PUBLICATIONS

AlllOb 4baTM7

NIST Special Publication 1000-5

June 2004

Progress Report on the

Federal Building and Fire Safety

Investigation of the

World Trade Center Disaster

Volume 6

Contains Appendices N, O, P, and Q

QC

loo _ National Institute of Standards and Technology • Technology Administration • U.S. Department of Con
1^
NIST Special Publication 1000-5

June 2004

Progress Report on the

Federal Building and Fire Safety

Investigation of the

World Trade Center Disaster

Volume 6

Contains Appendices N, O, P, and Q

June 2004

U.S. Department of Commerce

Donald L. Evans, Secretary

Technology Administration

Phillip J. Bond, Under Secretary for Technology

National Institute of Standards and Technology

Arden L. Bement, Jr., Director
Disclaimer

Certain commercial entities, equipment, products, or materials are identified in this document in order to describe a procedure or concept adequately or to trace the history of the procedures and practices used. Such identification is not intended to imply recommendation, endorsement, or implication that the entities, products, materials, or equipment are necessarily the best available for the purpose. Nor does such identification imply a finding of fault or negligence by the National Institute of Standards and Technology.

Disclaimer

The policy of NIST is to use the International System of Units (metric units) in all publications. In this document,

however, units are presented in metric units or the inch-pound system, whichever is prevalent in the discipline.

Use in Legal Proceedings

No part of any report resulting from a NIST investigation into a structural failure or from an investigation under the

National Construction Safety Team Act may be used in any suit or action for damages arising out of any matter mentioned in such report (15 USC 281a; as amended by P.L. 107-231).

National Institute of Standards and Technology Special Publication 1000-5

Natl. Inst. Stand. Technol. Spec. Publ. 1000-5, 1,054 pages (June 2004)

CODEN: NSPUE2

U.S. GOVERNMENT PRINTING OFFICE

WASHINGTON: 2004

For sale by the Superintendent of Documents, U.S. Government Printing Office

Internet: bookstore.gpo.gov —- Phone: (202) 512-1800 — Fax: (202) 512-2250

Mail: Stop SSOP, Washington, DC 20402-0001
Master Table of Contents

Volume 1

Table of Contents

List of Acronyms and Abbreviations

Metric Conversion Table

Preface

Executive Summary

Chapter 1 Interim Findings and Accomplishments

Chapter 2

Progress on the World Trade Center Investigation

Chapter 3

Update on Safety of Threatened Buildings (WTC R&D) Program

Chapter 4

Update on WTC Dissemination and Technical Assistance Program

Volume 2

Table of Contents

List of Acronyms and Abbreviations

Metric Conversion Table

Appendix A

Interim Report on the Analysis of Building and Fire Codes and Practices

Appendix B

Interim Report on Development of Structural Databases and Reference Models

for the WTC Towers

iii
Table of Contents

Appendix C

Interim Report on Analysis of Aircraft Impact into the WTC Towers

Voiume 3

Table of Contents

List of Acronyms and Abbreviations

Metric Conversion Table

Appendix D

Interim Report on Preliminary Stability Analysis of the WTC Towers

Appendix E

Interim Report on Contemporaneous Structural Steel Specifications

Appendix F

Interim Report on Inventory and Identification of Steels Recovered from the

WTC Buildings

Volume 4

Table of Contents

List of Acronyms and Abbreviations

Metric Conversion Table

Appendix G

Interim Report on Significant Fires in WTC 1, 2, and 7 Prior to September 11, 2001

Appendix H

Interim Report on Evolution of WTC Fires, Smoke, and Damage based on Image Analysis

Appendix I Interim Report on Assessment of Sprayed Fireproofing in the WTC

Towers—Methodology
June 2004 Progress Report

Volume 5

Table of Contents

List of Acronyms and Abbreviations

r

Metric Conversion Table

Appendix J

Interim Report on Experiments to Support Fire Dynamics and Thermal

Response Modeling

Appendix K

Interim Report on Subsystem Structural Analysis of the WTC Towers

Appendix L

Interim Report on WTC 7

Appendix M

Interim Report on 2-D Analysis of the WTC Towers Under Gravity Load and Fire

Volume 6

Table of Contents

List of Acronyms and Abbreviations

Metric Conversion Table

Appendix N

Interim Report on Analysis of First-Person Accounts from Survivors of the WTC

Evacuation on September 11, 2001

Appendix O

Interim Report on Telephone Interviews

Appendix P

Interim Report on Emergency Communications

Appendix Q

NIST's Working Hypothesis for Collapse of the WTC Towers
Table of Contents

This page intentionally left blank.

vi
List of Acronyms and Abbreviations

AAPOR American Association of Public Opinion Research

ABC American Broadcasting Company

ACI American Concrete Institute AISC American Institute of Steel Construction

AISI American Iron and Steel Institute ALE Arbitrary-Lagrangian-Evlerian

AMCBO Association of Major City/County Building Officials

ANSI American National Standards Institute ANSYS finite element model

ARA Applied Research Associates, Inc. ASCE American Society' of Civil Engineers

ASHRAE American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc. ASME American Society of Mechanical Engineers

ASTM ASTM International

AWS American Welding Society

BOCA Building Officials and Code Administrators

BOCA/BBC BOCA Basic Building Code

BPAT Building Performance Assessment Team

BPS ' Building Performance Study

BSI British Standards Institution

C/F cancer free CATI computer-assisted telephone interviews

CBR chemical, biological, and radiological

CBS Columbia Broadcasting System

CERF Civil Engineering Research Foundation

CFD computational fluid dynamics

CIB International Council for Research and Irmovation in Building and Construction

CII Construction Industry Institute CNN Cable News Network

vii
List of Acronyms and Abbreviations

CPP Cpimak Pptprk?i Pptpr^oti Inr CPU central processing unit

CRT cathode-rav tube

CTB&IJH r^oiinoil V-- wLillVXl onV7X1 Tfill 1 Clli 1^RiiilHinp^ Lit ?inH dilVJ- Tlrhan KJlL/ClLl l-[f»Hi'tat lluL/lLul CTE coefficient's V'WV/ 111 V'l^Xl Ll3 of\J 1 thermjil l.llv/lJlliC41 exnnnsion L/ClllOlWll DC/F RlazeShield OC/F fire nrotecfive in*\iilation

DL Hpad load

DTAP dissemination VAl lJOV^XI-XXI AU 1.1. Wll and UllVt technical 1 V/ wJ. IX 1 X V- Ul assistance UO lJ X O 1-vt.XX nropram LrX V/ C_,X UXX

FMS FmprcTpncv IVlpdicnl SIptvipp ' j_'iiiv'i ^viiv y ivi^v^iv^ui tov-i V iv^^ EMT j_^i Fmprppncv 1 1^1 c^^i 1^ y ivi^viiv^cii Mpdiral Tppim 1 ^ciiii ER&S Emory Roth & Sons

FBI Fpdpral 1 ^U.V.'l C4. 1 LJRiirpaii Lll ^Cl LI of\J 1 lllV^Oll In vp^ti (nation C^Ct llV/11 FCA FliiY 1 1 Li A porpd V^WiV^VJ. firp Cll FDNY ISIpw iiV/W YorV IWlIv r^itv V^l I y 1Firp 11 J_-/ Opnartmpnt L/C*i llll^llL

1FDSIV O Firp 1 11 w i^yiiciiiii^o Ovnfimip*s Slimiilatnr oiiiiciiciti^i FE finite clement

FEA finite XXllXLw element ^X^XXXV/XXL Jinjilv'^is UXXU.X y tjLiJ FEM fimtp plpmpnt modpl ' lllllLv.' Vp/l^lliL/lll ilHJU.Sh/1 FFMA XFpdpr^il v/Uv/icii i_-*iii^i Fmpropncv Kj^iiV' iVTanacrpmpnt A cjpnpv y iviciiici^wiiHi^iii ii.^v,^iivy FMRC Faptorv \/liitiiJil RpQp^ircVi C^nirn

FST Firp-^tn ipfi irp In tprfi^r*p FVM 1Fimtp lllll^ \/oliimp V V'lLlllIv^ IVHta-lllv^U IVIptliod

GFI Ciovpmmpnt V 1 v/ V^llIlllV/lll 1Fnmi'slipd L^llllOl 1 Vi 111 Infonnpition 1 V/1 1 1 ICl 1 1 v/11 GG ^icioo crlaQQ ovpr w crl?iQc V v-i ^lajj

GHz ^IgClllV.'l iZj GMS LLP riil^any VJllOdllZj iVlLlllCiy IVlnrrnv ^tpfippV kJ LV^IIV^^-'IV^ TIP J—.i-'l HAZ Vipfit fiffpptpd 7onp

HNSE Hugo Nue Schnutzer East

I T o O rlRR heat release rate HVAC heating, ventilating, and air conditioning

lAQ indoor air quality

IBC International Building Code
June 2004 Progress Report

1 V L J V /

T'nt(=*mcitir^"nfi1 r^Hp i r^iinfil TMTT TTrtf^rrTcifi^H IV/T Qni iTCi r^ln ifi n rr T^^^r* rin r\ 1 rvo"!;^ llllCgralCU. IViallUiaClUl 111^ i CdillUlUgy

Jr Jv juxui r. jvciiiicuy jLiiLCiiiaiiuiiai /\npuii

it's ToT\Q"n Tti /I n c1"t"i Q 1 ^"t'onodf/H ' Japdll iJlUUaulal olallUdlU

T FT? A J_,CollC Hj. IvUUCllaUll /AbaUClalCj

I PC i^drgc jj/Uuy oiiiiuidiiuii

r T live lUdU. LoT CTP1 Liveiiiiorc oUiiwdic i cLiiiiuiugy i^urpurdiiuii

MRP J3w^ r\ iNallUlldl DUllU-lil^ V_ULiC

iViUlllCipdl V_UUt Ul \^lllLdgU

N/TPT iVLrl iVicSadgc r dSSlIlg lIUcildLe

MRP iNdllUlldl DlUdUCdslUlg ^^Ullipdliy

iNdiiundi DOdiu oj riic vjiiuerwriiera

iNdiiundi v_^oriitrciicc ui oidics on ouiiuiiig i^uucs oc oidnudiu^, inc.

iNdUUIldl \_'UIli>ll ULUUIl odlCiy 1 Cdlll MFM IN HiVi/\A INdUUIldl niccincdi ividiiuidLLurcrb /\s5ULidiiuii

NFPA iNdUUIldl Flic FlULCV-'llUll /^oSUL-ldllUll

Xliitionjil i^dllvJlidi IXloLllU-lC Tnctitiitf^ ofKJL ULillLiill^ RiiilHincr ^fipnpPQ OL/idlVw'Co NTST Njitinnal l^CltlUllCli XlioLlLLLt^ Tn<\titiitp of\JL k_7Lt4.llU.Cli.VJ.C3 Stfinrlarrl^s anrl dllVl Tprhtinlopv ± ^V^llll\_'ll-/^ V

iN I V„DV_ INCvV 1 Uliv v^lLy DUllUlll^ UUC

MVPnOR iN I \^LJKJD iNcw I uiK v^iiy juepdi llllClll Ul OUllUlllga

NYPD IN 1 1 J_-/ T\fp\x/ iNCW Vr^rV 1 UliV C^ii^/ ^ILy XPr\lipp VJllvC L-/vp<ll Dpniirtmpnt Llllt/lll NYSRC TsIpw i>\^W Vnrk" IVJIIVO^t^itp ICllV^ LJRiiilHino" Lilll4111^ (^nriQtniptinn \^ v/IlO 11 LlW llWll (^nrlp V/UV/

P T PiinliP I JTUUIH^ L--dW

r/AJ.N I iNJ 1 Ul I /\u.iiiuiiiy Ul iNCW I uiJv diiu iNCW jciacy

PAPD Pr^Tt 1 I /AUHlUllLy Aiitnr^TT^A/ X^JllCC Pr^lipp 1-/Cpcli Dp'nii'rtTTiPnt LlllClil PC&F Paciiic Car and Foundry

PDM Pittsburg-Des Moines

PONYA Port of New York Authority

R&D research and development
List of Acronyms and Abbreviations

RWDI Rowan Williams Davis and Irwin, Inc. SBCCI Southern Standard Building Code

SDL superimposed dead load

SDO standards development organization

SEAoNY Structural Engineers Association of New York

SFPE Society of Fire Protection Engineering

SFRM spray-on fire resistant material or sprayed fire resistive materials

SHCR Skilling, Helle, Christiansen, & Robertson

SI metric ' >- SLB short legs back-to-back ^ SMA Shielded Metal Arc

SOD Special Operations Division

SOM Skidmore, Ownings & Merrill

SPH Smoothed Particle Hydrodynamics '

SQL Structured Query Language

SWMB Skilling, Ward, Magnussen, and Barkshire

TL Truss Lower Chord

TM Truss Middle Chord

TU Truss Upper Chord

UBC Uniform Building Code

UL Underwriters' Laboratories, Inc. use United States Code

USM United States Mineral Products Co.

VCBT Virtual Cybernetic Building Testbed

WABC WABC-TV New York

WCBS WCBS-TV New York

WF wide flange (a type of structural steel shape now usually called a W-shape). ASTM A 6

defines them as "doubly-symmetric, wide-flange shapes with inside flange surfaces that are substantially parallel."

WNBC NBC4 New York

WNYW FOX5 New York

WPIX WPIX-TV New York

WTC World Trade Center
June 2004 Progress Report

WTC 1 World Trade Center Tower 1 WTC 2 World Trade Center Tower 2 WTC 7 World Trade Center Building 7

xi
List of Acronyms and Abbreviations

Abbreviations

X by

± plus or minus

°C degrees Celsius

op degrees Fahrenheit

jam micrometer

2D two dimensional

3D three dimensional

cm centimeter

ft foot ^ square foot

Fy yield strength (AISC usage)

g acceleration (gravity)

g gram

gal gallon

h hour

in. inch

kg kilogram

kip a stress unit equal to 1 ,000 pounds

kJ kilojoule

kN kilonewton

kPa kilopascal

klb 1,000 pounds

ksi 1,000 pounds per square inch

kW kilowatt

kW/m- kilowatts per square meter

L liter

lb pound

m meter

square meter * mm millimeter

m/s meters per second
June 2004 Progress Report

TTiin minute

MT TTiPcaionlp

MPa megapascal

mph miles per hour

Xllo miproQPPnnH '

Msi millions pounds per square inch

MW megawatt

N newton

Pa pascal

pcf pounds per cubic foot

plf pounds per linear foot

psf pounds per square foot

psi pounds per square inch

s second

xiii
List of Acronyms and Abbreviations

This page intentionally left blank.

xiv
Metric Conversion Table

To convert from to Multiply by

AREA AND SECOND MOMENT OF AREA

square foot (fr)

square inch (in')

square inch (in")

square yard (yd")

square meter (m )

square meter (m")

square centimeter (cm")

square meter (m")

9.290 304 E-02

6.4516 E-04

6.4516 E+00

8.361 274 E-01

ENERGY (includes WORK)

kilowatt hour (kW * h)

quad (1015 BtuIT)

therm (U.S.)

ton of TNT (energy equivalent)

watt hour (W * h)

watt second (W * s)

joule (J)

joule (J)

joule (J)

joule (J)

joule (J)

joule (J)

3.6 E+06

1.055 056E+18

1.054 804 E+08

4.184 E+09

3.6 E+03

1.0 E+00

FORCE

dyne (dyn)

kilogram-force (kgf)

kilopond (kilogram-force) (kp)

kip(l kip=1000 Ibf)

kip(l kip=1000 Ibf)

pound-force (Ibf)

newton (N)

newton (N)

newton (N)

newton (N)

kilonewton (kN)

newton (N)

1.0 E-05

9.806 65 E+00

9.806 65 E+00

4.448 222 E+03

4.448 222 E+00

4.448 222 E+00

FORCE DIVIDED BY LENGTH

pound-force per foot (Ibf/ft)

pound-force per inch (Ibf/in)

newton per meter (N/m)

newton per meter (N/m)

1.459 390 E+01

1.751 268 E+02

HEAT FLOW RATE

calorieth per minute (calth/min)

calorieth per second (calth/s)

kilocalorieth per minute (kcalth/min)

kilocalorieth per second (kcalth/s)

watt (W)

watt (W)

watt (W)

watt (W)

6.973 333 E-02

4. 1 84 E+00

6.973 333 E+01

4. 1 84 E+03

XV
Metric Conversion Table

To convert from

LENGTH

foot (ft)

inch (in)

inch (in)

micron (m)

yard (yd)

to

meter (m)

meter (m)

centimeter (cm)

meter (m)

meter (m)

Multiply by

3.048 E-01

2.54 E-02

2.54 E+00

l.OE-06

9.144 E-01

MASS and MOMENT OF INERTIA

k'llopmnT-f'nrf'f' 'spronri sniifirpfl per meter (kgf * s"/m) kilogram (kg) 9.806 65 E+00

pound foot squared (lb * ft") kilogram meter squared (kg * m") 4.214 011 E-02

pound inch squared (lb * in") kilogram meter squared (kg * m") 2.926 397 E-04

ton, metric (t) kilogram (kg) 1.0 E+03

ton, short (2000 lb) kilogram (kg) 9.071 847E+02

MASS DIVIDED BY AREA

pound per square foot (lb/ft") kilogram per square meter (kg/m") 4.882 428 E+00

pound per square inch

(not pound force) (lb/in") kilogram per square meter (kg/m") 7.030 696 E+02

MASS DIVIDED BY LENGTH

pound per foot (lb/ft) kilogram per meter (kg/m) 1.488 164 E+00

pound per inch (lb/in) kilogram per meter (kg/m) 1.785 797 E+01

pound per yard (lb/yd) kilogram per meter (kg/m) 4.960 546 E-01

PRESSURE or STRESS (FORCE DIVIDED BY AREA)

kilogram-force per square centimeter (kgf/cm") pascal (Pa)

kilogram-force per square meter (kgf/m") pascal (Pa)

kilogram-force per square millimeter (kgf/mm~) pascal (Pa)

kip per square inch (ksi) (kip/in") pascal (Pa)

kip per square inch (ksi) (kip/in") kilopascal (kPa)

pound-force per square foot (Ibf/ft") pascal (Pa)

pound-force per square inch (psi) (Ibf/in") pascal (Pa)

pound-force per square inch (psi) (Ibf/in") kilopascal (kPa)

psi (pound-force per square inch) (Ibf/in") pascal (Pa)

psi (pound-force per square inch) (Ibf/in") kilopascal (kPa)

9.806 65 E+04

9.806 65 E+00

9.806 65 E+06

6.894 757 E+06

6.894 757 E+03

4.788 026 E+01

6.894 757 E+03

6.894 757 E+00

6.894 757 E+03

6.894 757 E+00

XVI
June 2004 Progress Report

To convert from to Multiply by

TEMPERATURE

degree Celsius (°C)

degree centigrade

degree Fahrenheit (°F)

degree Fahrenheit (°F)

kelvin (K)

kelvin (K)

degree Celsius (°C)

degree Celsius (°C)

kelvin (K)

degree Celsius (°C)

T/K = t/°C + 273.15 t/°C~t /deg. cent.

t/°C = (t/°F 2 32)/1.8 T/K = (t/°F + 459.67)/!.

t/°C = T/K 2 273.15

TEMPERATURE INTERVAL

degree Celsius (°C)

degree centigrade

degree Fahrenheit (°F)

degree Fahrenheit (°F)

degree Rankine (°R)

kelvin (K)

degree Celsius (°C)

degree Celsius (°C)

kelvin (K)

kelvin (K)

l.OE+00

l.OE+00

5.555 556 E-01

5.555 556 E-01

5.555 556 E-01

VELOCITY (includes SPEED)

foot per second (ft/s)

inch per second (in/s)

kilometer per hour (km/h)

mile per hour (mi/h)

mile per minute (mi/min)

meter per second (m/s)

meter per second (m/s)

meter per second (m/s)

kilometer per hour (km/h)

meter per second (m/s)

3.048 E-01

2.54 E-02

2.777 778 E-01

1 .609 344 E+00

2.682 24 E+01

VOLUME (includes CAPACITY)

cubic foot (ft^)

cubic inch (in^

)

cubic yard (yd^)

gallon (U.S.) (gal)

gallon (U.S.) (gal)

liter (L)

ounce (U.S. fluid) (fi oz)

ounce (U.S. fluid) (fl oz)

cubic meter (m )

cubic meter (m'')

cubic meter (m^)

cubic meter (m'^)

Hter (L)

cubic meter (m^)

cubic meter (m^)

milliliter (mL)

2.831 685 E-02

1.638 706 E-05

7.645 549 E-01

3.785 412 E-03

3.785 412 E+00

1.0 E-03

2.957 353 E-05

2.957 353 E+01

xvii
Metric Conversion Table

This page intentionally left blank.

xviii
Table of Contents

List of Figures N-iii

List of Tables N-iv

Appendix N

Interim Report on Analysis of First-Person Accounts from Survivors of the WTC

Evacuation on September 11, 2001 N-1

N. 1 Introduction N-1

N.2 Background Literature N-2

N.3 Study Objectives N-3

N.4 Methodology N-4

N.4. 1 Content Analysis N-5

N.4. 2 Variables Considered N-6

N.4.3 Procedure N-8

N.5 Study Results N-9

N.5. 1 Profile: Gender and Age N-9

N.5. 2 Location at the Beginning of the Event N-9

N.5. 3 Means of Egress Used N-10

N.5.4 First Cue Reported N-11

N.5. 5 Time to Start Evacuation N-1

N.5. 6 Conditions on Floors and in Stairwells N-1

N.5. 7 Obstructions During Evacuation N-1

N. 5 . 8 Announcement N-1

N.5. 9 Location When WTC 2 Was Hit N-14

N.5. 10 Location When WTC 2 Collapsed N-1

N.5.1 1 Location When WTC 1 Collapsed N-1

N.5. 12 Location When They Saw Firefighters N-1

N.5. 13 Time of Exit N-15

N. 5 . 1 4 Help Received and Help Given N-1

N.5. 15 Occupants with Disabilities or Injuries N-16

N.5.16Phone Calls N-17

N.5. 1 7 Knowledge of Situation N-17

N.5. 18 Influence of Others N-17

N-i
Appendix N

N.5. 19 Perception of Others N-18

N. 5. 20 Technology to Gain Information N-20

N.5.21 Impact of the 1993 Evacuation N-20

N.6 Summary Results N-20

N.7 Future Work N-22

N.8 Acknowledgments N-23

N.9 References N-23

Attachment 1 WTC First-Person Accounts Code Book N-27

N-ii
List of Figures

Figure N-1 . Distribution of publication dates of accounts N-9

Figure N-2. Gender and age distribution N-10

Figure N-3. Distribution of time to start evacuation N-1

Figure N^. Obstructions encountered during evacuation in both towers N-14

Figure N-5. Knowledge of situation in the towers N-1

Figure N-6. Distribution of perception of others between the towers N-1

Figure N-7. Distribution of gender and perception of others N-1

N-iii
List of Tables

Table N-1 . Questions on manifest information N-6

Table N-2. Questions on latent information N-6

Table N^3. Means of egress used within the towers N-10

Table N-4. First cues of event within the towers N-1

1

Table N-5. Adverse conditions on floor at impact N-1

3

Table N-6. Adverse conditions reported in the stairs during evacuation N-1

3

Table N-7. Time out of towers N-1

6

Table N-8. Gender and influence of others N-1

8

Table N-9. Distribution of age and perception of others N-20

N-iv
Appendix N

Interim Report on Analysis of First-Person Accounts from

Survivors of the WTC Evacuation on September 11, 2001

N.1 introduction

In the days following the September 11, 2001, attacks on the World Trade Center (WTC), the National

Fire Protection Association (NFPA) in collaboration with the National Research Council of Canada

decided to collect survivors' stories to document the event and to use this background material to develop

future studies on occupant behavior during the evacuation of the World Trade Center. First-person accounts were collected from newspapers, radio and television programs, e-mail exchanges, and a variety

of websites. Additional accounts were received at a later date from the National Institute of Standards

and Technology (NIST). This large quantity of material was coded and analyzed to obtain a better understanding of the personal evacuation experiences of different survivors located on the different floors of the two towers. This report documents that analysis. The analysis was solely based on written accounts and does not include first-person interviews conducted as part of the NIST investigation.

Rather, it provided background for the development of the telephone and face-to-face interviews

conducted for the NIST investigation.

At 8:46 a.m. on Tuesday, September 11, 2001, American Airlines Flight 1 1, a hijacked Boeing 767, hit WTC 1 of the WTC. This impact caused extensive damage on five floors, from 93 to 99 of the 1 10-story

high tower, trapping those above. Sixteen and a half minutes later, at 9:03 a.m., a second hijacked

Boeing 767, United Airlines Flight 175, struck WTC 2 of the WTC, damaging nine floors, from 77 to 85.

Despite the massive localized damage caused by the impact, each structure remained standing. However,

as each aircraft impacted the building, jet fuel on board ignited. Part of this fuel immediately burned off

in large fireballs that erupted at the impact floors. Remaining fuel flowed across the floors and down

elevator and utility shafts, igniting intense fires throughout upper portions of the buildings.

At 9:59 a.m., WTC 2, the second building to be hit, collapsed after burning intensely for 56 minutes.

WTC 1 withstood its injury longer than the South tower, collapsing to the ground at 10:28 a.m. after burning for 102 minutes (FEMA BPAT 2002). It is estimated that approximately 2,800 people were

killed and 800 others injured by the attacks and eventual collapse of the towers on September 11, 2001,

including building occupants and first responders (Cauchon 2001).

Although the events of September 1 1, 200 1, involved the WTC, the Pentagon and the hijacked airliners,

the evacuation of the two towers is the focus of this research. The attacks precipitated the evacuation of

the entire WTC complex. The evacuation of WTC 1 and WTC 2 was largely initiated by the occupants

themselves.

The WTC was a complex of seven buildings, including the two 1 10-story office towers. Approximately

50,000 people worked in each tower (100,000 total), with an estimated 70,000 visitors to the complex

during the course of a normal business day (Yamasaki 2002). However, the occupancy of the towers on

N-1
Appendix N

the morning of September 11, 2001, was not at its maximum capacity. According to USA TODAY,

5,000 to 7,000 people were in each tower at 8:46 a.m. that morning, the time of first impact

(Cauchon 2001). It has been suggested that the towers were not at their maximum capacity for several reasons. That morning marked New York City's mayoral primary, and it is assumed that many people

stopped to cast their ballots before heading in to work. The New York Stock Exchange does not open

until 9:30 a.m., therefore many people from trading firms had not come into work yet. Tuesday,

September 1 1, 2001, was the first day of school in several primary school districts, and many parents

accompany their children to school on this day. Visitor hours had not started yet, as the viewing platform

in the South Tower did not open to the public until 9:30 a.m. Perhaps the biggest factor of all was the

early hour—many simply had not arrived at work by 8:46 a.m. In addition, dozens of investment firms in the WTC had closed their offices or cut employment sharply. Some offices were leased but empty or under renovation (Cauchon 2001).

By certain measures, the evacuation of the WTC on September 11, 2001, could be termed a success (Cauchon 2001 ). Under the impacted floors, nearly every occupant who could physically get out did get

out. According to USA TODAY, in each tower, 99 percent of the civilian occupants below the crash sites survived. Their analysis shows that two-thirds of WTC 2 occupants started their evacuation of the upper

floors during the 16.5 minutes between the attacks, and survived. Among the occupants under the

impacted floors in WTC 1, 72 people died, whereas under the impacted floors in WTC 2, 4 people died.

It should be noted that some fraction of the deaths below the impacted floors in WTC 1 occurred in the

elevators, which were carrying people at the time of impact.

N.2 BACKGROUND LITERATURE

Understanding the basic concepts of human behavior in fire is necessary to envision occupants' likely

response during an emergency. Human behavior in fire is a scientific field that identifies facts, concepts

and relationships established through systematic observation and experimentation. What is known about

human behavior in fire is that the three dimensions of the emergency, namely the occupant, building and

fire characteristics, interact to explain or predict occupant response to fires (Proulx 2001).

During a fire, the nature of the information obtained, the limited time to react and the assessment of

danger will create a feeling of stress. This stress is not an abnormal reaction; on the contrary, stress is regarded as a necessary state to motivate reaction and action. During the course of the event, the intensity

of stress experienced will vary as a function of the information newly-perceived and the assessment of the

decision taken (Proulx 1993). Key factors which increase stress include: the perception of threat to oneself or others, the suddenness of the threat and the available time to respond or prepare, the amount of

sensory input needed to be processed, and the degree of physical effort (aerobic and anaerobic output)

that is engaged during the incident. If the individual is physically wounded or injured, the effect will be

even greater (Grossman 2002). Taking all of these factors into account, it can be said that most evacuees of the WTC were experiencing extremely high levels of stress.

Most people assume that individuals cease to act in a predictable, orderly fashion in the face of disaster,

and that norms which govern our behavior collapse into Durkheim's anomie, a state of normlessness

(Fisher 1998). This mindset, known as disaster mythology, has been greatly nourished by the mass media

and movie industry to capitalize on strong emotional images (Proulx 2002). Today, it is largely known

that in the face of the extreme stress of a disaster, there is an absence of widespread, irrational, antisocial

N-2
Interim Report on Analysis of First-Person Accounts from Survivors of WTC

and dysfunctional behavior that has often been described as 'panic' (Quarantelli 1998). Thus, the false but common belief that people will panic in disaster situations is a myth (Sime 1980, and Keating, 1982). In human behavior fire research, it is found that panic behavior is extremely rare (Proulx 2002). Decision

making during an emergency is, however, different from day to day decision making for three main

reasons (Janis and Mann 1977). First, there is much more at stake in emergency decisions—often the survival of the person and of the people he or she values the most is at risk. Second, the amount of time

available to make a decision before crucial options are lost is limited. Third, the information on which to base a decision is ambiguous, incomplete and unusual. Further it is usually impossible to look for more

appropriate information due to the lack of both time and the means to get information (Proulx 1993).

Turning to the literature of the evacuation of the WTC following the 1993 terrorist bombing, it was

concluded that there was a lack of panic flight during the evacuation, even though the occupants had to descend the crowded and smoky stairwells in total darkness. No official evacuation orders were issued by

recognized emergency and building officials after the explosion, and no official information was provided

about safe or proposed exit routes (Isner and Klem 1993). However, it was found that there was an

overall mood of orderly evacuation during the 1993 evacuation (Wenger et al. 1994; Fahy and Proulx

1995). This lack of panic during the 1993 evacuation may be explained by the fact that although the

explosion created immediate danger, it was not perceived by participants as particularly severe. Secondly, people were not alone; they were with coworkers, friends and associates. This web of social

integration among participants works against the adoption of norms that would support individual,

competitive flight behavior to favor the emergence of cooperative, altruistic, helping and orderly behavior

(Wenger et al. 1994).

In contrast to the panic scenario of a competitive scramble towards an exit, Dr. Jonathan Sime argues that the most common behavior during a fire is movement towards familiar persons and places (Sime 1985).

This is known as the affiliation model which suggests that detached groups will attempt to reunite before

evacuating, and evacuation movement is most likely to be through a familiar way in and out of the

building (Sime 1985). The grouping of people during an emergency is sometimes known as the milling

process: the communication process that takes place among participants in a crisis setting as they attempt

to define the situation, propose and adopt new appropriate norms for behavior and seek coordinated,

collective action (Wenger et al. 1994). High levels of social interaction were reported during the 1993

evacuation as the tenants engaged in milling behavior regarding the definition of the situation, the attempt

to give meaning to the crisis (i.e. to determine "What is happening?"), the appropriate response to it or proposed cues for action, and the attempt to give direction to the behavior of the participants by offering

new, emergent norms (i.e., "What should we do? What is appropriate?") (Wenger et al. 1994).

Identification of the information available to occupants in defining the situation is essential in attempting

to understand the decision-making process during an emergency. The social context of the occupants and

the opportunity to observe and interact with others are also fundamental considerations when attempting

to understand occupant response and the overall outcome of evacuations.

N.3 STUDY OBJECTIVES

This exploratory research project was conducted in order to gain an overall understanding of the

circumstances surrounding the evacuation of the WTC towers on September 11, 2001. More specifically,

this research project endeavors to gain insight into the variability of human behavior and response time

N-3
Appendix N

displayed during the evacuation, with the findings to be used as a guide for future research. This study can also provide insight for the NIST investigation into the WTC event. Human behavior data gathered

from this project will help to create a better understanding of the individual experiences of occupants in specific locations by documenting, to the extent possible, the information available to occupants, such as conditions on their floor and along their evacuation route, perceived behavior of others, and escape

conditions and timing.

