National Institute of Standards and Technology Final Plan:

National Building and Fire Safety Investigation 

of the World Trade Center Disaster

NIST Special Publication 1000-1

NIST Special Publication 1000-1

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

National Institute of Standards and Technology Final Plan:

National Building and Fire Safety Investigation 

of the World Trade Center Disaster

August 2002
NISTIR 6942-2

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, to 

preserve original references and quotes, units are presented using the 

inch-pound system throughout.

Use in Legal Proceedings

No part of any report resulting from a NIST investigation can 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).
Final Plan 

National Institute of Standards and Technology

National Building and Fire Safety Investigation of the World Trade Center Disaster

Goals: 

To investigate the building construction, the materials used, and the technical conditions 

that contributed to the outcome of the World Trade Center (WTC) disaster.

To serve as the basis for:

o Improvements in the way buildings are designed, constructed, maintained, and 

used;

o Improved tools, guidance for industry and safety officials;

o Revisions to codes, standards, and practices; and 

o Improved public safety.

Objectives:

The primary objectives of the NIST-led technical investigation of the WTC disaster are to:

1. Determine why and how WTC 1 and 2 collapsed following the initial impacts of the aircraft and 

why and how WTC 7 collapsed;

2. Determine why the injuries and fatalities were so high or low depending on location, including 

all technical aspects of fire protection, occupant behavior, evacuation, and emergency response;

3. Determine what procedures and practices were used in the design, construction, operation, 

and maintenance of WTC 1, 2, and 7; and

4. Identify, as specifically as possible, areas in building and fire codes, standards, and practices 

that are still in use and warrant revision.

Guiding Principles:

Active, comprehensive, independent, and objective technical investigation that is fully 

informed of the concerns and issues of all interested parties and within the limits of 

available resources.

Open and inclusive process in planning and conducting the investigation, and in 

publishing and disseminating findings and recommendations. 

Contribute to improving standards, codes, and practices to reduce future risks by 

focusing on:

o Fact-finding and analysis of the facts, and

o Validating and verifying existing knowledge.

Non-technical issues are outside scope of investigation: No findings of fault or negligence 

of any individual or organization.

Maintain ongoing liaison with professional community, public, and local authorities.

Project teams that include NIST staff and external world-class technical experts.

Source of Information for Plan Development: 

Formulation of the NIST investigation plan drew upon many sources of information from within 

and outside NIST. These include external experts and groups (industry, academia, and 

government), FEMA/ASCE Building Performance Assessment Team (BPAT) members, the 

Building Performance Study report of this team (FEMA Report 403, May 2002), NIST experts in 

building and fire safety, and the public-at-large. NIST held a public meeting in New York City on 
June 24, 2002 to gather comments and suggestions on the scope of the NIST investigation 

detailed in this plan. This plan has been refined based on that input, incorporating many of the 

suggestions received.

Program Context for the Investigation:

The building and fire safety investigation detailed in this plan is a 24-month study of the 

factors contributing to the probable cause (or causes) of collapse of the WTC Towers (WTC 1 

and 2) and WTC 7 and the associated fatalities and injuries. This program will investigate the 

building design and construction, the materials used, and the technical conditions that contributed 

to the outcome of these disasters following the initial impact of the aircraft. What is learned in 

examining WTC 1, 2 and 7 is expected to benefit new and existing buildings.

Parallel to the investigation is a proposed research and development (R&D) program to 

provide the technical basis for improved building and fire codes, standards, and practices. This 

program addresses work in critical areas such as structural fire safety, prevention of progressive 

collapse, building vulnerability reduction tools, and equipment standards for first responders. It 

includes BPAT recommendations for investigation of WTC 3, 4, 5, and 6, Bankers Trust, and 

peripheral buildings as well as recommendations for future studies to address specific issues of 

broader scope not covered by the BPAT. The intent is for the findings and recommendations to 

be introduced into the voluntary consensus process that is used to develop building and fire 

codes and standards in the U.S. The rate at which the recommendations of the investigation can 

be implemented will depend on the level of funding available to the R&D program.

