Risk Management Series
Primer 
to Design Safe School Projects in Case of 
Terrorist Attacks
December 2003


FEMA


FEMA 428 / December 2003


RISK MANAGEMENT SERIES

Primer to 
Design Safe School 
Projects in Case of 
Terrorist Attacks
PROVIDING PROTECTION TO PEOPLE AND BUILDING


www.fema.gov


Any opinions, findings, conclusions, or recommendations expressed in this 
publication do not necessarily reflect the views of FEMA. Additionally, neither FEMA 
or any of its employees makes any warrantee, expressed or implied, or assumes any 
legal liability or responsibility for the accuracy, completeness, or usefulness of any 
information, product, or process included in this publication. Users of information 
from this publication assume all liability arising from such use




The creation of the Department of Homeland Security (DHS) is one of the most 
significant transformations in the Federal Government in decades, establishing a 
department whose first priority is to protect the nation against terrorist attack. 
Within the DHS, the Directorate of Emergency Preparedness and Response (EP&R) is 
focused on ensuring that our nation is prepared for catastrophes, including both 
natural disasters and terrorist assaults.
This Primer for Protection of Schools Against Terrorist Attacks provides guidance to 
protect students, faculty, staff, and their school buildings from terrorist attacks. It also 
provides guidance to the building science community of architects and engineers 
working for local institutions on school projects.  
This document is intended for use by schools who feel that they are at risk to terrorist 
attacks. It provides necessary guidance to those who desire to increase the 
performance of their school and related infrastructure. Not all schools are at risk of 
terrorist attacks. The decision-makers in each school district should use current and 
available threat information from the proper sources to make this determination. 
The use of experts to apply the methodologies contained in this document is 
encouraged. 
This primer references several sources for additional information, including 
publications completed by other government agencies. The reader is encouraged to 
obtain additional guidance.
This document was prepared by the Building Sciences and Technology Branch of the 
Mitigation Division, part of EP&R. DHS would like to thank the following agencies 
for their contribution and input to this publication:
_	General Services Administration
_	Naval Facilities Engineering Service Center
_	Naval Facilities Command (NAVFAC) Criteria Office
_	USACE Protective Design Center
_	Department of Veterans Affairs
_	Centers for Disease Control and Prevention/National Institute for 
Occupational Safety and Health
_	Department of Justice, Office of Domestic Preparedness (DHS - Border and 
Transportation Security)
_	United States Air Force - Civil Engineer Support Agenc




FOREWORD AND ACKNOWLEDGMENT


BACKGROUND
The purpose of this primer is to provide the design community and school 
administrators with the basic principles and techniques to make a school that is safe 
from terrorist attacks and at the same time is functional, aesthetically pleasing, and 
meets the needs of the students, staff, administration, and general public. Protecting 
a school building and grounds from physical attack is a significant challenge 
because the ability to design, construct, renovate, operate, and maintain the facility is 
spread across numerous building users, infrastructure systems, and many building 
design codes. 
There is a strong interest in the United States (U.S.) in ensuring the safety of 
students, faculty, and staff in our schools. Schools are integral parts of their com-
munities. On any given weekday, nearly 53 million young people aged 5 to 17 attend 
more than 117,000 public and private schools where 6 million adults work as teachers 
or staff (counting students, faculty, and staff, this constitutes more than one-fifth of 
the U.S. population). Additionally, schools are resources for their communities.  
Many schools are used as shelters, command centers, or meeting places in times of 
crisis. Schools are also used widely for polling and voting functions. In some 
communities, schools are places of health care delivery.
Schools may or may not be the targets of terrorism, but they are certain to be affected 
by terrorism, whether directly or indirectly. On September 11, 2001, four elementary 
schools and three high schools located within 6 blocks of the World Trade Center 
were just beginning classes when the first plane hit the north tower. Thousands of 
children were exposed to the dust clouds from the collapsing buildings. Even those 
children not in the immediate vicinity experienced a great deal of anxiety. Children 
in at least three states (New York, New Jersey, and Connecticut) had parents working 
in or around the World Trade Center that day.  In the Washington, DC, area, schools 
faced similar situations after the Pentagon was attacked.1
Many Americans feel that schools should be the safest place our children can be, 
perhaps at times even safer than the homes in which they live. Security is not a 
standalone capability; it is a critical design consideration that should be constantly 
reviewed and scrutinized from the design phase through construction or reha-
bilitation and onto building use.
The focus of this primer will be on the threats posed by potential physical attacks on 
a school by terrorists. Attacking schools and school children could be a highly 
emotional and high profile event. At the time of publication of this primer, there 
have been no direct terrorist threats against a school known to the public; however, 
schools could be indirectly threatened by collateral damage from a terrorist attack 
directed at nearby facilities. Protecting a school against terrorist attack is a 
challenging task. A school may have considerable vulnerabilities, because of its well 
defined periods of use, designated access points, storage of sensitive personal 
information, minimal security forces, and numerous avenues of penetration and 
escape for attackers.
This primer should be used in conjunction with the Federal Emergency Management 
Agency (FEMA) 426, Reference Manual to Mitigate Potential Terrorist Attacks Against Buildings, 
and FEMA 427, Primer for Design of Commercial Buildings to Mitigate Terrorist Attacks.
SCOPE
This primer presents an approach to protecting schools at risk from terrorist attacks. 
The information presented is intended primarily for architects and engineers, or 
school administrators with a technical background. This publication is designed to 
meet the needs of all schools, including those with serious security concerns. 
Because security concerns of individual schools vary greatly, some users with modest 
security concerns may feel beleaguered by the amount of information and technical 
approach presented. They should feel free to select the methods and measures that 
best meet their individual situations while gaining a general appreciation of security 
concerns and risk management.
Several design philosophies and techniques have been incorporated into this primer, 
including the Department of Defense (DoD) Minimum Antiterrorism Standards, the 
Army and Air Force Security Engineering Manual, the General Services Ad-
ministration (GSA) Public Building Standards, the Department of Veterans Affairs 
(VA) Building Vulnerability Assessment Checklist, and the Centers for Disease 
Control and Prevention (CDC)/National Institute for Occupational Safety and Health 
(NIOSH) Guidelines for Airborne Contaminants.
ORGANIZATION AND CONTENT OF THE PRIMER
This publication contains many how-to aspects based upon current information 
contained in FEMA, Department of Commerce (DOC), DoD (including Army, Navy, 
and Air Force), Department of Justice (DOJ), GSA, VA, CDC/NIOSH, and other 
publications. It is intended to provide an understanding of the current 
methodologies for assessing threat/hazard, vulnerability, and risk, and the design 
considerations needed to improve protection of new and existing buildings and the 
people occupying them. As needed, this primer should be supplemented with more 
extensive technical resources, as well as the use of experts when necessary.
_		Chapter 1 presents a methodology for architects, engineers, and school 
administrators to analyze the safety of students, teachers, and staff for 
vulnerabilities to various terrorist threats. The methodology presented will assist 
schools in performing risk management by helping them to identify the best and 
most cost-effective terrorism mitigation measures for their unique security needs.
_		Chapters 2 and 3 discuss site and layout, and building design guidance and 
safety plans, respectively, and mitigation measures or comprehensive architectural 
and engineering design considerations to provide an acceptable level of 
protection. Specifically, Chapter 2 discusses comprehensive architectural and 
engineering design considerations for the school site, from the property line to 
the school building. Chapter 3 presents design considerations for the building 
envelope.
_		Chapter 4 is a brief discussion of explosive blast theory. Chapter 5 presents 
chemical, biological, and radiological (CBR) measures that can be taken to 
mitigate school vulnerabilities and reduce associated risk for these terrorist tactics 
or technological hazards.
_		Chapter 6 is a standalone description of the concept of safe rooms within 
schools that will resist CBR and blast threats intended to provide school board 
members and decision-makers with the basic components of a protective system.
_		Appendices A, B, and C contain acronyms, general definitions, and chemical 
and biological agent characteristics, respectively. Appendix B is an extensive 
glossary with terminology used in the report.
_		Appendices D and E present a comprehensive bibliography of publications 
(including information for obtaining the publications), and the associations and 
organizations capturing the building security guidance needed by the building 
sciences community (including web sites), respectively. 
_		Appendix F contains the Building Vulnerability Assessment Checklist.
ACKNOWLEDGEMENTS
Principal Authors:
Michael Chipley, UTD, Inc.
Wesley Lyon, UTD, Inc.
Robert Smilowitz, Weidlinger Associates, Inc.
Pax Williams, Battelle Memorial Institute
Contributors:
Milagros Kennett, FEMA, Project Officer, Risk Management Series Publications
Eric Letvin, Greenhorne & O'Mara, Inc., Consultant Project Manager
Michael Kaminskas, UTD, Inc.
Christopher Arnold, Building Systems Development, Inc.
Shawn Fenn, FEMA
Randall Hoffman, UTD, Inc.
Damian Kolbay, UTD, Inc.
Eve Hinman, ATC/Hinman Consulting Engineers, Inc.
Robert Burns, UTD, Inc.
Curt Betts, U.S. Army Engineer District, Omaha
Connie Deshpande, Department of Education
Bill Modzeleski, Department of Education
Randy Haslam, Jordan, Utah, School District
Deb Daly, Greenhorne & O'Mara, Inc.
Wanda Rizer, Greenhorne & O'Mara, Inc.
Julie Liptak, Greenhorne & O'Mara, Inc.
Bob Pendley, Greenhorne & O'Mara, Inc.

This primer was prepared under contract to FEMA. It will be revised periodically, and 
comments and feedback to improve future editions are welcome. Please send 
comments and feedback by e-mail to riskmanagementseriespubs@dhs.go v






TABLE OF CONTENT



FOREWORD AND ACKNOWLEDGMENTSi
CHAPTER 1 - ASSET VALUE, THREAT/HAZARD, VULNERABILITY, AND RISK1-
1
1.1   Asset Value Assessment 1-2
1.1.1  Identifying School Core Functions1-4
1.1.2  Identifying School Infrastructure1-4
1.1.3  Quantifying Asset Value1-5
1.2   Threat/Hazard Assessment1-7
1.2.1  Threat Identification1-9
1.2.2  Threat Definition1-13
1.2.3  Threat Assessment Products1-15
1.2.4  Design Basis Threat1-18
1.3   Vulnerability Assessment1-20
1.4   Risk Assessment1-23
1.5   The Risk Management Process1-28
CHAPTER 2 -  SITE AND LAYOUT DESIGN GUIDANCE 2-1
2.1   Land Use Considerations 2-2
2.2   Site Planning 2-4
2.2.1   Site Design2-4
2.2.2   Layout and Form2-4
2.2.3   Vehicular and Pedestrian Circulation2-9
2.2.4   Landscape and Urban Design2-10
2.3   Stand-off Distance2-14
2.4   Controlled Access Zones 2-16
2.5   Entry Control and Vehicular Access2-20
2.6   Signage2-21
2.7   Parking2-22
2.8   Loading Docks and Service Access2-24
2.9   Physical Security Lighting2-25
2.10  Site Utilities2-26
2.11  Summary of Site Mitigation Measures2-28
2.12  Crime Prevention Through  Environmental Design (CPTED)2-33
CHAPTER 3 - BUILDING DESIGN GUIDANCE AND SAFETY PLANS3-1
3.1  Architectural3-2
3.2   Building Structural and Non-structural Systems3-5
3.3  Building Envelope3-10
3.3.1 Building Exterior3-10
3.3.2  Exterior Wall Design3-10
3.3.3  Window Design3-12
3.3.4  Doors3-17
3.3.5   Roofs3-18
3.4   Mechanical Systems3-18
3.5   Electrical Systems3-24
3.6   Fire Protection Systems3-25
3.7   Communications Systems3-26
3.8   Physical Security Systems3-27
3.9   Summary of Building Envelope Mitigation  Measures3-29
3.10  Recommendations Based on the  Homeland Security Advisory System3-32
3.11  School Safety Emergency Management Plan3-33
3.12 Emergency Plans and Training3-36
CHAPTER 4 - EXPLOSIVE BLAST4-1
4.1   Blast Effects4-1
4.1.1  Building Damage4-3
4.1.2  Casualties and Injuries4-5
4.1.3  Levels of Protection4-5
4.2   Stand-off Distance and the Effects of Blast4-10
CHAPTER 5 - CHEMICAL, BIOLOGICAL, AND RADIOLOGICAL MEASURES5-1
5.1  Evacuation5-2
5.2   Sheltering in Place5-3
5.3   Personal Protective Equipment5-6
5.4   Air Filtration and Pressurization5-8
5.5   Exhausting and Purging5-8
5.6   CBR Detection5-9
5.7  Indications of CBR Contamination5-11
CHAPTER 6 - SAFE ROOMS WITHIN SCHOOLS6-1
6.1   Types of CBR Hazards6-2
6.1.1  Toxic Industrial Chemicals6-2
6.1.2  Incapacitating and Tear-producing Agents6-3
6.1.3  Biological Agents6-3
6.1.4  Radiological Agents6-4
6.2   Most Likely Delivery Methods for CBR Agents6-4
6.2.1  Internal Release6-5
6.2.2  External Proximate Release6-5
6.2.3  Remote Release6-5
6.2.4  Remote Release with Forewarning6-6
6.3   Vulnerability to Remote CBR Release6-6
6.4   Vulnerability to Remote CBR Release with  Forewarning6-10
6.5   Vulnerability to Internal CBR Release6-11
6.6   Vulnerability to External Proximate CBR Release6-11
6.7   Recommendations for CBR Protection  6-16
6.8   Safe Rooms in Response to the Domestic Explosive Threat6-16
6.9   Locating Safe Rooms to Mitigate Threats  6-20
6.10  Fragment Mitigating Upgrades  6-24
6.11  Structural Upgrades  6-30
APPENDIX A - ACRONYMS
APPENDIX B - GENERAL GLOSSARY
APPENDIX C - CBR AGENT CHARACTERISTICS
APPENDIX D - BIBLIOGRAPHY
APPENDIX E - ASSOCIATIONS AND ORGANIZATIONS
APPENDIX F - BUILDING VULNERABILITY ASSESSMENT CHECKLIST

