National Institute of Standards and T

Technology Administratio

U.S. Department of Comme

NIST Response to the World Trade Ce

Federal Building and Fire Safety Inv

of 

the World Trade Center Disas

Part I - Introduction

April 5, 2005
Outline Outline

• Part I — Introduction• Part IIA — WTC Towers Collapse • Part IIB — WTC Towers Collapse • Part IIC — WTC 7 Collapse• Part III — Baseline Performance • Part IV — Life Safety (Evacuatio

Response, Active Sys

• Part V — Procedures and Pract• Part VI — Issues and Recomme
National Context National Context

• The collapse of the World Trade Center structure

terrorist attacks of September 11, 2001 was one building disasters in recorded history – killing 274

• More than 400 emergency responders were amo

the largest loss of life for this group in a single inc

• Strong private sector, public, and Congressional 

comprehensive response to the World Trade Cen

• Congress passed and the President signed into l

2002, the National Construction Safety Team (NC

• Gives NIST authorities to investigate buildi• Modeled after the NTSB, with some differe
Fire & Emergency 

Service

IAFC, NASFM,

IAFF, FDNY, NYPD,...

Academics

IAFSS, ASME, 

LANL, MIT, 

Princeton, 

North

western, UT 

Austin, Georgia 

Tech, Penn State, 

Drexel, Wharton, 

Columbia, Lehigh, 

UMd, WPI,...

Industry Suppliers

W.R. Grace,

United Technologies, Sensors, Controls,...

Stakeholders and Partne

Stakeholders and Partne

Public-Private 

Response Plan

Construction Industry

CII, IAI, CERF, 

FIATECH, NIBS, AGC

Fire Safety 

Engineering

Private 

Consultants, 

SFPE,...

Othe

FE

USAC

CDC, 

IR

Insurance/

Testing labs

UL, FM Global, 

SwRI, IRI

Public/Groups

Skyscraper Safety,..

Occupants/Witnesses

Entrepreneurs/Inventors

Small Businesses, 

Students,... 
Dissemin

and Tech

Assistance P

Dissemin

and Tech

Assistance P

BPAT

Recommendations

BPAT

Recommendations

Govt.

Industry

Professional

Academic

Inputs/Actions

Govt.

Industry

Professional

Academic

Inputs/Actions

Public Inputs/

Efforts

Public Inputs/

Efforts

Research &

Development

Research &

Development

WTC

Investigation

WTC

Investigation

Res

Res

Guidance and Tools for

Improved Practices

Guidance and Tools for

Improved Practices

Tec

B

Tec

B

Owners, Contractors, Designers,

Emergency Responders and

Regulatory Authorities

S
NIST WTC Investigation Objectives NIST WTC Investigation Objectives

•

Determine:

• why and how the WTC Towers collapsed follo

impact of the aircraft, and 

• why and how the 47-story WTC 7 collapsed

•

Determine why the numbers of injuries and fatalit

high depending on location, including technic

al as

protection,

occupant behavior, evacuation, and e

•

Determine the procedures and practices that wer

design, construction, operation, and maintenance buildings

• Identify, as specifically as possible, areas in c

building and fire model codes, standards, and warrant revision


Credit: NOAA 

September 23, 2001
Some Specific Questions Some Specific Questions

 How and why did WTC 1 stand nearly twice as long as W

(102 min. vs. 56 min.) though they were hit by virtually ide

 What factors related to normal building and fire safety con

to the terrorist attacks of September 11, 2001, if any, coul

prevented the collapse of the W

TC towers?

 Would the undamaged WTC towers have remained stand

large building fire scenario?

 What factors related to normal building and fire safety con

could have saved additional WTC occupant lives or could loss of life among the ranks of first responders?

 How well did the procedures and practices used in the des

operation, and maintenance of the WTC buildings confor

practices, standards, and codes?
WTC Investigat

WTC Investigat

Analy

sis 

of Steel

Stru

Co

Evacuation

Baseline 

Perfor

m

ance& 

Impact 

Damage

Analy

sis of 

Codes and 

Practices

Active Fire 

Suppression

Thermal and

Tenability

Environment

Public InputsD

ocuments

Video/ PhotographicRecordsOral History DataEmergency Response RecordsRecov

ere

d Structural 

SteelBPAT Recommen

dations

Government, Industry, Professional, Academic In

p

uts

Public Inputs
System Design Concept
Source Unknown
Safety of WTC Towers in Aircraft C

Safety of WTC Towers in Aircraft C

• Buildings are not normally designed to withstand 

fuel-laden commercial airliners.