N.4 METHODOLOGY

In the moments following the attack of the WTC towers on September 11, 2001, journalists started interviewing survivors to obtain the story of their evacuation. These first-person accounts were presented on television or radio and published in newspapers, magazines, or websites and later reported in books

and special media programs. During the three months following the events, over 280 first-person accounts were collected. These accounts included media reports (newspapers, magazines, television and

radio), as well as material from books, training videos, personal websites and emails. The information

provided in some of these accounts was so detailed that it provided sufficient material for a study.

Additional accounts were gathered over the next year for a total of 745 first-person accounts from 465

individuals, as some survivors provided multiple accounts through different sources. The 435 accounts

retained for analysis are from evacuees of WTC 1 and WTC 2 only. Although numerous accounts were

found from occupants of the surrounding WTC complex, only those civilians who had evacuated the

actual towers were considered. For those survivors for whom numerous accounts were found, the information across the accounts was collapsed into one highly detailed account, containing the combined

information from all of the given accounts. For instance, 16 survivors provided five to 12 different accounts to the media. These survivors had dramatic accounts and, therefore, were of particular media

interest. The study involved no first-person interviews.

It is recognized that the use of first-person accounts published in the media as main sources of

information for a study has many limitations. The questions asked by reporters are unknown and can be

different for each journalist and with each interview. It is also noted that the date an account was

published does not necessarily represent the date that the specific interview took place; the account could

have been held at some point and then published at a later date. It is suspected that the most dramatic

experiences are reported and that some information may be emphasized or left unreported for the purpose

of the article. As stated by Dr. H.W. Fischer, the mass media has greatly reduced the level of flamboyant

exaggeration in what they report as typical behavioral and organizational response to disasters over the

last 50 years; however, since a larger portion of the news is now devoted to reporting disasters, a less than

accurate image is still commonly portrayed both in the print and broadcast media (Fischer 1998). It also must be stressed that the findings in this study are representative only of the individual experiences

captured in first-person accounts and cannot be generalized to the population of the two towers.

Recall of details of an event depends on many factors, including the intensity of the event, time since the

event, and influence from other information sources. Recollection of extreme events such as the WTC

attacks may be far better than ordinary daily events. Conversely, traumatic situations may result in memory impairment or "critical incident amnesia." Finally, with the intense media attention that the events of September 11, 2001, received, it is highly likely that this coverage influenced

survivors' recollection of events. This phenomenon, referred to as "contamination," occurs when

information outside of the actual experience is integrated into the reconstruction of memory
Interim Report on Analysis of First-Person Accounts from Survivors of WTC

(Grossman 2002). Since different occupants of the WTC had a range of experiences on and after September 1 1, it is unclear to what extent memory issues impacted the reports included in this study.

Despite the drawbacks of using media sources for the basis of research, however, some of the accounts

contained such a high level of detail, particularly the ones written by survivors themselves, they provided

justification for the analysis of this information. It should also be stressed that these media accounts are the only documented descriptions of the WTC evacuation and immediate reactions of the survivors, as no

research has been conducted or published 2 years after the events, regarding human behavior surrounding

the events of September 1 1

, 2001 . Since documenting human behavior is time sensitive and considerable

time has passed since the event, it may be said that these initial media accounts may hold significant

detailed and accurate inforrnation that may only be available in these accounts.

N.4.1 Content Analysis

The most appropriate social research method for analyzing media communications is content analysis. To

extract the important content from the accounts, a "questionnaire" was developed to "interview" each

account. This procedure was used by Johnson (1987) to analyze police file statements related to the

"Who Concert Stampede;"' it is also explained in some detail in Gamso's book "The Strategy of Social

Protesf" (1975). The approach relies on a series of identical questions used to "interview" each

document. Once the information is gathered in a qualitative or descriptive database, codes are developed

to reduce the variety of answers to each question to a manageable number. To ensure reliability of the

coding, at least two researchers independently review each account and compare their coding. Any

disagreement is discussed and resolved.

Questions to "interview" each account were designed to obtain manifest and latent information from the

745 first-person accounts. A majority of the questions, 30 of them, rely on manifest information or elements specifically reported in the account, such as the person's location at certain key moments. They

are listed in Table N-1 . The remaining three questions called for latent information, such as words

describing emotions. They are listed in Table N-2. Data was retrieved from the accounts and entered

into a qualitative database. Nominal and ordinal categories were conceptualized, which can be found in the coding scheme presented in Attachment 1 . It is important to note that not all questions were answered

for each account gathered, as a number of the accounts were incomplete. The fact that an individual's account is silent on some point does not mean that this factor was not important or relevant in that individual's evacuation. It simply means that it was not included in the published account or that it was

never mentioned by the individual. For those questions not addressed in the account, the category was

awarded the code "9" or "99," accounting for the lack of information regarding that specific question.

This lack of information for some items is the equivalent in a questionnaire survey to a respondent who

did not answer some of the questions. The information gathered in the qualitative database was coded

and transformed into a quantitative matrix from which descriptive statistics were calculated.

On December 3, 1979, 1 1 people were crushed to death as fans rushed the entrance of a stadium in Cincinnati, Ohio, to see a sold-out concert.

N-5
Appendix N

Table N-1. Questions on manifest information.

What is the date of pubHshed account? Heard fire alarm?

Gender? Location at WTC 2 impact?

Age/ Location at WTC 2 collapse?

hi which building was the person at the time of

first cue?

Location at WTC 1 collapse?

On what floor was the person at the time of first cue?

Location when met firefighters?

What was the first cue of event? At what time person exited the building?

How long did the person take to start evacuation? Who helped person during evacuation?

Did the person delay start time? Was the person disabled?

What mode of egress was used? Was the person injured?

What was the condition on floor? Location when person placed phone call? What was the condition on the stairs? Who was the phone call recipient?

Were obstructions encountered during evacuation? Was there social influence on decision making?

Heard announcement? Use other (non-phone) communication technology?

Location when WTC 2 announcement heard? Was person at the WTC during 1993 bombing?

Action after hearing WTC 2 announcement? Did the person rest during evacuation?

Table N-2. Questions on latent information.

What was the person's knowledge of the situation in the initial moment?

How serious did the person judge the situation to be?

What was the person's perception of others?

N.4.2 Variables Considered

Conceptualization and operationalization involve precisely defining how the variables were measured and

ensuring the attributes within those variables are mutually exclusive and exhaustive. There were 33

questions providing data ranging from demograhics and physical location, to response time and social

interaction during the evacuation. Coded data included the evacuees' gender, age and which building and

floor they were located in, as well as the date the account was published. The floors of the towers were

categorized as lower (basement to floor 42), mid (floor 43 to floor 76), and upper (floor 77 to floor 1 10)

based on the common areas referred to as "skylobbies" on the 44th and 78th floors, which separated the towers into three strata. The skylobbies on floors 44 and 78 served the occupants of floors 43 and 77,

respectively. Mode of egress was recorded as stairs, elevators or a combination of both.

The first cue of the event was categorized according to whether the cues were "audio," such as hearing an

explosion, crash or rumbling; "visual," such as seeing the plane approach the towers, or seeing fire, smoke or debris. Another category of first cue was "building movement" and was represented by feeling

the building shake, sway or tremble, whereas moving office furniture, falling ceilings, jolting in the

elevator and flickering lights were attributes of the variable category "contents movement." The

remaining three categories were "warned by others" (either verbally or through their behavior),

"physically impacted" (e.g., burned, fell from chair, thrown against a wall), and "smelled smoke or fumes

N-6
Interim Report on Analysis of First-Person Accounts from Sun/Ivors of WTC

or felt heat." These cues were coded as check-off items so that multiple initial cues could be captured.

Whether or not evacuees heard a building alarm during their evacuation was recorded in a separate field,

if mentioned.

Time to start evacuation was recorded as immediately, shortly after impact (where the occupant took less than 5 minutes to retreive belongings befora evacuating), delayed (representing those who took more than

5 minutes to start evacuating, taking time to search floors or gather company documents, etc.), stayed or

stuck.

Conditions of floors immediately after the building was hit were recorded in two ways. One field summarized the conditions as follows: "devastated," meaning combinations of conditions such as scattered debris, fire, darkness and fallen ceilings and walls were reported; "abnormal," in that there was some smoke, heat or the smell ofjet fuel; and "normal," represented by accounts describing usual

conditions on their floors. A series of check-off columns then recorded whether a person's account

reported the presence of specific conditions: door jammed, debris (e.g., from wall, floor or ceiling

collapses), smoke, dust, no power or darkness, smell of fumes, water, fire, crowds or injured people,

entrapment, or normal conditions. If the individual was not on an office floor when the building was

struck, that was recorded in an additional check-off column. This allowed the recording of multiple

conditions for each individual.

Similar check-off columns were used to record observations of conditions in stairwells during evacuation:

normal, door locked or jammed, crowded and/or hot, no power, water, cracked wall, debris, smoky or smell of fumes.

If and where the evacuees heard the announcement stating that WTC 2 was secure were also noted, as were their actions after hearing the announcment (i.e., continued evacuating, continued but saw others

return to offices, or returned to or remained in office). The survivors' location at the time of impact,

collapse of the towers and meeting of firefighters were also coded, as well as who helped them during the evacuation. Those who provided help were categorized as firefighters. Port Authority employees,

external officials such as NYPD, FBI, and coworkers. Individuals' disabilities were coded as "visually

impaired," "hearing impaired," "physically challenged" (e.g., obese, pregnant, or with asthma or heart

conditions), "wheelchair users," or 'injured." People who mentioned that they had aided a disabled or

injured person during the evacuation were also noted in this variable category, as were those who reported

seeing injured or disabled people during their evacuation.

Whether or not a person was present at the WTC during the 1993 bombing was recorded, as was whether

or not each person delayed his or her evacuation on September 11, 2001. Where the evacuee placed a phone call and the recipient of it were coded, along with whether or not they rested and where they rested. A series of check-off columns recorded if a person experienced obstructions, such as door jams, debris,

smoke, no power, smell of fuel, water, fire, crowds, injured and disabled people or became trapped during

the evacuation. Multiple entries were possible for each individual.

Other variables included the survivors' knowledge of the situation, recorded as "high" for those who

knew a plane had struck the towers or that there had been a terrorist attack; "moderate" for those who

thought there was a fire, bombing or judged the situation as a serious emergency; and "low" for those

who were not aware of the reasons behind the evacuation. The evacuees' indication of the level of

seriousness was recorded as "very serious," "somewhat serious" and "not serious" based on the perceived

N-7
Appendix N

tone of the account. The variable "perception of others" included the categories of "calm," in that evacuees felt others to be orderly and composed; "upset," which represented those who judged others as nervous, anxious or visibly bothered. For survivors who described others as hysterical or pushing and

shoving, this field recorded their perception of others as "momentarily panicked." When accounts

reported that those around them lent assistance to others, this field was coded as "helpful."

Social influence on decision making was categorized according to who influenced the evacuee: authority

figures, such as bosses or managers; groups of coworkers; or both authority figures and groups of

coworkers. If a person indicated that he or she took on a leadership role, that was also captured. Use of new communication technology including utilizing text messaging over pagers or wireless e-mail devices,

TV or radio to gain infonnation was noted. (See Attachment 1 for further variable category definitions.)

The time that people reached the outside was recorded. It must be stressed that most accounts did not

report specific times at which people took different actions. However, several occupants mentioned their location at key moments such as where they were when WTC 2 was hit or when WTC 1 or WTC 2

collapsed. For example, one survivor of WTC 1 reports, "When we got to the twentieth (floor) I remember hearing a rumble. One of the fellows looked at me and we knew it didn't sound good. It must

have been WTC 2 coming down" (Fink and Mathias 2002). Thus, it was deduced that this survivor was

on the 20th floor of WTC 1 at 9:59 a.m., when WTC 2 collapsed. Similarly, for many people, the time

they reached the outside could be estimated from their description of events (e.g., WTC 2 being struck,

WTC 2 collapsing) as they reached the outside.

N.4.3 Procedure

Various media avenues were utilized in gathering first-person accounts including television, radio,

newspapers, magazines, websites, books and special media programs. Personal websites and e-mails

written by survivors themselves were also used and are of particular interest, as they have not been altered by media editors in any way, but appear in their full, original format. During the three months following

the events, over 280 first-person accounts were collected. Eventually, a total of 745 accounts were

gathered from 465 individuals, as numerous survivors gave multiple stories to different journalists.

The accounts, which were gathered over a period of 18 months, were published up to 14 months after September 11, 2001. The distribution of published accounts over time is shown in Fig. N-I. Among the dated accounts studied, 51 percent were published in the first two weeks after September 11, 2001, with

another influx of accounts surfacing around the one-year anniversary, 10 months to 12 months after the

disaster.

Content analysis was performed on the 745 accounts using 33 questions for which the data was entered

into a qualitative spreadsheet. Duplicate accounts were merged, resulting in a final study size of 435

individuals who were present either in WTC 1 or WTC 2. The data was then coded and transferred into a matrix for analysis.

N-8
Interim Report on Analysis of First-Person Accounts from Survivors of WTC

275

250 -

22 5

-

u) 200

1 175 - u< 150-

° 125

0)E 100

05 Week of P u b lie a tio n

Figure N-1. Distribution of publication dates of accounts.

N.5 STUDY RESULTS

The raw data for each account was entered into an Excel spreadsheet and then coded. The coded data was

transferred into SPSS 1 1 .0 for statistical analysis. The statistical analysis conducted was essentially

descriptive statistics to organize and summarize the information. Inferential statistical tests were not conducted since the data obtained is not a representative sample of the population. Results presented in

this report should not be generalized to all occupants of the two towers on September 1 1, 2001. Although

they are reported using terms such as "the occupants" and "the survivors," the results refer only to the accounts analyzed.

N.5.1 Profile: Gender and Age

The study contained accounts from 435 survivors, ranging in age from 20 to 89 years old (mean ^ 39.5,

standard deviation = 1 1.8). Included were accounts from 118 women (27 percent) and 314 men

(72 percent); three accounts did not mention their gender (1 percent). It is speculated that the substantially

higher number of men involved in these accounts occurred because there were more men working in the

two towers than women or that men may be more likely to talk to the media than women. The breakdown

by gender and age is shown in Fig. N-2.

N.5.2 Location at the Beginning of the Event

There were 251 individuals who were located in WTC 1, comprising 58 percent, with the remaining

42 percent or 184 people from WTC 2. In WTC 1, 90 people (36 percent) were from upper floors (77 to 1 10), 79 people (3 1 percent) were from mid levels (43 to 76) and 58 people (23 percent) were from

the lower floors of WTC 1. Another 22 people (9 percent) were in elevators and two people did not

specify a location. In WTC 2, 94 people (51 percent) were from upper floors, 57 people (31 percent) were from mid floors, 28 people (15 percent) were from the lower levels of WTC 2 and five people did not specify a location. Although the distribution of accounts in the two buildings was not identical,

N-9
Appendix N

reports were obtained from the three strata in both buildings. It is likely that the higher fraction of

individuals in WTC 1 and in higher floors reflects the more dramatic stories of those closest to the airplane impact locations in WTC 1 and WTC 2.

20-35 36-50 5 1 -65 66 + Age

Figure N-2. Gender and age distribution.

N.5.3 IVIeans of Egress Used

On September 1 1, 2001 , almost all individuals from WTC 1 (198 people or 98 percent) reported using the

stairs to evacuate while three used both stairs and elevator and one used the elevator only. The person

who used the elevator for evacuation reported that he was in an elevator when the building was struck,

and the elevator stopped on one of the floors. He was able to use the elevator to move people from that floor to the lobby. Two of the three who used both stairs and elevators were initially trapped in an

elevator behind a 50th floor restroom. After freeing themselves, they were directed by firefighters to an

elevator to the 44th floor, from which point they walked down. The third person who used both stairs and

elevators rode with a person he was assisting from the 52nd floor to the 44th floor. Unable to find a working elevator on the 44th floor, he walked down the rest of the way. In WTC 2, 1 14 (72 percent of

the total for that building) used the stairs while 18 people (1 1 percent) used elevators and 26 (16 percent)

used a combination of elevators and stairs. These results are shown in Table N-3. Of the 44 people who

used the elevator to evacuate WTC 2, 37 were from floors served by the 78th sky lobby and 7 were fi^om

floors between the 44th and 78th sky lobbies. From these accounts, it seems that the higher up people were in WTC 2, the more likely they were to use the elevator as a means of egress.

Table N-3. IVIeans of egress used wil hin the towers.

WTC 1, N=202 WTC 2, N=158

Stairs 198 people (98.0 %) 114 people (72%)

Elevator 1 person (0.5 %) 18 people (11 %)

Stairs and elevator 3 people (1.5 %) 26 people (16%)

N-10
Interim Report on Analysis of First-Person Accounts from Survivors of WTC

N.5.4 First Cue Reported

The first cues of the event that were mentioned in the accounts were found to differ depending on which

tower the person was located. For WTC 1 , the first building hit, the most common first cue of the event

reported by 146 people (69 percent of people in that tower) was "building movement," such as feeling the building sway and tremble—many thought the building was going to tip over. WTC 2 occupants most

commonly reported first becoming aware of the event from visual cues (96 people) such as fire, debris

and smoke, most likely coming from WTC 1 . Several people reported more than one first cue, so they

may appear more than once in Table and percentages total more than 1 00 percent.

Table N-4. First cues of event within tlie towers.

First Cues WTC 1, N=212 WTC 2, N=145

Audio cues: heard explosion, crash, rumble 107 (50%) 69 (48 %)

Visual cues: saw fire, incoming plane, debris, smoke 87 (41 %) 96 (66 %)

Building movement: felt building sway, tremble, jolt 146 (69 %) 30(21 %)

Contents movement: furniture movement, ceiling falling 66(31 %) 1 1 (8 %)

Warning from others 14(7 %) 34 (23 %)

Impact 29 (14 %) 1 (1 %)

Smelled fumes or feh heat 12 (6 %) 16(11 %)

kiterestingly, only 25 people made any mention of building alarms in their evacuation accounts. Of

those, eight in WTC 1 and one in WTC 2 reported hearing alarms but did not specify where. Two in WTC 1 and one in WTC 2 heard alarms while on their floors and one person in each tower heard alarms

while in the stairs. Eight people in WTC 1 stated that they did not hear alarms. Three people in WTC 2

said they never heard alarms, but two of them were outside the building when it was hit.

N.5.5 Time to Start Evacuation

After perceiving these first cues, 101 people from WTC 1 (47 percent) immediately started evacuating,

while 84 people (52 percent) immediately started their evacuation of WTC 2. As can be seen in Fig. N-3,

similar numbers of people from both towers started evacuating shortly after the first cue of the event

(28 in WTC 1 versus 27 in WTC 2). Another 46 people in WTC 1 and 40 people in WTC 2 delayed their evacuation. Some 23 people in WTC 1(11 percent) reported they initially stayed, while 10 people from

WTC 2 (6 percent) also said they initially remained on their floors. Of the 16 people who reported being

stuck and therefore temporarily unable to start their evacuation, all but one were from WTC 1

Among occupants who initially decided to stay, it is noteworthy to mention a group in WTC 1. Two

survivors reported that a group of about 1 6 employees gathered in a conference room on Floor 64 of

WTC 1 . The group stayed in the room discussing the situation for approximately 1 hour before deciding

to evacuate the building.

Most of those who were not stuck but who took more than 5 minutes to begin evacuation delayed because

they took the time to complete activities such as searching the floor, securing documents, making calls, or giving instructions, or because they felt it was the right thing to do. Twenty-one of 63 people in WTC 1 (33 percent) and 13 of 45 people in WTC 2 (29 percent) delayed starting their evacuation because

N-U
Appendix N

1 20

1 00

80 >o

c

Q>= 60

a40 -

20

Im m e d S ho rtly S ta yed Stuck

Start Time

Figure N-3. Distribution of time to start evacuation.

they were completing activities such as those described above. Of those in WTC 1 who did not begin

their evacuation within 5 minutes, 12 people simply decided to stay (19 percent), compared to 20 people

in WTC 2 (44 percent ). In WTC 1, 17 of those who did not begin their evacuation within 5 minutes

(27 percent) were helping others or required assistance themselves, compared to only four people

(9 percent) in WTC 2.

N.5.6 Conditions on Floors and in Stairwells

It was possible to code multiple reported conditions on floors and in stairwells for each individual. Six

people in WTC 1 and seven people in WTC 2 indicated that conditions on their floor were normal after

their building was struck. For the 191 evacuees who commented on adverse conditions on their floors

after the plane hit their tower, similar results emerged between the towers, in terms of the large

proportions reporting smoke or debris and collapse damage on their floor. Specifically, the most

frequently reported adverse conditions in WTC 1 were smoke (55 percent or 74 people), debris or collapse of wall, ceiling or floor (72 people or 54 percent), fire (41 people or 31 percent), darkness or loss of power (20 people or 15 percent) and smell of fuel (13 people or 10 percent). In WTC 2, the most

frequently reported adverse conditions were debris or collapse of wall, ceiling or floor (38 people or 67 percent), smoke (25 people or 44 percent), darkness or loss of power (18 people or 32 percent), dust

(10 people or 18 percent), smell of fuel (7 people or 12 percent) and injured people (7 people or

12 percent). Seven people in WTC 1 who mentioned jammed doors were in the upper strata of the

building. Two people in WTC 2 who reported jammed doors had moved to middle floors of their building after the first impact. The complete details on conditions are presented in Table N-5.

A large number of evacuees (106 people) mentioned that the stairwells were crowded and hot during their evacuation (71 people in WTC 1 and 35 in WTC 2). A total of 27 indicated that conditions in the

stairwells were otherwise normal. For the 155 evacuees who commented on adverse conditions in the

stairwells during their evacuation (other than crowdedness), the majority in both towers reported smoke

and the smell of fuel in the stairs (79 people or 72 percent in WTC 1 and 29 people or 63 percent in

N-12
Interim Report on Analysis of First-Person Accounts from Survivors of WTC

WTC 2). For other types of conditions in stairwells, responses between the two towers were quite

different, as shown in Table N-6.

Table N-5. Adverse conditions on floor at impact

WTC 1, N=134 WTC 2, N=57

Debris (collapse) 72 (54 %) 38 (67 %)

Smoke 74 (55 %) 25 (44%)

Fire 41 (31 %) 20 (35 %)

No power, dark 20 (15 %) 18 (32%)

Smell of fumes 13 (10%) 7 (12 %)

Dust 9 (7%) 10 (18%)

Water 7 (5 %) 3 (5 %)

Door jammed 7 (5 %) 2 (4%)

Crowds, people injured 2 (1 %) 7 (12 %)

Trapped 5 (4 %) 2 (4%)

Table N-6. Adverse conditions reported in the stairs during evacuation

WTC 1, N=109 WTC 2, N=46

Smoke, smell of fuel 79 (72%,) 29 (63 %)

Water 49 (45 %) 4 (9%)

Dark, no power 14 (13 %) 9 (20%)

Debris (damage or belongings) 9 (8 %) 14 (30%)

Cracked walls 5 (5%) 14 (30 %)

Doors locked, jammed 12 (11 %) 2 (4%)

N.5.7 Obstructions during Evacuation

Tables N-5 and N-6 display details on the adverse conditions that resulted at the time of impact. These

were things that were observed but that might not have presented an obstacle. (For example, a person

might have reported seeing smoke or debris, without being impeded by that debris.) Obstructions are things that limited or otherwise affected a person's ability to evacuate. Many of the same items were cited

as both adverse conditions and obstructions. More than one obstruction during evacuation could be

recorded for each person. A total of 153 people in WTC 1 and 59 people in WTC 2 indicated

encountering obstructions during their evacuation. Almost half of the evacuees in each tower reported

encountering crowds and injured people in the stairways, and indicated that they interfered to some

degree in their evacuation (46 percent in each tower). The next most frequently reported obstructions were smoke and debris. The details are shown in Fig. N^.

Of the 22 evacuees who reported encountering jammed or locked doors, 20 were in WTC 1, and all but

three were located on upper floors. One of the WTC 2 evacuees reported that an elevator door was jammed by debris, and the other reported a locked door on reaching the bottom of the stairs. Of the 25

evacuees who reported being trapped, nine were in elevators, eight were trapped by debris or smoke when

N-13
Appendix N

their building was hit, five were trapped in the collapse of WTC 2, and three were trapped when WTC 1 collapsed.

80

70 -

60 -

50 -

0)e 40

30

20

1 0

0

IW TC 1 IW TC 2

Doorjam Debris Crowds Smoke No power Trapped Fire O b s tru ctio n

Figure N-4. Obstructions encountered during evacuation in botli towers.

N.5.8 Announcement

It is estimated that the WTC 2 announcement came over the public address system at approximately 9

a.m. The majority of survivors said they heard it just minutes before WTC 2 was struck, which occurred

at 9:03 a.m. As one survivor from the 103rd floor of WTC 2 describes it, "When we reached the 70th

floor we heard the announcement. The building was secure; no one needed to evacuate. We had

descended down 3 more floors to the 67th when the second plane hit our tower" (csmonitor.com 2001).

Of the 184 WTC 2 occupants, 96 people (52 percent) mentioned hearing this announcement in their accounts. The majority of them, 69 survivors, decided to disregard the instructions of the message and

continue their evacuation; however, 1 6 people ( 1 7 percent) said they remained in their offices or decided

to return back up to their offices after hearing the message. Those returning did not have time to travel very far before the second plane hit; at that point they all resumed their evacuation.

N.5.9 Location When WTC 2 Was Hit

Of the 273 survivors who mentioned their location at the time WTC 2 was hit, 36 people reported being

somewhere inside the stairwells of WTC 1, while 14 people reported being on various floors of WTC 1. Fifty-six did not give a specific location, and 15 had already reached the outside. Of the survivors from

WTC 2, 65 people reported they were in the stairs and 52 occupants reported they were on various floors within WTC 2. Four did not give a specific location, and 3 1 had already left the building. Of the people

who were on the floors within WTC 2, 19 were on the upper floors (77th and above) at impact and

survived. One of these occupants, who survived the plane impact on the 78th floor of WTC 2, describes

the stairwell: "a tornado of hot air and smoke and ceiling tiles and bits of drywall came flying up the

stairwell. In front of me, the drywall split from the bottom up" (csmonitor.com 2001).

N-14
Interim Report on Analysis of First-Person Accounts from Survivors of WTC

N.5.1 0 Location When WTC 2 Collapsed

WTC 2 was the first of the towers to collapse at 9:59 a.m. Of the 296 survivors who mentioned their location at the time of WTC 2's collapse, 230 people (78 percent) were outside of the buildings, on the

streets and surrounding areas. Some 47 people (16 percent) were still inside WTC 1 on lower levels from

the basement to the 42nd floor, and three people ( 1 percent) were on mid levels (43 to 76) in WTC 1 when WTC 2 fell. Thirteen did not give exact locations, and one was in an elevator. Three individuals were on the lower levels of WTC 2 (concourse) when it collapsed, and they survived.

N.5.1 1 Location When WTC 1 Collapsed

WTC 1, the second tower to collapse, fell at 10:28 a.m. As approximately 1 hour and 42 minutes had

passed since the initial WTC 1 impact, almost everyone who reported their location at the time WTC 1 collapsed was outside (263 people or 98 percent). Four people were on the lower levels of WTC 1, and

two were in the concourse when it collapsed, and they survived.

N.5.1 2 Location When They Saw Firefighters

For the evacuees who mentioned seeing firefighters during their evacuation, the location where they met

them was recorded to gain an understanding of the dispersion of emergency workers throughout the towers. For the 169 people who reported meeting firefighters, 143 people saw them in WTC 1, with only

26 people in WTC 2 mentioning their presence. In terms of floor location within WTC 1, it was found

that a majority of the people (76 people) saw firefighters in WTC 1 on the lower levels (basement to 43rd); 74 of them saw firefighters in the stairwells, and two on a floor. Another 21 people saw

firefighters on the mid floors (43rd to 76th)—17 of them were in the stairs while the other four people were on floors. Another three people saw firefighters on the upper floors (77th to 1 10th) in office areas. All three were trapped on the 83rd floor. One survivor stated: "We saw two flashlights belonging to two

New York City firemen. They told us to leave all of our possessions and to quickly follow them."

(Manning 2001). At the mezzanine, lobby or concourse level, 1 1 people reported seeing firefighters.

The remaining 3 1 occupants who saw firefighters inside WTC 1 did not give a location.

Among the 26 people who mentioned seeing firefighters in WTC 2, eight saw them on the lower floors (basement to 42nd), and two saw firefighters in the mid floors of the building (43rd to 76th). Seven

people saw firefighters at the mezzanine, lobby or concourse levels, while six people in WTC 2

mentioned seeing firefighters but did not indicate their locations. Three people indicated that they met

firefighters outside WTC 2.

N.5.13 Time of Exit

For evacuees from both towers who indicated at what time they exited, it was found that as more time

passed, a progressively greater number of people exited the building, as shown in Table N-7. Of the 183

WTC 2 occupants who indicated what time it was when they left the building, 77 exited between 9:31 and

9:58 a.m. WTC 2 collapsed at 9:59 a.m. Of the 211 WTC 1 occupants who indicated the time they left their building, 70 exited between 9:59 and 10:27 a.m. WTC 1 fell at 10:28 a.m. The six people who

exited the towers after 10:28 a.m. were rescued from the rubble by firefighters up to several hours after the collapse.

N-15
Appendix N

Table N-7. Time out of towers.

WTC 1 (impact - 8:46 a.m.)

N=211

WTC 2 (impact - 9:03 a.m.)

(LUIiapSc - y .jy a.in.) N=183

8:48 - 9:02 a.m. (before WTC 2 impact)19 37

0-03 — 9-30 fl m uo

9:31 -9:58 a.m. (before WTC 2 collapse)72 77

9:59- 10:27 a.m.

(after WTC 2 collapse)

70 0

10:28 a.m.

(after WTC 1 collapse)

5 1

N.5.14 Help Received and Help Given

Among the 435 accounts, 203 survivors described receiving help from others during their evacuation,

with some mentioning more than one source of help. Some 84 people (41 percent) were helped by Port Authority personnel. Firefighters provided direct help to 65 people (32 percent). Another 65 people

(32 percent) were helped by other first responders such as NYPD or other rescuers. Help from coworkers was received by 34 people (17 percent).

Overall, 166 people mentioned being comforted and reassured by passing firefighters. Several occupants

of the two towers helped others during the evacuation. Among the first-person accounts, 20 people said

they helped people with disabilities and 14 said they helped people who were injured during the event.

N.5.15 Occupants with Disabilities or Injuries

Among the 27 persons reporting a disability in their account, two were visually impaired, three were

hearing impaired, three used wheelchairs and 19 others were physically challenged such as suffering from

a heart condition, asthma, obesity, etc. Twenty-two people mentioned seeing people with disabilities.

Another 47 people who provided first-person accounts were injured that morning. Some accounts from

people who suffered injuries reported exiting the buildings later in the evacuation process. However, in numerous accounts occupants mention moving aside in the stairwells to let badly injured and burned

people pass, thus it is assumed that those with extreme injuries who were mobile exited the building faster than the majority of others. For instance, one survivor from floor 88 of WTC 1 who suffered bums to over 77 percent of her body reported that crowds parted in the stairwell to let her through (Kugler 2002).

These victims were all accompanied by coworkers or emergency workers. Twenty-five people mentioned

seeing injured people coming down in the stairwells.

Twenty-three individuals with disabilities and 43 with injuries mentioned a time to start. Of these

66 people, 50 percent (13 people with disabilities and 20 injured) started evacuating immediately,

5 percent (two disabled and one injured) left shortly after, 29 percent (7 disabled and 12 injured) delayed

evacuating, 14 percent (one wheelchair user and eight injured) initially decided to stay, and 3 percent (two

injured people) were initially stuck.

N-16
Interim Report on Analysis of First-Person Accounts from Survivors of WTC

N.5.16 Phone Calls

An overwhelming 87 percent of those who placed phone calls (151 people) were trying to contact their families and friends to let them know their whereabouts and gather information from them. Only

12 people (7 percent) tried contacting authorities, such as building security or calling 911, and 20 people

(12 percent) placed calls to their boss or colleagues. Eleven people (6 percent) did not say who they

called.

The majority of people who placed phone calls that morning did so once they were outside (93 people or 54 percent); however, many did not get through. Forty-four people (25 percent) mentioned that they

placed calls from their offices before evacuating, 13 people (8 percent) called from other floors and

10 people (6 percent) attempted to make phone calls while in the stairwells.

N.5.17 Knowledge of Situation

In judging the evacuees' knowledge of the situation, categories were created. A "high level" of

knowledge indicated knowing that planes had hit the towers or that there had been an explosion within the towers. Those who speculated about a bombing saw fire and debris or had reason to believe an emergency was occurring were said to have a "moderate level" of knowledge. Survivors who were not aware of the reasons behind the evacuation were classified as having a "low level" of knowledge. Level

of knowledge was coded for 330 people. As shown in Fig. N-5, survivors with "high levels" of

knowledge totaled 69; 214 people were judged to have a "moderate level" of knowledge and 47 survivors

had a "low level" of knowledge regarding the events of that morning.