An industry-led dissemination and technical assistance program (DTAP) is the third part of 

the proposed NIST response plan. The DTAP is designed to provide practical guidance and 

tools to better prepare facility owners, contractors, architects, engineers, emergency responders, 

and regulatory authorities to respond to future disasters. The DTAP is an important complement 

to the R&D effort in gaining acceptance of proposed changes to practice, standards, and codes. 

In addition, it will address BPAT recommendations for training and education of stakeholders.

The proposed NIST response plan complements, is responsive to, and goes beyond the BPAT 

efforts. The plan addresses all major recommendations contained in the BPAT report. NIST has 

also identified other critical issues that need study, especially in areas that impact life safety and 

engineering practice.

Scope and Rationale for Building and Fire Safety Investigation: 

The NIST building and fire safety investigation will focus exclusively on the WTC Towers and 

WTC 7. The results of this investigation could stimulate major changes in both U.S. building and 

fire codes and in engineering practice, despite the unique design features of the buildings or 

circumstances under which they collapsed. The lessons to be derived from the investigation will 

be applicable to a broad range of buildings types, not just the specific buildings that are studied. 

These real-life lessons will inform the R&D and DTAP elements of the NIST response plan and 

be extremely useful to the building and fire communities in considering needed changes to codes, 

standards, and practices. The following examples illustrate the value of an investigation focused 

on the WTC Towers and WTC 7.

The WTC Towers and WTC 7 are the only known cases of total structural collapse in high-rise 

buildings where fires played a significant role. These building collapses provide a unique source 

of information to understand the complexities associated with the dynamics of building fires and 

the collapse vulnerability of buildings to fires. Through the analysis of that information, the 
investigation will provide an excellent case study to apply and gain experience in the use of 

general methodologies for fire safety design and retrofit of structures.

In addition, lessons will be learned on:

The behavior of open-web steel trussed joists to withstand the thermal environment 

present in large fires. Joists are used in commercial and institutional buildings nationwide.

The behavior of fireproofing materials and the fire performance of connections used in 

steel structures.

Possible mechanisms - not considered previously - that could initiate progressive 

collapse in buildings as a result of fires and impact loads, and the critical role of pivotal 

components such as transfer girders and floor diaphragms.

The mechanical and metallurgical behavior of different grades of structural steel in these 

buildings (using steel recovered from the WTC site that is being stored at NIST).

There are equally important lessons to be derived for life safety that were outside the scope of the 

BPAT study.

The control of fire spread in buildings with potentially large open floor plans, and the 

effectiveness of compartmentation as a means to isolate fires in such buildings.

The role of occupant behavior and evacuation technologies and practices for tall 

buildings, including decision-making and situation awareness, time-constrained 

evacuation strategies, communications, role of floor wardens and fire safety directors, 

and issues concerning people with disabilities.

The role of current firefighting technologies and practices for tall buildings, including 

emergency response, equipment, pre-planning, and training, and the performance of 

active fire protection systems such as sprinklers, manual suppression, fire alarms, and 

smoke management systems.

Command, control, and communication systems for fire service response.

There are also important lessons to be derived for architectural and engineering practice that 

were not the focus of the BPAT study.

The technical evaluation process and practices used to assure safety whenever an 

innovative system is planned or an alternate method that deviates from existing building 

and fire codes is used.

The margin of safety and degree of structural redundancy to accommodate local failures 

from abnormal loads such as blast, impact, and accidental fires.

The NIST investigation will strive to study the disaster holistically, paying particular attention to 

the interplay between the building, the occupants, and the emergency responders. The review, 

analysis, modeling, and testing work will be based upon a solid foundation of technical evidence 

provided by critical data such as building documents, video and photographic records, oral 

histories, emergency response records, and recovered structural steel.