TABLES
Chapter 1
Table 1-1  Asset Value Scale1-6
Table 1-2   Nominal High School People and  Asset Value Assessment 1-7
Table 1-3 Homeland Security Threat Conditions1-10
Table 1-4 Event Profiles for Terrorism and  Technological Hazards1-15
Table 1-5 Threat Rating Scale 1-16
Table 1-6 Nominal High School Threat Assessment1-17
Table 1-7 Vulnerability Rating Scale1-21
Table 1-8 Nominal High School Vulnerability  Assessment1-22
Table 1-9 Risk Rating System1-24
Table 1-10 Risk Color Value System1-25
Table 1-11 Nominal School Risk Assessment Matrix1-26
Chapter 2
Table 2-1 Correlation of Mitigation Measures  to Threats2-30
Chapter 3
Table 3-1 Glazing Protection Levels Based  on Fragment Impact Locations3-13
Table 3-2 Correlation of GSA Glazing Performance  Conditions and DoD Levels of 
Protection  for New Buildings3-14
Table 3-3 Safety/Security Recommendations3-32

Chapter 4
Table 4-1 DoD Minimum Antiterrorism (AT)  Standards for New Buildings4-6
Table 4-2 Correlation of DoD Level of Protection  to Incident Pressure4-6
Table 4-3 Damage Approximations4-13
Chapter 5
Table 5-1 Indicators of a Possible Chemical Incident5-13
Table 5-2 Indicators of a Possible Biological Incident5-15
Table 5-3 Indicators of a Possible Radiological Incident5-15
Chapter 6
Table 6-1 Pressures Exerted on a School Building  Face by Wind6-13
FIGURES
Chapter 1
Figure 1-1 The assessment process model1-2
Figure 1-2 Typical building design and  construction process1-19
Figure 1-3 Risk management choices1-19
Chapter 2
Figure 2-1  Non-redundant critical functions collocated near loading dock2-6
Figure 2-2  Clustering to enhance surveillance  opportunities while minimizing views 
into  buildings2-7
Figure 2-3  Blocking of sight lines2-13
Figure 2-4  Improper building siting and view relationships2-13
Figure 2-5  Clear zone with unobstructed views2-14
Figure 2-6  Concept of stand-off distance2-15
Figure 2-7  Exclusive and non-exclusive zones2-17
Figure 2-8  Sample bollard applications2-18
Chapter 3
Figure 3-1  Re-entrant corners in a floor plan3-3
Figure 3-2  Glazed areas oriented perpendicularly  away from streets3-4
Figure 3-3  Offset doors through the foyer3-5
Figure 3-4  Side view of a test structure illustrating  performance conditions of Table 
3-23-13
Figure 3-5  An unprotected window after a large  explosion3-15
Figure 3-6  Sacrificial roof3-18
Figure 3-7  Example of protecting outdoor air intakes3-20
Figure 3-8  Another example of protecting air intakes3-21
Figure 3-9  Example of elevated air intake3-21
Figure 3-10  Example of enclosing an existing  vulnerable air intake3-22
Figure 3-11  Considerations for the design of a new  security system3-28
Figure 3-12  Physical security devices3-29
Chapter 4
Figure 4-1  Blast pressure effects on a structure4-4
Figure 4-2  Explosives environments - blast range to effects4-8
Figure 4-3  Blast analysis of a high school for a  typical car bomb detonated in the  
school's parking lot4-9
Figure 4-4  Blast analysis of a high school for a  typical large truck bomb detonated in  
the school's parking lot4-9
Figure 4-5  Relationship of cost to stand-off distance4-10
Figure 4-6  Incident overpressure measured in pounds  per square inch, as a function 
of stand-off  distance and net explosive weight  (pounds-TNT)4-13
Chapter 5
Figure 5-1  Example of chemical dispersion5-3
Figure 5-2  Universal-fit escape hood5-7
Figure 5-3  An IMS chemical detector designed for  installation in HVAC systems5-10
Figure 5-4  Placards associated with chemical incidents5-14
Figure 5-5  Placards associated with biological incidents5-15
Figure 5-6  Placards associated with radiological incidents5-1





ASSET VALUE, THREAT/HAZARD, VULNERABILITY, AND RISK 1 
his chapter presents methodologies for architects, engi-
neers, school administrators, and state and local officials 
working in the building sciences field to identify the most 
effective mitigation measures to achieve a desired level of 
protection against terrorist attacks. These methodologies 
will help designers define asset value and evaluate 
vulnerability assessment information for the purpose of 
integrating threat/hazard into a design basis. Architects 
and engineers will be able to identify the best and most 
cost-effective terrorism mitigation measures for each 
building's unique security needs. Mitigation measures are 
conceived by the design professional and are best 
incorporated into the building architecture, building 
systems, and operational parameters, with consideration 
for life-cycle costs. The methodologies described in this 
chapter can be used for new buildings during the design 
process, as well as for existing buildings undergoing 
renovation. A key tool in the assessment process is 
provided for the designer in the last section of this 
chapter, the Building Vulnerability Assessment Checklist. 
In order to create a safe school environment, many factors 
must be considered. Figure 1-1 depicts the assessment 
process presented in this primer to help each school 
identify the best and most cost-effective terrorism 
mitigation measures for its own unique security needs. 
Section 1.1 identifies the value of a school's assets (e.g., 
people, buildings, equipment, and processes) that need to 
be protected, recognizing that students, faculty, and staff 
will always be a school's most vital asset requiring 
protection. Section 1.2 describes how to conduct a 
threat/hazard assessment to identify and define the threats 
and hazards that could cause harm to a school. Section 1.3 
discusses how to perform a vulnerability assessment to 
identify school weaknesses that might be exploited by a 
terrorist or aggressor. Combining the results of the asset 
value, threat, and vulnerability assessments in Sections 1.1 
through 1.3, the next step in the assessment process is to 
perform a risk assessment (Section 1.4) to determine to 
what degree a school's assets are vulnerable 
Figure 1-1 The assessment process model 
to attack. The final step of the process is presented in 
Section 1.5, where risk management decisions are 
discussed to prioritize and decide on the best and most 
cost-effective terrorism mitigation measures to implement 
to achieve the desired level of protection. 
A school assessment is best performed by engineering and 
security professionals who are experts in risk management, 
building design, blast effects, and chemical, biological, and 
radiological (CBR) attacks, as well as the latest 
antiterrorism (AT) security measures. If it is not feasible to 
hire professionals, members of the design community 
and/or school administrators can perform an assessment 
using the methodology presented in this primer. Some 
schools may choose to take a hybrid approach, hiring 
specialists or consultants to help perform individual 
portions of the assessment process. 
1.1 ASSET VALUE ASSESSMENT 
This section will describe how to perform an asset value 
assessment (the first step of the assessment process), to 
identify people and the asset value. To facilitate 
identifying people and the value of a school's assets, it is 
useful to conduct interviews of the people who are most 
familiar with them. Inputs from school administrators, 
teachers, nurses, custodial staff, cafeteria staff, and 
students, as well as any others who can help identify the 
most valuable assets should be sought. In order to 
conduct productive interviews, a list of areas to be covered 
should be generated and prioritized prior to the actual 
interviews. Thorough planning and research to generate 
relevant questions will aid the process and yield better 
results. 
An asset is a resource of value requiring protection.1 An asset can be tangible (e.g., 
students, faculty, staff, school buildings, facilities, equipment, activities, operations, 
and information) or intangible (e.g., processes or a school's reputation). In order to 
achieve the greatest risk reduction at the least cost, identifying and prioritizing a 
school's critical assets is a vital first step in the process to identify the best mitigation 
measures to improve its level of protection prior to a terrorist attack. Recognizing that 
people are a school's most critical asset, the process described below will help identify 
and prioritize school infrastructure where people are most at risk and require 
protection. 
Identifying a school's critical assets is accomplished in a two-step process: 
Step 1: Define and understand the school's core functions and processes 
Step 2: Identify school infrastructure 
. _	 Critical components/assets 
. _	 Critical information systems and data 
. _	 Life safety systems and safe haven areas 
. _	 Security systems 

1 Appendix B is a glossary of assessment and security terminology. Appendix C contains chemical and biological agent characteristics. 
1.1.1 Identifying School Core Functions 
The initial step of an asset value assessment is the determination of core functions and 
processes necessary for the school to continue to operate or provide services after an 
attack. The reason for identifying core functions/processes is to focus the design team 
and school administrators on what a school does, how it does it, and how various 
threats can affect the school. This provides more discussion and results in a better 
understanding of asset value. Factors that should be considered include: 
. _	 What are the school's primary services or outputs? 
. _	 What critical activities take place at the school? 
. _	 Who are the school's occupants or visitors? 
. _	 What inputs from external organizations are required for a school's 
success? 


1.1.2 Identifying School Infrastructure 
After the core functions and processes are identified, an evaluation of school 
infrastructure is the next step. To help identify and value rank infrastructure, the 
following should be considered, keeping in mind that the most vital asset for every 
school is its people: 
. _	 Identify how many people may be injured or killed during a terrorist 
attack that directly affects the infrastructure. 
. _	 Identify what happens to school functions, services, or student 
satisfaction if a specific asset is lost or degraded. (Can primary services continue?) 
. _	 Determine the impact on other organizational assets if the component 
is lost or can not function. 
. _	 Determine if critical or sensitive information is stored or handled at the 
school. 
. _	 Determine if backups exist for the school's assets. 
. _	 Determine the availability of replacements. 

. _	 Determine the potential for injuries or deaths from any catastrophic 
event at the school's assets. 
. _	 Identify any critical faculty, staff, or administration whose loss would 
degrade, or seriously complicate the safety of students, faculty, and staff during an 
emergency. [Consider first responders or the personnel responsible for shelter 
operations at a school that is a designated shelter for natural hazards.] 
. _	 Determine if the school's assets can be replaced and identify 
replacement costs if the school building is lost. 
. _	 Identify the locations of key equipment. 
. _	 Determine the locations of personnel work areas and systems within a 
school. 
. _	 Identify the locations of any personnel operating "outside" a school's 
controlled areas. 
 ._	 Determine, in detail, the physical locations of critical support architectures: 
. � Communications and information technology (IT - the flow of critical 
information) 
. � Utilities (e.g., facility power, water, air conditioning, etc.) 
. � Lines of communication that provide access to external resources and 
provide movement of students and faculty (e.g., road, rail, air transportation) 
. _	 Determine the location, availability, and readiness condition of 
emergency response assets, and the state of training of school staff in their use. 


1.1.3 Quantifying Asset Value 
After a list of a school's assets or resources of value requiring protection have been 
identified, they should be assigned a value. Asset value is the degree of debilitating 
impact that would be caused by the incapacity or destruction of the school's assets. 
There are many scales that can be used, each with advantages and disadvantages. 
Because some people are used to working with linguistic scales, although many 
engineers and designers prefer numerical systems, this publication will use a 
combination of a seven-level linguistic scale and a ten-point numerical scale as shown 
in Table 1-1. Obviously, the key asset for every school is its people (e.g., students, 
faculty, and staff). They will always be assigned the highest asset value as in the 
example below. 
Table 1-1: Asset Value Scale 

Asset Value 

Very High 

10 
High 

8-9 
Medium High 

7 
Medium 

5-6 
Medium Low 

4 
Low 

2-3 
Very Low 

1 

Very High - Loss or damage of the school's assets would have exceptionally grave 
consequences, such as extensive loss of life, widespread severe injuries, or total loss 
of primary services and core functions and processes. 
High - Loss or damage of the school's assets would have grave consequences, such as 
loss of life, severe injuries, loss of primary services, or major loss of core functions and 
processes for an extended period of time. 
Medium High - Loss or damage of the school's assets would have serious 
consequences, such as serious injuries, or impairment of core functions and processes 
for an extended period of time. 
Medium - Loss or damage of the school's assets would have moderate to serious 
consequences, such as injuries, or impairment of core functions and processes. 
Medium Low - Loss or damage of the school's assets would have moderate 
consequences, such as minor injuries, or minor impairment of core functions and 
processes. 
Low - Loss or damage of the school's assets would have minor consequences or 
impact, such as a slight impact on core functions and processes for a short period of 
time. 
Very Low - Loss or damage of the school's assets would have negligible consequences 
or impact. 
Asset Value Example. A nominal list of assets for a typical high school with assigned 
value is presented in Table 1-2. Please note that this is a nominal example; each school 
should tailor its list to its own unique situation. In Section 1.4, the results of the asset 
value assessment will be combined with the results of a threat assessment (Section 1.2) 
and a vulnerability assessment (Section 1. 3) to determine total risk.