120

100 -

120

80

3 60

40

20

High Moderate

Level of Knowledge of Situation

Low

Figure N-5, Knowledge of situation in the towers.

N.5.18 Influence of Others

One hundred and ninety-one survivors reported that their decisions during the evacuation were influenced

by others. It appeared that 28 people were influenced by authority figures, such as their boss or manager,

N-17
Appendix N

and complied with their instructions. Another 97 survivors seemed to be influenced by groups of people

and coworkers. One person appeared to have been influenced by both authority figure(s) and the group. Many individuals indicated that they took on leadership roles that morning. Sixty-six people reported

they directed people to the stairs, searched for others, gave orders or somehow took part in organizing the

evacuation.

Males were more likely to perceive themselves as taking on leadership roles that morning than females

(see Table N-8). Thirty-eight women (59 percent of the females for whom influence could be inferred) were influenced by groups of coworkers, whereas only 58 men (46 percent) were apparently influenced

by the group. Concerning leadership roles, 52 men (41 percent) reported adopting this behavior,

compared to the 14 women who mentioned taking a leadership role (22 percent of the women).

Table N-8. Gender and influence of o1 hers.

Males, N=127 Females, N=64

Authority figures (boss, manager) 17 (13 %) 11 (17 %)

Groups/coworkers 58 (46 %) 38 (59 %)

Both authority and groups 0 (0 %) 1 (2 %)

Took a leadership role 52 (41 %) 14(22 %)

N.5.19 Perception of Others

How survivors perceived others during the evacuation was recorded for 268 people—others could have

been perceived as "calm," "momentarily panicked," "upset," or "helpful." Multiple responses could be

coded for each person. The results show that the majority (154 people or 57 percent) described people

around them as calm and orderly. Some 84 people (3 1 percent) judged others as "upset," which included

crying, shouting, nervous or anxious, but rational. There were 78 people (29 percent) who described

others as "momentarily panicked," in that they were pushing, shoving or generally displaying behavior

associated with chaos, while 59 people (22 percent) found others to be "helpful." More details are presented in Fig. N-6.

It was found that of 155 people in WTC 1, 93 survivors judged others to be "calm," compared to 61 of

1 13 people in WTC 2. Only 33 people in WTC 1 described others as "momentarily panicked," compared

to 45 people in WTC 2. For the people in WTC 2, the perception of "panic" occurred before WTC 2 was

hit for at least three occupants, while another 29 survivors described others around them as "panicky"

after WTC 2 was hit. For two others, the "panicky" behavior was reported at the point in time when each

tower collapsed. It was not clear from the other 1 1 accounts from WTC 2 when the people around them

were "panicky."

This variance in perception of others between the towers is illustrated by contrasting the following two

accounts. One survivor from the 65th floor of WTC 1 said that those in the stairwells "maintained their calm really well" and went on to say that, a couple of people started crying a little, but we said, 'We're

going to get out of here, we just have to take it one step at a time.' It wasn't quiet, people were talking-in

fact someone was laughing, it was pretty normal (Anderson 2001 ). It is proposed that the occupants of

N-18
Interim Report on Analysis of First-Person Accounts from Survivors of WTC

WTC 2 observed others "momentarily panicking" mainly once their tower had been hit. One survivor

from the 70th floor of WTC 2 said she and her coworkers walked down to the 59th floor and took an

elevator to the 44th floor, when at that point, another plane hit their tower and then there was a mad

scramble down the stairs with people pushing, shoving and yelling (Black 2001).

Calm Momentary panic Upset Helpful

Perception of Others

Figure N-6. Distribution of perception of others between the towers.

Perception of others and gender are compared in Fig. N-7.

120 115

Calm Momentary Panic Upset Helpful

Perception of Others

Figure N-7. Distribution of gender and perception of others.

The distribution of perception of others by age group is shown in Table N-9. It is interesting to note that some of the most dramatic language ("chaos," "total chaos," "mayhem") was used by the youngest males.

N-19
Appendix N

Table N-9. Distribution oi dge cinci pcrccpiion o

' ofhore

21-35 yrs old (N=74) 36-50 yrs old (N=58) 51-65 yrs old (N=21)

Calm 39 (53 %) 31 (53%) 9 (43 %)

Panicked 25 (34 %) 14 (24%) 6 (29%)

Upset 31 (42%) 22 (38 %) 4 (19%)

Helpful 16 (22%) 17 (29%) 8 (38%)

N.5.20 Technology to Gain Information

In addition to the people mentioned earlier who made cell phone calls from the stairwells, 10 people used

technology such as wireless e-mail devices and text pagers as a means of gathering information about the

situation. Thirteen listened to the radio or watched television, among them three evacuees who stopped to watch TV on the mid floors (43 to 76) of WTC 1 and saw live media coverage of the events.

N.5.21 Impact of the 1 993 Evacuation

Only nine percent, 41 people, reported being present during the 1993 bombing and evacuation of the WTC. Of them, three people explained that their experience in 1993 helped them decide to start their evacuation immediately on September 1 1, 2001. Five people who were present in 1993 mentioned being

better prepared this time with evacuation kits. These emergency escape kits were described as being

equipped with flashlights, masks, glow sticks, whistles and water (Murphy and Levy 2001). Another 1

8

people specifically mentioned that 1993 was on their mind during their evacuation, although they were

not present during the events of 1993.

Four survivors reported seeing photoluminescent stripes on the stairs, railings and stairwell doors—an improvement the Port Authority made following the 1993 bombing. As one survivor stated, "All you had

to do was follow those yellow-green stripes. They were wonderful." The stripes were especially valuable

when the emergency stairs stopped and people had to travel horizontally through mechanical equipment

spaces that had many doors (Masetti 2001 ). A paraplegic survivor from WTC 1 who was also present for the 1 993 evacuation of the WTC

commented on the successful use of an evacuation chair on September 11, 2001 . The evacuation chairs were part of the improvements made to the WTC evacuation process after the 1 993 bombing, and this survivor credits the chair with saving his life. In 1993, he was bounced down the stairs in his electric wheelchair from floor 69 to floor 43, where he was then transferred to a stretcher and carried down the

rest of the way. It took him 6 hours to evacuate from floor 69 in 1993. On September 1 1, 2001, using the

evacuation chair enabled him to escape floor 69 of WTC 1 and get to street level in 1 hour and

30 minutes. He went on to say, 'Tf it weren't for the evacuation chair and the 10 people that brought me

down, 1 would not have made it, that's for sure. That evacuation chair made the difference" (Fink and

Mathias 2002).

N.6 SUMMARY RESULTS

Although it is recognized that content analysis of first-person accounts has limitations, and the results cannot be generalized to all occupants of the towers, this methodology was found to be particularly usefiil

N-20
Interim Report on Analysis of First-Person Accounts from Survivors of WTC

in this case. With the large number of accounts that were gathered from a variety of sources (print

media, television, radio, internet, emails, etc.), the similar themes and experiences within these texts became more than merely anecdotal stories. Considering that a great majority of the accounts became

public within three weeks following the events and that recollection of human behavior is delicately time

sensitive, it was important to analyze this infonnation. This methodology could prove usefiil in future projects dealing with first-person accounts, although events of the magnitude of September 11, 2001,

which produced such a large number of first-person accounts, are extremely rare.

For the accounts gathered from media sources, it is recognized that they may represent the most dramatic

stories of the evacuation. At the same time, those survivors who have dramatic stories of escape may be more inclined to share them compared to other survivors who may judge their evacuation as less eventful. However, the accounts analyzed were from survivors located in several areas in each tower, providing a

distribution of floors from the upper, middle and lower strata of the two towers. In total, 745 accounts were analyzed, representing 435 survivors from WTC 1 and WTC 2.

An interesting and important observation involves the emergence of new first-person accounts from

survivors who had not previously shared their stories, around the first anniversary of the event. In trying

to explain this phenomenon, it is speculated that survivors who had not previously shared their stories were now prepared to do so after having time to cope and deal with their experience. Many of the evacuees mentioned that telling their stories proved to be a therapeutic exercise. Media sources may have

also held accounts gathered from an earlier date or searched for new, untold stories and published them as

part of the anniversary coverage.

An important observation stemming from the accounts analysis encompasses the issue of evacuation

strategies. It was found that 44 people, about 24 percent of WTC 2 occupants in this study, used the

elevators at some point during their evacuation. It has long been accepted among fire safety experts that people know they should not use elevators as a means of egress during an emergency, but those in WTC 2

who chose to use the elevators may have thought it was the quickest or safest route of escape and may

have believed that because they were not in immediate danger, they were justified in their decision to use

the elevators to evacuate. The same theme is echoed when examining the reactions of the 96 WTC 2 occupants who heard the public address announcement, which told them their building was secure and to return to their offices. Only 16 people took heed of this message and stopped their evacuation, making

their way back to, or remaining in, their offices. Through all accounts studied (with the possible

exception of one) there was no doubt that people understood the message, as there were no audibility or

intelligibility issues; the content of the message was clear. However, the majority of 69 occupants made

their decision based on the information that they had at that point in time and decided to disregard the order and continue evacuating. As one survivor stated, "I was thinking that there is a real difference of

opinion here about what my eyes are seeing and what the announcement was saying" (Murphy and

Levy 2001). The decision to carry on with the evacuation may also reflect the concept of commitment: as these occupants had already made the decision to leave, they pursued this task.

It is also interesting to note that the official procedure for emergencies in the WTC was to meet in the lobby area on each floor and wait for instruction. Nevertheless, the majority of occupants of both towers

decided to evacuate on their own after WTC 1 was hit, without waiting for an official building

announcement. Thus, this is further evidence that people will make decisions based on what they judge

the proper action to take despite official procedures.

N-21
Appendix N

Those who had experienced the 1993 terrorist bombing of the WTC left promptly. Although their past

experience could have suggested that the evacuation was going to be long and difficult and that people

who stayed behind would be evacuated by rescuers later on, very few used this rationale. Instead, most

occupants with experience from 1993 felt an urgency to leave immediately.

The results show that 18 people who were identified as having "high levels" of knowledge delayed

evacuating. Those who delayed their evacuation reported that they rushed to gather their belongings or went to backup important company files, for they suspected they would not be returning to the building

for an extended period of time. These are rational actions; therefore, it is concluded that those with "high

levels" of knowledge who delayed evacuating had to have been in areas where the perceived threat to personal safety was not high.

The overall impression of the emotional atmosphere during the evacuation, after reading all 745 accounts, was that of calm and order. Although some reported crying and being anxious or nervous, the majority

viewed themselves and others as composed. A stark contrast in perceived behavior was found to exist between the two towers, with the majority of WTC 1 occupants reporting others as "calm" (93 of

155 people), where as a large proportion of WTC 2 occupants perceived others to be "panicked" (45 of

1 13 people). The perception of "panic" occurred before WTC 2 was hit for at least three occupants, while

another 29 survivors perceived others as "panicked" after WTC 2 was hit. After their building had been

struck, WTC 2 occupants may have realized they were under attack, which could possibly explain the

heightened level of anxiety in the tower. (It is important to note, however, that the colloquial use of the

word panic more often describes a state of mind—high anxiety, for example—rather than the irrational actions that more correctly define "panic")

Emergency crews disrupted evacuation in the stairwells while going against traffic, but many evacuees who mentioned seeing firefighters felt reassured and safe due to their presence. It is assumed that this counter flow did not prevent occupants from evacuating, as the last people to exit reported being alone in the stairs while they were descending rapidly seconds before the collapse. Evacuees used technology

such as cell phones, wireless e-mail devices, and text messaging over pagers during their descent as a means of gathering information about the situation unfolding around them.

N.7 FUTURE WORK

Future research is needed to fully understand the evacuation behavior of the occupants who were in the

two towers of the WTC on September 11, 2001. A variety of approaches should be used to gather this information such as interviews and questionnaires. Unfortunately, the extended amount of time that has

elapsed since the events is an important factor to mitigate, since occupants' recollection may be

incomplete and contaminated by what has been seen, read, or heard since September 1 1, 2001.

Technology clearly played a role in providing occupants with information about the event during their evacuation. This phenomenon raises important issues regarding the information age and how new

technologies can be taken advantage of to aid in emergency situations. If technology can help to disseminate timely information to the public in times of crises, strategies should be developed to enable

authorities to fully utilize such technology.

N-22
Interim Report on Analysis of First-Person Accounts from Survivors of WTC

This major event, which was repeatedly broadcast on television around the world, may also influence fire safety in high-rise buildings in general. It is essential to study how the perception of risk in high-rise

buildings has changed since September 11, 2001. Do people who live, work or visit high-rise structures

feel more at risk of a potential fire or fear that the building might collapse if there is a fire? If the occupants feel more at risk, what is their likely behavior and response in future emergencies? Studies

should be conducted to explore the impact of high-rise risk perception on intended behavior in future emergencies. Are occupants prepared to follow procedures and instructions? Would they comply with a

protect-in-place approach or to move to a refuge floor? If all occupants want to evacuate to the ground

floor or exit during an emergency, requirements for stair design and building height might need to be

revisited. Drills should be conducted to observe unannounced emergency evacuations in high-rise

buildings, varying evacuation strategies and information provided to occupants to assess actual response. Longitudinal studies should also be conducted to assess the impact of September 1 1 over time on highrise building occupants.

The authors would like to express their appreciation to Amber Walker, formerly of the National Research

Council of Canada, for the work she did developing the original matrix format and undertaking the early

analyses that form the basis of this study. They would also like to thank Joseph Molis and

Norma Candeloro of NFPA for their contributions to this work.

Anderson, P., 2001. We the living: One company that made it. CNN, September 21.

Black, B., 2001. How the telephone linked an anxious family on September 11. Concordia's Thursday

Report, November 22.

Cauchon, D., 2001. For many on September 11, survival was no accident," USA TODAY, December 19.

csmonitor.com/2001/0917/plsl-usgn.html. The Christian Science Monitor, accessed September, 2002.

Federal Emergency Management Agency (FEMA), 2002. World Trade Center Building Performance

Study: Data Collection, Preliminaiy Obseii'ations, and Recommendations. Federal Insurance and

Mitigation Administration, Washington, D.C.

Fahy, R., G. Proulx. 1995. Collective Common Sense: A study of the human behavior during the World

Trade Center evacuation, NFPA Journal, Vol. 89, No. 2, pp. 59-67.

Fink, M., L. Mathias. 2002. Never Forget. An Oral History ofSeptember 11, 2001. Harper Collins

Publishers, New York, NY, pp. 124-127.

Fischer III, H.W., 1998. Response to Disaster. Fact versus Fiction and Its Perpetuation. University Press of America, Maryland, pp. 13-45. (With foreword written by Quarantelli)

Gamson, A.W., 1975. The Strategy ofSocial Protest, The Dorsey Press, Homewood, Illinois.

N.8 ACKNOWLEDGMENTS

N.9 REFERENCES

N-23
Appendix N

Grossman, D., B. Siddle. 2002. Critical Incident Amnesia: The psychological basis and the implications

ofmemoiy loss during extreme survival stress situations. The Firearms Instructor, Issue 3 1

.

Hays, W., 1994. Statistics, 5th ed. Harcourt Brace College Publishers, Orlando, Florida, p. 869.

Isner, M.S., T.J. Klem. 1993. Fire Investigation Report: World Trade Center Explosion and Fire, New

York, New York, February 26. National Fire Protection Association, Quincy, MA, p. 32.

Janis, L., L. Mann, 1977. Decision Making. Free Press, Macmillan Publishing Co., New York, NY.

Johnson, R.N. 1987. Panic at The Who Concert Stampede: An Empirical Assessment, Soc/a/ /'ro6/ew5',

Vol. 34, No. 4, pp. 362-373.

Keating, P. J., 1982. The Myth of Panic, Fire Journal, Vol 76, No. 3, National Fire Protection

Association, Quincy, MA, pp. 57-61.

Kugler, S., 2002. WTC victim leaves hospital, Boston Globe, January 30.

Manning, C, 2001. Goffstown man tells of his escape from 83rd floor, The Union Leader, September 15. Section A, Page 1

.

Masetti, A., 2001. Personal e-mail correspondence. December 10.

Murphy, D., Levy, C, 2001. The evacuation that kept a horrible toll from climbing higher, The New York

Times, September 2 1

.

Proulx, G., 1993. A stress model for people facing a fire, Journal ofEnvironmental Psychology, Vol.13,

pp. 137-147.

Proulx, G., 2001 . As of the year 2000, what do we know about occupant behavior in fire?, The Technical

Basis for Performance Based Fire Regulations, United Engineering Foundation Conference, San

Diego, pp. 127-129.

Proulx, G., 2002. Understanding human behavior in stressful situations. Workshop to Identify Innovative

Research Needs to Foster Improved Fire Safety in the United States, National Academy ofSciences,

Delegate Binder Section 7, Washington, D.C., pp. 1-5.

Sime. J.D., 1980. The Concept of Panic, Fires and Human Behaviour, D. Canter, Editor, John Wiley and

Sons, Ltd., pp. 63-81.

Sime, J.D., 1985. The outcome of escape behavior in the Summerland fire: panic or affiliation?. International Conference on Building Use and Safety Technology, Los Angeles, CA.

Wegner, D., B. Aguirre, G. Vigo, 1994. Evacuation behavior among tenants of the World Trade Center

following the bombing of February 26. Hazard Reduction Recovery Center Publications, Texas

A&M University.

N-24
Interim Report on Analysis of First-Person Accounts from Survivors of WTC

Yamasaki, M., 2002. World Trade Center Fact Sheet, Prepared by Minoru Yamasaki Associates,

Architects, www.m-yamasaki.com/projs/wtcfs.htm. Accessed on December 9.

N-25
Appendix N

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N-26
Attachment 1 WTC First-Person Accounts Code Book

1. BLDG - 'Building Location at the Time of Awareness / Perception of First Cue'

1 = Tower 1 , North Tower

2 = Tower 2, South Tower

3 = Plaza/Outside

4 = Concourse

5 = Mall

6 = PATH Train

7 = Bldg 7 or Bldg 3 99 = n/a

2. FLR - 'Floor Location at Perception of First Cue'

SPLIT COLUMN EXACT FLOOR AND CATEGORY

1 = Tl Lower (basement-42) in stairs

2 = Tl Lower (basement-42) on a floor

3 = Tl Mid (43-76) in stairs 4 = Tl Mid (43-76) on a floor

5 = Tl Upper (77-1 10) in stairs

6 = Tl Upper (77-1 10) on a floor

7 = Tl in stairs, level not specified

8 = Tl location not specified

9 = Tl mezzanine, lobby, concourse

10 = T2 Lower (basement-42) in stairs

1 1 = T2 Lower (basement-42) on a floor

12 = T2 Mid (43-76) in stairs

13 = T2 Mid (43-76) on a floor

14 = T2 Upper (77-1 10) in stairs

15 = T2 Upper (77-1 10) on a floor

16 = T2 in stairs, level not specified

17 = T2 location not specified

1 8 = T2 mezzanine, lobby, concourse

N-27
Appendix N

19 = Outside

22 - Tl elevator - lower floors

23 - Tl elevator - mid floors

24 - Tl elevator - upper floors

25 - Tl elevator, level not specified

99 = n/a

3. SEX - 'Sex of Evacuee'

1 = male

2 = female

99 = n/a

4. AGE CODE - 'Age of Evacuee'

SPLIT COLUMN EXACT AGE AND CATEGORY

1=21-35

2 = 36-50

3 = 51-65

4 = 66 +

99 = nya

5. DATE - 'Date of Record'

SPLIT COLUMN EXACT DATE MENTIONED

1 = Week of (09/1 1/2001-09/15/2001)

2 = 2 weeks after (09/16/2001-09/30/2001)

3=1-3 months after (10/01 /200 1 - 1 2/3 1 /200 1

)

4 = 4-6 months after (1/01/2002-3/31/2002)

5 = 7-9 months after (4/01/2002-6/30/2002)

6 = 10-12 months after (7/01/2002-9/30/2002)

99 = n/a

6. EGRESS - 'Evacuation Method'

1 = Stairs

^ 2 = Changed stairwells

3 = Elevator .^i

N-28
Interim Report on Analysis of First-Person Accounts from Survivors of WTC

4 = Combo of stairs and elevator

99 = n/a

7. FSTCUE - 'First Cue of Event' COLUMN CHECKED OFF FOR EACH INITIAL CUE MENTIONED

1 = Audio (boom, crash, explosion, thunder, blast, roar, rumbling)

2 = Visual (smoke, fire, bodies, plane approaching, panicked people, debris falling)

3 = Building Movement (impact, sway, shake, earthquake, rocking, jolt)

4 = Content Movement (chairs moving, ceiling falling, bounce in elevator, debris in halls/offices, lights flickering, change in air pressure, burned by fire)

5 = Warn by others (directly told or behavior of others)

6 = Physically impacted (burned, fell or thrown out of chair)

7 = Smelled fumes or Felt heat

99 = n/a

8. ALRM - Heard Alarm

1 = Yes, heard alarm

2 = Heard alarm on floor

3 = Heard alarm in stairs

4 = 'I did not hear an alarm'

99 = n/a

9. STTIME - 'Time to Start Evacuation'

1 = Immediately (ran, right away, rapidly): 1 minute

2 = Shortly after (short delay, picked up belongings, warn others): up to 5 minutes after

3 = Delayed (gathered belongings, look out window, make phone calls, watch TV, kept

working, checked security, planned with coworkers, shut equip off. Post T2 Impact)

4 = Stayed (to help: headcount, direct people, assisted coworkers, waited to be

rescued/given instructions; went up)

5 = Stuck (behind debris, walls, in elevator)

99 = n/a

10. CNDFL - 'Condition on Floor When Building was Hit'

1 = Devastated (combo of debris, fire, walls collapsed, ceiling/lights down,

darkness, water/sprinklers, smoke, jet fuel, glass, bodies)

N-29
Appendix N

2 = Abnormal (some smoke, heat, smell fuel, power out, dusty, debris past

windows, some reason for alarm/evacuation)

3 = Normal (usual working conditions)

99 = n/a (incl. not on floor when building was hit)

11. CNDFL - 'Condition on Floor'

COLUNM CHECKED OFF FOR EACH CONDITION MENTIONED.

1 = Normal

2 = Door Jammed

3 = Debris - Wall, ceiling collapsed

4 = Smoke

^

5 = Dust

6 = No power - dark

7 = Smell

8 = Water

9 = Fire

10 = Crowd, injuries

1 1 = Trapped

12 = Not on a floor

99 = n/a

12. STRS - 'Condition in Stairwell During Evacuation'

COLUMN CHECKED OFF FOR EACH CONDITION MENTIONED.

1 = Normal

2 = Door locked, jammed

3 = Crowd, hot

4 = No power

5 = Water

6 = Cracked wall

7 = Debris

8 = Smoky, smelly

99 = n/a

N-30
Interim Report on Analysis of First-Person Accounts from Survivors of WTC

13. ANCHRD - 'Heard Announcement'

1 = Tl Yes

2 = Tl No (mentioned specifically not hearing message)

3 = T2 Yes

4 = T2 No (mentioned specifically not hearing message)

99 = n/a

14. ANCACT - 'Action After Hearing T2 Announcement'

1 = Continued evacuating

2 = Continued evacuating saw some returned

3 = Returned to office/Stay on location

99 = n/a

15. ANCFLR - 'Location when T2 Announcement Heard'

10 = T2 Lower (basement-42) in stairs

1 1 = T2 Lower (basement-42) on a floor

12 = T2 Mid (43-76) in stairs

13 = T2 Mid (43-76) on a floor

14 = T2 Upper (77-1 10) in stairs

15 = T2 Upper (77-1 10) on a floor

16 = T2 in Stairs not specified

1 7 = T2 Location not specified

1 8 = T2 mezzanine, lobby, concourse

19 = Outside

20 = T2 in Elevator

99 = n/a

16. LT2IMP - 'Location at T2 Impact'

1 = Tl Lower (basement-42) in stairs

2 = Tl Lower (basement-42) on a floor

3 = T1 Mid (43-76) in stairs 4 = Tl Mid (43-76) on a floor

5 = Tl Upper (77-1 10) in stairs

6 = Tl Upper (77-1 10) on a floor

7 = Tl in stairs, level not specified

N-3I
Appendix N

8 = Tl location not specified (incl. Inside elevator)

9 = T 1 mezzanine, lobby, concourse

10 = T2 Lower (basement-42) in stairs

1 1 = T2 Lower (basement-42) on a floor

12 = T2 Mid (43-76) in stairs

1 3 = T2 Mid (43-76) on a floor

14 = T2 Upper (77-110) in stairs ,

15 - T2 Upper (77-1 10) on a floor

16 = T2 in stairs, level not specified _ ^

17 = T2 location not specified (incl. Inside elevator)

18 = T2 mezzanine, lobby, concourse

19 = Outside

99 = n/a

17. LT2C0L - 'Location at T2 Collapse'

1 = Tl Lower (basement-42) in stairs

2 = Tl Lower (basement-42) on a floor

3 = T1 Mid (43-76) in stairs

4 = T1 Mid (43-76) on a floor

5 = Tl Upper (77-1 10) in stairs

6 = Tl Upper (77-1 10) on a floor

7 = Tl in Stairs not specified

8 = Tl in Elevator

9 = Tl mezzanine, lobby, concourse

10 = T2 mezzanine, lobby, concourse

1 1 = T2 Lower (basement-42) in stairs

12 = Outside

13 = Other WTC building

14 = Subway

99 = n/a

18. LTICOL - 'Location at Tl Collapse'

1 = Lower Tl (basement-43) stairs

2 = Tl mezzanine, lobby, concourse

N-32
Interim Report on Analysis of First-Person Accounts from Survivors of WTC

3 = Outside

99 = n/a

19. LFFS - 'Location When Met Firefighters'

.

1 = Tl Lower (basement-42) in stairs

2 = Tl Lower (basement-42) on a floor

3 = Tl Mid (43-76) in stairs 4- Tl Mid (43-76) on a floor

5 = Tl Upper (77-110) in stairs

6 = Tl Upper (77-1 10) on a floor

7 = Tl in stairs, level not specified

8- Tl location not specified

9 = T 1 mezzanine, lobby, concourse

10 = T2 Lower (basement-42) in stairs

11 = T2 Lower (basement-42) on a floor

12 = T2 Mid (43-76) in stairs

13 = T2 Mid (43-76) on a floor

14 = T2 Upper (77- 110) in stairs

15 = T2 Upper (77-1 10) on a floor

16 = T2 in stairs, level not specified

17 = T2 location not specified

18 = T2 mezzanine, lobby, concourse

19 = Outside

99 = n/a

20. HELP - 'Who Helped Evacuee during Evacuation'

COLUMN CHECKED OFF FOR EACH HELPER MENTIONED

1 = Firefighter

2 = Port Authority (building staff/security)

3 = External Official (police, FBI, EMT, rescue workers)

4 = Coworkers

5 = Passed Firefighters in Stairs

99 = n/a

N-33
Appendix N

21. DSBLD - 'Evacuee Disability and Injury'

1 = Visual impairment

2 = Hearing impairment

3 = Physically challenged (obese, asthma, heart condition)

4 = Wheelchair user

5 = Injured during event (burned, sprained ankle, broken bones, emotional trauma)

6 = Helped disabled (during the evacuation)

7 = Saw disabled (during the evacuation)

8 = Helped injured j

9 = Saw injured

99 = n/a

22. B 1993 - '1993 WTC Bombing Presence'

1 = Yes

2 = Yes, prepared since (evacuation packs)

3 = Yes, reason evacuated early

4 = Yes, reason stayed

5 = No

6 = 1 993 bombing in the back of their mind but were probably not there at the time

99 = n/a

23. DELAY - 'Reason for Delay in Evacuation'

1 = Decide to stay

2 = Activity to complete before leaving (search floor, secure document, made calls, instruct others)

3 = Went Up/Return

4 = Stuck or trapped

5 = Help others, disabled or injured/Being helped

6 = Told to stay

99 = n/a

24. LPHONE - 'Location when Evacuee Made Phone Call'

1 = Office

2 = Other floor _ ^

3 = Stairs

N-34
Interim Report on Analysis of First-Person Accounts from Survivors of WTC

4 = Outside

5 = Multiple locations

99 = n/a

25. WPHONE - 'Recipient of Evacuee Phone Call' COLUMN CHECKED OFF FOR EACH GROUP MENTIONED

1 ^ Family and friends (spouse, parents, home)

2 = Colleague or boss

3 = Authorities (building security, 9-1-1)

99 = n/a

26. REST - 'Rest during Evacuation'

1 = Tl Lower (basement-42) in stairs

2 = Tl Lower (basement-42) on a floor

3 = Tl Mid (43-76) in stairs

4 = Tl Mid (43-76) on a floor

5 = Tl Upper (77-110) in stairs

6 = Tl Upper (77-110) on a floor

7 = Tl in stairs, level not specified

8 = Tl location not specified

9 = Tl mezzanine, lobby, concourse

10 = T2 Lower (basement-42) in stairs

11 = T2 Lower (basement-42) on a floor

12 = T2 Mid (43-76) in stairs

13 = T2 Mid (43-76) on a floor

14 = T2 Upper (77-110) in stairs

15 = T2 Upper (77-1 10) on a floor

16 = T2 in stairs, level not specified

17 = T2 location not specified

18 = T2 mezzanine, lobby, concourse

19 = Outside

99 = n/a

N-35
Appendix N

27. OBSTCN - 'Obstructions Encountered During Evacuation'

COLUMN CHECKED OFF FOR EACH OBSTRUCTION MENTIONED

1 = Door Jam (locked or jammed)

2 = Debris (wall falling, floor collapse, material damaged)

3 = Smoke

4 = No power •

5 = Smell (of fuel) ?

6 = Water

7 = Fire

8 = Crowd, disabled, injured

9 = Trapped by building rubble

99 = n/a

28. TMOUT - 'Time Evacuee Exited Building'

1 = T1: 8:48-9:02

2 = T1: 9:03-9:30

3 = T1: 9:31-9:58

4 = T1: 9:59-10:27

5 = T1/T2: 10:28+

6 = T2: 8:48-9:02

7 = T2: 9:03-9:30

8 = T2: 9:31-9:58

99 = n/a

29. KNWSIT - 'Evacuee's Knowledge of the Situation in the Initial Moment'

1 = High (terrorism/plane attack/ T2 collapsed/saw plane approaching/hitting building)

2 = Moderate (fire/bomb/earth quake/serious emergency/speculated plane/rumors)

3 = Low (reason for evacuation unknown or limited)

99 = n/a

30. SRSNSS - 'Level of Seriousness to Themselves in the Initial Moment'

1 = Very serious (fear, scared, want to get out ASAP)

2 = Somewhat serious (worried, did not know what was happening)

3 = Not serious (not concerned)

99 = n/a

N-36
Interim Report on Analysis of First-Person Accounts from Survivors of WTC

31. SOINFL - 'Social Influence on Evacuee's Decisions'

1 = Authority figure (boss, supervisor, manager)

2 = Coworkers/Group influence

3 = Survivor took leadership role 4 = Boss and group influence

99 = n/a

32. TCINFL - 'Technological Influence on Knowledge during Evacuation'

1 = Cell phone

2 = Blackberry, Text pager (deaf)

3 = TV, radio

4 = Walkie Talkie

99 = n/a

33. PERCEP - 'Perception of Others During Evacuation'

COLUMN CHECKED OFF FOR EACH PERCEPTION MENTIONED

1 = Calm/Orderly (civil, supportive, chatty, composed)

2 = Momentarily Panicked (running, pushing, shoving)

3 = Upset (crying, shouting, fearful, anxious)

4 ^ Helpful (assisting others)

99 = n/a

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Appendix N

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N-38
Table of Contents

List of Figures 0-iii

List of Tables 0-iv

Appendix 0

Interim Report on Telephone Interviews 0-1

0.1 Scope and Objective 0-1

0.2 Methodology 0-1

0.2.1 Sampling Frame 0-2

0.2.2 Tracking and Screening the Sample 0-2

0.2.3 Design Parameters 0-2

0.2.4 Expected Dispositions 0-3

0.2.5 Reserve Sample 0-3

0.2.6 Disproportionate Allocation 0-3

0.2.7 Final Sample Disposition Analysis 0-3

0.3 Telephone Interview Schedule 0-5

0.3.1 Preparedness and Training 0 6

0.3.2 Initial Experience on September 11, 2001 0-6

0.3.3 Interim Experience on September 11, 2001 0-7

0.3.4 Evacuation Experience on September 11, 2001 0-7

0.3.5 Respondent Background 0-8

0.4 Preliminary Results 0-8

0.4.1 Response Rate Analysis 0-8

0.4.2 Initial Building Populations 0 9

0.4.3 Occupant Characteristics 0-1

0.4.4 Previous Experience 0-13

0.4.5 Preparedness and Training 0-13

0.5 Summary 0-14

Attachment 1 CATI Advance Letter to Occupants 0-19

Attachment 2 Oral Consent Statement 0-21

O-i
Appendix O

Attachment 3 Telephone Interview Instrument 0-23

0-ii
List of Figures

Figure 0-1 . Employment start date at WTC. 0-12

O-iii
List of Tables

Table 0-1 . Disposition of the CATI sample and the total sample by tower

Table 0-2. Summary disposition rates by tower 0-5

Table 0-3. Response rate analysis for WTC 1 0-9

Table 0-4. Response rate analysis for WTC 2 0-9

Table 0-5. Reports of WTC decedents 0-1

0

Table 0-6. Occupancy estimates on September 1 1, 2001, by tower 0-1

1

Table 0 7. Age for WTC 1 respondents 0-11

Table 0 8. Age for WTC 2 respondents 0-12

Table 0-9. WTC fire drills in 12 months prior to September, 11, 2001 0-13

0-iv
Appendix 0

Interim Report on Telephone Interviews

0.1 scope and objective

Interviews with survivors of the World Trade Center (WTC) attacks were conducted using three methods:

telephone interviews, face-to-face interviews, and focus groups. This appendix will review four aspects

of the telephone interviews: methodology, sample disposition, telephone questionnaire, and preliminary

results of the telephone interviews for the pre-September 11, 2001, data. Significant additional analysis

will be completed over the next several months to develop as clear an understanding as possible of the

evacuation of WTC 1 and WTC 2 on September 11, 2001. These findings will be enhanced and

compared with findings from many other sources, including face-to-face interviews, focus groups, published accounts (see Appendix N of this report for a discussion of published accounts analysis), 9-1-1

records, and other materials.

