Practical Considerations for Blast Mitigation

Protus3Security Program Development


We were recently asked by a client to provide information on how they should protect their facility from potential vehicle-born improvised explosive devices. Although this information was written specifically for an educational facility, the principles of how and when to apply blast mitigation procedures and protocols are appropriate for a variety of other companies and organizations as well.

Planning for protection against high-yield, vehicle-born improvised explosive devices (VBIED) is a typical dilemma encountered by threat and vulnerability analysts in the U.S. since the Murrah Building was bombed in 1995. After the events of 9/11/01 and the advent of the Department of Homeland Security, a series of documents, references and recommendations have been published that seem to assume the worst case scenario with regard to use of extremely high-yield devices by an all-knowing and all-powerful enemy. These recommendations often seem devoid of threat-scale determinations and if taken literally, amount to extraordinarily costly and impractical remedies that most institutions, save the federal government who recommends them, cannot afford.

There is a propensity in government agencies to proffer military targeting doctrine and models for use in establishing vulnerability criteria for civilian targets. The most cited, CARVER, is a model used by special operations forces to establish a target priority by using a matrix that considers the uniqueness, lack of redundancy, quality of protection, and other characteristics of a target to determine what to strike. Use of sophisticated military models of this type is not appropriate for evaluating civilian targets because terrorists and other militant groups likely to conduct such an attack are not trained, equipped, or proficient at conventional military operations. Neither do they discern target attractiveness in the same objective manner as a military force nor are they disposed to employ the same doctrine, logic, or psychology.

As a matter of practice, security analysts and planners must consider the probability of an event as well as the criticality. It is possible to design and build blast resistant structures. External hardening of the fascia and reinforcement of the structure of existing buildings can provide protection from blast energy as it impacts the exterior surfaces and prevent intrusion of the energy into the interior spaces that are not resistant to lateral, vertical, or sheer forces.

It is also possible to isolate a structure geographically to a degree sufficient to mitigate over distance the effect of blast from even a very high yield conventional explosive device. However, this isolation may very well conflict with practical ingress and egress, and interfere to varying degrees with the purpose and use of the structure.

Standoff considerations are important in defeating the effects of any explosive device, and the bigger the charge, the greater the desired standoff distance required. Usually absent in these considerations is a realistic analysis of probability. Particularly noteworthy in most of these documents is the considerable overstatement of the size of the weapons that may be encountered. As an example, a statement has appeared in several DHS documents that truck born IEDs are ‘typically’ over 10,000 lbs in TNT equivalent yield. The Murrah Building bomb was around 6500 lbs. of ammonium nitrate (0.82 TNT equivalent) or about 5000 lbs. equivalent TNT yield in a rental box van. Another significant incident of a VBIED is relevant to this issue. In 1970, anti-war radicals bombed the University of Wisconsin-Madison with an approximately 1500 lb. ANFO device (approximately 1230 lb. TNT equivalent) in an Econoline van damaging the Army Mathematics Center in Sterling Hall and killing a researcher inside. The third significant VBIED attack was the New York World Trade Center and involved a charge of approximately 1500 lbs (1350 lbs TNT equivalent) of urea nitrate in a rented van. The device devastated the underground parking garage, killed six, and injured more than a thousand. The other significant attacks were against U.S. military and diplomatic facilities overseas and are not believed relevant to this discussion. Therefore, the projection of potential charge weight in the U.S. theatre of operations is not supported by history.

Terrorist threat evaluation centers on several unique factors. Any terrorist wants the most ‘bang for the buck’ because terrorism is a theatrical event. Timothy McVeigh did not perpetrate a ‘terrorist’ attack in Oklahoma City. This was an unconventional, direct military-style attack (guerrilla warfare) on a U.S. Government facility as a response to FBI actions in Ruby Ridge and Waco. Similarly, the Armstrong brothers’ bombing at the University of Wisconsin was an unconventional (guerrilla warfare) attack on a U.S. Army facility they perceived as a part of the of the Viet Nam war effort. The World Trade Center bombing was indeed a terrorist attack by Islamic fundamentalists on an icon of American prosperity, which was again attacked and destroyed on 9/11/2001. Considering these incidents, it is believed that a typical terrorist or guerrilla would seek to strike at an icon of America or a highly visible, representative target of their specific perceived enemy.

While it may be prudent to consider the possibility of high-yield bombing in considerations of building security on American campuses, it is also prudent to moderate assessments with a regard for threat probability. Creating permanently hardened structures is costly, and establishing permanent standoff zones can restrict property use needed for other purposes. All such considerations need to be based on a reality of the threat and the likelihood of an event occurring.

Protective standoff can be created temporarily when a threat environment presents itself through tactical use of exclusionary procedures and protective perimeters and devices that prevent unvetted vehicles from approaching a target building or entering a target area. This is a more flexible approach that can be applied to any location at any time as opposed to the creation of static, permanent, hard-site zones. Such security planning and development of doctrine and procedures should be considered and prepared to allow for quick creation of stand-off/exclusion zones and, depending on the perceived threat, implementation of tight screening procedures for vehicles or personnel.

These procedures and protocols should be based on the analysis of past use of IED’s in the U.S., a realistic appraisal of the potential target for attack by terrorists or other militant factions, a realistic assessment of the type and potential yield of an IED device, and the relative cost/use/threat efficiency of the specific target.


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Protus3 specializes in security system design, security consulting, corporate investigations and other investigative services. Partner with Protus3 and we will examine each situation to identify threats and develop solutions for your best outcome.

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