1.2 THREAT/HAZARD ASSESSMENT 
After identifying asset value, the next step in the assessment process is to conduct a 
threat/hazard assessment wherein the threats or hazards are identified, defined, and 
quantified. Within the Department of Defense (DoD), intelligence community, and 
law enforcement, the term "threat" is typically used to describe the design criteria for 
terrorism or manmade disasters. Within the Federal Emergency Management Agency 
(FEMA) and other civil agencies, the term "hazard" is used in several different 
contexts. "Natural hazard" typically refers to a natural event such as an earthquake, a 
flood, or a wind disaster. "Manmade hazards" are "technological hazards" and 
"terrorism." These are distinct from natural hazards primarily in that they originate 
from human activity. Furthermore, "technological hazards" are generally assumed to 
be accidental, and their consequences are considered unintended. For the sake of 
simplicity, this primer will use the terms "threat" and "hazard" when referring to 
terrorism and manmade disasters, respectively. 
Table 1-2: Nominal High School Asset Value Assessment

For terrorism, the threat is from aggressors (those people with intent to do harm) that 
are known to exist, have the capability for hostile actions, and have expressed 
intentions for using hostile actions. They may seek publicity for their cause or political 
gain through their actions to injure or kill people, and destroy or damage facilities, 
property, equipment, or resources. 
Aggressor tools can be forced entry tools, vehicles, or surveillance (visual/audio). 
Their weapons can be incendiary devices; small arms (rifles and handguns); stand-off 
military-style weapons (rocket propelled grenades or mortars); explosive devices; and 
CBR agents. Their tactics run the gamut: moving vehicle bombs; stationary vehicle 
bombs; exterior attacks (thrown objects like rocks, Molotov cocktails, hand grenades, 
or hand-placed bombs); stand-off weapons attacks (small arms, military or improvised 
direct and indirect fire weapons); covert entries (gaining entry by false credentials or 
circumventing security with or without weapons); mail bombs (delivered to individuals 
or institutions); airborne contamination (CBR agents used to contaminate the air, 
water, or food supply to a school); and waterborne contamination (CBR agents 
injected into the water supply of a school facility). 
A threat assessment is a continual process of compiling and examining all available 
information concerning potential threats and manmade hazards. It can be broken 
down into two processes (1) defining threats and (2) identifying threat event profiles 
and tactics. 
1.2.1 Threat Identification 
The beginning point for security design is to define threats (hazards) and tactics that 
may be employed. From a physical attack viewpoint, schools maybe susceptible to 
attack by a number of different threats and tactics especially in areas of high risk. 
Schools are typically site constrained, have well defined traffic control and entry 
points, and operate on standard schedules. Designers and school administrators need 
to evaluate attack objectives, threat event profiles, and the effects or impact of the 
attack on the school and its occupants. It should also be noted that weapons and 
tactics change faster than the construction of schools. Table 1-3 provides a broad 
spectrum of manmade threats/hazards to consider and can be used as a tool in the 
threat assessment process. An extensive list of potential chemical and biological agents 
that can be used in terrorist attacks is provided in Appendix C. Blast range effects are 
indicated throughout Chapter 4. 
Table 1-3: Event Profiles for Terrorism and Technological Hazards* 

Table 1-3: Event Profiles for Terrorism and Technological Hazards* (continued)

Table 1-3: Event Profiles for Terrorism and Technological Hazards* (continued)

Table 1-3: Event Profiles for Terrorism and Technological Hazards* (continued)

*ADAPTED FROM: FEMA 386-7, INTEGRATING HUMAN-CAUSED HAZARDS INTO MITIGATION PLANNING, SEPTEMBER 2002.


1.2.2 Threat Definition 
A threat (hazard) is any indication, circumstance, or event with 
the potential to cause loss of, or damage to an asset. It is impor-
tant to understand who are the people with the intent to cause 
harm; or who, by process, materials, or proximity, can cause in-
direct harm to a school building. With the goal of reducing the 
potential risk of a school building, the design team and school 
administration should seek threat assessment information from 
local law enforcement, the local office of the Federal Bureau of 
Investigation (FBI), State Health Departments, the Department of 
Homeland Security (DHS), and the Homeland Security Offices 
(HSOs) at the state level. In many areas of the country, there are 
threat coordinating committees that facilitate the sharing of 
information. Local fire departments and hazardous materials 
(HazMat) units will frequently understand the threat of 
technological hazards due to hazardous materials on school 
grounds as well as those in surrounding industries that could 
cause a collateral threat to schools. In many jurisdictions, the 
HazMat unit is part of the fire department. 
After information on potential aggressors is gathered, it should be analyzed. A 
common method to evaluate terrorist threats uses five factors: existence, capability, 
history, intention, and targeting. 
Existence addresses the questions: Who is hostile to our school building or 
community of concern? Are they present or thought to be present? Are they able to 
enter the country or are they readily identifiable in a local community upon arrival? 
Capability addresses the questions: What weapons have been used in carrying out past 
attacks? Do the aggressors need to bring them into the area or are they available 
locally? 
History addresses the questions: What has the potential threat element done in the 
past and how many times? When was the most recent incident and where, and against 
what target? What tactics did they use? Are they supported by another group or 
individuals? How did they acquire their demonstrated capability? 
Intention addresses the questions: What does the potential threat element or 
aggressor hope to achieve? How do we know this (e.g., published in books or news 
accounts, speeches, letters to the editor, informant)? 
Targeting addresses the questions: Do we know if an aggressor (we may not know 
which specific one) is performing surveillance on our school, nearby facilities, or 
facilities that have much in common with our school? Is this information current and 
credible, and indicative of preparations for terrorist operations (manmade hazards)? 
The threat/hazard analysis for a school can range from a general threat/hazard 
scenario shared by all members of a community to a very detailed examination of 
specific groups, individuals, and tactics that must be repelled or defended against by 
means of school design. The Homeland Security Advisory System has five threat levels 
that provide a general indication of risk of terrorist attack. In Table 1-4, the five factors 
commonly used to evaluate terrorist threats have been layered onto the Homeland 
Security Advisory levels. It illustrates threat levels and provides a representation of the 
likelihood of a terrorist attack. If the anticipated threat or projected character/use of 
the facility warrant, a detailed threat analysis should be developed in coordination 
with local law enforcement, intelligence, and civil authorities in order to more 
quantitatively determine the vulnerability or risk. All schools should identify actions to 
be taken for each threat level. A table with specific recommendations for schools 
based on the Homeland Security Threat Advisory Level is presented in Chapter 3 
(Table 3-3). 
Table 1-4: Homeland Security Threat Conditions 
_ Factor must be present _	Factor may or may not be present 
Please note the DHS does not use these threat analysis factors to determine threat level. 
SOURCE: COMMONWEALTH OF KENTUCKY OFFICE OF HOMELAND SECURITY.


1.2.3 Threat Assessment Products 
A threat assessment is a continual process of compiling and examining all 
available information concerning potential threats and manmade 
hazards. The product of a threat assessment is a list of threats and hazards 
with a threat rating assigned. The threat rating is a subjective judgment 
based on existence, capability, history, intention, and targeting. Often, 
information is sketchy and analysts must rely more on thejudgment of 
experts, statistical probability, and occasionally assumptions to help 
quantify and qualify the threat (all assumptions should be documented). 
The same combination of linguistic scale and numerical scale used in the 
asset value assessment (Table 1-1) can be used for the threat assessment 
as presented in Table 1-5. Assessing terrorist threats is much more diffi-
cult than assessing the risk from natural hazards such as earthquakes, 
floods, and winds. Historical data form the basis of threat and locality 
indicates vulnerability to a great extent in regard to natural hazards. For 
terrorist threats, the likelihood of occurrence is less defined and the 
associated vulnerabilities have many considerations that impact making 
good risk management decisions. 
Table 1-5: Threat Rating Scale 

Threat Rating 

Very High 


10 
High 


8-9 
Medium High 


7 
Medium 


5-6 
Medium Low 


4 
Low 


2-3 
Very Low 


1 

Very High - Known aggressors or hazards, highly capable of causing loss of, or damage 
to the school exist. One or more vulnerabilities are present. The aggressors are known 
or highly suspected of having intent to exploit the school's assets and are known or 
highly suspected of performing surveillance on a facility. 
High - Known aggressors or hazards, capable of causing loss of, or damage to the 
school exist. One or more vulnerabilities are present and the aggressors are known 
or reasonably suspected of having intent to exploit the school's assets. 
Medium High - Known aggressors or hazards, capable of causing loss of, or damage to 
the school exist. One or more vulnerabilities are present and the aggressor is 
suspected of having intent to exploit the school's assets. 
Medium - Known aggressors or hazards that may be capable of causing loss of, or 
damage to the school exist. One or more vulnerabilities may be present; however, the 
aggressors are not believed to have intent to exploit the school's assets. 
Medium Low - Known aggressors or hazards that may be capable of causing loss of or 
damage to the school exist. Aggressors have no intent to exploit the school's assets. 
Low - Few or no aggressors or hazards exist. Their capability of causing damage to 
the school's assets is doubtful. 
Very Low - No aggressors or hazards exist. 
Threat Assessment Example. A nominal list of threats/hazards with assigned threat 
rating is presented in Table 1-6. Please note that this is a nominal example; each 
school should tailor its list to its own unique situation. 
Table 1-6: Nominal High School Threat Assessment 
Stationary vehicle bomb 
Low 
2 
Attack with small arms 
Medium Low 
4 
Hydrogen sulfide "stink bomb" 
Medium 
5 
Forced entry at night to damage school 
property 
Medium High 
7 
Electronic attack to destroy or alter school 
academic records 
Medium High 
7 


1.2.4 Design Basis Threat 
Traditionally, the building regulatory system has addressed natural disaster 
mitigation (hurricane, tornado, flood, earthquake, windstorm, and snow storm) 
through prescriptive building codes supported by well-established and accepted 
reference standards, regulations, inspection, and assessment techniques. Some man-
made risks (e.g., HazMat storage) and specific societal goals (energy conservation 
and life safety) have also been similarly addressed. However, the building regulation 
system has not yet fully addressed most manmade hazards or terrorist threats. 
Soon after September 11, 2001, the New York City Building Department initiated an 
effort to analyze the building code in relation to terrorist threats. The task force 
issued a report recommending code changes based on the attack on the World 
Trade Center. The National Fire Protection Association (NFPA) has a committee on 
premises security and security system installation standards. These advancements 
may some day result in the building regulatory system developing prescriptive 
building codes to mitigate security threats. 
In the absence of such regulations, identifying design basis threats (e.g., threat tactics, 
weapons, tools, or explosives against which a building must be protected) should be 
considered as part of a school's threat assessment to facilitate the work of designers 
during new construction or rehabilitation of an existing school building. The DoD, 
General Services Administration (GSA), and Department of State (DOS) all have 
established processes to identify design basis threats for their facilities. 
The typical building design and construction process is sequential, progressing from 
identifying building use and design goals through actual construction. This process is 
illustrated in Figure 1-2. 
Figure 1-2 Typical building design and construction process 
In every school design and renovation project, there are ultimately three choices of 
how to address the risk posed by terrorism: 
1. 1.	Do nothing and accept the risk 
2. 2.	Perform a risk assessment and manage the risk by installing reasonable 
mitigation measures to achieve a desired level of protection 
3. 3.	Harden the building against all threats to achieve the least amount of 
risk 

Figure 1-3 is a graphical representation of the three choices. Since September 11, 
2001, terrorism has become a dominant concern. Life, safety, and security issues 
should be a design goal from the beginning for all schools. 
Figure 1-3 Risk management choices



1.3 VULNERABILITY ASSESSMENT 
A vulnerability assessment evaluates vulnerability, or any weaknesses that can be 
exploited by an aggressor, of critical assets across a broad range of identified threats 
and provides a basis for determining mitigation measures for protection of people and 
critical assets. 
The Building Vulnerability Assessment Checklist provided in Appendix F is based on 
the checklist developed by the Department of Veterans Affairs (VA) and compiles 
many best practices based upon technologies and scientific research to consider 
during the design of a new building or an assessment of an existing school building. 
It allows a consistent security evaluation of designs at various levels. The checklist can 
be used as a screening tool for an initial vulnerability assessment or be used by 
subject matter experts for a comprehensive vulnerability assessment of existing 
school buildings. 
The assessment of any vulnerability of a school building should be done within the 
context of the defined threats and the value of the school's assets. That is, each 
element of the school building should be analyzed for vulnerabilities to each threat 
and a vulnerability rating should be assigned. The same combination of linguistic scale 
and numerical scale used in the asset value and threat assessments (Tables 1-1 and 1-
5) can also be used for the vulnerability assessment as presented in Table 1-7. It should 
be noted that a vulnerability assessment may change the value rating of assets due to 
the identification of critical nodes or some other factor that makes the school's assets 
more valuable. 
Table 1-7: Vulnerability Rating Scale


Vulnerability Rating 

Very High 


10 
High 


8-9 
Medium High 


7 
Medium 


5-6 
Medium Low 


4 
Low 


2-3 
Very Low 


1 

Very High - One or more major weaknesses have been identified
that make the school's assets extremely susceptible to an aggressor
or hazard.

High- One or more significant weaknesses have been identified that

make the school's assets highly susceptible to an aggressor or hazard.
Medium High - An important weakness has been identified that
makes the school's assets very susceptible to an aggressor or hazard.

Medium - A weakness has been identified that makes the school's

assets fairly susceptible to an aggressor or hazard.
Medium Low - A weakness has been identified that makes the
school's assets somewhat susceptible to an aggressor or hazard.

Low - A minor weakness has been identified that slightly increases
the susceptibility of the school's assets to an aggressor or hazard.
Very Low - No weaknesses exist.

Vulnerability Assessment Example. To create the vulnerability
assessment of a school, a site vulnerability assessment should be
performed using the checklist in Appendix F. The results of the
vulnerability assessment are then analyzed in conjunction with the
results of the asset value and threat assessments developed earlier.
Each asset/threat pair is then assigned a vulnerability rating as
shown in Table 1-8 and forms the basis for identifying measures
to mitigate threat vulnerability and improve protection of the
building and its occupants. Please note that this is a nominal example; each school 
should tailor its list to its own unique situation.