The multimethod approach was selected for several reasons. First, multiple methods increase confidence

in the conclusions and findings when more than one method arrives at the same conclusions. Second, the

multiple objectives of the investigation mandated complementary approaches to accomplish all the goals. In other words, it is difficult to establish a scientific foundation for general findings while also broadly

investigating and establishing new facts and discovering unique events using only one method. Finally, concerns associated with the time latency since September 1 1, 2001, suggest the use of different

approaches and techniques in order to increase memory recall and accuracy.

The telephone interview questions and protocols met all Federal requirements regarding the Common

Rule for the Protection of Human Subjects, including Institutional Review Board (IRB) and National

Institute of Standards and Technology (NIST) approvals. Further, the telephone interview questions met

the requirements of the Paperwork Reduction Act, subject to Office of Management and Budget (0MB)

approval number 0693-0044.

0.2 METHODOLOGY

The survey objectives of the telephone interviews called for collecting 800 computer assisted telephone

interviews (CATI) of persons occupying either of the two WTC towers (WTC 1 and WTC 2) at the time

of the terrorist attacks on September 1 1, 2001 . The sample size of 800 and allocation of n=400 to each

tower were determined to simultaneously maximize the statistical precision within each tower. Primary

statistical analyses are in the form of tabulations and linear statistics (e.g., reporting of percentages and

average/means). Estimates of percentages from tower-specific survey data (at n=400) exhibit sampling

errors no greater than 2.5 percentage points, and 95 percent confidence intervals of percentages are no

0-1
Appendix O

greater than +/- 5 percentage points. This level of precision is more than adequate for examining

characteristics of occupants and egress attributes.'

Attempts were made to equally divide the respondents among WTC 1 and WTC 2 occupants (i.e., n=400 occupant interviews from each tower). Within each of the WTC buildings, independent

proportionate stratified samples of survivors were drawn. In other words, each occupant of a particular

tower had an equal probability of being selected.

0.2.1 Sampling Frame

The sampling frame (i.e., the list from which the sample was drawn) consisted of the names of occupants

from badge lists of WTC 1 and WTC 2. All occupants of the WTC were required to provide personal

data in support of issuing badges to clear through the security station at the entrance of each tower. The

badge lists were provided to NIST by the Port Authority of New York and New Jersey. The lists provide

name, floor of occupancy, employer, and social security number, the only available means of uniquely

identifying individuals.

0.2.2 Tracking and Screening the Sample

The badge lists contained September 1 1, 2001, occupants, occupants who were absent on the day of the

attacks, decedents, former occupants, and nonperson listings (false names used in sample testing). This means that a screening effort was needed to identify "eligible" badge list members—namely, those who

were inside WTC 1 or WTC 2 during the attacks. Moreover, the absence of telephone numbers for the

badge holders on the list necessitated a tracking/locating effort. The primary tracking mechanism was to search public databases using commercially available batch matching and Web-based search utilities. This necessitated a large sample to generate the 800 completed interviews.

0.2.3 Design Parameters

The number of occupant selections drawn into the sample was contingent on four key design parameters:

• The percentage of individuals from badge listings for whom a working telephone number

could be found (initial estimate: 80 percent tracking success)

• The percentage of badge listings that corresponded to a surviving WTC I or WTC 2 occupant on September 1 1, 2001 (initial estimate: 14 percent)

• The cooperation rate for screening the occupants (initial estimate: 65 percent)

Multivariate modeling such as correlation analyses, multiple linear regressions, and path analyses, are also a prominent part of

the survey analyses. Like the tabulations, these analyses are being conducted independently by tower. A sample size of n=400

per tower provides more than ample statistical power for the F tests used to detennine the significance of the regression models

(i.e., testing the null hypothesis that the ratio of explained variance to error/residual variance is equal to zero). For instance, in a multiple regression analysis featuring 20 independent variables, the sample size of 400, and 0.05 level of significance (Type I error), the power of the F test to detect an r statistic (i.e., proportion of explained variance) of 0.06 is just over 81 percent. See

also Chapter 9 of Cohen, J., 1988, Statistical Power Analysis for the Behavioral Science, Lawrence Erlbaum Associates, Inc., Hillsdale, N.J. Multivariate modeling results will be presented at a later date.

0-2
Telephone Interviews

• The interview response rate among September 1 1, 2001 survivors (initial estimate:

50 percent)

0.2.4 Expected Dispositions

In planning the CATI survey, a number of design parameters needed to be quantified in order to determine the number of persons to draw from the badge list. The expected disposition of the sample was

developed using the parameters defined in the aforementioned paragraph. A total sample of

22,735 persons from the badge list was needed to generate the desired 800 completed interviews. The

expected disposition by tracking efforts, screening, and interviewing are discussed later.

0.2.5 Reserve Sample

A reserve sample of about 14 percent (or about n=3,265) was added in the event additional sample size was needed due to unanticipated circumstances (e.g., the eligibility rate is lower than anticipated). This ) brought the total sample size to 26,000. The reserve was held "in reserve" while the main sample was

worked. Working the main sample allowed preliminary estimates of all design parameters to be

monitored so that an informed decision could be made on the necessity of releasing none, some, or all of

the reserve.

0.2.6 Disproportionate Allocation

The badge list contained different counts of persons from each tower, yet our sample design called for equal samples to be drawn from the collections of badge holders in WTC 1 and WTC 2. Thus, a disproportionate design (across tower strata) was employed. But within a tower, independent

proportionate samples were drawn using stratification by floor (within tower), employer (within floor)

and last name (within employer). This served to increase the statistical precision of the tower-specific

samples.

Thus, equal-sized samples of 13,000 selections were drawn from each of WTC 1 and WTC 2 badge lists. Each tower-specific sample was partitioned into 20 random replicates (comprising 5 percent of the total), and the reserve sample was determined by the last several random replicates for each tower. It is important to note that all badge holders fi^om WTC 1 floors 92 and above were omitted from sampling

because there were no survivors from those floors.

0.2.7 Final Sample Disposition Analysis

A total sample of 26,000 was drawn, comprising 13,000 names for each tower. Table 0-1 summarizes

the final disposition of the CATI sample and the total (locating) sample. The table is comprised of two

sets of rows. The top set pertains to the CATI sample and represents those sample persons for whom an

initial telephone number was identified prior to commencing the CATI survey operations. The bottom set of rows with the heading "Total Sample Disposition" represents the results of our locating/tracking effort used to identify usable telephone numbers associated with the sample subjects. (Recall that only name,

SSN and employer were available; no other contact information was readily available).

0-3
Appendix O

able 0-1. Disposition of the CATI sample and the 1total sam pie by towe

CATI Disposition wTc r WTC 2" Total % Distn

Interview 427 376 803 4.0 %

Partial intei-view 47 37 84 0.4 %

9/1 1 decedent 20 40 60 0.3 %

Other decedent 49 39 88 0.4 %

Not eligible 3,712 3,752 7,464 37.5 %

Language barrier 135 129 264 1.3 %

Eligible refrised to interview 138 139 277 1.4%

Other refusal 224 181 405 2.0 %

Respondent not interviewed 247 168 415 2.1 %

Can't contact/locate respondent 4,987 5,076 10,063 50.5 %

CATI total 9,986 9,937 19,923 100.0%

Total sample disposition: WTC 1 WTC 2 Total % Distn

Found initial telephone number 9,986 9,937 19,923 76.6 %

Unable to find a telephone number 3,014 3,063 6,077 23.4 %

Sample total 13,000 13,000 26,000 100.0%

a. Table data are unweighted. Tower location as indicated in the badge list and may differ from

reported tower location.

The bottom set of rows shows that telephone numbers were identified for just over three quarters

(76.6 percent) of the sampled subjects. Moreover, this rate was fairly uniform across towers. The

19,923 individuals with an initial telephone number were then loaded into the CATI sample management

system for calling. Ultimately, all reserve samples were used in the telephone survey. In the initial design parameters, it was assumed that 82 percent of the subjects would be locatable. While 76.7 percent

is close, many of the numbers were obsolete (e.g., disconnect, wrong number) and necessitated additional

tracking during CATI operations. Ultimately, by the end of data collection, only half the sample

(49.5 percent) represented confirmed contacts with subjects.

The top set of rows in Table 0-1 presents the final disposition of the sample by tower as well as for the

overall sample. Several statistics in the percentage distribution (rightmost) column are notable. First, we

were unable to contact subjects for half the sample (50.5 percent), due either to failures to answer the phone, answering machines, unusable numbers (e.g., wrong number, disconnected, business), etc. Most

of these telephone numbers represent "unlocatable" subjects—subjects for whom the initial telephone

number was incorrect. It bears reiterating that substantial additional research during CATI operations was

conducted using powerful subscription-based Web-based search engines. Unfortunately, little information was available for these individuals.

A second result of interest is the prevalence of ineligible subjects—those not in the building on the

morning of September 1 1, 2001 . An assessment of eligibility rates appears later in this appendix. A third

result is the existence of decedents—some from the September 1 1 attack and others from causes not

necessarily related to September 11, 2001 (e.g., cause unknown, naUiral causes). Most of the September

1 1 , 2001 , decedents were encountered due to a difference in the full (formal) name of the subject and the name that appeared on the badge list (e.g., the badge list sometimes contained maiden names, middle

O^
Telephone Interviews

names, nicknames, misspelled first or last names, out-of-sequence names, titles, and so on). This

impeded the ability to remove known decedents prior to calling.

The outcome of CATI operations on the final outcome rates is presented by tower in Table 0-2. The

table shows screening rates, interview rates, and rates of eligible occupants (among those who responded

to the screening questions). The first row shows that screening response rates were relatively uniform

across towers at about 46 percent. A screening response rate of 65 percent had been planned. Similarly,

interview response rates (among screened eligible subjects) were relatively stable across towers at about

49 percent. This is consistent with the planned interview response rate of 50 percent.

Table 0-2. Summary dis position rates by tower.

Disposition Rate WTC 1 WTC 2 Total

Screen 46.5 % 45.8 % 46.1 %>

Interview 48.6 % 49.5 % 49.0 %

Eligibility 18.9% 16.7% 17.8 %

Overall 22.6 % 22.7 % 22.6 %

Note: Definitions for "Rates" consistent with American Association of

Public Opinion Research (AAPOR) Standards, which may be found at http://www.aapor.org/pdfs/standarddefs2004.pdf

The eligibility rates were higher than expected - about 18 percent overall compared to the 14 percent

expected. The eligibility rate among WTC 1 subjects was slightly higher than those of WTC 2. However, the overall response rates are essentially uniform across towers, at 22.6 percent.

0.3 TELEPHONE INTERVIEW SCHEDULE

The telephone interview was conducted by a trained interviewer using a computer program which

provides questions and answer categories for the interviewer. Prior to calling, subjects received a letter that outlined the scope and purpose of the investigation, the purpose of the interview, and the telephone

call that came several days later. A full informed consent statement appeared in the letter, as well. A

copy of the letter can be found in Attachment 1 of this appendix.

When interviewers reached the subjects by telephone, the respondents were provided a description of the survey, the confidentiality of responses, the length of the interview, and the voluntary nature of

participation. They were then asked if they wished to participate, thereby obtaining oral informed

consent. The full text of the informed consent statement appears after the advance letter as Attachment 2.

The telephone interview instrument, Attachment 3 at the end of this appendix, includes the questions,

variable names, response options, and skip patterns directly from the computer program used by the interviewers. Variable names are used as shorthand for subsequent data analysis. Questions had a variety

of response option categories: multiple choice, interval, Likert scale, or open-ended. Open-ended

responses were minimized where possible due to the analysis burden and the fact that face-to-face

interviews are also being conducted. Skip patterns reduce burden on the respondent by skipping

questions that would not apply to a particular respondent. For example, a respondent would not be further questioned about fire drills if they did not receive fire drill training. Subsequent discussion of the

questions indicates whether a respondent was read a list of choices or was expected to give a free response.

0-5
Appendix O

The interview was designed with five primary groups of questions, covering emergency training and

preparedness, three stages of evacuation experience, and background infonnation about the respondent.

0.3.1 Preparedness and Training

The first group of questions served to measure the extent to which an occupant had any special level of

knowledge about the building, other than what would be obtained by perfonning their job. The most

prevalent special knowledge would be formal evacuation training, or fire drills. If a respondent indicated

that they participated in evacuation training during the 12 months prior to September 1 1, 2001, further questions were asked about the content of the training. The occupant's understanding of the emergency

procedures, or the way it was 'supposed to go,' was also measured. Next, a Likert Scale" measured the usefulness of the evacuation training in the context of their egress experience on September 11, ranging

from very helpful to very unhelpful. Finally, the respondent was asked whether he or she knew that there was a floor warden for their floor.

0.3.2 Initial Experience on September 11, 2001

The second group of questions covered the first moments of September 11, 2001, as experienced by the respondent, also known as the initial awareness period. How a person first became aware that something was not normal, whether in their building or the neighboring building, may have influenced subsequent

decisions. Examples of awareness channels may include sensory perception, such as feeling, hearing, or seeing the building shake, seeing or smelling fire or smoke, or may include a conversation with a person

inside or outside the WTC complex. Next, the respondent was asked to provide context to the initial moment of awareness. Context was first created by identifying what activity the respondent was

perfonning. Activities may include, but are not limited to, working, conversing with coworker(s), eating, or participating in a meeting. The respondent was then asked to recall the number of other people they were with at the first moment of awareness. People in groups often defer to group decisions rather than

making their own evacuation decisions. Next, a list of observations was read aloud and the respondent is asked to indicate whether they noticed the event during the period of initial awareness. These events included smoke, fire, fireballs, collapsed walls, jet fuel, severely or fatally injured people, sprinklers

going on, fire alann sounding, power outage or flickering lights, fallen ceiling tiles, and extreme heat. The event proximity was probed for every affirmative response to determine whether the observed event was in the immediate area or outside the building. If no affirmative responses were indicated, the respondent was asked whether they observed any disaster related events not previously mentioned.

Finally, the extent of any injuries to the respondent or those in the immediate area was ascertained, as well as whether the respondent felt that their life or the lives of other people were in danger.

A Likert Scale measures the degree to which the respondent agrees or disagrees with a statement. In this case, the scale measured helpfulness, including very helpful, helpful, unhelpful, and very unhelpfiil. A neutral response was not included.

0-6
Telephone Interviews

0.3.3 Interim Experience on September 11, 2001

The format of the interim experience group of questions mirrored the format of the initial awareness

questions. The interim time period was defined as the time after initial awareness, but before the person

entered a stairwell or elevator to leave the building. This time period may range from moments to tens of

minutes. The objective of the interim period questions was to determine what motivated/forced people to either immediately evacuate or delay their evacuation by some period of time.

Information about the nature of the event often forms the basis for decision-making during the interim

period. Many people may have found the environmental cues from the initial awareness period sufficient to initiate an immediate evacuation. Others may have required additional information in order to feel comfortable leaving the workplace. Occupants could have obtained information in two ways: passively

and actively. Passive information is information received without seeking it out. In other words, the

information was received regardless of whether the person felt it was needed. Active information is information which the respondent actively seeks and considers important with respect to their decision to evacuate. The respondent was first asked whether they received any additional information about the event during the interim period. If so, the source (who), the nature (what), and the channel (how) of the information was probed. Next, additional information sought out by the respondent was probed,

including the source, nature, channel, and whether the process was successfiil in gathering additional

information.

The perception of risk to the respondent's life, as well as the lives of others was asked in the same way as during the initial period, in order to determine whether the sense of risk was increasing or decreasing over

time. The interviewer probed about the activities of other people in the proximity of the respondent,

which may influence the respondent's subsequent choices. Whether people began evacuating prior to the respondent was specifically asked. Next, the respondent was asked about the activities they undertook

during the interim period, as well as activities that they wanted to do but could not. These activities included work-related actions, such as saving files or shutting machines down; personal actions, such as gathering belongings or calling people; or emergency-related actions, such as fighting fires/smoke, and

searching for or helping others. If a respondent was unable to accomplish an action, the action and the reason for being prevented from accomplishing the action was gathered.

As with the initial period, any observations of building damage or distress were collected. If the respondent received help in any way before initiating evacuation, the nature and source of the assistance was determined. The respondent was asked what the primary cue was which initiated their evacuation on September 1 1 and how many minutes passed before they started evacuating. Finally, the respondent was

asked whether anything prevented them from evacuating sooner than they reported.

0.3.4 Evacuation Experience on September 11, 2001

The next group of respondents completed the questions about the September 1 1 , 200 1 , evacuation

experience and focused on time spent in the stairwell and/or elevator(s). The respondent was first asked

whether they began their evacuation alone or with other people. Which stairwell (or elevator) the

respondent entered was collected as either the stair identification letter (A, B, or C) or the geographic

location, if known. Knowing where the stairwell emptied out at the bottom may also narrow down which

stairwell was used, which was collected near the end of this group of questions, [Stairs A/C (44 in. wide)

0-7
Appendix O

emptied out to the upper. Mezzanine level, while Stair B (54 in. wide) went to the lower. Concourse

level]. Next, the respondent's rationale for using a particular stairwell was probed. The respondent was

then asked whether they left the stairwell or turned back for any reason during the evacuation and, if so, why?

Some events and features of the stairwells aided the progress of the evacuation, while other features constrained the progress of the evacuation. The following features or events were identified to the respondents, who were asked to indicate whether it acted as an aid to their egress: instructions or

assistance from their floor warden, a police office, or fire fighter, support/encouragement from others, exit signage, and photoluminscent paint. The following items were identified to determine whether they

served to constrain the evacuation: crowded stairwells, counterflow (people moving up the stairs, against

the flow of occupants), disabled or injured people being taken down the stairwell, locked doors, poor

lighting, confusing or missing signage, and lack of clear instructions.

As with the initial and interim time periods, environmental cues related to fire smoke, jet fuel, and other

disaster-related observations were probed, as well as whether the observation was in the immediate area

or outside the tower. The final question about the respondent's own evacuation estimated the elapsed

time from entering the stairwell until they left the building. A concluding evacuation question determined

whether they knew why someone on their floor did not survive the WTC attack, if applicable.

0.3.5 Respondent Background

The final group of questions explored the background of the respondent relevant to evacuation. The first question identified any preexisting disabilities or injuries which made evacuation more difficult. The

respondent's age, gender, and primary language were collected. If the respondent was working in the

building prior to 1993, they were asked whether they were present during the February 26, 1993 bombing.

If so, respondents were asked questions about their evacuation experience.

The interview concluded with an open-ended opportunity for the respondent to say anything additional

about their evacuation experience on September 1 1, 2001 . Respondents who indicated that they had a

disability, were near the floors of impact, observed fire, smoke, or fireballs in their immediate area, or had

a role of building responsibility on September 11, 2001, were asked if they would be willing to participate

in a follow-up face-to-face interview.

0.4 PRELIMINARY RESULTS

The following section is a preliminary analysis of the telephone interview data. For this interim report,

only pre-September 1 1, 2001 questions, or occupant background, preparedness, and training data, are analyzed and presented. Data related to September 1 1, 2001, evacuation experiences are currently being

analyzed in the context of other data, such as face-to-face interviews and 9-1-1 tapes.

0.4.1 Response Rate Analysis

The response rate analysis of the telephone interview sample indicated an inverse relationship between

floor height and the rate of response in WTC 1, as shown in the last column of Table 0-3. The

nonresponse weight adjustment is the inverse of the overall response rate. For example, the inverse of

0-8
Telephone Interviews

25.3 percent is 3.95. In general, the weight adjustment for WTC 1 indicates that representative results should reflect that a single interview with a respondent high in the building is representative of more

occupants than a single interview with a person lower in the building.

Tab e 0-3. Response rate analysis for WTC 1

Floor Stratum

Number

of

Selections

Number

of

Interviews Screen Eligibility Interview Overall

Non-response

Weight

Adjustment

1 to 42 4,464 256 46.2 % 22.6 % 54.8 % 25.3 % 3.95 43 to 75 3,714 137 48.6 % 16.6% 45.8 % 22.3 % 4.49 76 to 92 1,802 34 42.7 % 14.7 % 30.1 % 12.9% 7.78

Floor missing 6 0 50.0 % 0.0 % N/A N/A

Total 9.986 427 46.5 % 18.9% 48.6 % 22.6 %

While a similar analysis of telephone interview response rates for WTC 2 (shown below in Table O^)

does not indicate a significant need to weight the results, it is a conservative assumption to be consistent

with WTC 1 analysis and the results will be weighted.

Table 0-4. Response rate analysis for WTC 2.

Floor

Stratum

Number

of

Selections

Number

of

Interviews Screen Eligibility Interview Overall

Non-response

Weight

Adjustment

1 to 42 4,339 143 44.8 % 14.8 % 49.7 % 22.3 % 4.49 43 to 75 3,187 134 45.0 Vo 17.7% 52.8 % 23.8 % 4.21 76 to 110 2,203 94 48.3 % 19.5 % 45.2 % 21.8% 4.58

Floor missing 208 5 50.5 % 9.5 % 50.0 %, 25.2 % 3.96

Total 9,937 376 45.8 % 16.7% 49.5 % 22.7 %

All subsequent telephone interview data analysis will thus reflect weighting of the results in order to more

accurately generalize the results. By convention, when a sample number is indicated (n = ), the sample

number will be the actual number of responses. Where percentages are indicated, however, the percentages were weighted to allow for generalization, unless otherwise indicated.

0.4.2 Initial Building Populations

The total building population is the sum of survivors and decedents. At the time of this report, the City of

New York has officially determined 2,749 people to be killed at the WTC on September 11, 2001; no

official breakdown of where people were killed presently exists. While an analysis of this issue by

Dennis Cauchon,^ a reporter for USA Today, in the months immediately following September 11, 2001, was remarkably complete, differences between his projections and the official numbers from the City of

New York and other official sources exist. These differences are shown in Table 0-5. For example, the

number of first responders depends upon the definition of first responder. The City of New York

published an occupational analysis of WTC decedents based upon a Census of Fatal Occupational Injuries

Cauchon, Dennis. 'For many on September 11. survival was no accident.' USA Today, December 20, 2001.

0-9
Appendix O

(U.S. Department of Labor, Bureau of Labor Statistics, in cooperation with the New York City

Department of Health and Mental Hygiene and State and Federal agencies). Four hundred and thirty- three decedent's occupations were listed as firefighting, police, or security. This number exceeds by 30

the number of FDNY, NYPD, and PAPD reported killed. This may be attributable to private security

forces present inside the towers on September 11, 2001, and/or first responders not employed by New

York City or the Port Authority. NIST is attempting to resolve these differences in order to fully

understand the initial building population.

Table 0-5. Reports of WTC decedents.

Decedent

Official NumbersUSA

Today"

WTC 1 occupants 1,434

At or above impact 1,360

Below impact 72

WTC 2 occupants 599

At or above impact 595

Below impact 4

First responders (total) 433 479

FDNY

rr-, o

343'-' NYPD 23'' PAPD 37^ UA 175 and AA 11 157

Uncertain location in towers 147

Bystanders 10

Total number of decedents 2,749"'" 2,826

a. Cauchon, Dennis. 'For many on Sept. 1 1, survival was no accident.' USA Today, December 20, 2001.

b. Summary of Vital Statistics 2002: The City of New York. Bureau of Vital Statistics, New York City Department of Health and

Mental Hygiene. December 2003.

c. Table WTC 8: Occupation of Decedents. All decedents classified as 'protective service' occupations, which includes firefighting, police, and guards.

d. World Trade Center Building Perfonnance Study. FEMA 403. May 2002.

e. Increasing FDNY's Preparedness (McKinsey Report). Available at: http://www.ci.nyc.ny.us/html/fdny/html/mck_report/index.shtml

f. Available at http://www.ci.nyc.ny.us/html/nypd/html/memorial 01. html

g. Available at: http://www.panynj.gov/AboutthePortAuthority

/PortAuthorityPolice/InMemorium/

h. Does not include 10 airplane hijackers for whom the City has not

issued death certificates.

Using the known eligibility rates allows for a projection of the survivors of WTC 1 and WTC 2 present in the building at 8:46 a.m. on September 11, 2001. The analysis indicates that WTC 1 had approximately

7,470 ± 750 surviving occupants, while WTC 2 had approximately 7,940 ± 920 occupants. Thus, the total population of survivors from both towers was 15,410 ± 1,180. Table 0-6 summarizes the projection of

population of WTC 1 and 2 on September 11, 2001. Pending resolution of decedent locations, the total

0-1

0
Telephone Interviews

building population at the time of the first airplane impact was 17,440 ± 1,180, calculated using the building decedent locations reported by Cauchon.

Table 0-6. Occupancy es timates on September 11, 2001, by tower.

WTC 1 WTC 2 Total

Number in sampling frame 39,454' 47,608 87,062

Survivor occupancy rate 18.9 % 16.7% 17.7%

Estimated total population of survivors 7,470 7,940 15,410

Statistical Precision Calculations

Sample n 427 376 803

Standard error (p)~ 1.90% 1 .92 % 1.36%

Standard error (total) 750 920 1,180

Confidence limits at 5 % ±1,470 ±1,790 ±2,320

Number of Occupant/Decedents

Decedents 1,434'' 599^ 2,033 - 2,192'

Total Building Population

8,900 8,540 17,440

a. Includes only occupants below floor 92.

b. Calculated from Cauchon as 1,434 + 599.

c. Calculated as 2,749 - 403 first responders - 157 airplane passengers.

0.4.3 Occupant Characteristics

The results of the background analysis of the average WTC occupant are identical to the precision

presented whether the data was weighted or unweighted. Occupants of the WTC towers were twice as

likely to be male as female (65 percent male [n=284]) for WTC 1 and 69 percent [n=250] for WTC 2). As shown in Table 0-7 and Table 0-8 below, the average age of the occupants was mid-forties, with a range of people from their early twenties to mid-seventies. The vast majority of respondents (92 percent

(n=739)) spoke English as their primary language, although no attempt was made to account for the fact that some telephone contacts ended with a language barrier and no interviews were conducted in any

language other than English.

Table 0-7. Age for WTC 1 respondents.^

N Valid 439

Refuse 1 Mean 45

Median 46

Minimum 22

Maximum 73

a. Mean and Median values are weighted. N,

Min, and Max are unweighted.

0-11
Appendix O

Table 0-8. Age for WTC 2

N Valid 361

Refuse 2 Mean 45

Median 44

Minimum 21 Maximum 74

a. Mean and Median values are weighted. N,

Min, and Max are unweighted.

Tenant and employee turnover at the WTC was not uncommon. Figure 0-1 shows the reported start dates for respondents in WTC 1 and WTC 2. In WTC 1, 4 percent (n=18) of the occupants had worked in the building since 1975. Further, 25 percent (n=l 10) had been working in the building prior to the 1993

bombing, although only 15 percent (n=64) of the WTC 1 respondents were present on February 26, 1993.

For WTC 1, 67 percent (n=287) of the occupants had started working in the building in the last four years

(1998-2001). The mean residence time in WTC 1 was over 5.6 years, while the median was 2 years.

1 1 1 1 1 1 1 1 1 1 1 1 1 1 1

1

YEAR STARTED AT WTC YEAR STARTED AT WTC 2 1

Percentages are weighted.

Figure 0-1. Employment start date at WTC.

Occupant tenure in WTC 2 demonstrated a similar trend. While only one respondent had worked in the

building since 1975, 25 percent (n=91 ) of the respondents had been working in the building prior to the 1993 bombing (with 16 percent (n=59) present on the day of the bombing). Another 51 percent (n=185)

started working in the building in the previous 4 years (1998-2001). The mean residence time in WTC 2

(n=360) was 5.9 years, while the median was 3 years.

Overall, 7 percent (n=56) had a formal responsibility or special knowledge about the building. These

respondents were fire safety staff, floor wardens, searchers, building maintenance, or security staff. Approximately 13 percent (n=105) of the respondents were employed by the Port Authority, which may

not imply a special knowledge of the building as some Port Authority employees had job duties related to functions outside the WTC.

0-12
Telephone Interviews

Some 6 percent (n=52) reported having a limitation which impacted their ability to evacuate. These

limitations included obesity, heart condition, needing assistance to walk, pregnancy, asthma, elderly,

chronic condition, recent surgery or injury, and other.

0.4.4 Previous Experience

Whether an occupant had a previous evacuation experience may have affected the decisions an individual

made during the September 11, 2001, evacuation. Further analysis will develop this hypothesis. Of the WTC 1 occupants present on September 1 1, 2001, 16 percent (n=64) were also present during the

1993 Bombing. In WTC 1, 60 percent (n=38) of evacuees in 1993 reported that they evacuated

immediately, 30 percent (n=20) reported that they waited to evacuate, and 9 percent (n=6) did not recall. Most (95 percent [n=53]) who were able to recall their 1993 evacuation decision felt that they made the

right decision, while 5 percent (n=3) did not believe they made the right decision.

Similarly, 16 percent (n=59) of WTC 2 evacuees on September 11, 2001, also evacuated in 1993. In WTC 2, however, only 75 percent (n=42) felt that they made the right decision in 1993, possibly due to the fact that many more waited to evacuate in 1993 in WTC 2 (69 percent (n=39)) than did so in WTC I

.

Only 31 percent (n=17) who reported their decision evacuated immediately from WTC 2 in 1993, keeping

in mind that the bomb had a more significant impact upon WTC I in 1993.

0.4.5 Preparedness and Training

Long a cornerstone of public policy on the emergency preparedness of office workers around the country,

the Port Authority required tenants to conduct regular fire drills and appoint employee floor wardens and

searchers. Overall, 66 percent (n=529) of WTC I and WTC 2 occupants reported participation in at least one fire drill in the 12 months immediately prior to September 1 1, 2001. Another 17 percent (n=I39)

reported that they did not participate in any fire drills in the 12 months prior to September 1 1, 2001, and

17 percent (n=135) did not know. Fire drill participation rates were similar between the two towers, as shown in Table 0-9.

Table 0-9. WTC fire drills in 12 months

prior to September, 11, 2001.

Number of Drills WTC 1" WTC 2" None 18%(n=78) 17 %(n=61)

1 13 %(n=57) 8 % (n=29)

2 21 %(n=90) 24 % (n=88)

3 1 1 % (n=47) 15 %(n=53)

4 10%(n=44) 9 % (n=32)

5-11 7%(n=31) 9 % (n=32)

1 2 or more 3 %(n=13) 4%(n=13)

Don't know 18 %(n=80) 15 %(n=55)

a. Percentages are weighted, n values unweighted.