• Safety of the WTC towers and their occupants in 

was a consideration in the original design.

Available Sources of Information:

• Port Authority (February 1964), three-page w

hite paper, “Salient poi

nts with regard 

World Trade Center towers,” dated 2-3-64.

• Port Authority (March 1964), three-page document, “period of vibration due to plane 

• Alternative Insurance Works (2001), World Trade Center Property Risk Report, Pre

Inc.

• The New Yorker (11/1

9/20

01), “The Tower Builder” by J

o

h

n Seabrook, Interview wi

• FEMA 403 (2002), World Trade Center Building Performance Study: Data Collectio

and Recommendations.

• Glanz and Lipton (2003), City in the Sky –

The Rise and the Fall of The –

World Tra
Available Information on Safety of 

Available Information on Safety of 

Towers in Aircraft Collision (1) Towers in Aircraft Collision (1)

Type of Aircraft: Boeing 707 (largest jet aircraft in 

DC-8

Speed of Aircraft: 600 mph (Port Authority, Februa

180 mph (FEMA 403, 2002)

Location of Impact: 80th floor (Port Authority, March 

Structural design: It appears that the design of the 

considered the impact of 707 aiindicated that such collision wouloc

al damage which could not ca

substantial damage to the buildi

NIST found no do

of any analysis suppor
Available Information on Safety of 

Available Information on Safety of 

Towers in Aircraft Collision (2) Towers in Aircraft Collision (2)

Fire safety:

There are two views on whether the effect o

contents was a consideration in the original 

• One view suggests that an analysis was done indica

would be the fact that all the fuel would dump into thwould be a horrendous fire.

• Another view suggests that the fuel load, and the fire 

cause, may not have been considered.

Life safety:

There are two views on the potential effect 

occupant life safety.

• One view, which did not consider the fires, suggests 

would not have endangered the lives and safety of oimmediate area of impact

• Another view, which considered the fires, recognized 

not survive even though the building structure would 
Context of Findings Context of Findings

 Buildings are not specifically designed to withstand the impact of fue

airliners. While documents from The Port Authority of New York and 

indicate that the impact of a Boeing 707 flying at 600 mph, possibly c

was analyzed during the design of the WTC towers in February/Marc

subsequent fires was not considered. Building codes do not require 

consider aircraft impact.

 Buildings are not designed for fire protection and evacuation under t

conditions similar to those caused by the terrorist attacks of Septem

 The load conditions induced by aircraft impacts and the extensive fir

which triggered the collapse of the WTC towers, fall outside the norm 

considered in building codes.

 Prior evacuation and emergency response experience in major even

collapse of tall buildings such as the WTC Towers and WTC 7 that w

everyday use; instead, that experience suggests that major tall build

conditions, not overall building collapse. 

 The PANYNJ was created as an interstate entity, under a clause of t

permitting compacts between states, and is not bound by the buildinlocal, state, or federal jurisdiction. The PAN

Y

N

J’s longstanding state

where appropriate, exceed requirements of local building and fire co
Data Collection and Sources Data Collection and Sources

• NIST based its review, analysis, modeling, 

a

nd t

esting w

ork f

on a solid foundation of technical evidence. This required acce

building documents, videographic and photographic records, emeand oral histories, in addition to sampl

es of recovered WTC steel.

• NIST rec

eived considera

ble cooperation and large vol

umes o

variety of organizations and a

gencies, includi

ng the building 

leaseholders, suppliers, tenants, first r

e

sponders, contractor

photographers, survivors, and families of victims. The documrel

ate to the d

esi

g

n, constructio

n, o

p

eration, inspection, mainten

a

emergency response, and evacuation of the WTC compl

ex.

• NIST received cooperation from The N

ational C

ommission on Ter

United States (9-11 C

ommission).