Table 1-8: Nominal High School Vulnerability Assessment

VH = Very High; H = High; MH = Medium High; M = Medium; ML = Medium Low; L = Low; VL 
= Very Low


1.4 RISK ASSESSMENT 
Risk is the potential for a loss of or damage to an asset. It is measured based upon the 
value of the asset in relation to the threats and vulnerabilities associated with it. Risk 
is based on the likelihood or probability of the hazard occurring and the conse-
quences of the occurrence. A risk assessment analyzes the threat (probability of 
occurrence), and asset value and vulnerabilities (consequences of the occurrence) to 
ascertain the level of risk for each asset against each applicable threat/hazard. Thus, 
a very high likelihood of occurrence with very small consequences may require 
simple, low cost mitigation measures, but a very low likelihood of occurence with very 
grave consequences may require more costly and complex mitigation measures. The 
risk assessment provides engineers, architects, and school administrators with a 
relative risk profile that defines which assets are at the greatest risk against specific 
threats. Chapters 2 and 3 explore mitigation measures to reduce the vulnerability 
and risk for valuable assets with a high risk. 
There are numerous methodologies and techniques for conducting a risk assessment. 
One approach is to assemble the results of the asset value assessment, threat 
assessment, and vulnerability assessment, and determine a numeric value of risk for 
each asset and threat/hazard pair in accordance with the following formula: 
Risk = Asset Value x Threat Rating x Vulnerability Rating 
The completed matrix provides a quantitative value for risk that can be converted into 
a linguistic value as shown in Table 1-9. The following rating system can be used for 
assessing the risk of schools. 
Table 1-9: Risk Rating System

Very High - The potential for loss or damage of the school's assets is so great as to 
expect exceptionally grave consequences, such as extensive loss of life, widespread 
severe injuries, or total loss of primary services, and core functions and processes. 
High - The potential for loss or damage of the school's assets is so great as to expect 
grave consequences, such as loss of life, severe injuries, loss of primary services, or 
major loss of core functions and processes for an extended period of time. 
Medium High - The potential for loss or damage of the school's assets is such as to 
expect serious consequences (e.g., as serious injuries, or impairment of core 
functions and processes for an extended period of time). 
Medium - The potential for loss or damage of the school's assets is such as to expect 
serious consequences (e.g., injuries, or impairment of core functions and processes). 
Medium Low - The potential for loss or damage of the school's assets is such as to 
expect only moderate consequences (e.g., minor injuries, or minor impairment of 
core functions and processes). 
Low - The potential for loss or damage of the school's assets is such as to expect only 
minor consequences or impact (e.g., a slight impact on core functions and processes 
for a short period of time). 
Very Low - The potential for loss or damage of the school's assets is so low that there 
would only be negligible consequences or impact. 
Because of the large amount of information in a risk assessment matrix, it is useful to 
assign a color code (red, yellow, or green) based on the total numeric value of risk 
determined based on the scale in Table 1-10. 
Table 1-10: Risk Color Value System 
As a minimum, mitigation measures to reduce risk and create an acceptable level of 
protection should be considered for those critical assets determined to be at highest 
risk. 
Risk Assessment Example. A nominal risk assessment is presented in Table 1-11 based 
on the asset value, threat, and vulnerability assessment examples presented earlier. As 
mentioned previously, each school should tailor its list to its own unique situation. 
Table 1-11: Nominal High School Risk Assessment Matrix

Table 1-11: Nominal High School Risk Assessment Matrix (continued)

Table 1-11: Nominal High School Risk Assessment Matrix (continued)


1.5 THE RISK MANAGEMENT PROCESS 
Risk management is the process of selecting and implementing mitigation measures 
to achieve an acceptable level of risk at an acceptable cost. Because it is cost-
prohibitive to protect against the entire range of possible threats, it is important to 
develop a realistic prioritization of mitigation measures. When considering mitigation 
measures, the following factors should be considered: 
. _	 Results of the risk assessment, including asset value and asset 
vulnerabilities 
. _	 Costs of the mitigation measures 

. _	 The value of risk reduction to the school 
. _	 Frequency with which the benefits of the mitigation measures will be 
realized 
. _	 The deterrence or preventive value of the mitigation measures 
. _	 The expected lifespan of the mitigation measures and the time value of 
money 

To evaluate prospective mitigation measures, the design team should first calculate 
new values of risk based on how the installation or use of mitigation measures would 
change vulnerability and/or asset values. Some mitigation measures will affect mul-
tiple asset/threat risk values. After the amount of risk reduction each mitigation 
measure will produce has been calculated, the cost of each mitigation measure 
should be estimated using resources such as R.S. Means Construction Cost Data. The 
final step is to perform a benefit/cost analysis to determine which mitigation 
measures will produce the greatest reduction of risk at an acceptable cost. 
When dealing with manmade hazards and terrorism, it is much more difficult to 
predict how often an event will occur and the deterrent value of mitigation measures. 
Although there are historical data to help predict how often natural hazards such as 
floods or tornadoes occur in various regions, the probability or frequency of manmade 
hazards/threats is not known. Therefore, subjective approaches for frequency must be 
combined with quantitative estimates of cost-effectiveness. 
Additionally, the deterrent or preventive value of a mitigation measure is also difficult 
to quantify. Deterrence, in the case of terrorism, may also have a secondary impact in 
that, once a school is "hardened," a terrorist may turn to a less protected building, 
changing the likelihood of an attack for both targets. For example, the Murrah 
Federal Building in Oklahoma City became the target of an aggressor when he was 
deterred from attacking his primary target, the FBI building, because it was too 
difficult to get the attack vehicle close to the target. He was able to park immediately 
adjacent to the Murrah Federal Building and successfully target the Bureau of 
Alcohol, Tobacco, and Firearms (ATF). 
All these factors should be considered when calculating the value of mitigation 
measures, and weighing their value against their cost. Ideally, sufficient resources 
would be available to achieve a desired level of protection against design basis threats 
through mitigation measures. This is not always the case, so it is also important that 
every school identify or designate an appropriate authority that is authorized to accept 
risk on behalf of the school. Sometimes when decisions are left up to committees or 
personnel at an inappropriate level, poor choices or decisions can be made. 
It is also essential to maintain analytic integrity and objectivity during the assessment 
process in order to achieve an honest and unbiased risk assessment. Legitimate 
differences of professional opinion may occur; therefore, it is also important that the 
process be transparent and repeatable. For example, there could be an honest 
disagreement about the threat rating assigned to an "electronic attack to destroy 
school records." An open and repeatable methodology facilitates healthy debate to 
help the risk acceptance authority, who is ultimately responsible, make informed 
decisions. 
In sum, the risk management process is a benefit/cost analysis to decide and prioritize 
which mitigation measures to implement to achieve the desired level of protection 
with available resources. This is accomplished by repeating risk assessment 
calculations adjusting for how mitigation measures change a school's asset values and 
vulnerabilities. As pointed out earlier, mitigation measures may also change how an 
aggressor views a school, thus changing the threat assessment as well.



SITE AND LAYOUT DESIGN GUIDANCE     

his chapter discusses comprehensive architectural and engineering design 
considerations (mitigation measures) for the school site, from the property line to the 
school building, including: land use, site planning, stand-off distance, controlled 
access zones, entry control and vehicular access, signage, parking, loading docks and 
service access, physical security lighting, and site utilities. The intent of this guidance is 
to provide concepts for integrating mitigation strategies to the design basis threats as 
identified during the risk assessment. Integrating security requirements into a larger, 
more comprehensive approach necessitates achieving a balance among many 
objectives such as reducing risk; facilitating proper school building function; aesthetics 
and matching architecture; creating a school environment conducive to learning; and 
hardening of physical structures beyond required building codes and standards for 
added security. 
The design community must work closely with school districts and school 
administrators to ensure that the optimal balance of all these considerations is 
achieved; thus, coordination within the design team is critical. Many school asset 
protection objectives can be achieved during the early stages of the design process 
when mitigation measures are the least costly and most easily implemented. Planners, 
architects, and landscape designers play an important role in identifying and 
implementing crucial asset protection measures while considering land use; site 
selection; the orientation of buildings on the site; and the integration of vehicle 
access, control points, physical barriers, landscaping, parking, and protection of 
utilities to mitigate threats. 
It is important to remember that the nature of any threat is always changing. Although 
indications of potential future threats may be scarce during the design stage, 
consideration should be given to accommodating enhanced protection measures in 
response to future threats that may emerge. School protection objectives must be 
balanced with other design objectives, such as the efficient use of land and resources, 
and must also take into account existing physical, programmatic, and fiscal constraints. 
2.1 LAND USE CONSIDERATIONS 
Land use is a broad planning process that encompasses zoning ordinances, subdivision 
regulations, and master planning. Regulating land use development has been a 
common practice in the United States for many years, with numerous regulations and 
other tools in use by state and local governments to influence the configuration of 
urban sites. Comprehensive planning can encourage certain types of development, 
incentives, allocation of resources, and capital improvement programs oriented to 
improve the security of areas vulnerable to manmade disasters. In most cases, sound 
site planning will increase the land area needed for individual school buildings and 
maximize the protection measures to be adopted. Other potential terrorist targets in 
the surrounding area should also be considered. Students and teachers might be 
killed or injured by collateral damage from a terrorist attack directed at another 
nearby facility. When designing a school, the designer should consider external and 
internal land use design concerns, including the characteristics of the surrounding 
area (e.g., construction type, occupancies, and the nature and intensity of adjacent 
activities), as well as the implications of these characteristics for the protection of the 
students, faculty, and staff on the school site under consideration. The amount of land 
available on the site for stand-off and the inherent ability of the school site to 
accommodate the implementation of natural and manmade antiterrorism and 
security design features could help the designers to determine if other measures such 
as hardening the school building should also be considered. 
It is important to recognize that conflicts sometimes arise between security-oriented 
site design and conventional site design. For example, open circulation and common 
spaces (which are desirable for conventional design) may be detrimental to certain 
aspects of security. 
When designing new school buildings or evaluating existing schools, the designer 
should evaluate key protection measures to ensure they are appropriate, desirable, 
and cost-effective in terms of mitigating the risk of potential terrorist attacks. Security 
measures must be evaluated carefully to understand which measures are truly 
beneficial and which are not practical. 
When making decisions about site antiterrorism and security, designers should 
consider the following: 
. _	 Adjacent land use and zoning plans for potential development that 
would impact security within the school (assess by using land use maps and 
Geographic Information Systems [GISs]) 
. _	 Building footprint(s) relative to total land available 
. _	 Building location(s) or, if undeveloped, suitable building location(s) 
relative to the site perimeter and adjacent land uses; distance between the perimeter 
fence and improved areas off site 
. _	 Access via foot, road, rail, water, and air; suitability to support a secure 
perimeter 
. _	 Current and planned infrastructure and its vulnerabilities, including 
easements, tunnels, pipes, and rights-of-way 
. _	 Infrastructure nodes that constitute single-point vulnerabilities 
. _	 Adjacent land uses and occupancies that could enable or facilitate 
attacks or that are potential targets themselves and thus present collateral damage or 
cascading failure hazards 
. _	 Proximity to fire and police stations, hospitals, shelters, and other 
critical facilities that could be of use in an attack 
. _	 Presence of natural physical barriers such as water features, dense 
vegetation, and terrain that could provide access control and/or shielding, or 
suitability of the site for the incorporation of such features 
. _	 Topographic and climatic characteristics that could affect the 
performance of chemical agents and other weapons 

_	 Observability from outside site boundaries; ability of vegetation in proximity to 
building or site to screen covert activity


2.2 SITE PLANNING 
The single most important goal in planning a site to resist terrorism and security 
threats is the protection of life, property, and operations. Decision-making in support 
of this purpose should be based first and foremost on a comprehensive assessment of 
the manmade threats and hazards so that planning and design countermeasures are 
appropriate and effective in the reduction of vulnerability and risk as described in 
Chapter 1. It is important to recognize that a given countermeasure can mitigate one 
or more vulnerabilities, but may be detrimental to other important design goals. This 
section will highlight several aspects of site design and will present some of the unique 
characteristics arising from their application to antiterrorism and security. 
2.2.1 Site Design 
Because the economics of development dictate the construction of schools, security 
concerns should be evaluated carefully. Conflicts sometimes arise between security 
site design and conventional site design. For example, open circulation and common 
spaces, which are desirable for conventional school design, are often undesirable for 
security design. To maximize safety, security, and sustainability, designers should 
implement a holistic approach to site design that integrates form and function to 
achieve a balance among the various design elements and objectives. Even if resources 
are limited, significant value can be added to a project by integrating security 
considerations into the more traditional design tasks in such a way that they 
complement, rather than compete with, the other elements.