Technical Approach: 

The technical approach of the NIST building and fire safety investigation will include the following 

phases over an estimated 24 month period:

Identification of Technical Issues and Major Hypotheses Requiring Investigation:

opportunity for public input (e.g., public meeting; website; Federal Register notice) in 

developing investigation plan; consultations with experts in structural and fire protection 
engineering and in construction, maintenance, operation and emergency response 

procedures of tall buildings); findings and recommendations of BPAT study and technical 

issues identified by other experts; analysis of inputs to establish priorities for 

investigation; review by Federal Advisory Committee.

Data Collection: inputs from building owners and operators, local authorities, designers, 

consultants, and contractors; data and information collected by the BPAT study; building 

and fire protection design documents, records, plans, and specifications; construction, 

maintenance, operation records, building renovations and upgrades; video and 

photographic data; field data; interviews and other oral and written accounts from building 

occupants, families of victims, emergency responders, building operators, and other 

witnesses; emergency response records including audio communications; and other 

records. 

Analysis and Comparison of Building and Fire Codes and Practices: analysis and 

comparisons of codes, standards, and specifications used for WTC buildings; comparison 

of codes with codes in other jurisdictions; review and analysis of practices used for 

design, construction, operation, maintenance, repair, renovations, and upgrades.

Collection and Analysis of Physical Evidence: structural steel, material specimens 

and other forensic evidence to the extent they have been collected or are otherwise 

available; analysis of metallurgical and mechanical properties of steel to evaluate its 

quality and to estimate temperature conditions in the buildings before collapse. 

Modeling, Simulation, and Scenario Analysis: aircraft impact on structures and 

estimated damage to interior and core structures and residual structural capacities; role 

of jet fuel and building contents in resulting fire; fire dynamics and smoke movement; 

thermal effect on structures and the effectiveness of fireproofing; effect of fire on 

structural response and vulnerability and the role of connections, flooring system, and 

core and exterior columns; occupant behavior and response including influence of 

communications and barriers to egress; evacuation issues including egress, control/fire 

panels, emergency response, and communications; fire protection system design and 

vulnerability; hypotheses for structural collapse including evaluation of system 

vulnerability to progressive collapse; probable collapse mechanisms and associated 

uncertainties. 

Testing to Re-Create Scenarios and Failure Mechanisms: reduced and real-scale 

tests to provide additional data and verify simulation predictions, especially for the effects 

of fires. 

Technical Findings and Recommendations: preparation of interim and final reports; 

peer review by established NIST Editorial Review Board; augmented NIST review to 

include senior management and legal; review of key reports by Federal Advisory 

Committee; finalize and disseminate via published reports, web, and media. 

Identify Needs for Changes to Codes and Standards: identify specific areas in need of 

change to codes, standards, and practices based on findings of investigation (note: 

specific recommendations and actions for proposed changes to codes, standards, and 

practices will be made via the R&D and DTAP programs). 
The NIST investigation plan includes eight projects that provide the focus for the technical work. 

These are:

Project #1: Analysis of Building and Fire Codes and Practices

Project #2: Baseline Structural Performance and Aircraft Impact Damage Analysis

Project #3: Mechanical and Metallurgical Analysis of Structural Steel

Project #4: Investigation of Active Fire Protection Systems

Project #5: Reconstruction of Thermal and Tenability Environment

Project #6: Structural Fire Response and Collapse Analysis

Project #7: Occupant Behavior, Egress, and Emergency Communications

Project #8: Fire Service Technologies and Guidelines. 

These projects are interdependent, and when considered together will meet the NIST 

investigation objectives. A detailed description of each of these eight projects is in Attachment 1.

Technical Expertise: 

The NIST building and fire safety investigation will include world-class technical experts from both 

within and outside NIST. External experts will be drawn from academia, practice, and government 

and used on an as-needed basis in various phases of the investigation. Several of these experts 

may have contributed to the BPAT study.

Federal Advisory Committee: 

NIST will charter a 7-10 member Federal Advisory Committee to provide advice to the NIST 

Director on all aspects of the investigation, including scope, approach, work plan, schedule, 

results, findings, recommendations, and interim and final technical reports. The Federal Advisory 

Committee will provide advice on the objectivity, thoroughness, and integrity of the investigation. 