One of the goals of fire drill training is to make occupants aware of the location of the emergency exits. Of respondents who reported participation in a fire drill, 93 percent (n=490) were instructed about the

0-13
Appendix O

location of the nearest stairwell. However, of the respondents who reported being shown a stairwell,

82 percent (n=432) did not enter or use the stairwell. Some 17 percent (n=92) reported that they did use

the stairs during a drill, while approximately 1 percent (n=5) reported not knowing. Overall, more than

half (51 percent (n=415)) of the occupants had never used a stairwell in WTC 1 or WTC 2 prior to September 11, while 48 percent (n=386) had used a stairwell. Two persons reported not knowing

whether they had used the stairs previously.

Another goal of the fire drills was to introduce the floor warden system and evacuation procedures. Most

occupants (82 percent (n=528)) with fire drill training were aware that there was a floor warden for their

floor. Approximately 70 percent (n=557) of all occupants reported that they were aware of the evacuation

procedures. When asked what those evacuation procedures comprised, however, answers varied

significantly, including: wait in hallway for further instructions; do not use elevators, use stairs; meet at a designated site outside the building for a head count; or proceed down (varied number of) flights of stairs and wait. Further analysis of the understanding and implementation of the emergency procedures is under

way.

0.5 SUMMARY

Eight hundred and three occupants of WTC 1 and WTC 2 were interviewed by telephone. Sample

disposition analysis indicated differential nonresponse, particularly for WTC 1 . In other words, the closer

the occupant was to the impact area in WTC 1 , the more likely it was that they would choose not to complete the telephone interview. Telephone interview percentages were then weighted to adjust for this

effect.

On the morning of September 1 1, 2001, 17,440 people (± 1,180) were present at WTC 1 and WTC 2. This does not include first responders. The initial population of both towers was similar: 8,900 (± 750) in WTC 1 and 8,540 (± 920) in WTC 2.

The average age of an occupant of the WTC towers was mid-forties. Two-thirds of WTC 1 occupants

had started working in the building during the previous 4 years (1998-2001), while half of WTC 2

occupants had begun working there during the same time period. Overall, 7 percent of occupants reported

having special knowledge about the building, and 6 percent reported a preexisting limitation to their mobility.

Of those present on September 1 1, 2001, 16 percent were also present during the 1993 bombing. Twothirds of occupants reported having participated in a fire drill in the 12 months immediately prior to September 1 1, while 17 percent reported that they received no training during that same period. Ninetythree percent of those participating in fire drills were instructed about the location of the nearest stairwell. Slightly over half of the occupants, however, had never used a stairwell at the WTC prior to September 1 1

.

Significant additional analysis is presently under way. It is particularly important that results of questions

related to the events, observations, and activities within the towers on September 11, 2001, be analyzed

within the context of the fmdings coming from face-to-face interviews, focus groups, and other data

collection activities.

0-14
Attachment 1 CATI Advance Letter to Occupants

Dear [Name]:

You are being asked to voluntarily participate in the federal investigation of the collapse of World Trade

Center structures on September 11, 2001. The National Institute of Standards and Technology (NIST) is investigating the cause of the collapse of the World Trade Center towers on September 1 1 in order to improve the way that building professionals, emergency responders, and regulatory authorities prepare for and respond to future emergency events.

Because you were an occupant of the WTC buildings, you have been identified as a person who can

provide NIST with information critical to its investigation. Your cooperation with the investigation

involves participating in a 20 minute telephone interview with a representative of our survey research

contractor, Datasource. The purpose of the interview is to gather information about where you were in the WTC buildings at the time of the September 1 1 events, what you observed and experienced, and how

you evacuated the building.

You may also be asked to participate in a voluntary face-to-face interview. Participating in the telephone

survey does not obligate you to participate in the face-to-face interview.

NIST and its contractors NuStats and Datasource will keep the identity of all participating individuals as confidential as possible. To the extent permitted by law, no one other than NIST, authorized Federal

officials, NIST contractors NuStats and Datasource, and Essex Institutional Review Board will have

access to your identity. Access to identifying information will only be provided to staff members on an

as-needed basis. Data will be reported in summary form.

NIST is a non-regulatory agency within the U.S. Department of Commerce and is conducting this investigation under the authority of the National Construction Safety Team Act (P.L. 107-231). The

investigation involves strict fact-finding. No part of the NIST Investigation report can be used in any suit or action for damages. For more information, see http://wtc.nist.gov.

A representative of Datasource will phone you in the next week or two. Please be aware that he / she will want to conduct the interview at your convenience. If you agree to do the survey, you may choose not to answer any question. If you wish, you can choose to withdraw your responses at any time during the interview or at the end of the interview.

If you have any questions or comments regarding your participation in the NIST investigation, please feel free to contact Dr. Johanna Zmud, NuStats project director, at 800-447-8287, ext. 2225 or Jason Averill,

NIST project director, at 301-975-2585. If you have any questions about your rights as a participant or if you have any concerns, you may contact the Essex Institutional Review Board, Inc. (IRB), 121 Main

Street, Lebanon, NJ; Phone: 908-236-7735. The IRB is a committee that has reviewed this research

investigational plan to help ensure that your rights and welfare are protected and that the investigation is carried out in an ethical manner.

Sincerely,

NIST OFFICIAL

0-15 Nisr
Appendix O

This page intentionally left blank.

0-16
Attachment 2

Oral Consent Statement

THE TELEPHONE INTERVIEWER USES THE FOLLOWING SEQUENCE OF STATEMENTS AND

QUESTIONS TO EFFECT ORAL CONSENT PRIOR TO BEGINNING THE INTERVIEW:

SUBJECT NAME:

Hi, may I please speak with <SUBJECT NAME>?

YES, CONTINUE I NO 2 SET CALLBACK

Hi, my name is and I am calling on behalf of the National Institute of Standards and Technology

(NIST). NIST is conducting the federal investigation of the World Trade Center disaster. Information

about the investigation is available at the website "wtc.nist.gov" or we can provide you a toll-free number to call. We are interviewing people about their experiences on September 1 1 . We sent you a letter about the study informing you of our call. Did you receive the letter?

YES 1 ASK IF THERE ARE ANY QUESTIONS

NO 2 ASK IF THERE ARE ANY QUESTIONS

SCREENER:

First, I need to ask you a few questions because we want to speak to people who had certain types of

experiences that may be especially helpful to NIST. For this study, we are conducting interviews with

people who were in WTC 1 or WTC 2 during the September 11, 2001 attacks.

(SCREEN) At the time of the attack, were you in WTC 1 or WTC 2 at the World Trade Center?

YES 01

NO 02 [THANK AND TERMINATE]

RF 99 [THANK AND TERMINATE]

(SCREEN) Which tower were you in?

WTCl 01

WTC2 02

OTHER, specify 97 [THANK AND TERMINATE]

RF 99 [THANK AND TERMINATE]

(SCREEN) What floor were you on?

<Enter floor number>

0-17
Appendix O

BASEMENT

CONCOURSE/LOBBY

PLAZA

OTHER, SPECIFY

DK

RF

990

991

992

997

998

999

PROGRAMMER NOTE: NEED CODED FLOOR NUMBER CATEGORIES FOR SAMPLE

TRACKING: : LOWER FLOORS (Tl : BASEMENT 42)

LOWER FLOORS (T2: BASEMENT - 42)

01

02

03

04

05

06

MIDDLE FLOORS (Tl: 43 ~ 76)

MIDDLE FLOORS (T2: 43 76)

UPPER FLOORS (Tl: 77 91)

UPPER FLOORS (T2: 77 - 1 10)

We would like you to participate in our study. Before we start, I'd like to read a statement to you about

this study to help you decide if you wish to participate:

In this study, we want to ask about when and how you left the tower you were in during the attack on

9/11. The information you provide will help engineers and emergency planners to improve the safety and

evacuation procedures for high rise buildings. The interview length is about 20 minutes and your

participation is voluntary. Because this interview involves recalling a traumatic event, you may

experience emotional discomfort. You are free to skip over any question you do not wish to answer. You

may take a short break or stop the questions at any time. We can also provide you counseling referrals if you like. Your identity will be kept as confidential as possible. To the extent permitted by law, no one

other than NIST, authorized Federal officials, NIST contractors NuStats and Datasource, and Essex

Institutional Review Board will have access to your identity. There are no direct benefits to participants.

Ifyou have any questions or comments regarding yoiu- participation in the NIST investigation, you may

contact Dr. Johanna Zmud, NuStats project director, at 800-447-8287, extension 2225. Ifyou have any

questions or concerns about your rights as a participant, you may contact the Essex Institutional Review

Board at 908-236-7735.

3a. Are you willing to participate?

YES, NOW 1

YES, LATER 2 [SET CALLBACK APPOINTMENT]

NO 99 THANK AND TERMINATE

0-18
Attachment 3

Telephone Interview Instrument

I would like to start by getting some background information. What year did you first start working at the

World Trade Center? RANGE: 1975 - 2001

$E 1975 2001

DK ' 9998

RF 9999

«YRWRK»

On September 11, 2001, were you in any of the following positions with the World Trade Center?

PORT AUTHORITY STAFF 1 FIRE SAFETY STAFF 2

FLOOR WARDEN OR SEARCHER 3

MAINTENANCE OR SECURITY STAFF 4

NONE OF THESE 0 X

DK 8

RF 9

«ROLES_01»

«ROLES_02»

«ROLES_03»

«ROLES_04»

During the year from September 11, 2000 to September 11, 2001, how many fire drills did you take part

in at the World Trade Center?

$E0 99

NONE 00 => SWLOC

DK 98 => SWLOC

RF 99 => SWLOC

«FIRED»

During these drills, were you ever instructed about the location of the emergency stairwell nearest to your

office?

YES 1 NO 2 => SWLOC

DK 8 => SWLOC

RF => SWLOC

«DEXIT»

How many emergency stairwells were you shown?

ONE 1 TWO 2

0-19
Appendix O

THREE

OTHER, SPECIFY

DK

RF

7

8

9

=> LVFSW

O

«HMEXT»

«0_HMEXT»

Before September 1 1 , had you learned in other ways about the locations of the three emergency

«SWLOC»

SKIP IF NO FIRE DRILLS

=> USESW

Else => +1

if FIRED=00,98-99

«SOUTI»

During any of the fire drills, did you leave your floor using one of the stairwells?

YES 1 NO 2 => USESW

DK 8 => USESW

RF 9 => USESW

«LVFSW»

Which stairwells did you use?

STAIRWELL A 1 STAIRWELL B 2

STAIRWELL C 3

OTHER, SPECIFY 7 O

DK 8

RF 9

«WHSW1_0I»

«WHSW1_02»

«WHSWI_03»

«WHSW1_04»

«0 WHSW1»

stairwells?

YES

NO

DK

RF

2

8

9

O-20
Interim Report on Telephone Interviews

Which side of the building was the stairwell located on?

=>+l

if NOT WHSW1=8

NORTH > 1 SOUTH 2

EAST 3

WEST 4 4

OTHER, SPECIFY 7 O

DK 8

RF 9

«WHSL1»

«0 WHSL1»

Had you ever used any of the emergency stairwells prior to September 1 1 ?

=> DHELP

ifLVFSW=l

YES 1 NO 2 => DHELP

DK 8 => DHELP

RF 9 => DHELP

«USESW»

SKIP FOR NO DRILLS AND NO USE OF STAIRWELLS

=> AEVOF

Else => +1

if FIRED=00,98,99 AND USESW>1

«S0UT2»

Which stairwell did you use?

STAIRWELL A 1 STAIRWELL B 2

STAIRWELL C 3 OTHER, SPECIFY 7 O

DK 8

RF 9

«WHSW2_01»

«WHSW2_02»

«WHSW2_03»

«WHSW2_04»

«0 WHSW2»

SKIP IF NO FIRE DRILLS

0-21
Appendix O

=> AEVOF

Else =>+l

ifFlRED=00,98-99

«S0UT3»

When you were evacuating on September 1 1

, how helpful was your experience during these drills?

=>+l

ifFlRED=00

VERY HELPFUL 1 SOMEWHAT HELPFUL 2

SOMEWHAT UNHELPFUL 3

VERY UNHELPFUL 4

DK 8

RF 9

«DHELP»

Prior to September 1 1 , were you aware of the evacuation procedures for your floor?

YES 1 NO 2 => FLWAR

DK 8 => FLWAR

RF 9 => FLWAR

«AEVOF»

Prior to September 1 1, what was the evacuation procedure you were told to follow?

LEAVE BUILDING IMMEDIATELY 1 GO TO ELEVATOR LOBBY 2

GO TO FLOORS UP OR DOWN 3

GO TO ROOF 4

STAY WHERE YOU ARE 5

OTHER, SPECIFY 7 O

DK 8

RF 9

«EVACP»

«0 EVACP»

Did you know that there was a Floor Warden for your floor?

=>+l

ifR0LES=l-4

YES

NO

DK

0-22
Interim Report on Telephone Interviews

RF 9

«FLWAR»

The next questions ask about 3 different time periods. The first series of questions asks about when you

first became aware that something had happened at the World Trade Center. This is a period ofjust a few

seconds. The next series of questions asks about the time from when you first became aware that something had happened, to the time you first entered a stairwell or elevator to exit the building. The

third series of questions asks about what happened during your evacuation, meaning the time from when

you first entered a stairwell or elevator until you exited the tower. At the end of the interview, I will ask

you if there is anything else about your experience on September 1 1 that you would like to contribute.

CONTINUE ' 1 D

«IFAWA»

Now thinking back to the morning of September 11, how did you first become aware that something had

happened at the World Trade Center?

$E 1 9

HEARD SOMETHING (BOOM, CRASH, EXPLOSION,

BLAST, ROAR, RUMBLING, ALARM)

SAW SMOKE OR FLAMES

SAW DEAD BODIES

SAW A PLANE

SAW DEBRIS

FELT SOMETHING (BUILDING MOVING, IMPACT, SHAKING,

SWAYING, ROCKING, JOLT, EARTHQUAKE)

FELL DOWN/FELL OFF CHAIR

WARNED BY SOMEONE AROUND ME

CONTACTED VIA PHONE

CONTACTED VIA EMAIL

PUBLIC ADDRESS SYSTEM

NEWS MEDIA (TELEVISION, RADIO)

OFFICE FURNITURE OR FIXTURES FALLING

FURNITURE OR OTHER ITEMS FALLING OVER/DOWN

OTHER, SPECIFY

DK

RF

«FAWAR»

«0_FAWAR»

What were you doing when you first became aware that something had happened to the World Trade

Center? PROBE: Anything else?

$E 1 9

WORKING INDEPENDENTLY 01

IN MEETING 02

01

02

03

04

05

06

07

08

09

10

1112

1314

97 O

98

99

0-23
Appendix O

UJN rriUJNE, 03

LncLJ^virNU/ WKl 1 liNLr tiVlAlL A/1 04

WAllllNU rvJK 1:;.L1:I,VAHJK Oj

KlUlINvj IfN E-LcVAHJK Oo . LHAl llN(j WllH LUWUKJsJbKS Q7

EATING/HAVING COFFEE 08

ENTERING BUILDING 09

OTHER, SPECIFY 97 O

DK 98 X

RF 99 X

«ACTV1 01

«ACTVI 02 »

«ACTVI 03 » «ACTV1 04»

«ACTVI 05 » «ACTV1 06»

«ACTV1 07 » «ACTV1 08»

«ACTV1 09»

«ACTV1 10»

«0 ACTV1»

At the moment when you first became aware that something had happened at the World Trade Center, did you

notice any of the following? FOLLOW UP: Was that in your immediate area or outside the Tower?

Did Not Notice Noticed in Immediate Area Noticed Outside the Tower

Smoke

Fire or Flames

Fireballs

Collapsed walls

Jet Fuel 1

Severely or fatally injured people 1

Sprinklers going on A fire alarm sounding

Power outage or flickering lights r

Fallen ceiling tiles Extreme heat

«NOT01_01»

«NOT01_02»

TIME PERIOD: I Were there any disaster related events going on around you at this time? => WHTW2

if OR[NOT0I-NOTI l]=2-3

YES . 1 NO 2 => WHTW2

DK 8 => WHTW2

RF 9 => WHTW2

«OEVEN»

0-24
Interim Report on Telephone Interviews

TIME PERIOD: 1 \Miat was going on?

ENTER RESPONSE

DK

RF

18

9

O

«GOING»

«0_GOING»

TIME PERIOD: 1

Were you still in<WHTOW>at this time'? IF YES. SELECT APPROPRIATE CHOICE IF NO, ASK

WHICH TOWER THEY WERE IN

WTC 1 1 WTC 2 2

DK 8

RF 9

«WHTW2»

TIME PERIOD: 1

And were you still on the<WHFLO>floor at this time? RANGE: 1 st - 11 0th FLOOR IF YES.

SELECT/ENTER FLOOR IF NO. ASK WHICH FLOOR THEY WERE ON AND SELECT/ENTER IT

«WHFL2»

«0_WHFL2»

TIME PERIOD: 1

At the moment when you first became aware that something had happened to the World Trade Center,

approximately how many people were with you? RANGE: 0 - 999 PEOPLE WE WANT THE

NUMBER OF PEOPLE THAT WERE IN THE SAME LOCATION AS THE RESPONDENT. (IN

THEIR LINE OF SIGHT)

$E 1 110

BASEMENT

CONCOURSE LOBBY

PLAZA

IN ELEVATOR

OTHER, SPECIFY

DK

RF

990

991

992

993

997

998

999

O

SE 0 999

NONE

DK

RF

«PE0P1»

00

98

99

=> YOUIN

=> YOUIN

=> YOUIN

0-25
Appendix O

TIME PERIOD: 1 Were any of these people injured at that time as a result of the event? YES 1 NO 2

DK 8

"

. RF 9

«PEOIN»

TIME PERIOD: I ,

Were you injured at that time, as a result of the event?

YES 1 NO 2 => ORISK

DK 8 ORISK

RF 9 ORISK

«YOUIN»

TIME PERIOD: 1

Would you say your injury was a. ... AN INJURY THAT DID NOT IMPACT YOUR ABILITY TO EVACUATE,

AN INJURY THAT DID IMPACT YOUR ABILITY TO EVACUATE BUT

WAS NOT LIFE THREATENING, OR

A LIFE THREATENING INJURY

OTHER, SPECIFY

DK

RF

«NATIN»

«0_NATIN»

TIME PERIOD: 1

Still thinking about the moment when you first became aware that something had happened at the World

Trade Center, did you believe that other people were in danger of being killed?

YES 1 NO 2

DK 8

RF 9

«ORISK»

TIME PERIOD: 1

Did you believe you were in danger of being killed?

YES 1

1

2

37 O

8

9

0-26
Interim Report on Telephone Interviews

NO 2

DK 8

RF 9

«YRISK»

> TIME PERIOD: 2 Now please think about the time period between when you first became aware that something had

happened and when you first entered a stairwell or elevator to leave the tower. During this entire time

period, were you given any additional information about what was going on? AFTER BECOMING

AWARE OF THE EVENT, BUT BEFORE EVACUATION.

YES 1 NO 2 => SEEKl

DK 8 => SEEKI

RF 9 => SEEKI

«GETIN»

TIME PERIOD: 2

Who gave you this information? PROBE: Anyone else? MANAGER/SUPERVISOR 1 COWORKER INSIDE BUILDING 2

FAMILY/FRIEND OUTSIDE BUILDING 3

POLICE/FIREFIGHTER 4

FLOOR WARDEN 5 MEDIA PERSON (TV/RADIO) 6

OTHER, SPECIFY 7 O

DK 8 X

RF 9 X

«WHINF_01»

«WHINF_02»

«WHINF_03»

«WHINF_04»

«WHINF_05»

«WHINF_06»

«WHINF_07»

«0_WHINF»

TIME PERIOD: 2

What information did you get? PROBE: Any other information?

INFORMATION ABOUT WHAT HAD HAPPENED 1 INSTRUCTIONS TO LEAVE 2

INSTRUCTIONS TO STAY - 3

OTHER, SPECIFY 7 O

DK 8 X

0-27
Appendix O

RF 9 X

«WHATI_01»

«WHATI_02»

«WHATI_03»

«WHATI_04»

«0_WHATI»

TIME PERIOD: 2

How did you get this information? PROBE: Any other way?

FACE TO FACE 1 TELEPHONE 2

^ EMAIL/BLACKBERRY \ 3

PA ANNOUNCMENT 4

TV/RADIO 5

OTHER, SPECIFY 7 O

DK 8 X

RF 9 X

«HOWGT_01»

«HOWGT_02»

«HOWGT_03»

«HOWGT_04»

«HOWGT_05»

«HOWGT_06»

«0_HOWGT»

TIME PERIOD: 2

And during this same time period, did you try to get additional information about what was going on?

AFTER BECOMING AWARE OF THE EVENT, BUT BEFORE EVACUATION

YES 1 NO 2 => 0RIS2

TRIED, BUT WAS UNABLE TO GET INFORMATION 3 => 0RIS2

DK 8 => 0RIS2

RF 9 =>0RIS2

«SEEKI»

TIME PERIOD: 2

Who did you go to for this information? PROBE: Anyone else? MANAGER/SUPERVISOR 1 COWORKER INSIDE BUILDING . 2

FAMILY/FRIEND OUTSIDE BUILDING 3

POLICE/FIREFIGHTER 4

FLOOR WARDEN 5

MEDIA PERSON (TV/RADIO) 6

0-28
Interim Report on Telephone Interviews

OTHER, SPECIFY

DK

RF

«GOINF_01»

«GOINF_02»

«GOINF_03»

«GOINF_04»

«GOrNF_05»

«GOINF_06»

«GOINF_07»

«0_GOINF»

TIME PERIOD: 2

7 O

8 X

9 X

What type of information did you try to find? PROBE; Anything else? INFORMATION ABOUT WHAT HAD HAPPENED 1 INSTRUCTIONS TO LEAVE 2

INSTRUCTIONS TO STAY 3

OTHER, SPECIFY 7 O

DK 8 X

RF 9 X

«WHAI2_01»

«WHAI2_02»

«WHAI2_03»

«WHAI2_04»

«0 WHAI2»

TIME PERIOD: 2

How did you get this information? PROBE: Any other way?

FACE TO FACE 1 TELEPHONE 2

EMAIL/BLACKBERRY 3

PA ANNOUNCMENT 4

TV/RADIO 5 OTHER, SPECIFY 7 0

DK 8 X

RF 9 X

«HOWG2_01»

«HOWG2_02»

«HOWG2_03»

«HOWG2_04»

«HOWG2_05»

«HOWG2_06»

«0 H0WG2»

TIME PERIOD: 2

0-29
Appendix O

And during the time between when you first became aware that something had happened at the World

Trade Center and when you first entered the stairwell or elevator to leave the tower, did you believe that other people were in danger of being killed? AFTER BECOMING AWARE OF THE EVENT, BUT

BEFORE EVACUATION

=> YRIS2

ifORISK=l

YES 1 NO 2

DK 8

RF 9

«0RIS2»

TIME PERIOD: 2

During that time period, did you believe you were in danger of being killed?

=> PEODO

ifYRISK=l

YES 1 NO 2

DK 8

RF 9

«YRIS2»

TIME PERIOD; 2

During this time period, what were the people around you doing? PROBE: Were they doing anything

else? AFTER BECOMING AWARE OF THE EVENT, BUT BEFORE EVACUATION

$E0 10

NOONE AROUND/WAS ALONE 00 X

TALKING TO OTHERS 01

GATHERING PERSONAL/WORK ITEMS 02

SEARCHING FOR OTHERS 03

CALLING OTHERS 04

FIGHTING FIRE/SMOKE 05

LOCKING UP 06

WORKING 07

EVACUATING THE TOWER 08

CRYING, RUNNING AROUND, IN SHOCK 09

HELPING OTHERS 10

OTHER, SPECIFY 97 0

DK 98 X

RF 99 X

«PEODO 01

O-30
Interim Report on Telephone Interviews

«PEODO_02»

«PEODO_03»

«PEODO_04»

«PEODO_05»

«PEODO_06»

«PEODO_07»

«PEODO_08»

«PEODO_09»

«PEODO_10»

«0_PEODO»

TIME PERIOD: 2

Did the people around you start evacuating before you did?

=> DOBEF

ifPEODO=08

YES 1 NO 2

DK 8

RF 9

«EVACB»

TIME PERIOD: 2

Did you do any of the following before starting your evacuation?

$E 1 9

TALK TO ANOTHER PERSON FACE TO FACE 0

GATHER PERSONAL ITEMS 02

TELEPHONE OTHER PEOPLE 03

CONTINUE WORKING 04

SAVE OR TRANSFER COMPUTER FILES 05

SEARCH FOR OTHERS 06

FIGHT FIRE OR SMOKE 07

MOVE TO ANOTHER FLOOR 08

HELP OTHERS 09

LOGGING OFF/SHUTTING DOWN COMPUTER 1

NONE OF THESE 1 1 X

«DOBEF_01»

«DOBEF_02»

«DOBEF_03»

«DOBEF_04»

«DOBEF_05»

«DOBEF_06»

«DOBEF_07»

«DOBEF_08»

TIME PERIOD: 2

0-31
Appendix O

Did you do anything else during this time?

ENTER RESPONSE 1 O

NO OTHER ACTIVITIES 0

DK 8

RF 9

«OACTI» «0_OACTI»

TIME PERIOD: 2

Before you began your evacuation, was there anything you wanted to do, but couldn't?

YES 1 NO 2 => SEEOl

DK 8 => SEEOl

RF 9 => SEEOl

«WANTD»

TIME PERIOD: 2

What was that? PROBE: Anything else?

$E 1 7 GATHER WORK ITEMS 01

GATHER PERSONAL BELONGINGS 02

CALL FRIEND/FAMILY MEMBER 03

FIND FRIEND/COWORKER 04

HELP FRIEND/COWORKER 05

LOCK UP 06

EVACUATE IMMEDIATELY 07

OTHER, SPECIFY 97 0

DK 98 X

RF 99 X

«WANAC_01»

«WANAC_02»

«WANAC_03»

«WANAC_04»

«WANAC_05»

«WANAC_06»

«WANAC_07»

«WANAC_08»

«0_WANAC»

TIME PERIOD: 2

Why couldn't you do that/those things?

$E 1 9

0-32
Interim Report on Telephone Inten/iews

AFRAID 01

LOCKED DOORS 02

PHONE LINES DEAD 03

INJURED 04

EXIT BLOCKED 05

TOO CROWDED ' 06

TOLD TO STAY IN BUILDEMG 07

TOLD TO LEAVE 08

FATIGUE 09

DISABLED 10

SMOKE 1

DAMAGE TO FLOOR 12

WAS HELPING OTHERS 13 OTHER. SPECIFY 97 O

DK 98

RF 99

«WHYNO_0I>

«WHYNO_02>

«WHYNO_03>

«WHYNO_04>

«WHYNO_05>

«WHYNO_06>;

«WHYNO_07>:

«WHYNO_08>:

«WHYNO_09>:

«WHYNO_10>:

«WHYN0_11>;

«WHYN0_12>:

«WHYN0_13>;

«WHYN0_14>;

«0 WHYNO»

Still thinking about the time between when you first became aware that something had happened at the World Trade

Center and when you entered the stairwell or elevator to leave the tower, did you notice any of the following?

FOLLOW UP: Was that in your immediate area or outside the Tower?

Did Not Notice Noticed in Immediate Area Noticed Outside the Tower

Smoke

Fire or Flames 1

Fireballs

Collapsed walls C

Jet Fuel

Severely or fatally injured people

Sprinklers going on A fire alarm sounding

Power outage or flickering lights

Fallen ceiling tiles Extreme heat

0-33
Appendix O

«SEE01_01»

«SEE01_02»

TIME PERIOD: 2

Were there any disaster related events going on around you at this time?

=>EVACF • ifOR[SEE01-SEEll]=2-3

YES 1 NO 2 =>HELPY

DK 8 , =>HELPY

RF 9 =>HELPY

«ODISE»

TIME PERIOD: 2

What was going on?

ENTER RESPONSE 1 O

DK 8

RF 9

«G01N2»

«0 G0IN2»

TIME PERIOD: 2

Were you still on the<WHFL2>floor at this time? RANGE: 1st - 1 10th FLOOR IF YES,

SELECT/ENTER FLOOR IF NO, ASK WHICH FLOOR THEY WERE ON AND SELECT/ENTER IT

$E 1 110

=>+l

if (AND[SEE01-SEE11]=1) AND PEODO>0 AND PEODO<98

BASEMENT 990

CONCOURSE/LOBBY 991

PLAZA 992

ELEVATOR 993

OTHER, SPECIFY 997

DK 998

RF 999

«EVACF»

«0_EVACF»

TIME PERIOD: 2

Did anyone help you in any way before you started your evacuation?

0-34
Interim Report on Telephone Interviews

YES 1 NO 2 => DECID

DK 8 DECID

RF 9 => DECID

«HELPY»

TIME PERIOD: 2

Who helped you? PROBE: Anyone else? WE WANT THEIR ROLE NOT THE NAME OF THE

PERSON

POLICE OFFICER/FIREFIGHTER 1 COWORKER 2

STRANGER 3

FLOOR WARDEN 4

MANAGER/SUPERVISOR 5

OTHER, SPECIFY 7 O

DK 8 X

RF 9 X

«WHOHE_01»

«WHOHE_02»

«WHOHE_03»

«WHOHE_04»

«WHOHE_05»

«WHOHE_06»

«0_WHOHE»

TIME PERIOD: 2

What did they help you with? PROBE: Anything else? $E 1 7 LOCATING OTHERS 01

HELPING OTHERS 02

FINDING EXITS 03

TREATING YOUR INJURIES 04

PROVIDED INFORMATION/INSTRUCTIONS 05

GATHER BELONGINGS 06

CALM DOWN/EMOTIONAL ASSISTANCE 07

OTHER, SPECIFY 97 O

DK 98 X

RF 99 X

«WHATD_01»

«WHATD_02»

«WHATD_03»

«WHATD_04»

«WHATD 05»

«WHATD 06»

0-35
Appendix O

«WHATD 07»

«WHATD_08»

«0_WHATD»

TIME PERIOD: 2

What was the one thing that made you decide to evacuate?

WAS TOLD TO EVACUATE 1 FRIENDS CO-WORKERS EVACUATED : 2

AFRAID/FELT IN DANGER 3

FIRE ALARM WAS GOING OFF 4

SAW SMOKE 5

SAW FIRE '6

OTHER, SPECIFY ^ 7 O

DK 8

RF 9

«DECID»

«0 DECID»

How many minutes had passed before you started to evacuate? IF NEEDED: How much time passed

between when you first became aware that something had happened to the World Trade Center and when

you entered the stairwell or elevator to leave the tower. THIS IS NOT TIME TO EVACUATE.

PLEASE CLARIFY WITH RESPONDENT IF TIME APPEARS TOO LONG. RESPONDENT WAS

IN<WHTW2> RANGE FOR WTC 1: 1 - 103 MINUTES RANGE FOR WTC 2: 1 - 75 MINUTES

$E 1 103

DK 998

RF 999

«TIMEP»

SKIP FOR TOWERS

=> EVAC2

Else => +1

ifWHTW2=2

«SKIP1»

Did you begin your evacuation. . . WE ARE INTERESTED IN WHAT THEY KNOW NOW. THEY

MAY NOT HAVE KNOWN WHEN THEY WERE EVACUATING, BUT NOW THEY CAN TELL US

WHEN IT WAS.

BEFORE THE PLANE HIT WTC 2 1 AFTER THE PLANE HIT WTC 2, BUT BEFORE THE WTC 2

COLLAPSE 2

AFTER THE WTC 2 COLLAPSE 3 V

DK - 8

RF 9

0-36
Interim Report on Telephone Interviews

«EVAC1»

SELECT

$S NS=2 C0=1 IN=EVAC1<=1 ;C0=2 1N=EVAC1<=2 ; BEFORE THE PLANE HIT WTC 2 1 AFTER THE PLANE HIT WTC 2, BUT BEFORE THE WTC 2 COLLAPSE 2

AFTER THE WTC 2 COLLAPSE 3

DK 8

RF 9

«SEL1»

SELECT2

BEFORE THE PLANE HIT WTC 2 AFTER THE PLANE HIT WTC 2, BUT

AFTER THE WTC 2 COLLAPSE

DK

RF

«SEL2»

Did you begin your evacuation. .

=> EVCSO

ifEVACl>0

BEFORE THE PLANE HIT WTC 2 1 AFTER THE PLANE HIT WTC 2 2

DK 8

RF 9

«EVAC2»

SELECT4

$S C0=1 IN=EVAC2<=1 ; BEFORE THE PLANE HIT WTC 2 AFTER THE PLANE HIT WTC 2 DK

RF

«SEL3»

Was there anything that kept you from evacuating sooner?