• Local authorities provi

ding i

nformation i

ncluded The Port Authority 

Jersey (PANYNJ) and its consultants and contractors and severaincluding The Fire Department of the City of New York (FDNY); TDepartment (NYPD); The New York City (NYC) Law Department; Design and Construction (DDC); The NYC Department of BuildingOffice of Emerge

ncy Man

a

g

e

m

e

nt (OEM). 
Data Collection and Sources (2) Data Collection and Sources (2)

• The Occupational Safety and Health Administration provided corre

regarding the evacuation experience of WTC occupants on Septem

• NIST received i

nformation from Sil

verstein Properties and its cons

the group of compani

es that insured the WTC towers and its techn

Lacl

ede Steel; U.S. Mineral Products Co. and Isolatek Internationa

Associates; W.R. Grace & Co.; Citigrou

p, formerly Salomon Smith 

American Airli

nes; and Boeing. 

• The inf

ormation from Silverstein and the insurance companies incl

technical work compl

eted by b

oth parties as part of the i

nsurance l

towers, such as reports on the structural collapse, fire spread and test results for the WTC towers. In addition, technical experts for bprovided extensive briefings t

o t

he W

TC investigation t

eam and dis

environment and the evacuation procedures in the buildings.

• NIST received i

nformation on floor plans, furnishings, and contents 

buildings.

• NIST was unable to gather a small portion of information since tha

the WTC buil

dings collapsed. How

ever, the avail

able information

w

purposes of the i

nvestigation.
Role of WTC Investigation Role of WTC Investigation

• Bring clarity to important technical issues related 

collapses and loss of life based on objective and the facts in the following areas:

•

Building performance (e.g., BPAT Rec

ommen

•

Occupant behavior and evacuation 

•

Emergency response procedures

• Develop findings and recommendations to addres

affecting the safety of buildings, occupants, first rcommunities that face the risk of terrorist threats.

• Develop findings and recommendations to addres

affecting the general safety of buildings, occupanand communities.
WTC Investigation Status WTC Investigation Status

• Investigation nearing completion; drew talent from NIST, outside

contractors; $16 million investigation; $5.5 million awarded in co

•

Two public updates issued (December 2002, December 2003); 

reports issued (

May 2003, June 2004). Full text available on W

•

Three public meetings held:

• June 24, 2002 (NYC) to present draft WTC investigation plan and s

• February 12, 2004 (NYC) to solicit comments on (1) technical aspe

additional information that NIST might consider, (3) areas to be conrecommendations.

• August 24, 2004 (Chicago) to observe fire resistance test of WTC f

Laboratories

•

Six media/public briefings on investigation progress, extensive b

of the National Construction Safety Team Advisory Committee, 2003) to solicit public inp

ut for first-person interviews of occupa

•

Current findings may be revised and additional findings may be 

• NIS

T is not making any recommendations at this time; all re

made in the final report.
Schedule for Completion of Invest

Schedule for Completion of Invest

•

Major focus is on writing the Investigati

on reports; technical work is 

•

The time required t

o write and review t

he comprehensive set of dra

constitute final WTC investigation findings and recommendations ithe report.

•

The NIST reports include the overall investigation report for the WT

project reports, and 34 supporting technical rep

orts, totaling s

ome 

enormous task has taken NIST longer to accomplish than ori

ginally 

•

NIST is committed to putting accuracy, quality, and completeness

whatever time is req

uire

d to d

o the job rig

ht.

•

NIST plans to release a draft of the final report for public comment 

comment period of about 6 weeks after rel

ease of the draft report; 

final Investigation report i

n September 2005.

•

WTC 7 report will be issued as a supplement to the mai

n re

p

ort: dr

2005; final for D

ecember 2005.

• Decoupling of WTC 7 report necessary to accommodate overlapp

on WTC towers.

• This change affects mainly the collapse analysis; other WTC 7 wo

other Investigation reports.

•

WTC Conference: Putting Recommendations into Practice, Se
WTC Investigation Reports WTC Investigation Reports

7A Acc7B Inst

4A FireHistory4B FireSprinklers4C FireAlarms4D SmokeManagement

WTC To

w

ers

Investigation Rep

ort

Building and 

Fire Codes

Baseline

Performance & 

Aircraft Impact

Steel

Analysis

Active Fire 

Protection

Thermal 

Reconstruction

Occu

Beha

Egr

WTC Towers: 

Structural 

Collapse

1A Design andConstruction1B StructuralCode Comparison1C StructuralModifications1D Fire Protection 

&

Life Safety Provisions1E Fire CodeComparison 1F Comparisonof NYC Codes1G Fire Protection& Life Safety A

mend.