2.2.2 Layout and Form 
The overall layout of a school site (e.g., the placement and form of its buildings, 
infrastructures, and amenities) is the starting point for development. Choices made 
during this stage of the design process will steer decision-making for the other 
elements of the site. A number of aspects of site layout and building type present 
security considerations and are discussed below. 
_	 Clustered versus dispersed functions. There is a strong correlation between 
building functions and building layout and forms. Typically, the former dictates 
the other two. Depending on the site characteristics, the occupancy requirements, 
and other factors, school buildings may cluster key functions in one particular 
area or have these functions designed in a more dispersed manner. Both patterns 
have compelling strengths and weaknesses in terms of security. 
Concentrating key functions in one place may create a target-rich environment 
and increase the risk of collateral impacts. Additionally, it increases the potential 
for the establishment of more single-point vulnerabilities, such as indicated in 
Figure 2-1. This figure shows several key functions grouped in a particular area of 
the building (i.e., the mechanical rooms, stairs, telephone switch room, and 
loading docks). If these areas become a target, the school may be closed for a 
substantial period of time, even if the attack is not severe and the rest of the 
school remains unharmed. However, grouping high-risk activities, concentrations 
of personnel, and critical functions into a cluster can help maximize stand-off 
from the perimeter and create a "defensible space." This also helps to reduce the 
number of access and surveillance points, and minimize the size of the perimeter 
needed to protect the school areas. 
In contrast, the dispersal of key functions reduces the risk 
that an attack on any one part of the site will impact the other 
parts. However, this could also have an isolating effect and 
reduce the effectiveness of on-site surveillance, increase the 
complexity of security systems and emergency response, and 
create a less defensible space. 
To the extent that site, economic, and other factors allow, the designer should 
consolidate school designs that are functionally 
Figure 2-1 Non-redundant critical functions collocated near loading dock 
compatible and have similar threat levels. For example, 
visitor areas and receiving/loading areas constitute a 
school's innermost line of defense, because they are 
the first places where people and materials enter the 
school building. Logically, they should be physically 
separated from other key functions such as the main 
operational areas or where people concentrate. 
. _	 School building orientation. The orientation of a school building can 
have significant impact on its performance, not only in terms of energy efficiency, but 
also the ability to protect occupants (see Figure 2-2). A school building's orientation 
relative to its surroundings defines its relationship to that area. In aesthetic terms, a 
school building can open up to the area or turn its back; it can be inviting to those 
outside, or it can "hunker down" defensively. The physical positioning of a building 
relative to its surroundings may seem more subtle, but can be a greater determinant of 
this intangible quality than exterior aesthetics. Nevertheless, the proximity of a 
vulnerable 
. _	 Open space. The incorporation of open space into school site design 
presents a number of benefits. First and foremost is the ability to easily monitor an 
area and detect intruders, vehicles, and weapons. Closely related to this benefit is the 
stand-off value of open space; as discussed in Chapter 4, blast energy decreases as the 
inverse of the cube of the distance from the seat of the explosion, so every additional 
increment of distance provides increasingly more protection. In addition, pervious 
open space allows stormwater to percolate back into the ground, reducing the need 
for culverts, drainage pipes, manholes, and other covert site access and weapon 
concealment opportunities. Also, if the open space is impassible for vehicles (as in the 
case of a wetland or densely vegetated area), it can provide not only environmental 
and aesthetic amenities, but prevent vehicle intrusion as well. 
. _	 Infrastructure and lifelines. Providing power, gas, water, wastewater, 
and communications services is one of the most basic requirements of any school 
development. At the site scale, all critical lifelines should have at least one layer of 
redundancy, or backup. By eliminating single-point vulnerabilities, designers will 
reduce the chance that service will be interrupted if an attack damages or destroys a 
lifeline either outside the school perimeter or on site. It is important to note that 
collocating a backup lifeline with its primary lifeline does not eliminate single-point 
vulnerability; only physical separation can substantially increase the likelihood of 
continuity of service. 

Additionally, all controls, interconnections, exposed lines, and other vulnerable 
elements of school infrastructure systems should be protected from access and 
exploitation by surveillance and/or physical countermeasures. Service entrances 
and other secondary access points should be monitored and access-controlled; 
special attention should also be paid to any locations where multiple systems or 
primary and backup systems come together, such as control rooms and 
mechanical spaces. Again, these facilities should be designed for maximum 
observability, including the use of opportunity reduction and target hardening 
strategies where appropriate, and should be equipped with adequate lighting and 
emergency communications capabilities wherever possible. For additional 
information, see Sections 2.9 and 2.10.


2.2.3 Vehicular and Pedestrian Circulation 
The movement of people and materials into, through, and out of a school facility is 
determined by the design of its access, circulation, and parking systems. Such systems 
should be designed to maximize efficiency while minimizing conflicts between vehicle 
and pedestrian modes. Designers should begin with an understanding of the school's 
transportation requirements based on an analysis of how the school will be used. This 
includes studying the number and types of access points that are required, bus 
requirements, the parking volume needed, where users need to go to and from, and 
the modes of transportation they will use. Several aspects of transportation planning 
can impact security and are discussed below. 
_	 Roadway network design. Streets are generally designed to minimize travel time 
and maximize safety, with the end result typically being a straight path between two 
or more endpoints. Although a straight line may be the most efficient course, 
designers should use caution when orienting streets relative to school buildings 
requiring high protection. Designers should design a roadway system to minimize 
vehicle velocity, thus using the roadway itself as a protective measure. This is 
accomplished through the use of several strategies. 
First, straight-line or perpendicular approaches to school buildings should not be 
used in a school at high risk, because these give vehicles the opportunity to gather 
the speed necessary to ram through protective barriers and crash into or 
penetrate buildings. Instead, approaches should be parallel to the fa�ade, with 
berms, high curbs, appropriate trees, or other measures used to prevent vehicles 
from departing the roadway. A related technique for reducing vehicle speeds is 
the construction of serpentine (curving) roadways with tight-radius corners. 
Existing streets can be retrofitted with barriers, bollards, swing gates, or other 
measures to force vehicles to travel in a serpentine path. Again, high curbs and 
other measures should be installed to keep vehicles from departing the roadway in 
an effort to avoid these countermeasures. 
Less radical than these techniques are traffic calming strategies, which seek to use 
design measures to cue drivers as to the acceptable speed for an area. These 
include raised crosswalks, speed humps and speed tables, pavement treatments, 
bulbouts, and traffic circles. In addition to creating a more pedestrian-friendly 
environment, which increases "eyes on the street" surveillance, designing 
roadways to physically limit speeds can have the added benefits of increasing 
safety and, subsequently, lowering liability. Designers should be aware, however, 
that many of these techniques can have detrimental effects for emergency 
response, including slowing response time, interfering with en route emergency 
medical treatment, and increasing the difficulty of maneuvering fire apparatus. 
They also may present problems for snow removal, and their outer ends should 
remain flat so that bicycles can proceed unimpeded. 
_	 Parking. Surface lots can be designed and placed to keep vehicles away from 
school buildings, but they can consume large amounts of land and, if constructed 
of impervious materials, can contribute greatly to stormwater runoff. They can also 
be hazardous for pedestrians if dedicated pedestrian pathways are not provided. 
For additional information, see Section 2.7.


2.2.4 Landscape and Urban Design 
Designing to meet user needs while maintaining stewardship of the natural and built 
environments becomes increasingly more challenging when security requirements 
are factored in. Design principles at the school site should include an emphasis on 
selection of low-impact development techniques and environmental stewardship; 
compatibility of context and relationship with adjacent uses, forms, and styles; 
establishment of scale and identity through aesthetic design; connectivity among 
buildings, uses, activities, and transportation modes; resource conservation; cultural 
responsiveness; and the creation of appealing public spaces. These objectives are 
generally achieved through the work of two closely related disciplines, landscape 
design and urban design. For the purposes of this document, these two disciplines 
are virtually overlapping and will, therefore, be addressed together. 
_	 Landscape design. Many landscape features can be used in school design to 
enhance security. Landscape design features should be used to create the level of 
protection without turning the school into a fortress. Elements such as landforms, 
water features, and vegetation are among the building blocks of attractive and 
welcoming spaces, and they can also be powerful tools for enhancing security. 
These features can be used not only to define or designate a space, but also to 
deter or prevent hostile surveillance or unauthorized access. Vegetative groupings 
and landforms can even provide some level of blast shielding. Stands of trees, 
earthen berms, and similar countermeasures generally cannot replace setbacks, 
but they can offer supplementary protection. However, landscaping can also have 
detrimental impacts for safety and security, and designers should consider the 
unique requirements of the school project to ensure that the landscape design 
elements they choose will be appropriate and effective. 
With careful selection, placement, and maintenance, landscape elements can 
provide visual screening that protects school gathering areas and other activities 
from surveillance without creating concealment for covert activity. However, 
dense vegetation in close proximity to a school building can screen illicit activity 
and should be avoided. Additionally, thick ground cover such as English ivy or 
vegetation over 4 inches tall such as monkey grass can be used to conceal bombs 
and other weapons; in setback clear zones, vegetation should be selected and 
maintained with eliminating concealment opportunities in mind. Similarly, 
measures to screen visually detractive components such as transformers, trash 
compactors, and condensing units should be designed to minimize concealment 
opportunities for people and weapons. 
_	 Urban design. Numerous urban design elements present opportunities to provide 
school security. The scale of the streetscape should be appropriate to its primary 
users, and it can be manipulated to increase the comfort level of desired users 
while creating a less inviting atmosphere for users with malicious intent. However, 
even at the pedestrian scale, certain operational requirements must be 
accommodated. For example, although efficient pedestrian and vehicle circulation 
systems are important for school functions and operations, they are also critical for 
emergency response, evacuation, and egress, and must be able to accommodate 
vehicles up to the largest fire apparatus in the community. Furthermore, despite an 
emphasis on downsizing the scale of the streetscape, it is critical to maintain the 
maximum stand-off distance possible between vehicles and structures. 
At the school perimeter, walls and fences used for space 
definition may be hardened to resist the impact of a weapon-
laden truck; however, planters, bollards, or decorative 
boulders could accomplish the same objective in a much more 
aesthetically pleasing manner. Such an approach also creates 
permeability, which would allow pedestrians and cyclists to 
more easily move through the space. 
Landscape and urban design inherently define the "lines of 
sight" in a space. These techniques seek to deny aggressors a 
"line of sight" to a potential target, either from on or off site. This 
increases the protection of sensitive information and operations 
by using stand-off weapons (see Figures 2-3 and 2-4). In addition 
to the use of various types of screening options, anti-surveillance 
measures (e.g., using building orientation, landscaping, 
screening, and landforms) to block sight lines can also be used. 
Depending on the circumstances, landforms can be either beneficial or detrimental 
to anti-surveillance. Elevated sites may enhance surveillance of the surrounding area 
from inside the facility, but may also allow observation of on-site areas by adversaries. 
School buildings should not be sited immediately adjacent 
Figure 2-5 Clear zone with unobstructed views



2.3 STAND-OFF DISTANCE 
The most cost-effective solution for mitigating explosive effects on school 
buildings is to keep explosives as far away from them as possible. The 
distance between an asset and a threat is referred to as the stand-off 
distance as shown in Figure 2-6. There is no ideal stand-off distance; it is 
determined by the type of threat, the type of construction, and desired 
level of protection. The easiest and least costly opportunity for achieving 
appropriate levels of protection against terrorist threats is to incorporate 
sufficient stand-off distance into school designs. Maximizing stand-off 
distance also ensures that there is opportunity in the future to upgrade 
school buildings to meet increased threats or to accommodate higher 
levels of protection. Stand-off distance must be coupled with appropriate 
building hardening as discussed in Chapter 3, to provide the necessary 
level of protection to the school. 
Figure 2-6 Concept of stand-off distance 
For schools located in high-risk areas, additional considerations follow: 
. _	 The first mode of site protection is to create "keep out zones" that can 
ensure a minimum guaranteed distance between an explosion (i.e., from a vehicle) 
and the school structure. 
. _	 The perimeter line is the outermost line that can be protected by the 
security measures incorporated during the school design process. It is recommended 
that the perimeter line be located as far as is practical from the building exterior. 
Many vulnerable school buildings are located in urban areas where only the exterior 
wall of the building stands between the outside world and the building occupants. In 
this case, the options are obviously limited. Often, the perimeter line can be pushed 
out to the edge of the sidewalk by means of bollards, planters, and other obstacles. To 
push this line even further outward, restricting or eliminating parking along the curb 
often can be arranged with local authorities. In some extreme cases, elimination of 
loading zones and the closure of streets are an option. 

. _	 "Keep out zones" can be achieved with perimeter barriers that cannot 
be compromised by vehicular ramming. A continuous line of security should be 
installed along the perimeter of the site to protect it from unscreened vehicles and to 
keep all vehicles as far away from the school as possible. 
. _	 The following critical building components should be located away 
from main entrances, vehicle circulation, parking, and maintenance areas. If this is 
not possible, harden as appropriate: 

�	 Emergency generator, including fuel systems, day tank, fire sprinkler, and water 
supply 
. � Normal fuel storage 
. � Telephone distribution and main switchgear 
. � Fire pumps 
. � Building control centers 
. � Uninterrupted power supply (UPS) systems controlling critical functions 
. � Main refrigeration systems if critical to building operation 
. � Elevator machinery and controls 
. � Shafts for stairs, elevators, and utilities 
. � Critical distribution feeders for emergency power 


2.4 CONTROLLED ACCESS ZONES 
For a school at high risk, one method to attain the appropriate protection is with the 
creation of a controlled access zone. These zones define minimum distances between 
a school building and potential threats through the installation of barriers (such as 
bollards, planters, fountains, walls, and fences). The barriers are designed to withstand 
assaults by terrorist vehicles; however, their placement must be designed to allow for 
access by fire and rescue vehicles in the event of an emergency. Selection of barriers is 
based on operational considerations related to vehicle access and parking. Good 
design principles for high-risk schools endorse the complete surround of a school 
building with a stand-off zone that has perimeters set at distances that consider threat 
levels, desired level of protection, building construction, and land availability. Entry 
into the controlled area should only be through an entry control point. 
When designing schools at high risk, controlled access zones may be exclusive or non-
exclusive, as shown in Figure 2-7. An exclusive zone is the area surrounding a school 
building within the exclusive control of the building. Anyone entering an exclusive 
zone must have a purpose related to the building. A non-exclusive zone is either a 
public right-of-way or a particular area related to the main school building. 
The following are some security considerations applicable to controlled access zones 
and enforcement: 
. _	 Design and select barriers based on threat capabilities. 
. _	 If the limited availability of land precludes the creation of an exclusive 
zone, the use of screening surrounding the school building is an alternative. 
. _	 Design and locate security devices to establish consistent rhythm 
patterns within the site. Incorporate subtle and aesthetically pleasing security 
measures to reach the desired level of protection. 
. _	 Locate security measures so that they do not impede the free access to 
school public entrances or internal pedestrian flow. Miscellaneous decorative 
elements (e.g., flag poles, fountains, pools, gardens, and similar features) may be 
located within access ways to slow movement or restrict access. 
. _	 Use a combination of barriers. Some barriers are fixed and obvious 
(fences and gates), while others are passive (sidewalks far away from buildings, curbs 
with grassy areas, etc.). See Figure 2-8. 

