoroughly employ recommended changes in
construction and incident response techniques, they will continue to be
vulnerable.  HST

From fertilizer to fury

During the 1980s, when the United States and
Pakistan were supporting Afghan guerrillas against the Soviet Union,
American instructors trained the mujahedin fighters in hit-and-run
tactics and unconventional warfare.

As part of that effort, the U.S. Defense
Intelligence Agency (DIA) conducted a secret program to train the
mujahedin in the art of unconventional warfare, including training them
to construct fertilizer bombs—huge plastic barrels containing a highly
combustible mixture of ammonium nitrate and fuel oil.

On February 26, 1993, at approximately 12:18
pm, veteran Afghani mujahedin linked to al Qaeda detonated an
approximately 1,200 to 1,500 pound fertilizer bomb on the second level
of the World Trade Center parking basement. The resulting blast
produced a crater 150 feet in diameter and five floors deep.
Approximately 6,800 tons of material was displaced by the blast.

The bomb that brought down the Murrah federal
office building in 1995 was also a fertilizer bomb, this time weighing
in at 4,800 pounds of combustible material.


Shoring up the targets and
learning from the past

Following the Oklahoma City and Khobar Towers
bombings, the Oklahoma City-based National Memorial Institute for the
Prevention of Terrorism (MIPT), the U.S. Army Corps of Engineers’
Protective Design Mandatory Center of Expertise (PDMCX), and the U. S.
Army Engineer Research and Development Center, began working to ensure
that the lessons learned from not only the attacks on the Murrah and
Khobar Towers buildings, but other military, government and civilian
facilities that have been ravaged by terrorist bombs, are integrated
into planning, construction, protection and response.

Established with congressional funding in
1997 “to prevent terrorism on U.S. soil or mitigate its effects,” MIPT,
now funded by the Department of Homeland Security, is finishing work on
an interactive 3D simulation of the Murrah building bombing. It is
founded on the database of injuries sustained in the blast that were
meticulously catalogued by the Oklahoma State Department of Health
(OSDH). Impressed with the OSDH’s work, the department was tasked by
DoD to study how the occupants of the Khobar Towers were killed and
injured as part of the Pentagon’s official study of that bombing with
the purpose of planning anti-terrorist building construction and
incident response.

When completed, the OKC Bombing Injury Study
(OBIS) simulation will provide researchers and investigators with a
structured, graphical “standard of blast injury database.” This
immersive 3D environment will allow users to visually navigate through
the Murrah building from the moment of the blast through its aftermath
to study how death and injury occurred. General (Ret.) Dennis J.
Reimer, the former Army Chief of Staff who directs MIPT, explained that
the simulation will be invaluable for understanding lessons learned in
order to improve building security andsite hardening.

A non-graphical database compiled on the
Khobar Towers bombing by DoD has been offered to MIPT, which Plans and
Special Projects Officer Jim Gass and external affairs director Ken
Thompson said is being evaluated to determine whether it, too, can be
incorporated into the OBIS simulation.

Thompson said MIPT is excited about the
opportunity to make use of the Khobar Towers database, but cautioned
that the data may not be easy to integrate. “We’ll just have to look at
how the data is formatted—whether it is compatible to the degree that
it can be merged” without significant software development and expense

Nevertheless, plenty has been learned about
both bombings. This vast knowledge base, as well as information gleaned
from other bombings and terrorist acts, have and are being integrated
into a variety of “lessons learned” products produced by MIPT and the
federal government that are specifically tailored for everything from
construction of more bomb-resilient buildings to what first responders
need to know to respond to the bombing of a large building complex.

MIPT’s intent is to transform the OBIS
database into a powerful 3D database in order to make the software more
readily available and affordable to researchers and agencies that need
a structured graphical database standard of blast injury data. This
software, which advances beyond present 2D exterior blast models into
3D interior models, is useful in understanding lessons learned from
past incidents in order to improve future building security and site
hardening, and better understanding of the types of injuries that can
be expected from a bomb and where specific types of injuries are most
likely to occur.

Although the OBIS database is an important resource, and already has
been used to support a number of studies, distribution and use of the
database is not as widespread as it could be because the cost of the
graphical software used to access the data is prohibitive to many
users. Many researchers have algorithms for blast analysis but no
geographic interface. This creates problems in referencing the OBIS
graphical database.