1H Post-Const.Modifications WTC1&21I Post-Const.Modifications WTC 71J WTC 7 FuelSystem 

9 

reports

totaling 

about 

1,500 

pages

3A Contemp.Steel Specs.3B SteelInventory3C SteelDamage3D MechanicalSteel3E PhysicalProperties

2A BaselinePerformance2B AircraftImpact

6A Passive FireProtection6B FireResistance Test6C ComponentAnalysis6D GlobalAnalysis

5A 

Visual

Evidence5B SteelExperiments5C SingleWorkstation5D CeilingTile5E MultipleWorkstation 5F FireSimulation5G FireStructure Interface

34

reports

totaling 

about 

8,000 

pages

43 reports for WTC Tow

ers; 5 r

eports for WTC 
Disclaimer No. 1

Certain commercial entities, equipment, products, or materials adocument in order to describe a procedure or concept adequateof the procedures and practices used. Such identification is not recommendation, endorsement, or implication that the entities, pequipment are necessarily the best available for the purpose. Nidentification imply a finding of fault or negligence by the Nationaand Technology.Disclaimer No. 2The policy of NIST is to use the International System of Units (mpublications. In this document, however, units are presented in pound system, whichever is prevalent in the discipline. Disclaimer No. 3:Pursuant to section 7 of the National Construction Safety Team Ahas determined that certain evidence received by NIST in the coInvestigation is “voluntarily provided safety-related information” t

related to the building failure being investigated” and that “disclo

would inhibit the voluntary provision of that type of information” [

In addition, a substantial portion of the evidence collected by NIS

Investigation has been provided to NIST under nondisclosure ag
Disclaimer No. 4:

NIST takes no position as to whether the design or construction compliant with any code since, due to the destruction of the WTC 

not verify the actual (or as-built) construction, the properties and 

materials used, or changes to the original construction made ovebuildings. In addition, NIST could not verify the interpretations o

applicable authorities in determining compliance when implemenWhere an Investigation report states whether a system was desirequired by a code provision, NIST has documentary or anecdotwhether the requirement was met, or NIST has independently coanalyses indicating whether the requirement was met.Use in Legal Proceedings

No part of any report resulting from a NIST investigation into a st

an investigation under the National Construction Safety Team Acsuit or action for damages arising out of any matter mentioned in 281a, as amended by P.L. 107-231).
Dissemin

and Tech

Assistance P

Dissemin

and Tech

Assistance P

BPAT

Recommendations

BPAT

Recommendations

Govt.

Industry

Professional

Academic

Inputs/Actions

Govt.

Industry

Professional

Academic

Inputs/Actions

Public Inputs/

Efforts

Public Inputs/

Efforts

Re

Research &

Development

Research &

Development

WTC

Investigation

WTC

Investigation Re

Guidance and Tools for

Improved Practices

Guidance and Tools for

Improved Practices

Tec

B

Tec

B

Owners, Contractors, Designers,

Emergency Responders and

Regulatory Authorities

S
Safety of Threatened Buildings R

Safety of Threatened Buildings R

Increased Structural Integrity Enhanced 

Prevention of Progressive CollapseTo develop and implement performance 

criteria for codes and standards, tools, and practical guidance for prevention of progressive structural collap

se.

Fire Safe Building Structures

To develop and implement verified and improved standards, tools, methodology and guidance for the fire safety design and 

retrofit of concrete and steel str

uctures.

Fire Protective CoaSteel - Predictive crite

protective coatings to aof materials with reducextreme events.