Figure 2-8 Sample bollard applications 
. _	 Consider using landscape materials to create barriers that are soft and 
natural rather than manmade where physical barriers are required. 
. _	 Use vehicles as temporary physical barriers by placing them in front of 
buildings or across access roads. 
 ._	 Maintain as much stand-off distance as possible between potential vehicular 
bombs and the school building. 
. � Provide traffic obstacles near entry control points to slow down traffic. 
. � Consider vehicle barriers at building entries and drives. 
. � Offset vehicle entrances from the direction of a vehicle's approach to force a 
reduction in speed. 
. � Position gates and perimeter boundary fences outside the blast vulnerability 
envelope, when possible. 
. � Provide a vehicle crash resistance system in the form of a low wall or earth 
berm, if the threat level warrants it. 
. _	 Design entry control points (if provided) to screen the building from 
vehicles entering it. 
 ._	 Provide passive vehicle barriers to keep stationary vehicle bombs at a distance 
from the school building. 
. � Use high curbs, low berms, shallow ditches, trees, shrubs, and other physical 
separations to keep stationary bombs at a distance. 
. � Do not allow vehicles to park next to perimeter walls of the secured area. 
Consider using bollards or other devices to keep vehicles away. 
. _	 Provide adequate lighting to aid in threat detection in controlled 
access zones. 
. _	 Use CCTV to control entry points, the site perimeter, and exclusive and 
non-exclusive zones. 


2.5 	ENTRY CONTROL AND VEHICULAR ACCESS 
In the case of a school, the objective of the design professional is to save lives by 
mitigating building damages and reducing the chances of a catastrophic collapse of 
the building at least until it is fully evacuated. Although there are many forms of 
attacks against a school, from the standpoint of school structural design, the vehicle 
bomb governs design because historically it has been used on multiple occasions by 
terrorists. Where a school perimeter barrier is required for security, it will be necessary 
to provide points of access through the perimeter for school users (i.e., students, 
faculty, staff, visitors, and service providers). An entry control point or guard building 
serves as the designated point of entry for site access. It provides a point for 
implementation of desired/required levels of screening and access control. The 
objective of the entry control point is to prevent unauthorized access to school 
grounds while maximizing the rate of authorized access by foot or vehicle. These 
measures will not be required for all schools; they may only be appropriate for schools 
considered at high risk. Designs should be flexible to allow implementation of 
increased security controls when schools are placed in high alert and easing of 
controls at lower threat levels. For a school considered to be at high risk, the following 
should be considered in the design of entry control points: 
. _	 Design entry roads to schools so that they do not provide direct or 
straight-line vehicular access to the main building. Route major corridors away from 
key school areas and functions. 
. _	 Design access points at an angle to oncoming streets so that is difficult 
for a vehicle to gain enough speed to break through them. 
. _	 Minimize the number of access roads and entrances into a school. 
. _	 Provide a drop-off/pick-up lane for buses only. 

. _	 Minimize the number of driveways or parking lots that students will 
have to walk across to get to the school building. 
. _	 Designate an entry to the school for commercial, service, and delivery 
vehicles, preferably away from key school areas and functions, whenever possible. 
. _	 Design the entry control point and guard building so that the 
authorization of approaching vehicles and occupants can be adequately assessed, and 
the safety of both gate guards and approaching vehicles can be maintained when a 
school is placed at high alert). 
. _	 Design (if they are required) traffic calming strategies and barriers 
(road alignment, retractable bollards, swing gates, or speed bumps) to control vehicle 
speed and slow incoming vehicles before they reach the gate so that entry control 
personnel have adequate time to respond to unauthorized activities. 
. _	 Provide inspection areas that are not visible to the public. Place 
appropriate landscape plantings to accomplish screening. 
. _	 Provide pull-over lanes at site entry gates to check suspect vehicles. 
Also, provide a visitor/site personnel inspection area to inspect vehicles prior to 
allowing access to the school site. 
. _	 Consider providing a walkway and turnstile for pedestrians and a 
dedicated bicycle lane. 


2.6 SIGNAGE 
Signs are an important element of school security. They are meant to keep intruders 
out of restricted areas. Confusion over site circulation, parking, and entrance locations 
can contribute to a loss of site security. Signs should be provided off site and at school 
entrances; there should be on-site directional, parking, and cautionary signs for 
students, faculty, staff, visitors, service vehicles, and pedestrians. Unless required, signs 
should not identify sensitive areas. A comprehensive signage plan should include the 
following: 
. _	 Prepare entry control procedures signs that explain current entry 
procedures for drivers and pedestrians. 
. _	 Prepare traffic regulatory and directional signs that control traffic flow 
and direct vehicles to specific appropriate points. 
. _	 Consider using street addresses or building numbers instead of 
detailed descriptive information inside the school grounds. 
. _	 Minimize the number of signs identifying high-risk areas; however, a 
significant number of warning signs should be erected to ensure that possible 
intruders are aware of entry into restricted areas. 
. _	 Minimize signs identifying critical utility complexes (e.g., power 
stations and significant gas, water, and sewer). Post easily understandable signs to 
minimize accidental entry by unauthorized visitors into critical areas. 
. _	 In areas where English is one of two or more languages commonly 
spoken, warning signs must contain the other language(s) in addition to English. The 
signs should be posted at intervals of no more than 100 feet and should not be 
mounted on fences equipped with intrusion-detection equipment. 
. _	 Locate variable message signs, which give information on 
site/organization special events and visitors, far inside site perimeters. 


2.7 PARKING 
Parking restrictions can help to keep potential threats away from a school building. 
In urban settings, however, curbside or underground parking is often necessary and 
sometimes difficult to control. Mitigating the risks associated with parking requires 
creative design measures, including parking restrictions, perimeter buffer zones, 
barriers, structural hardening, and other architectural and engineering solutions. 
The following considerations may help designers to implement parking measures for 
schools that may be at high risk: 
. _	 Locate vehicle parking areas away from school buildings to minimize 
blast effects from potential vehicle bombs. 
. _	 Provide separate parking areas for students, faculty, staff, and visitors 
who may be going in and out during the school day. (This allows the main student 
parking lot to be closed off during the school day.) 
. _	 If possible, locate visitor or general public parking near, but not on, the 
site itself. 
. _	 Locate general parking in areas that provide the fewest security risks to 
school personnel. 
. _	 Consider one-way circulation within a school parking lot to facilitate 
monitoring for potential aggressors. 
. _	 Locate parking within view of occupied school buildings while 
maintaining stand-off. 
. _	 Prohibit parking within the stand-off zone. 
. _	 Request appropriate permits to restrict parking in the curb lane for 
school vehicles or key employee parking only where distance from the building to the 
nearest curb provides insufficient setback, and compensating design measures do not 
sufficiently protect the building from the assessed threat. If necessary, use structural 
features to prevent parking. 
. _	 Provide appropriate setback from parking on adjacent properties, if 
possible. Structural hardening may be required if the setback is insufficient. In new 
designs, it may be possible to adjust the location of the school building on the site to 
provide adequate setback from adjacent properties. 
. _	 When establishing parking areas, provide emergency communications 
systems (e.g., intercom, telephones, etc.) at readily identified, well-lighted, CCTV 
monitored locations to permit direct contact with security personnel. 

. _	 Provide parking lots with CCTV cameras connected to the security 
system and adequate lighting capable of displaying and videotaping lot activity. 
. _	 If possible, prohibit parking beneath or within a school building. 
. _	 If parking beneath a building is unavoidable, limit access to the parking 
areas and ensure they are secure, well-lighted, and free of places of concealment. 
 ._	 Apply the following restrictions If parking within a school building is required: 
. � Public parking with identification (ID) check 
. � School vehicles and school employees and students only 
. � Selected school employees only, or those requiring security 


2.8 LOADING DOCKS AND SERVICE ACCESS 
Loading docks and service access areas are commonly required for a school building 
and are typically desired to be kept as invisible as possible. For this reason, special 
attention should be devoted to these service areas in order to avoid intruders. Design 
criteria for school loading docks and service access include the following: 
. _	 Separate by at least 50 feet, loading docks and shipping and receiving 
areas in any direction from utility rooms, utility mains, and service entrances, 
including electrical, telephone/ data, fire detection/alarm systems, fire suppression 
water mains, cooling and heating mains, etc. 
. _	 Locate loading docks so that vehicles will not be allowed under the 
building. If this is not possible, the service area should be hardened for blast. Loading 
dock design should limit damage to adjacent areas and vent explosive forces to the 
exterior of the building. 
. _	 If loading zones or drive-through areas are necessary, monitor them 
and restrict height to keep out large vehicles. 

. _	 Avoid having driveways within or under school buildings. 
. _	 Provide adequate design to prevent extreme damage to loading docks. 
The floor of the loading dock does not need to be designed for blast resistance if the 
area below is not occupied and or does not contain critical utilities. In certain cases, 
significant structural damage to the walls and ceiling of the loading dock may be 
acceptable; however, the areas adjacent to the loading dock should not experience 
severe structural damage or collapse. 
. _	 Provide signage to clearly mark separate entrances for deliveries. 


2.9 PHYSICAL SECURITY LIGHTING 
Security lighting can be provided for overall school ground/ building illumination 
and the perimeter to allow security personnel to maintain visual-assessment during 
darkness. It may provide both a real and psychological deterrent for continuous or 
periodic observation. Lighting is relatively inexpensive to maintain and may reduce 
the need for security personnel while enhancing personal protection by reducing 
opportunities for concealment and surprise by potential attackers. 
Provide sufficient lighting at entry control points to ensure adequate lighting for the 
area. Where practical, place lighting elements as high as possible to give a broader, 
more natural light distribution. This requires fewer poles (less hazardous to drivers) 
and is more aesthetically pleasing than standard lighting. 
The type of site lighting system used depends on the school's overall security 
requirements. Four types of lighting are used for security lighting systems: 
_	 Continuous lighting is the most common security lighting system. It consists of a 
series of fixed lights arranged to flood a given area continuously during darkness 
with overlapping cones of light. 
. _	 Standby lighting has a layout similar to continuous lighting; however, 
the lights are not continuously lit, but are either automatically or manually turned on 
when suspicious activity is detected or suspected by the security personnel or alarm 
systems. 
. _	 Movable lighting consists of manually operated, movable searchlights 
that may be lit during hours of darkness or only as needed. The system normally is 
used to supplement continuous or standby lighting. 
. _	 Emergency lighting is a backup power system of lighting that may 
duplicate any or all of the above systems. Its use is limited to times of power failure or 
other emergencies that render the normal system inoperative. It depends on an 
alternative power source such as installed or portable generators or batteries. Consider 
emergency/backup power for security lighting as determined to be appropriate. 


2.10 SITE UTILITIES 
Utility systems can suffer significant damage when subjected to the shock of an 
explosion. Some of these utilities may be critical for safely evacuating people from 
the school building. Their destruction could cause damage that is disproportionate 
to other building damage resulting from an explosion. To minimize the possibility 
of such hazards, apply the following measures: 
. _	 Where possible, provide underground, concealed, and protected 
utilities. 
. _	 Provide redundant utility systems (particularly electrical services) to 
support school security, life safety, and rescue functions. 
. _	 Consider quick connects for portable utility backup systems if 
redundant sources are not available. 
. _	 Prepare vulnerability assessments for all utility services to the school, 
including all utility lines, storm sewers, gas transmission lines, electricity transmission 
lines, and other utilities that may cross the site perimeter. 

. _	 Protect drinking water supplies from waterborne contaminants by 
securing access points, such as manholes. If warranted, maintain routine water testing 
to help detect waterborne contaminants. 
. _	 Minimize signs identifying critical utilities. Provide fencing to prevent 
unauthorized access and use landscape planting to conceal aboveground systems. 
. _	 Locate petroleum, oil, and lubricants storage tanks and operations 
buildings downslope from all other occupied school buildings. Locate fuel storage 
tanks at least 100 feet from buildings. 
. _	 Consider providing utility systems with redundant or loop service, 
particularly in the case of electrical systems. Where more than one source or service is 
not currently available, provisions should be made for future connections. In the 
interim, consider "quick connects" at the building for portable backup systems. 
. _	 Decentralize a school's communications resources, when possible; the 
use of multiple communication networks will strengthen the communications system's 
ability to withstand the effects of a terrorist attack. 
. _	 Place trash receptacles as far away from the building as possible; trash 
receptacles should not be placed within 30 feet of a building. 
. _	 Provide a school-wide public address system that extends from the 
interior to the exterior of buildings. 
. _	 Conceal and harden incoming utility systems within schools to provide 
blast protection, including burial or proper encasement wherever possible. 
. _	 Locate utility systems at least 50 feet from loading docks, front 
entrances, and parking areas. 
. _	 Route critical or fragile utilities so that they are not on exterior walls or 
on walls shared with mailrooms. 