YES, RECORD RESPONSE 1 O

NO 2

DK 8

RF 9

1 BEFORE THE WTC 2 COLLAPSE 2

3

8

9

12

8

9

0-37
Appendix O

«EVCSO»

«0_EVCSO»

TIME PERIOD: 3

When you began your evacuation, were you alone or with other people? PEOPLE THAT THEY KNOW,

PEOPLE THAT THEY WERE TALKING WITH

ALONE 1 WITH OTHER PEOPLE 2

DK 8

RE 9

«ALONE»

^

TIME PERIOD: 3

Which stairwell did you use for your evacuation?

STAIRWELL A

STAIRWELL B

STAIRWELL C

USED ELEVATOR

OTHER, SPECIFY

DK

RE

12

3

4 =>FOLAI

7 O

8 X

9 X

«STAIR 01» «STAIR_02»

«STAIR_03»

«STAIR_04»

«STA1R_05»

«0 STAIR»

TIME PERIOD: 3

Which side of the building was the stairwell located on?

/WHYST

if NOT STA1R=8,7

NORTH 1 SOUTH 2

EAST 3 WEST 4

OTHER, SPECIFY 7 O

DK 8

RF 9

«WHISI»

«0 WHISI»

TIME PERIOD: 3

0-38
Interim Report on Telephone Interviews

Why did you choose that/those stairwell(s) for your evacuation? PROBE: Any other reason?

CLOSEST ONE 1 FOLLOWED OTHER PEOPLE TO IT 2

OTHER EXITS WERE BLOCKED 3

SAME AS I USED IN PREVIOUS EMERGENCY 4

I WAS TOLD TO USE THIS STAIRWELL 5 OTHER, SPECIFY 7 O

DK 8 X

RF 9 X

«WHYST_01»

«WHYST_02»

«WHYST_03»

«WHYST_04»

«WHYST_05»

«WHYST_06»

«0_WHYST»

TIME PERIOD: 3

At any time during your evacuation, did you leave that/those stairwell(s)? DO NOT INCLUDE PEOPLE

WHO FOLLOWED THE PASSAGE WHERE THE STAIRWELLS START AND END.

YES 1 NO 2 => FOLAl

DK 8 => FOLAl

RF 9 => FOLAl

«LEVST»

TIME PERIOD: 3 Which floor were you on when you left the stairwell? IF RESPONDENT UNSURE, SELECT 997 AND

RECORD RANGE OF FLOORS EXAMPLE: 34-40

$R 1 110

UNSURE, RECORD RESPONSE 997 O

«FLLST»

«0_FLLST»

TIME PERIOD: 3 Why did you leave the stairwell? PROBE: Any other reason?

$E 1 9

I GOT LOST 01

WAS TOLD TO LEAVE STAIRWELL 02

TO HELP SOMEONE 03

TO GO BACK AND GET SOMETHING 04

TOO CROWDED 05

0-39
Appendix O

SMOKE IN STAIRWELL 06

PATH OBSTRUCTED 07

A LOCKED DOOR 08

STAIRWELL LED TO A FLOOR 09

OTHER, SPECIFY 97 O

DK 98

RF 99

«WHYLS 01»

«WHYLS_02»

«WHYLS_03»

«WHYLS_04»

«WHYLS_05»

«WHYLS_06»

«WHYLS_07»

«WHYLS_08»

«WHYLS 09»

«WHYLSJO»

«0 WHYLS»

Screen [Template 3] -> FL0A5

=>+!

ifFLWAR>l

Did any of the following help you evacuate while you were in the building?

Yes No DK RF

Instructions or assistance from your floor warden

Instmctions or assistance from Police or Firefighters

Support and encouragement from others r

Exit signs c Ij Photo luminescent paint in stairwells t

1

«FOLAl»

Screen [Template 3] -> EVCM7

=>+l

if NOT STAIR<4

O^O
Interim Report on Telephone Interviews

Did any of the following make your evacuation more difficult while you were in the building?

Yes Nn DK RF

Crowded stairwells L L

Firefighters or Police moving up stairwell C

Disabled or injured people being taken down stairwell D

Locked doors c: C

Poor lighting

Confusing or missing signs D

Lack of clear instructions 1" r r

«EVCM1»

Screen [Template 3] -> EXPl 1

Please tell me if you noticed any of the following at any time during your evacuation. FOLLOW UP: Was that in your immediate area or outside the Tower?

Did Not Notice Noticed in Immediate Area Noticed Outside the Tower

Smoke j

Fire or Flames

Fireballs

Collapsed walls

Jet Fuel

Severely or fatally injured people I

Sprinklers going on A fire alarm sounding

Power outage or flickering lights C

Fallen ceiling tiles r [ Extreme heat 1

«EXP01_01»

«EXP01_02»

TIME PERIOD: 3

During your evacuation, did you turn back at any time? "TURN BACK" MEANS "GO BACK UP".

YES 1 NO 2 => EXITS

DK 8 => EXITS

RF 9 => EXITS

«TURNB»

0-41
Appendix O

TIME PERIOD: 3

Why did you turn back? PROBE: Any other reason?

$E 1 7

I GOT LOST 01

I WAS TOLD TO TURN BACK 02

TO HELP SOMEONE 03

TO GET SOMETHING 04

IT WAS TOO CROWDED 05

SMOKE IN THE STAIRWELL 06

MY PATH WAS OBSTRUCTED 07

OTHER, SPECIFY - 97 0

DK 98 X

RF 99 X

«WHYTB_01»

«WHYTB 02»

«WHYTB_03»

«WHYTB 04»

«WHYTB_05» ^

«WHYTB_06»

«WHYTB 07»

«WHYTB 08»

«0_WHYTB»

TIME PERIOD: 3

Did you exit the stairwell or elevator to the mezzanine or to the concourse?

MEZZANINE 1 CONCOURSE 2

OTHER, SPECIFY 7 O

DK 8

RF 9

«EXITS»

«0_EXITS»

TIME PERIOD: 3

How much time passed between the moment you first began your evacuation to when you exited the

Tower? PLEASE CLARIFY WITH RESPONDENT IF TIME APPEARS TOO LONG. RESPONDENT

WAS IN<WHTW2> RANGE FOR WTC 1: 1 - 103 MINUTES RANGE FOR WTC 2: 1 - 75 MINUTES

$E 1 103

DK 998

RF 999

«TIMP2»

SKIP FOR TOWERS

0^2

ll
Interim Report on Telephone Interviews

=> +2

Else =>+l

ifWHTW2=2

«SKIP2»

TIME PERIOD: 3

Did you exit the tower. .

ELIMINATE -> 2

ACCORDING TO NOT SELl-SEL 2

BEFORE THE PLANE HIT WTC 2 => GETOU

AFTER THE PLANE HIT WTC 2 BUT BEFORE THE

WTC 2 COLLAPSE, OR 2 => GETOU

AFTER THE WTC 2 COLLAPSE 3 GETOU

DK 8 GETOU

RF 9 => GETOU

«EXIT1»

TIME PERIOD: 3

Did you exit the tower. .

Eliminate -> According to NOT SEE

Before the plane hit WTC 2, or After the plane hit WTC 2 DK

RF

«EXIT2»

Please remember that this study is intended as a fact finding mission and not a fault finding mission. It is crucial that we determine why some people were successful in their evacuation while others were not. Was there anyone on your floor that was not successful in their evacuation?

YES 1 NO 2 =>PHYSI

DK 8 =>PHYSI

RF - 9 =>PHYSI

«GETOU»

Why didn't they make it out? PROBE: Any other reason?

$E 1 8 WAS INJURED

WAS DISABLED

REFUSED TO LEAVE

DID NOT THINK IT WAS SERIOUS

01

02

03

04

0^3
Appendix O

STAYED BACK TO HELP SOMEONE 05

WAS TOLD TO STAY 06

STRUCTURAL DAMAGE 07

SMOKE OR FIRE 08

OTHER, SPECIFY 97 O

DK 98 X

RF 99 X

«WHYNG 01»

«WHYNG_02» : «WHYNG 03»

«WHYNG_04»

«WHYNG 05»

«WHYNG_06»

«WHYNG 07»

«WHYNG 08»

«WHYNG_09»

«0 WHYNG»

On September 1 1, 200 1, did you have any physical problems that made it more difficult for you to leave

the tower? Please do not include injuries caused by the incident or evacuation.

YES 1 NO 2 => AGE

DK 8 => AGE

RF 9 =>AGE

«PHYS1»

What type of physical problem? PROBE: Anything else? $E 1 9

BLIND/PARTIALLY BLIND 01

DEAF 02

IN WHEELCHAIR 03

NEED WALKING ASSISTANCE 04

OBESITY 05

HEART CONDITION 06

PREGNANT 07

ASTHMA 08

ELDERLY 09

OTHER, SPECIFY 97 O

DK 98 X

RF 99X

«LIMIT_01»

«LIMIT_02»

«LIMIT 03»

«LIMIT_04»

«LIMIT_05»

«LIMIT 06»

0^4
Interim Report on Telephone Interviews

«LIMIT_07»

«LIMIT_08»

«LIMIT_09»

«LIMIT_10»

«0_LIMIT»

What is your age? RANGE: 1 - 98 YEARS

$E 1 99

RF 99

«AGE»

READ ONLY IF YOU CAN'T TELL. What is your gender?

MALE 1 FEMALE 2

RF 9

«GEND»

What language do you speak best?

ENGLISH 1 SPANISH 2 OTHER, SPECIFY 7 O

DK 8 RF 9

«PLANG»

«0_PLANG»

Were you working in WTC 1 or WTC 2 during the 1 993 bombing? => SAY11 ifYRWRK>1993

YES 1 NO 2 => CONCR

DK 8 => CONCR

RF 9 => CONCR

«WBOMB»

During the 1993 bombing, did you evacuate immediately or wait to evacuate?

EVACUATE IMMEDIATELY 1 WAIT TO EVACUATE 2

DK 8 => +2

RF 9 => +2

«EVBOM»

0^5
Appendix O

At the time of the 1993 bombing, did you feel you that your decision to<EVBOM>was the right decision?

YES 1 NO 2

DK 8

RF 9

«DEC93»

After the 1 993 bombing how concerned were you that terrorists would attack the World Trade Center?

Were you... EXTREMELY CONCERNED 1 . ^ VERY CONCERNED 2

' MODERATELY CONCERNED 3 SLIGHTLY CONCERNED 4

NOT AT ALL CONCERNED 5

DK 8

RF 9

«CONCR»

Is there anything else you would like to say about your experience on September 1 1?

YES, RECORD RESPONSE 1 O

NO 2

DK 8

RF 9

«SAY11»

«0_SAY11»

IMPACT FLOOR FLAG

=> *

if 1F(((WHTW2=1 AND WHFL2>91 AND WHFL2<99) OR (WHTW2=2 AND WHFL2>77 AND

WHFL2<111)),1,0)

IMPACT FLOOR FLAG 1

«FFLAG»

163: LFLAG

Single

min = 1 max =1 1=1

2003/09/18 15:21

LOCATION FLAG

=> *

if IF(( WHFL2>990 AND WHFL2<994), 1 ,0) LOCATION FLAG 1

0^6
Interim Report on Telephone Interviews

«LFLAG»

EVENT FLAG

=> *

if IF(((AND[NOT02-NOT06]=2-3) OR (AND[SEE02-SEE06]-2-3) OR (AND[EXP02-EXP06]=2-

3)),1,0)

EVENT FLAG 1

«EFLAG»

DISABILITY FLAG

=> * ifIF((PHYSI=l),l,0)

DISABILITY FLAG 1

«DFLAG»

ROLE FLAG

ifIF((ROLES=I-4),l,0)

ROLE FLAG 1

«RFLAG»

We may be interested in learning more about your experience on September 1 1 . Would it be okay if we

follow up with you sometime in the future to get more detailed information on your evacuation

experience?

=>+!

ifFFLAG+LFLAG+EFLAG+DFLAG+RFLAG==0

YES - 1 NO 2

«FOLUP»

PRESS ENTER TO CONTINUE

Those are all the questions we have. The valuable information you provided will help designers and

engineers improve building safety, and help emergency planners improve building evacuation procedures.

Thank you so much for taking the time to talk with me, and have a good day/evening. Good-bye.

END OF SURVEY I D =>/INT99

«THANK»

0-47
Appendix O

This page intentionally left blank.

0-48
Table of Contents

List of Figures P-ii

List of Tables P-iii

Appendix P

Interim Report on Emergency Communications P-1

P.l Introduction P-1

P. 2 Report Objectives P-1

P. 3 Radio and Telephone Communications P-2

P.3 . 1 Telephone Communications Recordings P-3

P.3 .2 First-Person Accounts of Telephone Communications P-3

P.4 Communications Files Processing and Preliminary Evaluation P-3

P.4. 1 Audio Data Files and Processing P-3

P.4. 2 Audio Data Computer Software P^

P. 5 Analysis of Audio Communications Files P-5

P. 5. 1 Communications Transcription P-5

P. 5 . 2 Transcription Methods P-6

P. 5. 3 Assessment of Radio Communications Quality P-6

P. 5. 4 Training of Transcribers P-7

P. 6 Radio Communications Concepts P-7

P. 7 Communications Data Analysis P-7

P. 7.1 PAPD Radio Communications P-8

P.7.2 FDNY Radio Communications P-8

P.7.3 NYPD Radio Communications P-1

1

P. 7. 4 Radio Communications Readability Analysis P-12

P. 7. 5 Observations on Radio Communications P-14

P. 7. 6 Preliminary Chronology of Emergency Communications P-1

5

P. 8 Findings P-24

P.9 References P-25

Attachment 1 Communications of the Port Authority of New York and New Jersey P-27

P-i
List of Figures

Figure P-1. PAPD police desk Channel 26/W plot of percent transmission versus time P-10

Figure P-2. FDNY City-wide high-rise Channel 7 (PAPD Channel 30) plot of percent

transmission versus time P-10

Figure P-3. NYPD Division 1 channel plot of percent transmission versus time P-1

1

Figure P^. NYPD Special Operations Division channel plot of percent transmission

versus time P-1

1

Figure P-5. PAPD police desk Channel 26/W radio communications readability P-12

Figure P-6. FDNY City-wide high-rise repeater Channel 7 at the WTC site (PAPD Channel 30),

radio communications readability P-1

3

Figure P 7. NYPD Special Operations Division channel radio communications readability P-13

Figure P-8. NYPD Division 1 channel radio communications readability between FDNY

personnel in the lobby of WTC 2 and FDNY personnel some 40 or more floors up

inside the same building P-14

P-ii
List of Tables

Table P-1 . Comparison of radio transmissions before and after the first aircraft impact P 9

Table P-2. Comparison of average and maximum radio transmission times before and after first aircraft impact P-9

P-iii
Appendix P

This page intentionally left blank.

P-iv
Appendix P

Interim Report on Emergency Communications

P.1 INTRODUCTION

On September 11, 2001, radio and telephone communications played a significant role in the operations

of emergency responders at the World Trade Center (WTC). Radio and telephone communications were

a primary means of communicating information to emergency responders concerning the incident. These

forms of communication were also used by emergency responders to communicate with people trapped in the WTC buildings and people attempting to evacuate from the buildings. They were used to communicate between members of the same emergency responder departments for planning and

operations at the incident, and they were used to communicate between different departments or responding organizations at the incident.

Each of the governmental departments that had emergency responders at the WTC—New York City Fire

Department (FDNY), New York City Police Department (NYPD), and the Port Authority Police

Department (PAPD)—depended on their ability to communicate to accomplish their mission and to obtain information related to operations safety at the incident. Personnel from each of the departments

used radios, cellular phones, and wired or landline telephones for communications during the incident. In

addition, the emergency responders relied on the most basic form of communication, direct face-to-face

communications.

As a normal practice during a typical emergency response many radio and telephone communications are recorded by the respective departments that respond to an incident. These recordings are normally made

by the departments to provide an accurate record of operations during an incident. These records are often used by departments during review of incident operations. They are also used for investigative

purposes and are sometimes used as evidence in legal cases. During the attack on the WTC many of the

emergency responder communications were recorded and preserved. This study is based on these

recordings. In addition, information gathered by personnel from the National Institute of Standards and

Technology (NIST) during first-person interviews with more than 1 00 emergency responders has

contributed to the report.

P.2 report objectives

The objective of this study is to develop a better understanding of the role that emergency

communications played during the attack on the WTC, and to quantify information related to communications effectiveness. Although there have been numerous reports of radio equipment failures during the emergency response at the WTC, the only radio system examined in this study is that of the FDNY WTC site high-rise repeater that was installed by the Port Authority. This report does not address

issues related to the technical capabilities of any other radio equipment. The analysis of handie-talkies

and other radio equipment is in progress and will be addressed in a following report.

P-1
Appendix P

Many factors are associated with the ability of emergency communications to be successful. The

following objectives were set in this report:

• To document radio and telephone communications operations

• To document radio communications readability or understandability

• To quantifying radio communications traffic volume

• To understand the impact of traffic volume on communications readability and the transfer of

information

• To identify communications associated with dispatch and arrival of responders

• To identify communications related to evacuation and emergency response operations

• To identity communications related to building conditions at the WTC and the impact of this information on the emergency response

P.3 RADIO AND TELEPHONE COMMUNICATIONS

Both the Port Authority of New York and New Jersey (PANYNJ) and the NYPD supplied copies of audio

recordings from the emergency response operations at the WTC. The PANYNJ provided digital copies of

the audio communications tapes recorded by them during the incident. These recordings included

communications from emergency response personnel, maintenance personnel, PAPD personnel, and a recording of the FDNY's Channel 30 radio repeater that was located at the WTC. Channel 30 was a Citywide channel designated by FDNY for use in high-rise building operations. The Port Authority had

installed this radio repeater system at the WTC for use by FDNY after the 1993 bombing.

The NYPD submitted their communications to NIST in the form of audio tapes that were copies of the

original tapes recorded on September 11, 2001. These tapes included radio communications from NYPD

internal department operations.

FDNY communications recordings were not available from the incident location that day because the

primary Field Communications truck was in the shop for repairs and a backup Field Communications van was used in its place. The backup Field Communications van did not have the capability to record the on- scene incident command or tactical communications; also, the backup van was destroyed when the towers

collapsed. Therefore, the best record of radio communications available to NIST on FDNY operations came from the FDNY/PAPD Channel 30 tape and first-person accounts provided by FDNY personnel

during their interviews. The Channel 30 tape provides a limited amount of information on FDNY

communications and operations at the incident, but it does provide insight into FDNY operations inside

WTC 2.

Each audio communications file was received from the source with the starting and ending times marked

on the media jacket or the surface of the media. A list of all communications recordings acquired from

the various departments is found in Attachment 1 at the end of the report.

P-2
Interim Report on Emergency Communications

P.3.1 Telephone Communications Recordings

Because telephone communication (both landUne and cellular phone) was a contributing part of the emergency communications process during the incident, NIST received copies of telephone emergency

response communications from the PANYNJ. Identification information for these recordings is also

listed in Attachment 1. The City of New York provided NIST with opportunities to review their telephone recordings for 9-1-1 Emergency Operators and FDNY fire dispatchers in their New York City

offices. At this time, the telephone recordings have been reviewed and documented, and the analysis

work is still in progress. A detailed analysis of emergency telephone communications will be covered in a following report.

P. 3. 2 First-Person Accounts of Telephone Communications

As mentioned earlier, more than 1 00 first-person interviews were conducted with emergency responders

that reported to the WTC incident. The following information was drawn from these interviews:

• Before the attack occurred on the WTC both the landline and cellular systems appeared to be

working normally.

• Only moments after the first aircraft impacted WTC 1 , the landline and cellular telephone

systems were stressed by increased caller volume that made it difficult to get messages

through. This condition continued for many hours following the attack.

• Telephone calls from the WTC to the 9-1-1 emergency operators and statements from various

individuals being interviewed shows that even though WTC 1 and WTC 2 were severely

damaged by the aircraft impact and fires, many of the landline telephones in the buildings

continued to work up until the collapse of WTC 2.

• After the collapse of WTC 2, a number of cellular phone systems were not functional in the area of lower Manhattan.

• After the collapse of WTC 2, there were still some landline telephones working within the

city block areas adjacent to the WTC site.

An evaluation of methods for listening to the recorded communications files was carried out. Comparisons were made between the functionality of using tape recorders versus that of using digital

computer-based software for listening to the various emergency response communications files. It became apparent that the computer based listening system had advantages over the use of tape recorders.

Some of the advantages of the computer based system are the ease of operation, ability to use the computer monitor for visually observing the beginning and end of communications periods, and the

ability to easily and accurately reverse through a recording to a selected location so that a selected section

P.4 COMMUNICATIONS FILES PROCESSING AND PRELIMINARY

EVALUATION

P.4.1 Audio Data Files and Processing
Appendix P

of a communication could be listened to multiple times. As a result, it was decided to conduct the audio

communications study using the computer based audio software system. This decision had a direct impact on the type of data format and media that would be needed for conducting the audio

communications study. Therefore, NIST requested that audio communications be provided in a digital

format on CD-ROM disks.

The communications recordings provided by the PANYNJ were digital files that were copied onto CD-ROMs, and they were in a format that could be played by computers while using audio player

computer software. The audio recordings on each of the NYPD cassettes had to be converted to a digital

fonnat, and each file was then recorded onto a CD-ROM disk. In addition, some of the recordings that were received were recorded at very low amplitude that made it diftlcult to hear the communications.

NIST used professional-quality computer audio software to increase the low audio volume recordings to a usable audio level. - v

P.4.2 Audio Data Computer Software

Three different types of software were used while conducting communications analysis on the audio

recordings. Each of these software packages incorporated a clock for timing the audio recording and

important communications during the incident.

The first, Sound Forge 6.0, a product of Sonic Foundry, Inc., of Madison, Wisconsin, is a professional

digital audio editor (Sonic 2002). It possesses tools that can assist with increasing audio quality and

volume of digital audio recordings. It has a graphic output to the computer monitor that allows for rapid

evaluation of large audio files. It is also capable of operating as a tool for spectrum analysis. As a spectrum analyzer, it can be used to analyze waveforms by frequency, and it helps to identify noise

problems in communications data. In addition, the audio waveforms can be expanded on various scales

for detailed analysis. This software was used throughout the study for analysis of the recordings that required audio adjustments to improve quality.

The other two software packages were used as general purpose audio players. They both possess the same basic capabilities and were applied in this audio analysis process based on user preference.

Windows Media Player, a digital media player software package, is a product of Microsoft, Inc. (Microsoft 2003). This media player can be downloaded from the Internet. The player allows for viewing of audio wave forms from the digital audio files that are being listened to. It allows for easily

changing a computer's audio volume, and it may be used effectively for locating specific points on an

audio recording. The software also allows for movement through an audio file in a reverse direction so

that selections of an audio file can be listened to multiple times.

WinAmp3 is a media playback software package for Windows that can be downloaded from the Internet, and it is a product of Nullsoft, Inc. (Nullsoft 2002). This player allows for viewing of audio wave forms

from the digital audio files that are being listened to. It allows for easily changing a computers audio

volume and it may be used effectively for locating specific points on an audio recording. The software

also allows for movement through an audio file in a reverse direction so that selections of an audio file can be listened to multiple times.

P-4
Interim Report on Emergency Communications

P.5 ANALYSIS OF AUDIO COMMUNICATIONS FILES

Analysis of the communications recordings was a multistep process that began with sorting and

cataloging the files. The initial sort separated radio communications files from telephone

communications files. The files were also cataloged as it related to emergency response operations:

PANYNJ, PAPD, FDNY, and NYPD. The respective files were then checked for content and primary

emergency response channel files were selected for analysis first. Primary emergency response channels were channels specifically used by PAPD, NYPD, and FDNY for conducting emergency response

operations at the WTC. The secondary charmels relate to maintenance channels and other emergency

responder channels that were not directly associated with operations at the WTC.

Analysis was carried out using the computer based software media players described above. The

professional quality digital audio software, Sound Forge 6.0, was used for listening to and enhancing

audio files that were difficult to hear. The two other media player software packages, Windows Media

Player and WinAmp3, were used to listen to the majority of audio recordings.

P. 5.1 Communications Transcription

Two different processes were used to transcribe the emergency communications. Data for the primary

emergency communications files were put into a spreadsheet format so that a detailed analysis of results could be made. The overall analysis work is continuing; however, some of the data put into the spreadsheets was used to assist in quantifying communications quality and the radio traffic volume as

related to time, as will be discussed in Section P. 7. The second and simplest form of communications

transcription was the verbatim transcription of the communications into a word processor data file, which was used to record the secondary communications files.

The primary communications audio files were selected for complete transcription to generate information

concerning the quality of communications. The files selected were the FDNY Channel 7/PAPD

Channel 30 radio repeater, the PAPD police desk radio channel, and the NYPD Special Operations

Division channel and Division 1 . These files included the following:

• Time of the radio transmission (radio transmission time was taken from the media player

clock and was adjusted for the start time supplied with the communications file.)

• Type of radio transmission (voice or tone only for primary emergency response

communications channels)

• Readability signal quality (done only for the primary emergency response communicafions

radio channels)

• Content of the communication

As the communications transcripts were being prepared, the names of individuals identified during the

communications were deleted to protect the identity of individuals and to adhere to the confidentiality

agreements with the various organizations that supplied the communications data files.

P-5
Appendix P

P. 5. 2 Transcription Methods

As mentioned earlier, the communications transcripts were generated using three different computer

based media players. The media players were installed on computer systems that were stand alone and

isolated from the internet. The process for preparing a communications transcript was the following:

• The communications data file was loaded onto the computer.

• The media player was opened and the data file was selected.

• The spreadsheet on the computer was opened and prepared for data input.

• The transcriber would queue the communications recording to the beginning and check to be

sure that the media player clock time was zeroed.

• The data file starting time was put into the spreadsheet.

• The communications recording was started, and the output was written into the spreadsheet.

• To improve accuracy of the transcripts, a second transcriber checked sections of the transcript

against the audio recording.

For audio passages that were difficult to understand on the first pass, multiple passes of the section were

used to improve comprehension.

P. 5. 3 Assessment of Radio Communications Quality

The Readability, Signal Strength, and Tone system for rating the quality of radio communications is used

widely throughout the field of radio communications and is described in The ARRL Handbookfor Radio

Communications (ARRL 2003). This system is broken into three distinctive groups that can be rated: Readability, Signal Strength, and Tone. The rating for tone is only used to identify the quality of radio

communications for ''Continuous Wave" transmissions, and it does not apply to this analysis as "Tone"

does not relate to voice communications. For voice radio communications, only "Readability" and

"Signal Strength" are used. Signal Strength" is usually read from a signal strength meter at the time of

the actual radio communication and is not available on the audio recordings.

Thus, in this study "Readability" only was used for rating the primary emergency responder radio

communications channel recordings. It is recognized that this form of analysis is subjective, and it relates

to the ability of an individual to hear and understand the radio communications. In an attempt to minimize the influence of the subjective rating system, individuals with extensive experience using radio

communications and project staff trained by the experienced personnel were used to conduct the analysis. In addition, communication periods from the various recorded data sets were reviewed by more than one

P-6
Interim Report on Emergency Communications

person where radio communications readability was difficult. The rating table for communications

readability is listed below (ARRL 2003):

Readability (the term "readable" means "understandable"):

1 - Unreadable2 Barely readable, occasional words distinguishable

3 - Readable with considerable difficulty

4 - Readable with practically no difficulty

5 - Perfectly readable

P. 5.4 Training of Transcribers

Four NIST personnel were used to transcribe the emergency responder communications files. This

included the Project Leader and three other staff personnel. The transcription protocol listed above was

plarmed and tested by the two senior NIST personnel, including the project leader. When the protocol was found to be acceptable, the two other NIST personnel were trained by the senior members of the group. After the basic transcription training was completed, each of the new transcribers was given a communications file to transcribe. This communications file had previously been transcribed by the two

senior persormel. After the file was transcribed by the new transcriber, their results were compared to that transcribed by the senior persormel. When it was demonstrated that the new transcriber had a full understanding of the transcription process, they were then assigned communications files to transcribe.

Currently, for most emergency responder radio systems the only way to produce a totally clear communication that can be received and understood is for only one communications signal to be

transmitted at a time on a given radio frequency. This means that only one person can transmit a radio

message at a time without creating communications interference on that radio frequency. With these

systems, if two or more radio transmissions are made on the same radio frequency at the same time, signal

mixing may occur and the communications may not be understandable. This difficulty with radio

communications is often referred to as doubling. Under these conditions, usually the radio with the highest transmitting power will override transmissions from the lower-power radios and only the highestpower radio signal will be heard. This is often the case where an emergency response radio system uses a higher-power base station for dispatch communications or where a repeater is used to amplify a radio

system's signal output. Where multiple radio communications are received by a radio repeater, signal

mixing is likely to occur and the communications will not be understandable (ARRL 2003).

Over the last several years radio communications technology has undergone some significant

advancements, particularly with cellular phones. These new systems can increase the effective use of the radio frequency/time factors related to radio communications (ARRL 2003), and are now beginning to be

applied to emergency responder communications equipment.

This analysis of communications addresses five major factors: (1) radio traffic volume,

(2) communications duty cycle, (3) readability of communications, (4) operation of the FDNY site highP.6 RADIO COMMUNICATIONS CONCEPTS

P.7 COMMUNICATIONS DATA ANALYSIS

P-7
Appendix P

rise repeater at the WTC, and (5) the development of a chronology of radio communications from the

incident.

The first two factors, radio traffic volume and communications duty cycle, are directly related, and each

has an impact on readability, the ability to understand and also deal with the information being

communicated. Generally, as radio traffic rate increases, the operations duty cycle approaches overloaded

conditions. With very high traffic volumes it becomes more difficult for personnel at central communications facilities and personnel in the field to respond to the volume of traffic. Human operators

of communications equipment become overloaded with work because not only do the operators have to verbally communicate with personnel over the radio, but they must often transfer the information gained

to other locations. The transfer of information may also be done verbally using other communications

systems or it may be done by hand through keyboard inputs or by both methods. Analysis of the radio

traffic for each of the departments shows periods where radio traffic rates during the surge conditions

potentially resulted in situations where base station radio operators were unable to relay important

information.

P.7.1 PAPD Radio Communications

All radio communications evaluated for this report experienced traffic volume surge conditions as a result of the attack. The traffic volume surge greatly exceeded the traffic volume experienced under normal

operating conditions.

PAPD Channel 26/W is used to demonstrate typical radio communications and operations conditions that occurred with the PAPD before and during the incident. This radio channel is used by PAPD police

officers, NYPD supervisors and FDNY Engine 10 and Ladder 10 for communications at the WTC site. Tables P-1 and P-2 compare the number of transmissions and their length of time before and after the

first aircraft impacted WTC 1 . The percent of radio transmissions versus time are also shown on

Fig. P-1. This percent of radio transmission, as well as others discussed in this report, was calculated

based on the sum of transmission time and no transmission time over a given period of time. These data

show that there was a 13 percent rate of radio transmissions on the PAPD police desk channel just prior to the aircraft impact. After the first aircraft impact on WTC 1 the radio communications were occurring

87 percent of the time. This surge in communications significantly impacted the functional capability of

the radio system. After approximately 10 minutes, communications dropped to a steady operating level of 48 percent capacity.

P.7.2 FDNY Radio Communications

The communications for this FDNY, City-wide, high-rise building, radio Channel 7 was recorded by

PAPD on their Channel 30. The Port Authority installed this high-rise repeater at the WTC for FDNY

following the 1993 bombing. This FDNY channel was used primarily by FDNY personnel during

operations in WTC 2. Personnel using this channel were FDNY Chief Officers, Company Officers,

Aides, and firefighters.

P-8
Interim Report on Emergency Communications

Table P-1. Comparison of radio transmissions before and

after the first aircraft impact.

Department

Number of transmissions

before first aircraft impact

(20 min period)

Number of transmissions

after first aircraft impact

(20 min period)

PAPD 42 176 FDNY 39 134

NYPD

Division 1

J. 225

NYPD Special

Operations

Division

No data 192

a. Data only available for 2 min prior to first aircraft impact

Table P-2. Comparison of average and maximum radio transmission

times before and after first aircraft impact.

Department

Average time per transmission before

first aircraft impact and maximum (s) Average time per transmission after

first aircraft impact and maximum (s) PAPD 3.8 (maximum 21.8) 3.3 (maximum 19.7)

FDNY 3.8 (maximum 50.9) 3.1 (maximum 19.5)

NYPD

Division 1

1 .9 (maximum 5.9) 3.4 (maximum 12.6)

NYPD

Special

Operations

Division

No data 5.7 (maximuin 31.5)

Note: All minimum transmission times were typically less than 1 s and were often related to the keying of a microphone.

While looking at these data it is important to keep in mind that several FDNY personnel at the incident

did not think that the WTC site, high-rise channel, radio repeater was working. This is based on radio

communications tests that were conducted by two Chief Officers working inside WTC 1 when the first Command Post was being set up in that lobby. A record of this radio communications test was recorded on the PAPD Channel 30 tape. Following this radio test, a Chief Officer involved in the test chose to use

different channels for command and tactical communications during the incident. However, as FDNY

operations increased in WTC 2, it was determined by members of the FDNY that the high-rise channel was functioning and use of the channel developed.