Fire Resistance oTechnical basis for aprediction methodoloresistance properties in perfor

mance-base

Fire Resistance of SDevelop efficient test meresistance of steel; Beneadequately tested under 
Safety of Threatened Buildings R&

Safety of Threatened Buildings R&

Improved Emergency

Egress & Access

Building & 

Equipment St

Occupant Behavior and EgressReliable predictions of time to egressEmergency Use of ElevatorsTechnical and procedural means to allow use of elevators during emergencies for evacuation of occupants with disabilities from, and for first r

esponder access to, high 

rise buildings

Equipment StanResponders -

T

building infor

mat

infor

med fire figh

Standard InfoStandard buildthat facilitate ssystem behav

Technologies for BCBR Attacks - Anafor assessment and vulnerability of build

Cost-effective User-friendly tooowners/managecost-effective stof terrorist and e
Dissemination and Technic

Dissemination and Technic

Assistance Program Assistance Program

 Concept:

Engage leaders of the construction and building community iimplementation of needed changes to practices, standards, a

 Functions:

Provide inputs and participate in developing best practices, gvulnerability assessment and reduction, guidance on standarRepresent public interest.Timely adoption, dissemination, and use of investigation r

eco

R&D outputs.

 Partners:

Cod

es and standards developers, e.g., ICC, NFPA, ASME, A

Professional, engineering organizations, e.g., IAFC, ASCE, SIndustrial/trade bodie

s, e.g. CII, FIATECH, CERF, NIBS,...
Web site Web site http:// http://wtc.nist.go

Email to Email to wtc@nist.gov

Facsimile to (301) 975 Facsimile to (301) 975-6122

Regular mail: Regular mail:

WTC Technical Information Repository

Technical Information Repository

100 Bureau Drive, Gaithersburg, MD 2

Bureau Drive, Gaithersburg, MD 2
Background Slides Background Slides
National Construction Safety T

National Construction Safety T

PL 107

-231

• Congress directs NIST to investigate building failures that 

“substantial loss of life or that posed significant potential life.”

• NIST investigations are to assess building performance and em

evacuation procedures.

• Building failures include those caused by extreme natural events (e

tornadoes, floods, etc.), building or community-scale fires, failures d

active use, acts of terrorism, Presidential disaster declarations, activResponse Plan.

• Modeled by Congress after the Natio

nal Transportation Sa

NIST with similar authorities.

• NIST is carrying out the World Trade Center investigation 

Nightclub Fire investigation under the authority of the Act.

• NIST is required to establish and deploy an investigation t

building failures to the maximum extent possible.
Earth

q

uakes

San Fernando, CA (1971)Mexico City, Mexico (1985)Loma Prieta, C

A (1989)

Northridge, CA (1994)Kobe, Japan (1995)Kocaeli, Turkey (1999)

H

urricanes

Camille, MS/LA (1969)Alicia, Galveston, T

X (1983)

Hugo, SC (1989)Andre

w, FL (1992)

Hurricane Mitch and Georges, LAC (1998)

Constru

ctio

n/Building 

Skyline Plaza Apartments, Bailey’s Crossroads, VA (1973)Willo

w Island Cooling Tower, W

V (1978)

Kansas City Hyatt Regency, Kansas City, MO (1981)Riley Road Interchange, East Chicago, IN (1982)Harbor Cay Condominium, Cocoa Beach, FL (1981)L’Ambiance Plaza, Hartford, CT (1987)Ashland Oil Tank Collapse, Floreffe, PA (1988)U.S. Embassy, Mosco

w, USS

R (1987)

Murrah Federal Building, Oklahoma City, OK (1995)

Tornado

e

s

Jarrell, T

X (1997)

Spencer, SD (1998)Oklahoma City, OK (1999)

Fir

e

s

DuPont Plaza Hotel, San Juan, PR (1986)First Interstate Bank Building, Los Angeles, C

A (1988)

Loma Prieta Earthquake, CA (1989)Hillhaven Nursing Home (1989)Pulaski Building, Washington, D.C. (1990)Happyland Social Club, Bronx, NY (1990)Oakland Hills, CA (1991)Hokkaido, Japan (1993)Watts St, New York City (1994)Northridge Earthquake, CA (1994)Kobe, Japan (1995)Vandaila St, Ne

w York City (1998)

Cherry Road, Washington, DC (1999)Keokuk, IA (1999)Houston, T

X (2000)

Phoenix, AZ (2001)

Prior NIST Prior NIST Investigatio

Investigati

Results:•

Probable technica

•

Lessons learned: 