Committee meetings will be announced in the Federal Register. The NIST Director will appoint 

individuals to the committee who are recognized for distinguished professional service, possess 

broad technical expertise and experience, and have a reputation for independence, objectivity, 

and impartiality. Members will represent a balance of the diverse disciplines relevant to the 

investigation, including structural engineering, fire protection engineering, metallurgy, firefighting, 

human behavior, property insurance, and architecture. Members will be selected to avoid conflicts 

of interest. They shall not: be current NIST employees, be the recipient of an active NIST grant or 

contract directly related to the WTC investigation, represent parties affected directly by the 

investigation, participate in the conduct of the investigation, or participate in litigation on matters 

directly and specifically within the scope of the NIST investigation.

NIST Secretariat: 

The Director of NIST has established a secretariat to coordinate NIST-level activities in support of 

the investigation and to maintain ongoing liaison with the Executive Branch, the Congress, the 

public, and the media. NIST recognizes that there will be significant public and media interest in 

the investigation. NIST has assigned a spokesperson to provide press announcements and 

coordinate media briefings during the course of the investigation. NIST will also provide 

information via reports and briefings to the Executive Branch and Congress at their request. The 

secretariat includes representatives of the Building and Fire Research Laboratory, Congressional 

and Legislative Affairs, Budget Division, Public and Business Affairs Division, NIST Counsel, 

Program Office, Acquisition and Logistics Division, Occupational Health and Safety Division, and 

the Management and Organization Division.

Liaison with the Professional Community, the Public, and Local Authorities: 

NIST will maintain ongoing liaison with the professional community, the general public, and local 

authorities over the course of the investigation through briefings and presentations. NIST has 
established a website to communicate information related to the investigation (http://wtc.nist.gov). 

This information will also be available in print; every effort will be made to ensure that those 

without internet access can receive the same information by mail. In addition, NIST has assigned 

a special liaison to interact with the families of building occupants and first responders. NIST 

recognizes the vital role that those individuals and groups have to play in providing input to the 

NIST investigation. NIST also believes that it is appropriate and important to keep these families 

and organizations informed about the progress of the investigation.

Impact and Outcomes:

The NIST investigation aims to establish the probable technical causes of the collapse of the 

WTC towers after the aircraft impact and WTC 7 and the associated loss of life and injuries. 

Implementation of the results of the NIST investigation, in conjunction with those of the R&D and 

Dissemination and Technical Assistance elements of the NIST response plan, will restore 

confidence by making buildings safer nationwide, enhancing the safety of fire and emergency 

responders, better protecting building occupants and property, and providing better emergency 

response capabilities and procedures in future disasters. 

The findings and recommendations of the NIST investigation will support and guide future work 

that will develop and disseminate guidance and tools, assess and reduce vulnerabilities, and 

produce the technical basis for cost-effective changes in national codes, standards, and 

practices. A private sector coalition, representing key industry, standards, codes, and 

professional organizations, has worked with NIST to establish the response plan to meet longerterm needs. The goal of the response plan is to produce cost-effective design and retrofit 

measures as well as operational guidance for building owners and emergency responders.

Table 1: Outputs for National Building and Fire Safety Investigation 

of the World Trade Center Disaster

Technical Area Project # Outputs

Identification of 

Technical Issues 

and Major 

Hypotheses

Planning 

Phase

Public Meeting to gather comments on scope of 

NIST investigation plan. 

Implementation Plan for NIST Investigation. 

Major Hypotheses and Technical Issues for 

Investigation 

Analysis of 

Building and Fire 

Codes and 

Practices 

1

Report(s) on the code provisions, procedures, and 

practices used in the design, construction, 

operation, and maintenance of the structural, 

passive fire protection, and emergency access and 

evacuation systems of the WTC 1, 2, and 7. 