Preliminary analysis by NIST indicates that the repeater was operating at the WTC; however, there also

appears to be some type of malfunction with the communications equipment. This malfunction was

detected by the FDNY officers during the initial communications test, but it was not identified. As a

result, this radio frequency was not primarily being used by many emergency responders. Two

hypotheses are currently being studied related to the malfunction: (1) damage to the repeater antenna system and (2) failure of the radio hand set located at the Fire Command Desk in the lobby of WTC L

Two failure modes are being considered, (1) the radio handset was broken, and (2) the volume on the handset was turned down. The evaluation of the repeater and its operation is still under way, and final

P-9
Appendix P

conclusions have not yet been drawn concerning the repeater's performance. Additional information will

be covered in the WTC Investigation final report.

Traffic load for this FDNY channel is summarized in Tables P-1 and P-2 and in Fig. P-2. Figures P-1

and P-2 shows that there was a significant peak in radio traffic that approached an 80 percent level which

then dropped to a near steady high level of operations several minutes following the aircraft impact. The

communications traffic level following the aircraft impact was four times greater than the level prior to impact.

c

o

o

0) Q.

100

90

80 \

70

60

50

40

30

20

10

0

Second Aircraft Impact

'First Aircraft Impact

20

"Time (minutes)

Figure P-1. PAPD police desk Channel 26/W plot of percent

transmission versus time.

40

co

o

Q.

0 20

Time (Minutes)

Figure P-2. FDNY City-wide high-rise Channel 7 (PAPD Channel 30)

plot of percent transmission versus time.

40

P-IO
Interim Report on Emergency Communications

P.7.3 NYPD Radio Communications

The third example illustrates radio communications for the NYPD Division 1 channel and the NYPD

Special Operations Division channel. The Division 1 channel was used by police officers and supervisory

police officers. The Special Operations Division channel was used by senior level NPYD management,

supervisory police officers, Emergency Service Unit personnel, and aviation unit personnel.

The communications recordings provided by NYPD did not typically contain communications that preceded the attack. However, the Division 1 radio channel recording did start approximately 2 minutes

before the first aircraft impacted WTC 1. This 2 minute period provides a limited sample of the level of

radio communications prior to the attack. The volume of NYPD communications is shown in Tables P-1

and P-2. These data demonstrate that NYPD had a similar surge in radio traffic immediately following

the attack. Figure P-3 shows that the level of transmissions before the attack was at approximately

15 percent. Following the attack the level of transmissions jumped to over 90 percent and then settled down to a level of 63 percent. Radio traffic on the Special Operations Division channel was even higher,

as shown in Fig. P^, peaking near the 95 percent level and staying in the 80 percent range over the

remainder of the sample period.

10 12 14 Time (rnnutes)

Figure P-3. NYPD Division 1 channel plot of percent transmission versus time.

10090

80

7060

50 40

30

20

10

0

Second Aircraft Irrpact

First Aircraft Impact at Zero Time

10 Time (M inutes)

20

Figure P-4. NYPD Special Operations Division channel plot of

percent transmission versus time.

P-ll
Appendix P

P. 7.4 Radio Communications Readability Analysis

As each of the communications files was transcribed a readabiUty value was assigned for each attempt to communicate. Results of this analysis are shown in Figs. P-5 through P-8. Analysis of these data

showed that the ability to transmit a complete message was difficult during the communications surge. Data showed that approximately one-third to one-half of the radio communications for each of the three

departments did not exceed a readability level of 2. These emergency communications were not complete

and may have not been fully understood. The largest fraction of readability for all radio communications

analyzed was recorded at a readability level of 3. This means that this fraction of communications was

readable, but audio and radio transmission problems were being experienced. Some conditions that will cause poor communications quality are:

• Background noise either at the transmission point or receiving point or both,

• Operating health of transmitting and receiving radios and anterma systems,

• Doubling or crossing of radio signals caused by multiple transmissions at the same time on

the same radio frequency, and

• Radio transmissions that may be affected by alternating materials or electromagnetic

interference.

Note: Readability scale:

1 - Unreadable 4. - Readable with practically no difficulty 2 - Barely readable, occasional words distinguishable 5. - Perfectly readable

3 - Readable with considerable difficulty Figure P-5. PAPD police desk Channel 26/W

radio communications readability.

P-12
Interim Report on Emergency Communications

Note: Readability scale:

1 - Unreadable 4. - Readable with practically no difficulty 2 - Barely readable, occasional words distinguishable 5. - Perfectly readable

3 - Readable with considerable difficulty Figure P-6. FDNY City-wide high-rise repeater Channel 7

at the WTC site (PAPD Channel 30), radio communications readability.

Note: Readability scale:

1 - Unreadable 4. - Readable with practically no difficulty 2 - Barely readable, occasional words distinguishable 5. - Perfectly readable

3 - Readable with considerable difficulty Figure P-7. NYPD Special Operations Division

channel radio communications readability.

P-13
Appendix P

3

32%

Note: Readability scale:

1 - Unreadable 4 - Readable with practically no difficulty 2 - Barely readable, occasional words distinguishable 5 - Perfectly readable

3 - Readable with considerable difficulty Figure P-8. NYPD Division 1 channel radio communications readability

between FDNY personnel in the lobby of WTC 2 and FDNY personnel

some 40 or more floors up inside the same building.

In addition, approximately 25 percent of the radio communications had readabihty levels 4 or above.

Typically, the higher readability levels were produced by the various department base stations that operate at a higher radio transmission output power than the hand held radios. However, there is one

exception: several of the radio communications on the FDNY City-wide high-rise radio channel, the PAPD recording of Channel 30. It appears that the repeater was operating at the WTC site. Several of the

radio communications on this channel were assigned readability values of four and five as the FDNY

began its operations in WTC 2. In addition, some of these 4 and 5 readability value radio

communications were occurring between FDNY personnel in the lobby of WTC 2 and FDNY personnel some 40 or more floors up inside the same building.

P. 7. 5 Observations on Radio Communications

All of the radio systems analyzed appeared to work well during the period of normal operations before the

attack on the WTC. It was noted that Channel W of the PAPD was experiencing some difficulty with a

handie-talkie radio transmitting a carrier wave as a result of an open or keyed microphone, which

disrupted communications on that channel. PAPD personnel recognized the problem and were busy

trying to correct it just before the first plane struck WTC 1. The keyed microphone problem continued

after the attack occurred. NYPD also had a problem with an open or keyed microphone after the incident

began, occurring on the Special Operations Division channel. The problem was recognized and efforts were also made by the NYPD desk operator to get the problem cleared up. Initial attempts to correct the open microphone problem appeared to be successful.

P-14
Interim Report on Emergency Communications

Also, the data above for the various departments demonstrate the significant changes that occurred in radio communications traffic during the incident. It is evident that PAPD, FDNY, and NYPD all experienced similar surges in radio traffic volume following the first aircraft impact into WTC I . It is also interesting to note that when the second aircraft struck WTC 2, 17 minutes later, there was no major

surge in radio communications. This may be attributed to the fact that the initial emergency response

assignments had already been made and that operations had already begun at the WTC, and an additional

surge in radio communications was not needed. In addition, it is observed from the communications

recordings and from first-person interviews that the emergency responders were trying to limit their use of the radios to reduce interference on their operating frequencies.

P.7.6 Preliminary Chronology of Emergency Communications

The following are lists of selected chronological communications messages that provide information

concerning (1) dispatch and arrival of emergency response units, (2) evacuation, (3) emergency response

operations, (4) emergency response communications, and (5) observations of building conditions.

Note: These chronologies are based on the best possible data provided to NIST for the analysis. The

times are given to represent the exact event sequence. Based on the variations of recorded clock times for the data and times assigned for each recording provided by the departments, it is estimated that the error

for time with these chronologies is likely to be on the order of +2 minutes.

Dispatch and Arrival of Emergency Responders Chronology

This chronology clearly demonstrates that the emergency response to the World Trade Center was

immediate. Within the first 3 minutes of the aircraft impact on WTC 1, PAPD was responding by

providing information on the incident to the police desk, FDNY had dispatched 26 units to the incident,

and NYPD had called of a department mobilization that included dispatching aviation units to the incident

for visual assessment. In less than 10 minutes, PAPD had called a chemical mobilization; NYPD had

dispatched five ESU teams and had two aviations units at the scene providing observations. In less than

30 minutes, 121 FDNY units had been dispatched to the scene and 30 units had signaled their arrival at the scene. This response combined with the activities undertaken demonstrates a high level of

professionalism by the various departments.

8:46 a.m. FDNY Chief makes report that an airplane has struck the upper floors of a WTC building and

transmits a first and second alarm.

PAPD officer reports to the police desk an explosion at the WTC.

8:48 a.m. 26 FDNY units dispatched. NYPD calls for a department mobilization.

8:49 a.m. NYPD requests for aviation to get in the air and make a visual assessment. 8:50 a.m. PAPD officer calls for a chemical mobilization.

8:52 a.m. 5 NYPD Emergency Service Units dispatched.

NYPD aviation requests landing zone in the vicinity of the WTC.

NYPD aviation unit arrives at the WTC and examines possibilities of roof rescue. 8:54 a.m. NYPD aviation advises they have two units in the air to do aerial survey. 8:59 a.m. FDNY Chief calls for all but one Rescue Squad to the WTC.

9 a.m. 66 FDNY units have been dispatched at this time.

9:03 a.m. FDNY Marine unit reports that a second plane struck WTC 2.

9: 15 a.m. 121 FDNY units dispatched and 30 FDNY units signal* their arrival. 9:29 a.m. FDNY dispatcher relays that a department-wide recall has been instituted.

P-15
Appendix P

9:59 a.m. 171 FDNY units dispatched and 74 FDNY units signal their arrival. 10:29 a.m. 214 FDNY units dispatched and 103 FDNY units signal their arrival. Note: Arrival times are determined from 10-84 signals transmitted by units as they arrive at their assigned location. A 10-84 signal is sent by a firefighter fi-om a fire department vehicle by pressing a button on the communications console.

Evacuation Chronology

The evacuation chronology exhibits a mix of responses to the incident. It provides insight into the successes and shortcomings of the evacuation from the WTC buildings and site. The first noteworthy

event is that multiple orders were given by a senior PAPD police officer to evacuate the WTC buildings

and the entire complex. There is no evidence that these orders were transmitted to appropriate persormel

at the site to initiate the full evacuation of the complex. Data from these communications also show that the evacuation process was not always orderly and controlled. This is demonstrated by the fact that the

first people jumped from WTC 1 at 8:52 a.m., only 6 minutes after the first aircraft struck WTC 1. In

addition, it was reported that people were running from the PATH trains, and a report came in to the

PAPD police desk from a police officer in WTC 5 stating that "1 have people going crazy." However, it

is a fact that most of the evacuation process from the WTC complex was orderly. This chronology also

provides a view of the professionalism of the PA, PAPD, and building security personnel that held their posts in the face of life threatening conditions to assist people in the evacuation. In addition, these

communications provide some basic information related to the status of people trapped in the buildings

and the fact that the buildings elevators were not functioning or dangerous to use. Finally, several cases

are listed where injured, elderly, or physically impaired people are not able to walk down the stairs in the

building and need assistance to evacuate.

8:47 a.m. PAPD police desk receives a message to evacuate the building (WTC 1) and send people out towards WTC 5 PAPD police desk receives a message from a PAPD officer instructing employees to avoid

the Concourse.

8:48 a.m. PAPD police desk receives two orders from a senior police officer calling for the evacuation

of the building.

8:52 a.m. PAPD police desk receives report from police officer that people are jumping out of the windows from WTC 1

.

8:53 a.m. PAPD police desk report indicates that people are running from the PATH trains. 8:55 a.m. PAPD police desk handles message calling for the evacuation of the Plaza

FDNY dispatcher relays information that people are trapped on floor 106 of WTC 1. 8:56 a.m. PATH trains are still bringing people into the WTC site. PAPD police desk message attempts to assemble personnel at WTC 1 exits to the plaza to show people how to get out. One Port Authority person responds to the message that he

cannot get over to the building exits because glass is falling all over the place.

PAPD police desk receives a radio message that they need assistance in WTC 4 because

people are attempting to exit the building.

8:57 a.m. PAPD police desk: a message is sent stating, "Don't let anyone in the building evacuate to the Plaza at this time."

8:58 a.m. PAPD police desk instruction to security guards: hold your post and don't allow people into the Plaza or out onto the Courtyard.

PAPD police desk reports that people are trapped on floor 79 WTC 1

.

8:59 a.m. PAPD police desk: a senior PAPD officer calls for the evacuation of WTC 1 and WTC 2.

P-16
Interim Report on Emergency Communications

PAPD police desk: a senior PAPD officer calls for the evacuation of the entire WTC

complex, all buildings.

9 a.m. PAPD police desk: a police officer asks if building five should be evacuated and he was told

to stand by.

PAPD police desk receives a report that there are people trapped inside suite 47 1 1 of WTC 1 and can't get out. PAPD police desk: orders were given to evacuate WTC 1, B4 level. PAPD police desk: a Port Authority employee calls in that he is on floor 27 in the C staircase and has a man in a wheel chair and needs assistance.

9:01 a.m. PAPD police desk: a senior PAPD officer calls for the evacuation of all buildings in the WTC

complex.

9:02 a.m. PAPD police desk: Port Authority person calls in reporting that he is stuck in an elevator on

floor 78 of WTC 1 in car number 81 A.

9:03 a.m. A second aircraft strikes WTC 2. 9:04 a.m. PAPD police desk: a call is made to evacuate everybody from the building now. Note: Building not identified. 9:05 a.m. PAPD police desk: a police officer indicates that WTC 4 is being evacuated. He is then

going to WTC 5. He also reports that, "1 have people going crazy."

PAPD police desk: a report comes in that Port Authority employees heard people stuck inside

of some elevators and also report that they are getting them out. Note: Building and location not identified. PAPD police desk: a call comes in to get everybody off the complex.

9:07 a.m. PAPD police desk: a report comes in that somebody is stuck in an elevator on floor 76. Note: Building not identified. 9:08 a.m. PAPD police desk report from an officer that debris is falling from WTC 2 by WTC 4 and

Liberty Street, and to let the people out of WTC 4. 9:09 a.m. PAPD police desk report is received indicating that FDNY is entering elevator bank 11, 12. Note: Building not identified. Elevators 11 and 12 are shuttle elevators. Elevator 1 1 goes

from the lobby to the 44th floor. Elevator 12 goes from the lobby to the 78th floor. 9:10 a.m. PAPD police desk receives a report that the express elevators could be in jeopardy of falling. Note: Building not identified.

9: 12 a.m. PAPD police desk receives a radio report from the Command Desk in the lobby of WTC 2

that they cannot pick up the Warden phones and that they are making announcements telling

people not to stay at the Warden phones. Note: This communication indicates that the Warden phones in WTC 2 were not working. Warden phones are located on each floor of the building for the use of floor wardens. They are wired for communications with the fire

' command desk in the building lobby.

9:14 a.m. PAPD police desk receives confirmation that no elevators are working. Note building not

identified. 9:16 a.m. FDNY radio dispatcher advises a chief that there are people trapped in WTC 1 at the

following locations: floor 82 east side; floor 83, room 831 1; floor 103, room 103 near the

comer, floor 104; and floor 106. WTC 2 at the following locations: floor 82 west side, floor 88, and floor 89. 9:17 a.m. PAPD police desk reports that four callers have made contact and need assistance on

floor 106 of WTC 1. 9:20 a.m. PAPD police desk receives a message from an officer that no one is down on the B4 level of

WTC 1. 9:23 a.m. FDNY radio dispatcher advises FDNY Field Communications Unit that 100 people are overcome in WTC 1 on the northwest and southwest corner of floor 103. The dispatcher also

reports that Ladder 3 reports numerous injuries in the stairwell of floor 35 on up.

P-17
Appendix P

9:24 a.m. PAPD police desk receives a report from an officer that people from floor 64 are now coming

down onto the courtyard level of WTC 1

.

9:28 a.m. PAPD police desk receives a radio report of an injured person with bum injuries caused by a

falling elevator. Note: Location of injured person was provided as A20. This may mean WTC 1 on floor 20 on the A stairway.

9:29 a.m. PAPD police desk reports that there is a medical emergency in the B stairway; there is a person that cannot walk down. The people are coming down from floor 51, and the person

needing assistance has asthma. Note: Building not identified. 9:30 a.m. PAPD police desk receives a report that two elderly people on floor 51,

B stairway, WTC 1 , cannot walk down and need medical assistance.

9:37 a.m. PAPD police desk recorded the following message: "All World Trade Center units to the

Command Post. All World Trade Center units escort everybody over the land bridge on West

Street to the Financial Center. Do not, repeat, do not send people out into the Concourse on

to south side." 9:45 a.m. PAPD police desk receives a report that officers are sending people down, evacuating on the A stairway in WTC 1

.

PAPD police desk copies a request for crowd control on Broadway. Answer to the request is that the City police should be responding.

9:56 a.m. PAPD police desk receives a report that WTC 1 is not completely evacuated and that people

are still coming out of each stairway.

Emergency Response Operations Chronology

This section provides a view of the emergency response operations carried out by FDNY, NYPD, and

PAPD at the WTC. The chronology highlights several communications that identify cases where

emergency responders are assisting injured people, call for EMS assistance, and search for functioning

elevators to help evacuate injured people. Some fires in the buildings are identified and some fire fighting

operations in WTC 2 are identified. Communications from PAPD provide information on the locations of

many people that were trapped in the buildings and in elevators. Several communications provide insight

into FDNY operations in WTC 2 and show that some fire fighters actually reached the 78th floor in WTC 2. This assent to the 78th floor was assisted by the use of an elevator that operated up until just

before the building collapsed. The elevator became stuck in the elevator shaft and the firefighter

operating the elevator was chopping his way out when the building collapsed. Several radio

communications provide insight into the difficulty that emergency responders had trying to climb the

stairs of the WTC. Cases are noted where FDNY personnel had to stop and rest. Radio communications

for the FDNY channel 7 repeater also point out the difficulty that some firefighters had with the

identification of the two buildings. The exchange of communications by FDNY personnel at 9:29 a.m.

clearly shows this difficulty. Several communications from NYPD aviation units show how the aircrews

repeatedly accessed the possibility of landing on the roof of WTC 1 and reported that conditions were not

safe for landing. However, at 9:38 and 9:40 a.m. an aviation unit calls in for permission to land on the

roof of WTC 1 . No evidence has been found that indicates that people were seen on the tower roof or that conditions had improved when these radio requests were made. Interviews with aviation personnel

indicate that many of them were highly troubled by the number of occupants trapped in the buildings and

the number of people jumping from the buildings, and they were distressed that they were unable to help

them. At 9:43 a.m. the order came from a senior police department official that no one from the aviation

units is to rappel on the building's roofs. Communications in this section also provides information that many people were coming to the WTC to volunteer their assistance. This assistance was turned away as the emergency responders felt that they needed to get everybody away from the WTC complex.

P-18
Interim Report on Emergency Communications

8:46 a.m. An aircraft strikes WTC 1. 8:49 a.m. PAPD police desk a message is received that Emergency Medical Service (EMS) is needed

because there is an injured security guard. The message was not complete; the location was

not understandable.

8:50 a.m. FDNY establishes a command post in the lobby of WTC 1

.

PAPD police desk message from an officer on the B2 level of WTC 1 that there are two

workers injured on that level and that EMS is needed ASAP.

PAPD police desk receives a radio call from FDNY Ladder 10 requesting information from

PAPD about which building was struck and the location of the fire, WTC 1 or WTC 2. FDNY uses a Port Authority Radio for the communication.

8:52 a.m. NYPD aviation unit arrives at the WTC to examine possibilities for roof rescue. 8:56 a.m. PAPD police desk recording: an officer calls for an ambulance at WTC 4 for an injured person. 8:58 a.m. NYPD aviation unit advises that they are unable to land on the roof due to heavy smoke

conditions.

9 a.m. PAPD police desk receives a message that there is an injured person between floors 14 and

15 of WTC 2. 9:01 a.m. PAPD police desk receives a report of a fire in a parking lot. 9:02 a.m. PAPD police desk receives a report of a gas leak. (Incomplete message, location of leak not

identified.)

9:03 a.m. An aircraft strikes WTC 2. 9:03 a.m. PAPD - by this time a PAPD senior officer has called three times for the evacuation of the

World Trade Center, WTC 1 and WTC 2, and then "all buildings in the complex."

9:03 a.m. PAPD police desk reports that another aircraft has stuck WTC 2. 9:05 a.m. PAPD police desk, an officer calls in and requests that every ambulance that can be spared be

sent to the WTC.

9: 10 a.m. FDNY dispatcher receives message that people are trapped on floor 86 of WTC 2.

9: 1 1 a.m. FDNY reports that Engine 10 requests that all responding units stop short of the WTC

buildings, either north or south of Liberty and West Street because of the large number of

parked ambulances and debris falling from the buildings.

9: 1 7 a.m. FDNY radio communications on the City-wide, high-rise Channel 7 (PAPD Channel 30)

indicates that they are using an elevator for operations in WTC 2. 9: 18 a.m. FDNY radio communication from WTC 2 indicates they have one elevator working to floor 40, and it is staffed by a firefighter from Ladder 15. PAPD police desk receives a report that FDNY is abandoning its command post and going

across the street. 9:22 a.m. FDNY radio communications on the City-wide, high-rise Channel 7 (PAPD Channel 30)

states that a Battalion Chief is on floor 43 or WTC 2 in the B stairway.

FDNY Battalion Chief now located on floor 43 of WTC 2 receives a message from a FDNY

member in the lobby that NYPD Emergency Service police officers (Emergency Service

Unit) want to provide support for him. The Battalion Chief gives the Emergency Service

Unit police officers direction to his location on floor 43 in the B stairway.

9:26 a.m. NYPD aviation unit advises that it is impossible to land on the roof at this time.

9:29 a.m. FDNY radio communicaUons on the City-wide, high-rise Channel 7 (PAPD Channel 30): a Battalion Chief is communicating that he is located inside "Tower 2, the South Tower." A

firefighter follows the communication attempting to correct the Chief by saying that he was

actually in the "North Tower, Tower 2." This communication confused the actual location of

the Battalion Chief, who later came back on the radio reporting that he was in the South

Tower. Interviews with FDNY personnel conclusively show that the Battalion Chief was

actually inside WTC 2, the South Tower.

P-19
Appendix P

9:30 a.m. PAPD police desk receives a report that EMS is setting up a triage station in the lobby of

WTC 2. 9:32 a.m. FDNY radio communications on the City-wide, high-rise Channel 7 (PAPD Channel 30):

firefighters have been able to get to floor 55 inside WTC 2. 9:38 a.m. NYPD aviation unit calls in to request a landing on the roof of the North Tower as soon as possible.

9:39 a.m. FDNY radio communications on the City-wide, high-rise Channel 7 (PAPD Channel 30):

FDNY officer inside WTC 2 indicates that he is sending 10 to 15 injured people down to floor 40 and that the firefighter at that location should take the injured to the building's lobby

in the elevator. The officer also requests that the firefighter operating the elevator bring an EMS crew back up with him.

9:40 a.m. NYPD officer advises that they need the aviation units on the roof as soon as possible.

9:41 a.m. FDNY radio communications on the City-wide, high-rise Channel 7 (PAPD Channel 30):

Hazmat 1 reports that they are on floor 48 of WTC 2 in the B stairway.

9:42 a.m. FDNY radio communications on the City-wide, high-rise Channel 7 (PAPD Channel 30) a

firefighter informs the Battalion Chief that he cannot find any elevator banks that are operating above floor 40. The Chief advises the firefighter that he should climb the

B stairway from his location.

PAPD police desk receives a report that people have arrived and want to volunteer to help

and where should they be sent. Answer: "Right now just send everybody away from the

World Trade. We are not letting anybody come close to it." PAPD police desk receives a radio report that a triage center has been set up at WTC 4 at Victoria's Secret. 9:43 a.m. NYPD officer advises that no one is to rappel onto the top of the buildings. Note: The term "rappel" in this case refers to the process of emergency responders using

ropes suspended from a helicopter to descend onto the roof of a building.

9:44 a.m. PAPD police desk receives a communication that "They haven't evacuated the Fire

Command over here in building 2 or 1." 9:45 a.m. FDNY radio communications on the City-wide, high-rise Channel 7 (PAPD Channel 30): a

firefighter calls the Battalion Chief and reports that they had to take their coats off. 9:49 a.m. FDNY radio communications on the City-wide, high-rise Channel 7 (PAPD Channel 30):

Battalion Chief instructs firefighter that it is imperative that he get down to the lobby

command post to get some people up to floor 40. Injured people are being sent down from

floor 70. The firefighter is inside an operating elevator and is reporting that it is not operating

properly and expresses concerns about the elevator becoming stuck in the shaft. 9:50 a.m. PAPD police desk receives a message that FDNY needs a resuscitator on floor 19, B corridor

of WTC 1. 9:54 a.m. FDNY radio communications on the City-wide, high-rise Charmel 7 (PAPD Channel 30): a Battalion Chief calls for a ladder company in the A stairway to extinguish two fires. They are attempting to stretch building hose lines on about floor 78. FDNY radio communications on the City-wide, high-rise Channel 7 (PAPD Channel 30): a

firefighter calls to the Battalion Chief that he is on floor 55 and must stop to rest. PAPD police desk message indicates that an officer is located on floor 22, fire command

center and that there is heavy traffic in the B stairway. The person indicates that they cannot

release any emergency locked doors due to fire and the loss of electrical power.

Note: Communication appears to originate from WTC 1

.

PAPD police desk receives a report that there are 1 8 passengers stuck in an elevator on

floor 78 sky lobby of WTC 2 and that firefighters are working to get them out. They request

EMS at the location on the double.

P-20
Interim Report on Emergency Communications

9:56 a.m. FDNY radio communications on the City-wide, high-rise Channel 7 (PAPD Channel 30):

inside WTC 2, a firefighter states they are in the B stairway and that they will have to put some fire out in order to get to the A stairway.

9:57 a.m. PAPD police desk receives reports by radio on Channel X and by phone at 435-2131 from

floor 78 of WTC 2 that people are coming out of the elevator banks.

At and below floor 79 of WTC 2, FDNY, NYPD, and PAPD personnel are evacuating

occupants, assisting the injured, and fighting fires. FDNY radio communications on the City-wide, high-rise Channel 7 (PAPD Channel 30): a

firefighter in WTC 2 reports that he is trapped in an elevator in the elevator shaft and that they are chopping their way out. 9:59 a.m. FDNY Marine unit reports the collapse of WTC 2. 10:28 a.m. FDNY Marine unit advises that the second WTC tower collapsed.

Emergency Response Communications Chronology

This chronology provides information on communications difficulties experienced by NYPD and PAPD

following the attack on the WTC. Much has been published concerning the communications difficulties experienced by FDNY during the incident, and first person interviews with FDNY personnel confirms some of these difficulties. However as shown by this chronology, FDNY was not the only emergency

responder department that experienced radio equipment and communications difficulties. There are reports of radios not working well and communications showing that some personnel were not being

heard or responded to. Also, some of the radio transmissions demonstrate the failure to communicate as a

result of radio traffic surge conditions.

The chronology provides examples of numerous cases where radio transmissions were not understood

because of "crossing or doubling" of radio signals when too many people are trying to talk at one time.

8:45 a.m. PAPD police desk Channel W: requests a radio check to locate an open microphone on a handie-talkie radio. 8:49 a.m. PAPD police desk requests, as a result of the surge in radio traffic volume, that police officers

stay off the air. PAPD police desk Channel W: extended period with an open microphone, lots of background

noise and people talking.

8:50 a.m. PAPD police desk receives a message that the officer did not copy the previous transmission

and asks what is going on. 8:51 a.m. NYPD Special Operations Division channel: a dispatcher advises a police lieutenant that his

message was crossed and to repeat it. A message came through that he can't get ahold of someone on the cell phone.

8:53 a.m. NYPD Special Operations Division channel: a dispatcher advises a police department truck

that their radio message is cutting off and all that the dispatcher got was something about the upper floors. 8:54 a.m. PAPD police desk is reporting that it is having trouble reading incoming radio transmissions.

PAPD police desk receives a message that an officer is having trouble reading radio messages

because of so much commotion on the floor. 8:59 a.m. NYPD Special Operations Division channel: a dispatcher advises a police truck that their radio message is breaking up, and the dispatcher asks what units he wants to respond.

9 a.m. NYPD Special Operations Division channel: dispatcher advises that various units are crossing

each other and that the dispatcher cannot understand them.

9:01 a.m. PAPD police desk Channel Y: a microphone is stuck open, interfering with communications.

P-21
Appendix P

9:02 a.m. NYPD Special Operations Division channel: a police officer asks the dispatcher if the last transmission was heard. The police office asks twice. There is no answer.

9:03 a.m. PAPD police desk receives a report that someone has found a supervisor's radio that has been

lost. NYPD Special Operations Division channel: an officer in an NYPD car requests that units

give their messages slowly.

9:05 a.m. FDNY chief officers conduct tests of the City-wide, high-rise repeater located at the WTC.

9:07 a.m. NYPD Special Operations Division channel: a police officer requests that the air be cleared

for emergency vehicles and personnel unimpeded.

9:08 a.m. NYPD Special Operations Division channel: a dispatcher advises officers directing traffic that they are coming over the air. Approximately 30 s later the dispatcher advises a second

time that the officers directing traffic are coming over the air and requests that they stop.

9:09 a.m. NYPD Special Operations Division channel: a Special Operations Division officer requests

that the dispatcher designate two channels for this emergency, one for units on the scene and

one for units that are responding.

9: 1 1 a.m. NYPD: a backup transmitter for City-wide communications is put into service in anticipation

of potential problems with the primary transmitter.

9: 12 a.m. NYPD City-wide channel: a dispatcher advises that "We need to keep this frequency clear unless it is in regards to the level four mobilization."

NYPD Special Operations Division channel: dispatcher state "Only emergency transmissions

are to be made on this frequency."

FDNY Chief begins using the FDNY channel 7 repeater while working inside WTC 2. PAPD police desk receives a radio report from the Fire Command Desk in the lobby of

WTC 2 that they cannot pick up the Warden phones and that they are making announcements

telling people not to stay at the Warden phones. Note: This communication indicates that the

Warden phones in WTC 2 were not working.

9:15 a.m. PAPD police desk Channel W: a radio microphone is stuck open.

9: 19 a.m. NYPD Special Operations Division channel: a dispatcher advises a police officer that his message was being cut off and that only part of the message was copied.

9:20 a.m. NYPD Special Operations Division channel: a dispatcher advises that there is an open carrier and the units should check their radios.

9:22 a.m. NYPD Special Operations Division channel: a dispatcher advises a police truck that his radio

message was unreadable.

NYPD Special Operations Division channel: the dispatcher advises a second time that there is an open carrier and that messages are not being understood.

9:23 a.m. NYPD Special Operations Division channel: the dispatcher advises that the two frequencies

are the Manhattan 10 (Interoperability Channel) and the City-wide. The dispatcher also

advises that the various units are crossing.

9:25 a.m. PAPD police desk Channel W: a radio microphone is stuck open and interfering with

communications. Radio signals are garbled and broken, and there is a high level of

background noise.

9:30 a.m. PAPD police desk Channel X has a communication indicating that everybody should turn

their phone off. 9:3 1 a.m. PAPD police desk Channel X: a Port Authority officer is questioned as to whether they have

brought any red bags with radios for the fire department. The answer is no, and is it safe to go into the building.

9:32 a.m. NYPD City-wide channel: a unit advises that he cannot communicate, his radio is going in and out and the cell phone is not working.

9:36 a.m. NYPD Special Operations Division channel: a police officer reports that the telephones at his location are not working. Note: Location not identified.

P-22
Interim Report on Emergency Communications

9:43 a.m. NYPD Special Operations Division channel: a police officer advises that he heard over an AM radio that a plane had crashed into the Pentagon.

9:49 a.m. PAPD police desk instructs officer that he was speaking too fast and that he must slow down

so that he could be understood.

9:53 a.m. NYPD Special Operations Division charmel: the dispatcher advises all units to check their portable radios for an open carrier. 9:54 a.m. NYPD City-wide channel: a dispatcher requests "Keep the air clear. We have problems in the City. Keep the air clear right now."

9:55 a.m. PAPD police desk Channel Z: police officers are having trouble reading communications

over the radio and indicate that they will try to call on the telephone.