•

Improvements to 

practices, technol

•

Establish future r

Existing Authoriti

• NCST Act (2002): buil

emergency response pr

• NIST Act (1986): struc• NEHRP Reauthorizati• National Post-Storm D

storms and floods

• National Response Pla

disaster operations and and industrial hazard an

• Fire Prevention and C

investigations
Some of WTC Response Plan’s A

Some of WTC Response Plan’s A

• Ame

ric

a

n Concrete Institute, Strategic Dev

elopment Counc

• Ame

ric

a

n Society of Civil Enginee

rs, and Civil Engineering 

• Ame

ric

a

n Society of Heating, Refrigerating, a

nd Air-Conditi

• American Society of Mechanical Engineers• Associated General Contractors• Building Owners and Managers Association• Construction Industry Institute, and the Fully Int

egrated and 

Technol

ogy (FIATECH)

• Construction Industr

y Round Table 

• International Association of Fire Chiefs• International Code Council• National Association of State Fire Marshals• National Conference of States on Building Codes and Stand• National Fire Protection Association • National Institute of Building Sciences and International All

Interoperability--North America

• Skyscraper Safety C

ampaign

• The Infrastructure Security Partnership
Challenges Addressed Challenges Addressed

• Strong, conflicting public perspectives• Competing collapse hypotheses• Need for significant advances in state-of-the-art

• Need for developing NCST rules, human subjects 

• Coordination with 9/11 Commission and local auth• Blending “investigation” needs with “research” cult• Leading and managing an extended inv

estigation 

(85 staff from 3 NIST Laboratories; 124 contractorexperts; 27 secretariat/institutional support staff)
The Extended WTC Investigation T

The Extended WTC Investigation T

•

WTC Investigation Team 

•

Other NIST Technical Staff 

•

Secretariat/Institutional Support 

•

Contractor Staff 

•

Experts (Contract/Employee) 

=

Total 
Enabling Actions Enabling Actions

• NIST Actions:

• NIST Director established a World Trade Center study secretariat 

prior to formal announcement of the investigation—to ensure that 

NIST—public affairs, legal, contracts, congressional, budget, safetwork to effectively support the investigation.

• NIST Director selected a new 5-year project on “Failure Analysis o

funding from proposals submitted to the highly competitive NIST-w

• Administration Actions:

• Requested $16 million funding for the WTC investigation.• Requested funding increases for the WTC R&D and DTAP progra

$4 million in FY 2004 and FY 2005, $2 million in FY 2006).

• Congressional Actions:

• House Science Committee held two standing-room only hearings i• Appropriated funds for the WTC investigation ($16 million) and for 

programs ($3 million increase in FY 2003).

• Passed the National Construction Safety Team Act (P.L. 107-231)

on October 1, 2002.
NCST Advisory Committee NCST Advisory Committee

z Appointed by the NIST Director.z Functions...

•

Review procedures and reports

•

Evaluate activities of teams

•

Assess implementation of 

recommendations

•

Annual report to Congress

z Reviewed WTC Investigation plan, 

progress, findings, and draft recommendations at 6 meetings. 

z Reviewed all WTC progress reports and 

final reports

z Membership balances broad scope of 

disciplines and interests

MembersDr. Charles 

Thorn

Dr. Robert 

Dr. Robert 

Unive

Unive

Mr. Philip D

Mr. Philip D

Assoc

Assoc

Professor G

Colleg

Colleg

Dr. Kathlee

Dr. Kathle

e

Colora

Col

or

Mr. Paul Fi

Mr. Paul F

(retire

Mr. David C

Mr. David C

Professo Professor F

r F

of Ca

of Ca

Dr. Joh Dr. J

ohn B

Consu

Consu
Examples of Extensive Media Cove

Examples of Extensive Media Cov

• Wire Serv

• Assoc• Reuter• United 

• TV and Ra

• CBS E• CNN In• WABC• WNBC• Fox Ne• NY1• C-Spa• NPR• WNYC 

• Metro 

• Newspapers

• The New York Times• The Washington Post• The Wall Street Journal• The International Herald Tribune

• The Guardian (UK)• New York City newspapers• Major U.S. newspapers• International newspapers

• Magazines and Books

• The 9/11 Commission Report• City in the Sky (Gl

anz & Lipton)

• 102 Minutes (Dwyer & Flynn)

• Engineering News-Record• Popular Mechanics