Baseline 

Structural 

Performance and 

Aircraft Impact 

Damage Analysis

2

Report(s) on the baseline performance of WTC 1 

and 2 under design, service, and abnormal loads 

and the analysis of aircraft impact damage on the 

structural, fire protection, and egress systems. 
Mechanical and 

Metallurgical 

Analysis of 

Structural Steel

3

Report(s) on the mechanical and metallurgical 

properties and quality of steel, weldments, and 

connections from steel recovered from WTC 1, 2, 

and 7. 

Investigation of 

Active FireProtection 

Systems

4

Report(s) on the performance of the active fireprotection systems in WTC 1, 2, and 7 and their 

role in fire control, emergency response, and fate of 

occupants and responders. 

Reconstruction of 

Thermal and 

Tenability 

Environment

5

Report(s) on the reconstruction of the time-evolving 

temperature, thermal environment, and smoke 

movement in WTC 1, 2, and 7 for use in evaluating 

the structural performance of the buildings and 

behavior and fate of occupants and responders. 

Structural Fire 

Response and 

Collapse Analysis

6

Report(s) on the response of the WTC Towers to 

fires with and without aircraft damage, the response 

of WTC 7 in fires, the performance of open-web 

steel joists, and the most probable structural 

collapse mechanisms for WTC 1, 2, and 7. 

Occupant 

Behavior, Egress, 

and Emergency 

Communications

7

Report(s) on the behavior and fate of occupants 

and responders, both those who survived and 

those who did not, and analysis of the performance 

of the evacuation system. 

Fire Service 

Technologies and 

Guidelines

8

Report(s), building on the work of the work done by 

the Fire Department of New York and McKinsey & 

Co., that: document what happened during the 

response by the fire services to the attacks on the 

World Trade Center until the collapse of WTC 7; 

identify issues that need to be addressed in 

changes to practice, standards, and codes; identify 

alternative practices and/or technologies that may 

address these issues; and identify R&D needs that 

advance the safety of the fire service in responding 

to massive fires in tall buildings. 

Technical Findings 

and 

Recommendations

Reporting 

Phase

Interim and Final Reports of the Investigation, 

including probable technical causes of the disaster 

and identification of areas in of codes, standards, 

and practices that warrant change. 

Attachment 1

Description of Investigation Projects

Project #1: Analysis of Building and Fire Codes and Practices

Purpose: To obtain, review, and analyze applicable building code provisions and project 

documents and to determine the procedures and practices that were used in the design, 

construction, operation, and maintenance of the structural, fire protection, and emergency access 

and evacuation systems of WTC 1, 2, and 7, and to provide input to other investigation projects.

Technical Approach: This project focuses on gathering background information that governed 

the design, construction, operation, and maintenance of the WTC buildings as related to 

structural and fire safety performance. The major sources of information will be historical records 

that have been maintained by various entities involved in the design, construction, operation, and 

maintenance of the structural system, the passive fire protection systems, and the emergency 

access and evacuation system. In addition, building code provisions that governed the project will 

be compared with code provisions of other jurisdictions that governed tall buildings at the time of 

design and construction of the WTC buildings. A summary will be prepared of those aspects of 

the structural, passive fire protection, and emergency access and evacuation systems that may 

have bearing on the structural performance, occupant evacuation, and loss of lives on September 

11, 2001. This project is divided into eight tasks as follows:

Task 1—Review design calculations and project documents. Available documents related to the 

original design will be reviewed to establish the design loads and methods used to proportion 

structural components. Special effort will be devoted to documenting the approval process for 

those aspects of the structural system used in the WTC towers that were not covered by the 

provisions of the governing code and to document abnormal loads anticipated at the time of the 

original design of the WTC towers. Available project and as-built drawings (structural, 

mechanical, architectural) will be obtained for use by other investigation projects.

Task 2—Review building construction. Available construction documentation (such as 

construction logs, change orders, test and inspection reports) will be reviewed. Significant events 

encountered during construction (and over the life of the buildings) that may have impacted the 

performance of the structural, passive fire protection, and elevator systems will be identified and 

documented. The architectural configuration will be established for the affected stories of WTC 1 

and 2 and WTC 7 on September 11 before the attacks.