Not fast enough

Following a study of the 9/11 attack on the
Pentagon, experts again recognized that there was a need for extensive
research and development in progressive collapse and extreme lateral
column response. Structural security issues were addressed. They were:

  • Consolidation of information on prevention of progressive collapse
  • Influence of extreme column deformations on load-carrying capacity
  • Influence of extreme column deformations on loads within a statically indeterminate structure
  • Energy-absorbing capacity of reinforced-concrete elements
  • Ability of a structure to withstand extreme impact

In the aftermath of the Oklahoma City
tragedy, President Clinton established a task force to review federal
building vulnerability. The task force consisted of representatives
from the US Marshals Service, Department of Justice (DoJ), General
Services Administration (GSA), Department of State, Secret Service, DoD
and FBI. Upon completing a nationwide review of security within the
federal office building inventory in the United States, the group
issued a final report, Vulnerability Assessment of Federal Facilities,
also known as “the DoJ Report,” on June 28, 1995. It recommended
government-wide security standards for federal facilities, and provided
the basis for GSA to implement a costly nationwide security enhancement

Several monthslater, in October, the
Interagency Security Committee (ISC) was established by Executive Order
12977. It has three primary security responsibilities for nonmilitary
activities: establish policies for security in and protection of
federal facilities; develop and evaluate security standards for federal
facilities; develop a strategy for ensuring compliance with such
standards and oversee the implementation of appropriate security
measures in federal facilities; and take the necessary actions to
enhance the quality and effectiveness of security and protection of
federal facilities.

The report called for each federal facility
to be enhanced with a minimum set of security standards based on
specific security needs and requirements. It also recommended that
security upgrades first be addressed by building level security
committees (BSCs). The resulting building-by-building evaluations were
to be reviewed and assessed by GSA. Buildings are now categorized along
four levels; Level IV is the highest in terms of building security,
Level I is the lowest. Each Level IV building must establish a Building
Security Committee, composed of federal employees, Federal Protective
Service officers and union representatives who are charged with
reviewing and assessing existing security measures and making
recommendations to meet minimum standards as outlined in the DoJ Report.

Despite these requirements, by Sept. 2002, a
year after the 9/11 attacks, the ISC was found to have “had limited
success in fulfilling its responsibilities,” the General Accounting
Office (GAO) concluded following an audit. The “ISC has carried out
some elements of its responsibilities, but it has made little progress
on several other assigned responsibilities,” it reported.

The GAO informed a dismayed Congress that the
“ISC has made little or no progress in other elements of its
responsibilities, such as developing and establishing policies for
security in and protection of federal facilities, developing a strategy
for ensuring compliance with security standards, overseeing the
implementation of appropriate security in federal facilities, and
developing a centralized security database of all federal facilities.”

For nearly a decade, however, the GAO had
reported in numerous audits that the security of federal buildings,
both domestically and abroad, was inadequate. Security at State
Department buildings was especially hampered throughout the early 1990s
due to significant budget cuts. These in particular dramatically
impacted foreign US building security, according to classified State
department memos on the matter made available to HSToday. These
deficiencies didn’t begin to be addressed until after the Murrah and
Khobar building bombings—and even then, only well into the end of the

By late 2001 there were still problems, as the House Special Oversight Panel on Terrorism learned during a hearing in June.

“The General Accounting Office briefed the
panel on work they are doing with respect to force protection at
domestic military bases. I for one found their preliminary findings
somewhat disturbing,” said Rep. Jim Saxton (R-NJ), chairman of the
panel. “For example, five years after the Khobar Towers terrorist
attack, many domestic U.S. military installations still have not had
vulnerability assessments done. Moreover, there appears to be no
requirement that base commanders implement the force protection
recommendations that flow from these assessments, most of which are not
dependent on additional resources.”

In the aftermath of the Khobar Towers
bombing, the Joint Requirement Oversight Council (JROC) was created
within the JointStaff to coordinate assessments of vulnerabilities of
U.S. military installations in the United States and abroad to
terrorist attack and to provide recommendations designated to address
identified security shortfalls. “The Joint Service-Integrated
Vulnerability Assessment (JSIVA) process is a key tool in the
Department’s combating terrorism effort; however, I have questions
about its effectiveness,” Saxton said.    

The following year, the GAO reported that
“over its seven-year existence, ISC [had] developed and issued security
design criteria and minimum standards for building access procedures;
disseminated information to member agencies, for their consideration
and implementation, on entry security technology for buildings needing
the highest security levels; and, through its meetings and 13 working
groups, provided a forum for federal agencies to discuss
security-related issues and share information and ideas.”

Although the Department of Homeland Security
(DHS) now has a significant role in the protection of federal
buildings, including their physical design, the ISC’s role is unclear.
Also unclear is how DHS is accomplishing its mission, according to
background interviews with GAO, DoD and congressional staffers familiar
with the matter.

Dr. W. Gene Corley, the structural engineer
who spearheaded the American Society of Civil Engineers study of the
Oklahoma City bombing, made it clear in 1998 in testimony before
Congress that “the major challenge facing all of us is the effective
transfer of this knowledge into common practice. We must take steps now
to ensure that the existing body of knowledge and the results of future
research are readily available for future designers and engineers.

“One of the best ways of doing this is through
the development of a national consensus standard that can be adopted
and used by all practicing engineers. ASCE, as the leader in producing
standards for the civil engineering profession, stands ready to assist
the federal government in developing this much needed standard,” he

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The Government Technology & Services Coalition's Homeland Security Today (HSToday) is the premier news and information resource for the homeland security community, dedicated to elevating the discussions and insights that can support a safe and secure nation. A non-profit magazine and media platform, HSToday provides readers with the whole story, placing facts and comments in context to inform debate and drive realistic solutions to some of the nation’s most vexing security challenges.

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