9:57 a.m. PAPD police desk Channel X: a report is received that an officer is responding to WTC 1 Fire

Command and that he had been trying to contact the Command Center on floor 22, but they

didn't know how to operate the other set of communications equipment.

9:59 a.m. NYPD Special Operations Division channel: an Emergency Service Unit police officer calls several times for the dispatcher. The dispatcher answers each time and apparently was not heard by the calling unit. 10:03 a.m. NYPD Special Operations Division channel: a dispatcher requests that some units standby

while the needs of other units are addressed.

10:05 a.m. NYPD Special Operations Division channel: the dispatcher advises that all units need to talk one by one. The dispatcher further advises that units are cutting each other off. 10:09 a.m. NYPD Special Operations Division channel: an Emergency Service Unit advises the dispatcher that he can hear the dispatcher but is not sure if the dispatcher is hearing him.

10:10 a.m. NYPD Special Operations Division channel: the dispatcher advises that there are three units

trying to talk at the same time and requests, "One at a time."

Condition of the WTC Towers Chronology

Information provided by this chronology partially describes the variable conditions found in WTC 1 and

WTC 2 towers. It is shown that the impact of the first aircraft into WTC 1 produced an explosive

condition all the way down to the building's basement. The impact of the aircraft into what appears to be

WTC 2 produced jet fuel fires in the building on the 51st floor. Other communications indicate that there was no smoke or fire on the 68th, 73rd, or 74th floors, the walls in stairway B had been breached. A

telephone call to a New York City Radio 9-1-1 telephone operator at 9:36 a.m. indicates that a floor in the 90's level of WTC 2 had collapsed. Information from this call concerning the floor collapse appears to be

misstated by the NYPD Division 1 radio operator in the message transmitted at 9:41 a.m. and again at 9:51 a.m. Communications from the NYPD aviations units describe a steady deterioration of the two

WTC towers before they collapsed.

8:47 a.m. PAPD police desk reports that there is a fire on floor 22 of WTC 1. PAPD police desk receives a report that there is a lot of debris on floor 22 of WTC 1

8:49 a.m. PAPD police desk reports that there is damage and a lot of debris on floor 22 of WTC 1. 8:51 a.m. PAPD police desk receives a call that an explosion was observed in the basement of the B 1 level of WTC 1 . The police desk informs the officer on the B 1 level that what he saw

resulted from an explosion on the upper floors of the building.

8:57 a.m. PAPD police desk receives report that water pipes are broken on the B4 level of WTC 1. 9:02 a.m. PAPD police desk receives message from a person trapped in an elevator on floor 78 of

WTC 1 that the area has smoke, and water and debris are coming down from above.

9: 10 a.m. PAPD police desk receives a report that there is burning jet fuel on floor 5 1 of one of the towers. Note: Communications suggest this is WTC 2.

9: 1 3 a.m. PAPD police desk receives a report that WTC 1 is flooding.

P-23
Appendix P

9:32 a.m. PAPD police desk receives a message from an officer that the WTC Concourse is flooding.

9:36 a.m. New York City 9-1-1 telephone operator receives a message from an occupant of WTC 2 that a floor had collapsed below them in the 90's level. 9:41 a.m. NYPD dispatcher advises units that floor 106 in WTC 2 is collapsing and that the message comes from someone on that floor. 9:47 a.m. FDNY radio communications on the City-wide, high-rise Channel 7 (PAPD Channel 30): a

firefighter inside WTC 2 reports that he is standing in the B stairway on floor 74 and there is no smoke or fire problem. He reports that the stairway walls have been breached on floors 73

and 74. Another FDNY unit in the same stairway reports that the walls were also breached on floor 68. 9:49 a.m. NYPD aviation unit gives a radio report stating that "large pieces" are falling from WTC 2. 9:51 a.m. NYPD dispatcher advises that at WTC 2, floor 106 is crumbling per communications with

victims trapped on the floor. 9:58 a.m. NYPD aviation unit advises that the south tower is coming down.

10:06 a.m. NYPD officer advises that it isn't going to take much longer before the north tower comes down and to pull emergency vehicles back from the building.

10:20 a.m. NYPD aviation unit reports that the top of the tower might be leaning.

10:21 a.m. NYPD aviation unit reports that the north tower is buckling on the southwest comer and

leaning to the south. NYPD officer advises that all personnel close to the building pull back three blocks in every

direction.

10:27 a.m. NYPD aviation unit reports that the roof is going to come down very shortly.

10:28 a.m. NYPD officer reports that the tower is collapsing.

P.8 FINDINGS

The following is a list of preliminary findings based on the current status of emergency responder

communications analysis:

1. After the first aircraft struck the WTC, there was a peak increase in emergency responder

radio communications by approximately a factor of 5, followed by an approximate factor of

3 steady level of radio communications.

2. A surge in communications traffic volume made it more difficult to handle the flow of

communications and delivery of information.

3. Analysis of the radio communications records received by NIST indicates that roughly onethird to one-half of the radio messages transmitted during these radio traffic surge conditions were not complete messages nor understandable.

4. Preliminary analysis of the FDNY City-wide, high-rise Channel 7 (PAPD Channel 30)

recording indicates that the WTC site repeater was operating.

5. Communications records and interviews indicate that smoke and heat conditions on the top of

the two WTC buildings prevented the NYPD helicopters from conducting safe roof

evacuation operations.

6. NYPD aviation unit personnel reported critical information about the impending collapse of

the WTC towers several minutes prior to their collapse. No evidence has been found to

P-24
Interim Report on Emergency Communications

suggest that the information was further communicated to all emergency responders at the

scene.

P.9 REFERENCES

ARRL. (American Radio Relay League). 2003. The ARRL Handbookfor Radio Commimicatiom.

Newington, CT.

Microsoft (Microsoft, Inc.). 2003. Windows Media Player, http://www.microsoft.com.

Nullsoft (Nullsoft, Inc.). 2002. WinAmp 3. http://www.winamp.com.

Sonic (Sonic Foundry, Inc.). 2002. Sound Forge 6.0. Madison, WI.

P-25
Appendix P

This page intentionally left blank.

P-26
Attachment 1 Communications of the Port Authority of

New York and New Jersey

The National Institute of Standards and Technology received duplicates of many radio and telephone

channels. The tapes listed below cover a wide range of times. All recordings cover at least from 0845 to 0958. The remainder of the communications can be placed in two categories as follows: 0705 to 0958

and 0705 to 1800.

Central Police Desk (CPD): Police Command Channel 2 to 39 - Each one of these recordings is 198 minutes long.

CPD Ch. 002 -CPD wav -Not assigned

CPD Ch. 003 -CPD wav -Not assigned

CPD Ch. 004 -CPD wav -Not assigned

CPD Ch. 005 -CPD wav -Not assigned

CPD Ch. 006 -CPD wav -Not assigned

CPD Ch. 007 -CPD wav -Not assigned

CPD Ch. 008 -CPD wav -Not assigned

CPD Ch. 009 -CPD wav -Not assigned

CPD Ch. 010 -CPD wav -Not assigned

CPD Ch. Oil -CPD wav -Not assigned

CPD Ch. 012 -CPD wav -Not assigned

CPD Ch. 013 -CPD wav -Not assigned

CPD Ch. 014 -CPD wav -Not assigned

CPD Ch. 015 - SPEN 1 State Police Emergency Network. wma

CPD Ch. 016 - Radio SPEN 2 State Police Emergency Network.wma

CPD Ch. 017 - Radio (Ch. A) PA Area Wide.wma

CPD Ch. 018 - Radio (Ch. W) LT Police.wma

CPD Ch. 019 CPD.wav - Not assigned

CPD Ch. 020 - CPD.wav - Not assigned

CPD Ch. 021 - Phone 9-1-1 Emergency.wma (Note: Recording was blank.)

CPD Ch. 022 - Phone 9-1-1 Emergency.wma (Note: Recording was blank.)

CPD Ch. 023 - Phone SGT's Desk - 201-216-6800.wma

CPD Ch. 024 - Phone Clerk - 201-216-6800.wma

CPD Ch. 025 Phone TTY NY- 20 1-2 16-6800. wma

CPD Ch. 026 Phone Clerk Extra - 201-216-6800.wma

CPD Ch. 027 - Phone TTY NJ - 201-216-6800.wma

CPD Ch. 028 Phone Absence Control Line 1 - 201-216-6988.wma

CPD Ch. 029 - Phone Absence Control Line 2 - 201-133-6988.wma

CPD Ch. 030 - Phone 800 number SGT's Desk - 201-216-6858.wma

CPD Ch. 03 1 - Desk TTY number 3. wma

CPD Ch. 032 - CPD.wav - Not assigned

CPD Ch. 033 CPD.wav - Not assigned

CPD Ch. 034 - CPD.wav - Not assigned

CPD Ch. 035 - Phone 201-963-7247 Assignment Line 800-776-8580.wma

P-27
Appendix P

CPD Ch. 036 - Phone 201-963-7248 Assignment Line 800-776-8580.wma

CPD Ch. 037 - Phone 201-963-7249 Assignment Line 800-776-8580.wma

CPD Ch. 038 - Phone 201-659-3028 Toll Rob 800-TOLL-ROB.wma

CPD Ch. 039 - Phone 201-216-6794 Drug Tip 800-828-PAPD.wma

PATH Police Command: Ch. 02 to 31 - Recordings vary in length from 106 minutes to 193 minutes.

PATH Ch. 02 Phone Desk Right.wma

PATH Ch. 03

PATH Ch. 04

PATH Ch. 05

PATH Ch. 06 - SGT. desk.wma

PATH Ch. 07 - Tour Commander,wma

PATH Ch. 08 - Report Room,wma

PATH Ch. 09 - Juvenile Room.wma

PATH Ch. 10 - Reserve Room 2 16-6078.wma

PATH Ch. 11 - Phone Desk Left. wma

PATH Ch. 12 - Jersey City Fire Department.wma

PATH Ch. 13 - Jersey City Medical Center.wma

PATH Ch. 14 - Jersey City Police. wma

PATH Ch. 15 -NYPD.wma

PATH Ch. 16

PATH Ch. 17 PATH Ch. 18

PATH Ch. 19 - Conference Room l.wma

PATH Ch. 20 - Conference Room 2. wma

PATH Ch. 21 - Radio (R2) Train Master. wma

PATH Ch. 22 - PD Wall (Desk Area).wma

PATH Ch. 23 - Court Office 1 .wma PATH Ch. 24 - Court Office 2. wma

PATH Ch. 25 - Court Sgt.wma

PATH Ch. 26 - Radio (Rl) Train Master.wma

PATH Ch. 27 - Radio (R30) Communications.wma

PATH Ch. 28

PATH Ch. 29

PATH Ch. 30

PATH Ch. 31

WTC Police Desk 1: Ch. 002 to 039 - Each one of these recordings is 171 min.

Ch. 002 WTC.wav

Ch. 003 WTC.wav

Ch. 004 WTC.wav

Ch. 005 WTC phone 435-8456 clerk.wav

Ch. 006 WTC phone 435-8462 clerk.wav

Ch. 007 WTC phone 435-2135 TC.wav

Ch. 008 WTC phone 435-3541 desk left.wav

Ch. 009 WTC phone 435-3541 desk center.wav Ch. 010 WTC phone 435-3541 desk right.wav

Ch. 01 IWTC phone 435-8460 conf room.wav

Ch. 012WTC .wav

P-28
Interim Report on Emergency Communications

Ch 01 VV 1 V pilUllC ^JJ'JJ ly UlllLC.WaV

Ch 014 WTP VV 1 \^ UliCCl llllC iTi-ZiN 1 .WdV

Ch 01 s VV 1 \w Hirprt LlllC^l linp llllC NVr IN 1 JJ/iVlO. FM*s wnv WdV

Ch 01 fi WTC VV 1 V, L/ilVJllC J J / UL>VJ ilUVJi WdlUCll. VVdV Ch 017 V/ 1 / WTC VV 1 V- riirppf LillCCl iinp Tirp r*r\TnTTi?inH W/Tr 1 llllC illw CVJlllllldllU VV 1 l.WdV

Ch 01 8 WTC VV 1 nirpr't u.iicd linp Tirp r^OTnm^inH W/Tr O wrct^r liiic xiic ^L/imiidiiu. VV 1 ^.WaV

Ch 01 Q W/TC VV 1 v_ Ch 070 VV i WdV

Ch 071 WTr VV 1 pxiuiic H-jj-zi puiicc icbcrvc rin.wdv

Ch 079 WTr VV 1 \^ Ch 07^ WTr VV 1 uinjiic ^ z.y^o u.cbx\..wdv

Ch 074 WTr XdClXU \_-XX. /\.WdV

Chv_ 11. 07S WTr VV 1 v_ XdUXU v,Xl. D.WdV

Ch 07^i WTr VV 1 IdCXXU v-Xl. VV.WdV

Ch 077 WTr VV 1 \_ ret H 1 r\ rn )t \x/q\7 XdLlliJ v^ll. yv.wdv

Ch\^ 11. 078 WTr VV 1 \_ vex IdUlU Him rn \\/Ci\7 V_X1. I .WdV

Ch 07Q WTr VV 1 v_ XaUlU VwXl. Z^.WdV

Ch OW WTr VV 1 rULy I ldU.XU.WdV Chv^ll. 0'\ 1 WTr VV 1 WdV

Ch 0'^7 WTr VV 1 WdV

Ch 0^^J J WTr VV 1 WdV

\^n. W 1 c wav

Ch. 035 WTC wav

Ch. 036 WTC wav

Ch. 037 WTC wav

Ch. 038 WTC wav

Ch. 039 WTC wav

Newark International Airport: Police Command - Ch. 02 to 39

EWR Ch. 002

EWR Ch. 003

EWR Ch. 004

EWR Ch. 005

EWR Ch. 006

EWR Ch. 007

EWR Ch. 008 - Phone 733-7525 - Newark PD.wma

EWR Ch. 009 - Phone PL234846 - Ehz. PD.wma

EWR Ch. 010 - Phone PL92866- Newark PD.wma

EWR Ch. 01 1 - PL234881 - Eliz. FD.wma

EWR Ch. 012 - Phone PL230333 - AFA.wma

EWR Ch. 013

EWR Ch. 014 - Phone PL234979 - REMCS.wma

EWR Ch. 015 - FAA Tower Crash Alarm. wma

EWR Ch. 016

EWR Ch. 017

EWR Ch. 018 - PNPD PVL - OSNA660-650.wma

EWR Ch. 019 - Phone 589-6321 - PNPD.wma

EWR Ch. 020 - Phone 589-0292 - PNPD.wma

EWR Ch. 021 - Phone 961-6666 - Line 3.wma

EWR Ch. 022 - Phone 961-6666 - Line 4. wma

P-29
Appendix P

EWR

EWR

EWR

EWR

EWR

EWR

EWR

EWR

EWR

EWR

EWR

EWR

EWR

EWR

EWR

EWR

EWR

Ch. 023

Ch. 024

Ch. 025

Ch. 026

Ch. 027

Ch. 028

Ch. 029

Ch. 030

Ch. 031

Ch. 032

Ch. 033

Ch. 034

Ch. 035

Ch. 036

Ch. 037

Ch. 038

Ch. 039

Radio " EWR Command - SOOMhz.wma

Radio EWR ARFF SOOMhz.wma

Radio EWR TAC 1 - SOOMhz.wma

Radio - Central police desk - SOOMhz.wma

Radio - EWR Detectives. wma

Police desk left phone ~ 96 1-6230.wma

PoHce desk phone center - 96 1-6230.wma

Police CAD desk phone - 96 1-6230. wma

Police desk right phone - 96 1-6230.wma

Phone 961-6666 - Line 2. wma

Phone 96 1 -6666 - Line 1 .wma

Radio Ch. Z - Operations & Terminals.wma

- Radio - Ch. X - Facility maintenance.wma

Radio Ch. B - Maintenance. wma

NYPD WTC Communications:

NYPD Special Operations Division

Tape 1, 08:46-09:33

Tape 2, 09:32- 10:18

Tape 3, 10:18-11:04

NYPD City-wide 1 radio. Tape 4, 08:40 - 09:27

Tape 4b, 09:27- 10:12

Tape 5c, 10:12-11.59

Tape 5d, 10:59- 11:46

NYPD Division 1, Tape 6, 08:45 - 9:30

Tape 7, 09:29- 10:15

Tape 8, 10:14-11:00

P-30
Table of Contents

Appendix Q

NIST's Working Hypothesis for Collapse of the WTC Towers Q-1

Q.l Objectives Q-1

Q.2 Approach Q-1

Q.3 Factors to Evaluate the Working Hypothesis Q-2

Q.4 The Working Hypothesis Q-2

Q.5 Issues Still Being Investigated Q-6

Q-i
Appendix Q

V

This page intentionally left blank.

Q-ii
Appendix Q

NIST's Working Hypothes[s for Collapse of the

WTC Towers

In response to the terrorist attacks of

September 11, 2001, and the resulting collapse of

the World Trade Center (WTC) buildings, the National Institute of Standards and Technology

(NIST) has been investigating possible collapse

scenarios. Establishing the sequence of events

that led to the towers collapsing is important in determining which factors allowed the buildings

to hold up for as long as they did without

collapsing, and which factors, if any, could have

delayed or prevented the collapse of the WTC

towers. Understanding these factors will provide

valuable information on which to base

recommendations for improvements to buildings

practices, standards, and codes that may be

warranted.

Q.1 OBJECTIVES

The objectives of the NIST analysis are:

• Establish how and why the WTC

towers collapsed after the aircraft impact, i.e., the 'triggering event'

• Determine the most probable collapse

sequence

• Identify the factors that have the

strongest influence on the most

probable sequence

Background

NIST has estimated that 17,400 occupants (± 1,200) were present in the WTC towers on the morning of September 1 1 , 2001 , about equally divided between

the two buildings (8,900 in WTC 1 and 8,540 in WTC 2). 2,159 building occupants and an additional 433 first responders, including security guards, were

reported to have lost their lives that day. This does not include aircraft passengers and crew or bystanders.

Approximately 87percent of the WTC tower occupants were able to evacuate successfully. More than 99 percent of occupants below the crash impact areas had sufficient time prior to collapse of the buildings to safely evacuate. WTC 1 stood for one hour and

43 min after impact; WTC 2 collapsed 56 min after it was struck.

Preliminary estimates indicate that about 20 percent or more of those in the WTC towers who lost their lives may have been alive in the buildings just prior to their collapse. This includes nearly all of the first responders and 76 building occupants below the floors of impact. There were 72 fatalities reported in WTC 1 and 4 fatalities reported in WTC 2, not including first responders, below the floors of impact.

Buildings are not designed to withstand the impact of fuel-laden commercial airliners. However, Port Authority documents indicate that the impact of a Boeing 707 flying at 600 mph and possibly crashing

into the 80th floor had been analyzed during the design of the WTC towers in February/March 1964. While NIST has not found evidence of the analysis, the documents state that such a collision would result in localized damage only, and that it would not cause

collapse or substantial damage to the WTC towers. The effect of fires due to jet fuel dispersion and ignition of building contents was not considered in the 1964 analysis. Loss of life in the immediate area of

aircraft impact was anticipated, but loss of life from fire and smoke was not considered.

Q.2 APPROACH

To identify the most probable of the technically possible collapse sequences, NIST is adopting an approach that combines mathematical modeling, well-established statistical and probability based analysis

methods, laboratory experiments, and analysis of photographic and video evidence. The approach

accounts for variations in models, input parameters, analyses, and observed events. It allows for

Q-1
Appendix Q

evaluation and comparison of possible collapse hypotheses based on different damage states, fire paths,

and structural responses to determine the following:

1 . The most probable sequence of events from the moment of aircraft impact until the initiation of global building collapse;

2. How and why WTC 1 stood nearly twice as long as WTC 2 before collapsing (103 min

versus 56 min), though they were hit by virtually identical aircraft;

3. What factors, if any, could have delayed or prevented the collapse of the WTC towers.

Q.3 FACTORS TO EVALUATE THE WORKING HYPOTHESIS

In further evaluating the working hypothesis for the collapse of the WTC towers, NIST is considering the following factors:

• The relative contr ibutions of aircraft impact damage and subsequent fires

• How safe each building was immediately after aircraft impact but before fire weakened the

structures, i.e., to what extent the capacity of the buildings to carry design loads' was reduced

• Relative roles of the perimeter and core columns' and the composite floor system,^ including

connections

• The role played by fireproofing, especially the extent to which fireproofing may have been

damaged due to aircraft impact

• Whether the undamaged towers would have remained standing in a "maximum credible fire""*

• The role compartmentation (i.e., areas divided by fire-rated walls) may have played, i.e., what

would have happened if the floors had been separated into 7,500 or 10,000 ft" compartments

with 1 h fire-rated partition walls or separations

Q.4 THE WORKING HYPOTHESIS

NIST has developed a working hypothesis to explain the sequence of events from aircraft impact until the

initiation of global structural collapse. This hypothesis will be further refined based on the results of

The design of the WTC towers was governed by gravity and lateral wind loads.

' The perimeter columns were designed to carry both gravity and wind forces and acted together as a framed-tube system. The

core columns were designed to carry only gravity loads and not required to provide frame action.

' The composite floor truss system, which included long-span open-web bar joist elements, was designed to carry floor loads to the supporting core and perimeter columns. It also acted as a diaphragm that distributed wind forces to the perimeter columns

of the framed-tube system and provided lateral stability to the perimeter columns. A maximum credible fire for the WTC towers is assumed to have the following characteristics: the sprinkler system is compromised, overwhelmed, or not present; there is no active firefighting; combustible building contents averaging 10 psf (in the range of about 5 to 20 psf for conventional office buildings); floor-to-floor fire spread to next upper floor at 30 or 60 min; and ventilation from windows broken by fire and a total of 50 ft' of air leakage between floors.

Q-2
NIST's Working Hypothesis for Collapse of the WTC Towers

NIST's continuing comprehensive analyses to identify specific load redistribution paths and damage

scenarios that are possible for each building, from which the most probable collapse sequence will be

identified. NIST welcomes comments from technical experts and the public on the working hypothesis.

NIST's working hypothesis is based on analysis of the available evidence and data, consideration of a range of hypotheses (including those postulated publicly by experts), and a newly enhanced

understanding of structural and fire behavior. It is consistent with all current evidence held by NIST,

including photographs and videos, eyewitness accounts, and emergency communication records. NIST's

analysis allows for different sequences of events and different possible event paths for each building.

To accommodate the aircraft impact and subsequent fire damage, the structure redistributed loads from

structural element to structural element via redundant load paths and maintained overall structural

stability. Structural collapse began when the structure was not able to redistribute loads any further. The

working hypothesis addresses the following chronological sequence of major events; specific load

redistribution paths and damage scenarios are currently under analysis:

1 . Aircraft impact damage to perimeter columns

with redistribution of column loads to adjacent

perimeter columns and to the core columns via

the hat truss;

2. After breaching the building's exterior, the

aircraft continued to penetrate into the buildings, damaging core columns with

redistribution of column loads to other intact core and perimeter columns via the hat truss and floor systems;

3. The subsequent fires, influenced by

post-impact condition of the fireproofing,

further weakened columns and floor systems

(including those that had been damaged by

aircraft impact), triggering additional local

failures that ultimately led to column

instability;

4. Initiation and horizontal progression of

column instability ensued when redistributing

loads could not be accommodated any fiarther. The collapses then ensued.

Aircraft Impact Damage to Perimeter Columns

Initially, the WTC towers withstood the impact virtually identical aircraft. Based on video that NIST has

obtained, it is known that WTC 2, which collapsed first and in about half the time as WTC 1, vibrated for over 4 min at an oscillation rate nearly equal to that measured for the undamaged building after it was

struck, indicating that the buildings were continuing to respond normally. The lightly damped (about

1.2 percent of critical damping) oscillation had a maximum amplitude of approximately 20 in. at the roof

Role of the Hat Truss System

The purpose of the hat truss was to support

gravity and wind loads on the antenna. It was not designed to resist lateral forces on

the towers, and, in an undamaged state, it did not have a significant role in carrying

gravity loads. Lateral loads due to wind were distributed to the framed-tube system

via diaphragm action of the floor system.

The hat truss was connected to each

perimeter face at only four points, all at the same level (at the 108th floor just below the concrete floor slab). The 47 core columns were connected to diagonal elements,

heavier transfer beams, or smaller beam

elements in the hat truss. Most of the core columns extended to the roof level, but four core columns, which were only minimally

connected to the hat truss, terminated at floor 110. The hat truss provided minimal

redistribution of loads (less than 10 percent) from perimeter columns to core columns. Most of the load redistributed due to aircraft impact damage occurred on

the external face through vierendeel action.
Appendix Q

level, where sway was about 3 ft to 4 ft under design wind conditions. Based on this information,

structural damage to perimeter columns as a result of aircraft impact of the framed-tube system appears to have played a minimal role in initiating the collapse. Perimeter column bowing prior to collapse occurred on other faces (i.e., fire floors on the south face of WTC 1 and east face of WTC 2) that were not severed

by the aircraft.

Aircraft Impact Damage to Core Columns

The core columns were designed to carry only gravity loads and not required to provide frame action.

The aircraft trajectory at impact suggests damage to the core columns occurred as follows:

WTC 1 —The aircraft was traveling about 450 mph and hit the tower near the center of the north face

damaging floors 93 to 99. The aircraft fiilly entered the core area and severed or damaged central core columns in the north-south direction. Aircraft and building debris accumulated in the remaining core area and south-side floor areas as contents were displaced from the point of impact.

WTC 2—The aircraft was traveling about 550 mph and hit the tower near the southeast comer of the

building damaging floors 77 to 85. Core columns to the south and east were severed or damaged.

Aircraft and building debris accumulated in the core area and floor areas to the east and north.

Severed core columns redistributed their loads in three ways, depending on how many and which core columns were severed.

1 . Isolated core columns were severed. Severed column and tributary floor loads at and above

the point of impact were redistributed locally at each floor to adjacent intact core columns via core floor framing. This was limited by shear/bending capacity of floor-framing connections

to adjacent columns.

2. Critical (e.g., comer) core columns and/or several other core columns were severed. The

severed column and tributary floor loads, at and above impact floors, redistributed to intact core columns via the hat tmss. Significant hat truss deflections may have occurred if there was adequate connection capacity since the severed core columns and the associated floors were hanging from the hat tmss which was not designed to carry such loads. This was

limited by the tensile capacity of bolted splices in the severed core columns,

tensile/compression capacity of hat tmss members, and tensile capacity of column

connections to the hat tmss.

3. Extent of core column failures precluded redistribution through the hat tmss and/or exceeded

redistribution capacity of the hat truss: severed column and associated floor loads, at and

above floors of impact, redistributed to intact core and perimeter columns via the core and

composite truss floor system. Floors were subjected to combined bending and diaphragm

action (e.g., consider the scenario of no core columns in the floor span direction to visualize

this action). The overall capacity of the floors was limited by shear capacity of

floor-to-column connections (including perimeter columns) and tensile/bending capacity of

composite tmss floor connections to core or perimeter columns. Significant sagging of the hat truss system may have occurred if its capacity was exceeded.
NIST's Working Hypothesis for Collapse of the WTC Towers

Relative Roles of Fires and Aircraft Impact

Fires played a major role in collapse initiation. The tower structures withstood the initial aircraft impacts

and remained stable. While aircraft impact damage did not, by itself, initiate building collapse, it had the

ft)llowing harmftal effects that then contributed greatly to the subsequent fires:

• Compromised the sprinkler and water supply systems,

• Dispersed jet ftiel and ignited building contents over large areas,

• Created large accumulations of combustible matter containing aircraft and building contents,

• Increased air supply into the buildings (through broken windows and holes in the sides of the buildings, and between floors due to damaged floors, vertical shafts, and columns) permitted

significantly higher energy release rates than would normally be seen in ventilation limited

building fires, allowing the fires to spread rapidly within and between floors, and

• Damaged ceilings enabling "unabated" heat transport over the floor-to-ceiling partition walls

and to the floor trusses, spandrels, and tops of columns.

The jet fuel, which ignited the fires, was mostly consumed within the first few minutes after impact. The

fires that burned for almost the entire time that the buildings remained standing were due mainly to burning building contents and, to a lesser extent, aircraft contents, not jet fuel.

Thermal Effects on Columns and Floors

Some floors in WTC 2 experienced partial collapse due to

aircraft impact. For example, partially collapsed floor slabs were visible on the east and north faces. This included

failures at the edges with perimeter columns causing floor edge sagging. There is no visible evidence of hanging floors

in WTC 1.

• Fires may have had the following thermal

effects: core columns and core floors may have

been further weakened, with reduced ability to carry and/or redistribute load, causing such

loads to be redistributed to other core and

perimeter columns consistent with the residual reserve capacities of these columns and the transfer mechanisms (i.e., hat truss and floor system).

• The floor system may have been further weakened, either along the span of the floor system

or localized at connections with columns. The weakening floor system may have pulled the

perimeter columns inward (observed on the south face of WTC 1 and the east face of WTC 2

minutes prior to building collapse) and then initiated connection failures at perimeter or core columns.

Role of Fireproofing

The post-impact condition of the fireproofing

played a key role in the structural response

to fires. The post-impact condition of the

fireproofing depends on the condition of the

fireproofing prior to aircraft impact and the extent to which fireproofing was damaged

due to aircraft impact. The fire-affected floors in WTC 1 had, in general, upgraded or

thicker fireproofing (1 .5 in. specified) while,

in general, those in WTC 2 did not have

upgraded fireproofing (0.5 in. specified].

Q-5
Appendix Q

• Perimeter columns may have been further weakened, with reduced abihty to carry loads. Thermal effects could also cause inward bowing of perimeter columns due to differential temperatures between the inner and outer faces of the columns. The loads that could no

longer be carried by the weakened columns would have been redistributed to adjacent

perimeter columns.

Column Instability and Collapse Initiation

The perimeter columns were designed as part of a framed-tube system to carry both gravity and wind

forces. Instability of perimeter columns resulted from a combination of (1) redistributed loads from the core columns via the floor system and possibly the hat truss, (2) inward bowing due to thermally

weakened and sagging floors, (3) increased unsupported length due to failed floors, and (4) thermal

effects directly on the perimeter columns. '

The instability of a few perimeter columns spread instability across the entire face and around the comers

just before or during collapse initiation. The initiation or spread of perimeter column instability also may

have been facilitated by the hoop stress demand on the framed-tube system exceeding the capacity of the

spandrels (horizontal steel plates) that tied the perimeter columns together (e.g., at the northeast comer of

WTC 2).

The initiation of global collapse for both towers was first observed by the tilting of the sections above the

impact regions of both WTC towers. The top section of WTC 1 rotated to the south (observed via

antenna tilting in a video recording) and the top of WTC 2 rotated to the east and south and twisted in a counterclockwise motion. The primary direction of tilt of each tower was around the weaker axis of the core (north-south for WTC 1 and east-west for WTC 2). The rigid body rotation associated with the

tilting and the propagation of column instability are synchronous processes that initiated global collapse.

The rigid body rotation may have caused forces such as shear and torsion to spread the column instability

laterally.

Q.5 ISSUES STILL BEING INVESTIGATED

Over the next few months, NIST will continue to investigate the following technical issues and modify its working hypothesis as needed. Findings on these issues will be included in the final report.

• Aircraft impact damage to stmctural components, fireproofing, and hat tmss connections.

• Distribution of aircraft/building contents.

• Thermal effects on core columns and core floors, especially extent of fires and growth

history.

• Thermal effects on welded perimeter columns, especially temperature gradients on columns.

• Extent of load redistribution to intact core columns and their reserve capacity to accommodate thermal loads.

Q-6
NIST's Working Hypothesis for Collapse of the WTC Towers

• Capacity of hat truss connections to perimeter columns, especially to meet the demands of

aircraft impact and any torsional effects.

• Capacity of hat truss to accommodate the load redistribution from severed columns.

• Capacity of bolted splices in the severed core columns to carry loads to the hat truss.

• Relative magnitude of the load redistribution provided by the local core floor, hat truss, and

the core-truss floor system for each tower.

• Axial/shear/bending capacity of floor connections to core and perimeter columns.

• Effect of localized fires on floor truss connections.

• Mechanisms to propagate instability laterally in the perimeter columns (e.g., shear and torsion

forces induced by a rigid body movement)

• Capacity of spandrels, including splices, to carry shear transfer in the framed-tube system,

especially at the comers.

• Role of bolted splices on instability of perimeter columns.

• Outward bowing of perimeter columns due to thermal expansion of floors.

• Effect of uneven floor thermal expansion on perimeter column instability due to potential

biaxial bending.

• Comparison and reconciliation of working hypothesis with observed facts (photographs and

videos, eyewitness accounts, emergency communication records).

• Examination of other possible or probable hypotheses.

Q-7
Appendix Q

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Q-8