Task 3—Review passive fire protection features. Those codes and standards that applied to the 

passive fire protection features of the WTC buildings will be reviewed. This includes those in 

effect at the time of construction and those in effect during occupancy. Also included are 

documents on the passive structural fire protection system used in the buildings such as 

fireproofing, compartmentation, fire stops, and enclosures around egress paths. The structural 

integrity and fire safety performance of the enclosure shaft for the elevators and stairs will be 

studied. The maintenance records of the passive fire protection systems will be reviewed. 

Relevant modifications made to the passive fire protection systems during the service life of the 

buildings and after the 1993 bombing will be documented.

Task 4—Review emergency access and evacuation systems. Review the design, operation, 

maintenance, and inspection of the emergency access and evacuation systems (e.g., stairwells 

and elevators) in the WTC towers and the condition of these systems at the time of collapse of 

the buildings. Collect the relevant literature and review existing U.S. and international standards 

and identify design characteristics and maintenance practices applied to such systems in WTC 1 
and 2 that affected their performance on September 11, 2001. Standards and practices for 

firefighter lifts and FDNY policies will be reviewed to evaluate the potential effectiveness of such 

technology in improving firefighter effectiveness and reducing firefighter losses.

Task 5—Code comparisons. The New York City, the New York State, and national model codes 

that were in effect when the buildings were designed will be documented. Specific provisions in 

those codes will be compared with design requirements for the WTC 1, 2 and 7 buildings. Focus 

will be on the structural loading criteria and provisions for structural fire protection, active and 

passive fire protection systems, and emergency access and evacuation. Code provisions will be 

compared for high-rise construction in other code jurisdictions with those that governed the 

design of the WTC towers. Current model code provisions will also be compared with those then 

in effect that governed the design and construction of the WTC buildings. In addition, provisions 

for code enforcement will also be compared.

Task 6—Review maintenance records. A review will be conducted of maintenance and 

renovation that may have affected the structural system and the passive fire protection system. 

The objective is to develop the most accurate representation of the structural systems, including 

the condition of the structural fire protection, as they existed in the portions of the buildings 

affected by aircraft impacts on September 11, 2001.

Task 7—Document structural modifications following the 1993 bombing. The structural 

modifications that were made after the 1993 bombing will be reviewed to determine whether they 

may have affected the structural system of the WTC buildings.

Task 8—Report preparation. The results of this project will be synthesized into a chapter to 

describe the design, construction, and maintenance of and modifications to the WTC buildings. 

The structural configuration, passive fire protection systems, and emergency access and 

evacuation system at the time of the attack will be described. In addition, the internal condition of 

the architectural and mechanical systems will be documented with input from other investigation 

projects. The project staff will contribute to drafting the final investigation report for review by the 

Federal Advisory Committee.

Outputs and Estimate of Time-to-Completion(1):

1. Interim report that documents the design basis for the WTC buildings and describes the 

process by which the innovative structural system was approved and the abnormal loads from 

aircraft impact anticipated in the original design of the WTC towers (6 months).

2. Interim report that summarizes pertinent construction data for the WTC buildings (9 months).

3. Interim report that documents code provisions related to high-rise construction and structural 

fire safety (9 months).

4. Interim report that documents maintenance and modifications that may have affected the 

structural and passive fire protection systems within the affected regions of the buildings. This 

includes modifications resulting from the 1993 bombing (10 months).

5. Interim report on regulations and practices related to the passive fire protection features 

systems in the buildings (9 months).

6. Interim report on the design, operation, maintenance, and performance of emergency access 

and evacuation systems in the WTC towers (6 months).
7. Draft chapter for final report that describes the design, construction, operation, and 

maintenance of and modifications to the structural, passive fire protection, and emergency access 

and evacuation systems, and that documents the probable conditions of the buildings at the time 

of the attacks on September 11, 2001 (16 months).

(1) Estimated time-to-completion is from start of investigation.