. _	 Ensure that the redundant utilities are not collocated or do not run in 
the same chases. This minimizes the possibility that both sets of utilities will be 
adversely affected by a single event. 
. _	 Ensure backup systems are located away from the systems components 
for which they provide backup. 
. _	 Mount all overhead utilities and other fixtures weighing 31 pounds (14 
kilograms) or more to minimize the likelihood that they will fall and injure school 
occupants. Design all equipment mountings to resist forces of 0.5 times the equipment 
weight in any direction and 1.5 times the equipment weight in the downward 
direction. This standard does not preclude the need to design equipment mountings 
for forces required by other criteria such as seismic standards. 
. _	 Ensure that access to crawl spaces, utility tunnels, and other means of 
under school building access is controlled to limit opportunities for aggressors placing 
explosives underneath buildings. 
. _	 Screen, seal, or secure all utility penetrations of the site's perimeter to 
prevent their use as access points for unauthorized entry into the school site. If access 
is required for maintenance of utilities, secure all penetrations with screening, grating, 
latticework, or other similar devices. 


2.11 	SUMMARY OF SITE MITIGATION MEASURES 
A general spectrum of site mitigation measures ranging from the least protection, cost, 
and effort going to the greatest protection, cost, and effort for a school site is 
presented below. Detailed discussions of individual measures can be found earlier in 
the chapter. This is a nominal ranking of mitigation measures. In practice, the 
effectiveness and cost of individual mitigation measures may be different for specific 
applications. Table 2-1 can be used by designers and school administrators to correlate 
the mitigation measures described in this chapter to specific terrorist threats and 
tactics. 
. �	Place trash receptacles as far away from the school building as possible. 
. �	Remove any dense vegetation that may screen covert activity. 
. �	Use thorn-bearing plant materials to create natural barriers. 
. �	Identify all critical resources in the school area (fire and police stations, hospitals, etc.) for 
design consideration. 
. �	Identify all potentially hazardous facilities in the area (nuclear plants, chemical labs, etc.). 
. �	Use temporary passive barriers to eliminate straight-line vehicular access to areas of limited 
access. 
. �	Use vehicles as temporary physical barriers during elevated threat conditions. 
. �	Make proper use of signs for traffic control, building entry control, etc. Minimize signs 
identifying high-risk areas. 
. �	Identify, secure, and control access to all utility services to the school. 
. �	Limit and control access to all school crawl spaces, utility tunnels, and other means of under 
building access to prevent the planting of explosives. 
. �	Utilize GIS to assess adjacent land use. 
. �	Provide open space inside the fence along the school perimeter. 
. �	Locate fuel storage tanks at least 100 feet from all occupied school buildings. 
. �	Block sight lines through building orientation, landscaping, screening, and landforms. 
. �	Use temporary and procedural measures to restrict parking and increase stand-off. 
. �	Locate and consolidate high-risk land uses in the interior of the school site. 
. �	Select and design barriers based on threat levels. 
. �	Maintain as much stand-off distance as possible from potential vehicle bombs. 
. �	Separate backup utility systems. 
. �	Conduct periodic water testing to detect waterborne contaminants. 
. �	Enclose the perimeter of the school. Create a single controlled entrance for vehicles (entry 
control point). 
. �	Establish law enforcement or security force presence for schools facing high threats. 
. �	Install quick connects for portable utility backup systems. 
. �	Install security lighting in areas where needed. 
. �	Install CCTV cameras in areas where needed. 
. �	Mount all equipment to resist forces in any direction. 
. �	Include security and protection measures in the calculation of school land area requirements. 
. �	Redesign and construct parking to provide adequate stand-off for vehicle bombs. 
. �	Position buildings to permit occupants and security personnel to monitor the site. 
. �	Do not site the school building adjacent to potential threats or hazards. 
. �	Locate critical school building components away from the main entrance, vehicle circulation, 
parking, or maintenance area. Harden as appropriate. 
. �	Provide a site-wide public address system and emergency call boxes at readily identified 
locations. 
. �	Prohibit parking beneath or within a school building. 
. �	Redesign and construct access points at an angle to oncoming streets. 
. �	Designate entry points for commercial and delivery vehicles away from high-risk areas. 
. �	In urban areas, push the perimeter out to the edge of the sidewalk by means of bollards, 
planters, and other obstacles. For even better stand-off, push the line even farther outward by restricting or 
eliminating parking along the curb, eliminating loading zones, or through street closings. 
. �	Provide intrusion detection sensors for all utility services to the school. 
. �	Provide backup utility systems to support school security, life safety, and rescue functions. 
. �	Conceal and/or harden incoming utility systems. 
. �	Install active vehicle crash barriers. 

Table 2-1 Correlation of Mitigation Measures to Threats*

Table 2-1: Correlation of Mitigation Measures to Threats* (continued)

CONTROLLED ACCESS ZONES 






Exclusive zone/Non-exclusive zone 
_ 
_ 



_ 



Clear zone 
_ 
_ 



_ 



Fencing and physical barriers 
_ 
_ 
_ 
_ 
_ 
_ 



Active barriers 
_ 
_ 
_ 
_ 
_ 
_ 



Passive barriers 
_ 
_ 
_ 


_ 




ENTRY CONTROL AND VEHICULAR 
ACCESS 









Minimize access roads 
_ 
_ 



_ 
_ 


Control points 
_ 
_ 
_ 
_ 
_ 
_ 



Active monitoring 
_ 
_ 
_ 
_ 
_ 
_ 
_ 
_ 
_ 
Provide enhanced protection at school entrances 
_ 
_ 
_ 
_ 
_ 
_ 



Include pull-over lanes at checkpoints to inspect 
vehicles 
_ 
_ 
_ 
_ 
_ 
_ 



Avoid straightline vehicular access to high-risk 
areas 
_ 
_ 







Avoid straightline entry approach roads 
_ 
_ 







Locate vehicle parking areas far from high-risk 
areas 
_ 
_ 







Provide separate service and delivery access 
_ 
_ 







Route major corridors away from high-risk areas 
_ 
_ 

_ 
_ 




Locate high-risk resources remote from primary 
roads 
_ 
_ 

_ 
_ 




Minimize directional identification signs 
_ 
_ 
_ 
_ 
_ 
_ 



Limit vehicular access to high-risk areas 
_ 
_ 
_ 
_ 
_ 
_ 



SIGNAGE 
Minimize signage 
_ 
_ 
_ 
_ 
_ 
_ 
_ 
_ 
_ 

Table 2-1: Correlation of Mitigation Measures to Threats* (continued)

Table 2-1: Correlation of Mitigation Measures to Threats* (continued)

* ADAPTED FROM U.S. AIR FORCE INSTALLATION FORCE PROTECTION GUIDE.


2.12 	CRIME PREVENTION THROUGH ENVIRONMENTAL 
DESIGN (CPTED) 
CPTED is a crime reduction technique that has several key elements applicable to the 
analysis of building function and site design against physical attack. It is used by 
architects, city planners, landscape and interior designers, and law enforcement with 
the objective of creating a climate of safety in a community by designing a physical 
environment that positively influences human behavior. Although CPTED principles 
are not incorporated into the assessment process presented in this primer, it is useful 
to briefly discuss CPTED because it is often entwined with terrorism protection 
measures. 
CPTED concepts have been successfully applied in a wide variety of applications, 
including streets, parks, museums, government buildings, houses, and commercial 
complexes. The approach is particularly applicable to schools, where outdated 
facilities are common. Most schools in the United States were built 30 to 60 or more 
years ago. Security issues were almost nonexistent at the time, and technology was 
dramatically different. As a result, building designs are not always compatible with 
today's more secu-rity-conscious environment. 
According to CPTED principles, depending upon purely conventional physical 
security measures (e.g., security guards and metal detectors) to correct objectionable 
student behavior may have its limitations. Although employing physical security 
measures will no doubt increase the level of physical security, in some cases physical 
security measures employed as stand-alone measures may lead to a more negative 
environment, thereby enhancing violence. In short, employing stand-alone physical 
security measures may fail to address the underlying behavioral patterns that adversely 
affect the school environment. CPTED analysis focuses on creating changes to the 
physical and social environment that will reinforce positive behavior. 
CPTED builds on three strategies: 
. _	 Territoriality (using buildings, fences, pavement, sign, and landscaping 
to express ownership) 
. _	 Natural surveillance (placing physical features, activities, and people to 
maximize visibility) 
. _	 Access control (the judicial placement of entrances, exits, fencing, 
landscaping, and lighting) 

A CPTED analysis of a school evaluates crime rates, office-referral data, and school 
cohesiveness and stability, as well as core design shortcomings of the physical 
environment (e.g., blind hallways, uncontrolled entries, or abandoned areas that 
attract problem behavior). The application of CPTED principles starts with a threat 
and vulnerability analysis to determine the potential for attack and what needs to be 
protected. Protecting a school from physical attack by criminal behavior or terrorist 
activity, in many cases, only reflects a change in the level and types of threats. The 
CPTED process asks questions about territoriality, natural surveillance, and access 
control that can: 
. _	 Increase the effort to commit crime or terrorism 
. _	 Increase the risks associated with crime or terrorism 
. _	 Reduce the rewards associated with crime or terrorism 
. _	 Remove the excuses as to why people do not comply with the rules and 
behave inappropriately 

The CPTED process provides direction to solve the challenges of crime and terrorism 
with organizational (people), mechanical (technology and hardware), and natural 
design (architecture and circulation flow) methods. 
CPTED concepts can be integrated into expansion or reconstruction plans for existing 
buildings as well as new buildings. Applying CPTED concepts from the beginning 
usually has minimal impact on costs, and the result is a safer school. Each school, 
district, and community should institute measures appropriate for their own 
circumstances because there is no a single solution that will fit all schools. 
Many CPTED crime prevention techniques for a school complement conventional 
terrorism and physical attack prevention measures. For example, as part of the 
CPTED strategy of improving territoriality, schools are encouraged to direct all 
visitors through one entrance that offers contact with a receptionist who can 
determine the purpose of the visit and the destination, and provide sign-in/sign-out 
and an ID tag prior to building access. These CPTED measures are similar to and 
complement physical security entry control point stations. 
However, in some cases, CPTED techniques can conflict with basic physical security 
principles. The CPTED strategy of natural surveillance calls for locating student 
parking in areas that allow ease of monitoring. A design that locates student parking 
close to the principal's office also reduces vehicle stand-off and could create a 
vulnerability of the school structure to a vehicle bomb. In cases where CPTED 
techniques conflict with security principles, designers and school administrators 
should seek innovative solutions tailored to their unique situation.



BUILDING DESIGN GUIDANCE AND SAFETY PLANS 
his chapter addresses explosive blast and CBR concerns 
from terrorist attacks, highlighting mitigation measures, 
including architectural, structural, and building envelope 
systems, and school safety plans. After the site design 
considerations to enhance protection presented in 
Chapter 2 have been taken into account, additional 
building design measures, such as hardening and CBR 
mitigation measures, must be considered to protect school 
occupants. Historically, the majority of fatalities that occur 
in terrorist attacks directed against buildings are due to 
building collapse. This was true for the Oklahoma City 
bombing in 1995 when 87 percent of the building 
occupants who were killed were in the collapsed portion 
of the Murrah Federal Building. 
When considering mitigation measures for explosive blast 
threats, the primary strategy is to keep explosive devices as 
far away from the school building as possible (maximize 
stand-off distance). This is usually the easiest and least 
costly way to achieve a desired level of protection. In cases 
where sufficient stand-off distance is not available to 
protect against progressive collapse of a school building 
(i.e., schools located in urban settings), hardening of the 
building's structural systems may be required. Designers 
should try to minimize hazardous flying debris during an 
explosive event because a high number of injuries can 
result from flying glass fragments and debris from walls, 
ceilings, and non-structural features. Another 
consideration is to balance the hardening of the building 
envelope so that the columns, walls, windows, and glazing 
have approximately equal response for damage and 
injury/casualty for the design basis threat weapon at the 
available stand-off distance. Window design is the element 
that is usually the most diverse in conventional 
construction. Good blast engineering is a multi-disciplinary 
effort that requires the concerted efforts of the architect, 
structural engineer, mechanical engineer, and the other 
design team members in order to achieve a balanced 
building envelope. 
When considering mitigation measures for CBR hazards, heating, ventilation, and air 
conditioning (HVAC) systems are of particular concern. A school building can 
provide protection against CBR agents released outdoors if the flow of fresh air is 
filtered or interrupted; however, HVAC systems can also become an entry point and 
distribution system for hazardous contaminants. If installed, HVAC air filtration and 
air-cleaning systems can reduce the effects of a CBR agent by removing the 
contaminants from the air within a building. There are a variety of ways to protect 
school building occupants from airborne hazards. These protective measures can be 
as simple as defining a protective action plan or as complex as strict design measures 
practical only for new construction. Specific HVAC design measures will be discussed 
in this chapter. In addition, Chapter 5 contains a discussion of CBR protective actions. 
School building design should be optimized to facilitate emergency evacuation, 
rescue, and recovery efforts through effective placement, structural design, and 
redundancy of emergency exits and critical mechanical/electrical systems. Through 
effective structural design, the overall damage levels may be reduced to make it easier 
for people to get out safely and allow emergency responders to enter safely. The 
designer must also balance measures to protect people with the requirements of the 
Americans with Disabilities Act Accessibility Guidelines (ADAAG), Uniform Federal 
Accessibility Standards (UFAS), National Fire Protection Codes (NFPC), and all 
applicable local building codes. Additional information is available in FEMA 426, 
Reference Manual to Mitigate Potential Terrorist Attacks Against Buildings, and FEMA 427, 
Primer for Design of Commercial Buildings to Mitigate Terrorist Attacks. 
3.1 ARCHITECTURAL 
Several architectural considerations can be implemented to mitigate the effects of a 
terrorist bombing on a school facility. These considerations often cost nothing or 
very little if implemented early in the design process. 
The shape of the school building can contribute to the overall damage to the 
structure. For example, "U" or "L" shaped buildings tend to trap shock waves, which 
may exacerbate the effect of explosive blasts. For this reason, it is recommended that 
re-entrant corners be avoided (see Figure 3-1). In general, convex rather than concave 
shapes are preferred when designing the exterior of a school building. Other 
considerations follow: 
. _	 Orient school buildings horizontally rather than vertically to reduce 
the building's profile and exposure. 
. _	 Elevate the ground floors of school buildings above grade to prevent 
vehicles from being driven into the facility. 
. _	 Avoid eaves and overhangs, because they can be points of high local 
pressure and suction during blasts. When these elements are used, they should be 
designed to withstand blast effects. 
. _	 Locate utility systems away from likely areas of potential attack, such as 
loading docks, lobbies, and parking areas. 
. _	 Orient glazing perpendicular to the primary facade to reduce exposure 
to blast and projectiles (see Figure 3-2). 
. _	 Avoid having exposed structural elements (e.g., columns) on 
the exterior of the school.


Figure 3-1 Re-entrant corners in a floor plan 
SOURCE: U.S. AIR FORCE, INSTALLATION FORCE PROTECTION GUIDE 
Figure 3-2 Glazed areas oriented perpendicularly away from streets 
. _	 Connect interior non-load bearing walls to the structure with flexible 
connections. 
. _	 Place areas of high visitor activity away from key assets. 
. _	 Eliminate hiding places within the school building. 
. _	 Locate assets in areas where they are visible to more than one person. 
. _	 Use interior barriers to differentiate levels of security within a school 
building. 
. _	 Stagger doors located across from one another in interior hallways to 
limit the effects of a blast through the school structure (see Figure 3-3). 
. _	 Provide foyers with reinforced concrete walls, and offset interior and 
exterior doors from each other in the foyer. 
. _	 Locate stairwells required for emergency as remotely as possible from 
areas where blast events might occur. 

. _	 Wherever possible, do not discharge stairs into lobbies, parking, or 
loading areas. 
. _	 Separate unsecured areas of the main school building as much as 
possible. For example, a separate lobby pavilion or loading dock area outside of the 
main footprint of the building provides enhanced protection against damages and 
potential building collapse in the event of an explosion. This can also be done by 
creating internal "hard lines" or buffer zones, using 

SOURCE: U.S. AIR FORCE, INSTALLATION FORCE PROTECTION GUIDE 
secondary stairwells, elevator
shafts, corridors, and storage areas Figure 3-3 Offset doors through the foyer
between public and secured areas.

_	 Place parking areas outside the main footprint of the 
school building to reduce the vulnerability to 
catastrophic collapse.


3.2 	BUILDING STRUCTURAL AND 
NONSTRUCTURAL SYSTEMS 
For schools that require high security measures, explosive 
blast threats may govern building design. A structural 
engineer should determine the school design features 
needed to achieve the desired level of protection against 
the design blast threat, considering both the collapse of 
the school building as well as incipient injuries and 
fatalities of students, faculty, and staff. 
Progressive collapse is a situation where local failure of a 
primary structural component leads to the collapse of 
adjoining members which, in turn, leads to additional 
collapse. Hence the total damage is disproportionate to 
the original cause. Progressive collapse is a chain reaction 
of structural failures that follows from damage to a 
relatively small portion of a structure. 
All new school buildings should be designed with the intent of reducing the potential 
for progressive collapse as a result of an abnormal loading event, regardless of the 
required level of protection. The following structural characteristics (from GSA 
Progressive Collapse Analysis and Design Guidelines for New Federal Office Buildings and Major 
Modernization Projects, November 2000) should be considered in the initial phases of 
structural design. Incorporation of these features will provide a much more robust 
structure and decrease the potential for progressive collapse. 
. _	 Redundancy. The use of redundant lateral and vertical force resisting 
systems is highly encouraged when considering progressive collapse. Redundancy 
tends to promote a more robust structure and helps to ensure that alternate load paths 
are available in the case of a structural element(s) failure. Additionally, redundancy 
provides multiple locations for yielding to occur, which increases the probability that 
damage will be constrained. 
. _	 The use of ductile (flexible) structural elements and detailing. 

It is critical that both the primary and secondary structural elements be capable of 
deforming well beyond the elastic limit without experiencing structural collapse. 
Hence, the use of ductile construction materials (i.e., steel, cast-in-place 
reinforced concrete, etc.) for both the structural elements and connection 
detailing is encouraged. The capability of achieving a ductile response is 
imperative when considering an extreme redistribution of loading such as that 
encountered in a structural element(s) failure. 
. _	 Capacity for resisting load reversals. Both the primary and secondary 
structural elements should be designed to resist load reversals in the case of a 
structural element(s) failure. 
. _	 Capacity for resisting shear failure. Primary structural elements 
maintain sufficient strength and ductility under an abnormal loading event to 
preclude a shear failure. If the shear capacity is reached before flexural capacity, a 
sudden, 

non-ductile failure of the element could potentially lead to a 
progressive collapse of the structure. 
Both the GSA and DoD take a threat-independent approach to progressive collapse. 
The goal of a threat-independent approach is not to prevent collapse from a specific 
design threat, but to control and stop the continuing spread of damage after 
localized damage or localized collapse has occurred. 
The GSA and DoD require that the structural response of a building be analyzed in a 
test that removes a key structural element (e.g., vertical load carrying column, section 
of bearing wall, beam, etc.) to simulate local damage from an explosion. If effective 
alternative load paths are available for redistributing the loads, originally supported by 
the removed structural element, the building has a low potential for progressive 
collapse. 
For higher levels of protection from blast, cast-in-place reinforced concrete is 
normally the construction type of choice. Other types of construction such as properly 
designed and detailed steel structures are also allowed. Several material and 
construction types, although not disallowed by these criteria, may be undesirable and 
uneconomical for protection from blast. 
The following guidelines are commonly used to mitigate the effects of blast on 
structures and to mitigate the potential for progressive collapse. See sidebar for details 
and more guidance. 
_	Use multiple barrier materials and construction techniques to mitigate the effects 
of blast on a structure at less expense than a single material or technique. 
. _	 Incorporate internal damping into the structural system to absorb blast 
impact. 
. _	 Use symmetric reinforcement to increase the ultimate load capacity of 
the structure. 
. _	 Incorporate design redundancy and alternative load paths to help 
mitigate blasts and reduce the chance of progressive collapse. The Murrah Federal 
Building's structural system did not have any redundancy for the slab and beam 
systems. 
. _	 Strengthen the structural system to help resist the effects of a blast. 
. _	 Incorporate inelastic or post elastic design to allow the structure to 
absorb the energy of the explosion through plastic deformation. 
. _	 Recognize that components might act in directions for which they were 
not designed. This is due to the engulfment of structural members by blast, the 
negative phase, the upward loading of elements, and dynamic rebound of members. 
Making steel reinforcement (positive and negative faces) symmetric in all floor slabs, 
roof slabs, walls, beams, and girders will address this issue. Symmetric reinforcement 
also increases the ultimate load capacity of the members. 
. _	 Ensure that lap splices fully develop the capacity of the reinforcement. 
. _	 Stagger lap splices and other discontinuities. 
. _	 Control deflections around certain members, such as windows, to 
prevent premature failure. Additional reinforcement is generally required. 
. _	 Use wire mesh in plaster to reduce the incidence of flying fragments. 
. _	 Avoid the use of masonry when blast is a threat. Masonry walls break up 
readily and become secondary fragments during blasts. 

. _	 Use ductile connections for steel construction and develop as much 
moment connection as practical. Connections for cladding and exterior walls to steel 
frames should develop the capacity of the wall system under blast loads. 
. _	 Avoid single-point failures that can cascade, producing widespread 
catastrophic collapse. A prime example is the use of transfer beams and girders that, if 
lost, may cause progressive collapse and are, therefore, highly discouraged. 
. _	 Incorporate redundancy and alternative load paths into design to 
mitigate blast loads. One method of accomplishing this is to use two-way 
reinforcement schemes where possible. 
. _	 Minimize column spacing so that reasonably sized members can be 
designed to resist the design loads and increase the redundancy of the system. A 
practical upper level for column spacing is 30 feet for the levels of blast loads 
described herein. 
. _	 Minimize floor to floor heights. Unless there is an overriding 
architectural requirement, a practical limit is generally less than or equal to 16 feet. 
. _	 Use architectural or structural features that deny contact with exposed 
primary vertical load members in school lobbies. A minimum stand-off of at least 6 
inches from these members is required. 
. _	 Minimize the use of venetian blinds and false ceilings, and locating 
equipment such as light fixtures, partitions, ductwork, and air conditioners above 
ceilings wherever possible. These items may become flying debris in the event of an 
explosion. Placing heavy equipment such as air conditioners near the floor rather than 
the ceiling is one idea for limiting this hazard; using exposed ductwork as an 
architectural device is another possibility. 


3.3 BUILDING ENVELOPE 
3.3.1 Building Exterior 
The exterior envelope of the school building is the most vulnerable to an exterior 
explosive threat because it is the part of the building closest to the weapon. It also is 
a critical line of defense for protecting the occupants of the school building. 
The design philosophy to be used here is that simpler is better. Generally simple 
geometries, with minimal ornamentation (which may become flying debris during an 
explosion) are recommended. If ornamentation is used, it is recommended that it 
consists of a lightweight material such as timber or plastic, which is less likely to 
become a projectile in the event of an explosion than, for example, brick, stone, or 
metal.


3.3.2 Exterior Wall Design 
The exterior walls provide the first line of defense to prevent air-blast pressures and 
hazardous debris from entering the school building. At a minimum, the objective of 
design is to ensure that these members fail in a flexible mode rather than in a brittle 
mode such as shear. The walls also need to be able to resist the loads transmitted by 
the windows and doors. Beyond ensuring a flexible failure mode, the exterior wall may 
be designed to resist the actual or reduced pressure levels of the defined threat. 
Special reinforcing and anchors should be provided around blast-resistant window and 
door frames. 
Poured-in-place reinforced concrete will provide the highest level of protection, but 
solutions like pre-cast concrete, reinforced concrete masonry unit (CMU) block, and 
metal studs may also be used to achieve lower levels of protection. 
For pre-cast panels, consider a minimum thickness of 5 inches with two-way 
reinforcing bars placed at spacing not greater than the thickness of the panel. 
Connections into the structure should provide as a straight a line of load transmittal as 
practical, using as few connecting pieces as possible. 
For CMU block walls, use 8-inch block walls, fully grouted with vertical centered 
reinforcing bars placed in each cell and horizontal reinforcement at each layer. 
Connections into the structure should be able to resist the ultimate lateral capacity of 
the wall. A preferred system is to have a continuous exterior CMU wall that laterally 
bears against the floor system. For increased protection, consider using 12-inch blocks 
with two layers of reinforcement. 
For metal stud systems, use metal studs back to back and mechanically attached, to 
minimize lateral torsion effects. To catch exterior cladding fragments, attach a wire 
mesh to the exterior side of the metal stud system. The supports of the wall are to be 
designed to resist the ultimate lateral capacity load of the system. 
When designing schools in areas perceived as high risk, engineers and architects 
should consider the following recommendations: 
. _	 Substitute strengthened building walls and systems when stand-off 
distances cannot be accommodated. 
. _	 Use ductile materials capable of very large plastic deformations without 
complete failure. 
. _	 Design exterior walls to resist the actual pressures and impulses acting 
on the exterior wall surfaces from the threats defined for the school building. 
. _	 Design exterior walls to withstand the dynamic reactions from the 
windows. 
. _	 Design exterior shear walls to resist the actual blast loads predicted 
from the threats specified. Consider shear walls that are essential to the lateral and 
vertical load bearing system, and that also function as exterior walls, to be primary 
structures. 
. _	 Consider reinforced concrete wall systems in lieu of masonry or curtain 
walls to minimize flying debris in a blast. 

. _	 Reinforced wall panels can protect columns and assist in preventing 
progressive collapse, because the wall will assist in carrying the load of a damaged 
column. 
. _	 Give special consideration to construction types that reduce the 
potential for collapse where exterior walls are not designed for the full design loads. 
. _	 Consider use of sacrificial exterior wall panels to absorb blast. 


3.3.3 Window Design 
Window systems (e.g., glazing, frames, anchorage to supporting walls, etc.) on the 
exterior fa�ade of a school building should be designed to mitigate the hazardous 
effects of flying glass during an explosion event. In an effort to protect school 
occupants, designers should integrate the features of the glass, connection of the glass 
to the frame (bite), and anchoring of the frame to the building structure to achieve a 
"balanced design." This means all the components should have compatible capacities 
and theoretically would all fail at the same pressure-pulse levels. In this way, the 
damage sequence and extent of damage are controlled. Table 3-1 presents six GSA 
glazing protection levels based on how far glass fragments would enter a space and 
potentially injure its occupants. Figure 3-4 depicts how far glass fragments could enter 
a structure for each GSA performance condition. 
Table 3-1: Glazing Protection Levels Based on Fragment Impact Locations1 
* In conditions 2, 3a, 3b, 4 and 5, glazing fragments may be thrown to the outside of the protecte