Project #2: Baseline Structural Performance and Aircraft Impact Damage 

Analysis

Purpose: To evaluate the role of the structural system design and the abnormal loads from 

aircraft impact on the collapse of the WTC towers by: (1) developing reference structural, 

mechanical, and architectural (SMA) models of the WTC towers, (2) establishing baseline 

performance of each of the towers under normal design loading conditions (gravity and wind), (3) 

estimating probable damage to the SMA systems of the towers due to aircraft impact, (4) 

comparing differences between anticipated and actual abnormal loads posed by aircraft impact, 

and (5) estimating the structural reserve capacities of the towers to accommodate abnormal loads 

under service conditions and the reserve capacities after aircraft impact.

Technical Approach: This project focuses on establishing the performance of the WTC towers 

under normal design loads, estimating the probable damage to the structural, mechanical, and 

architectural (SMA) systems, and evaluating the effect of the aircraft impact on the reserve 

capacity of the WTC towers. These damage estimates are required for reconstructing the fire and 

smoke environment and for analyzing structural fire response and collapse. In addition, a 

comparison will be conducted between the response and damage to the towers due to the impact 

of the Boeing 767 aircraft and the abnormal load condition of a Boeing 707 aircraft impact as 

considered in the original design. This project will also evaluate the reserve capacities of the 

towers immediately after impact. This project is divided into six tasks as follows:

Task 1—Develop SMA models of the two towers. The structural plans for the two towers will be 

studied to select appropriate structural modeling strategies for the different response analysis 

objectives. The models will need to recognize the special features of the structural system such 

as the floor diaphragms systems consisting of open-web steel trussed joists and a composite 

slab, the exterior prefabricated spandrel beam and column elements, and the variety of 

connection details used in the towers. The models will have varying levels of complexity ranging 

from frame elements for the entire structural system to detailed finite element meshes of shell 

elements for the structure in the vicinity of the level of impact. These models, after third-party 

review, will be used by other investigation projects dealing with the structural performance of the 

towers. To simplify modeling efforts, a database will be developed for the two towers with 

geometries, dimensions, and material properties of the various structural members. CAD models 

will be developed to represent mechanical and architectural systems. Mechanical models will 

include HVAC, elevators, and water supply systems while architectural models will include interior 

layouts, stairways, fire suppression systems, etc.

Task 2—Analyze the structural models of the towers under design loading and service loading 

conditions, estimate the structural reserve capacities, and evaluate the effectiveness of the floor 

system to prevent column buckling. Estimate the resistance of the stairwell construction to 

pressure loads.

Task 3—Simulate the Boeing 767 aircraft crashes into the towers to estimate the extent of 

damage to SMA systems. The analysis of the aircraft crash will be performed at various levels of 

complexity ranging from energy and momentum conservation calculations to state-of-the-art, 
three-dimensional, and large-deflection finite element analyses of both the aircraft and the towers. 

The simulations will account for the speed, direction, and mass and stiffness distribution of the 

aircraft. This task will use WTC tower steel properties, including high strain rate properties, 

obtained from the project on Metallurgical and Mechanical Analysis of Structural Steel. The 

primary purpose of this task is to provide estimates of the probable damage to structural systems 

- including floors and exterior tube and interior core columns, and the load redistribution provided 

by the outrigger truss system - rather than the damage done to the aircraft. Therefore, the level of 

complexity of the aircraft model will be selected to achieve this analysis objective. The simulation 

of the aircraft crash into the towers will account for the several sources of uncertainty pertaining 

to the towers and the aircraft to obtain uncertainty bounds for the results. Structural models of the 

damaged towers will be developed for use in subsequent analyses.

Task 4—Analyze the towers for the abnormal loads from an impact of a Boeing 707, flying at the 

speed assumed in the design, to estimate the extent of damage and the reserve capacity after 

impact. The results of this analysis will be compared with information that may be available on the 

damage estimated in the original design of the towers. A comparison will be conducted between 

the results of tasks 3 and 4 to evaluate the differences in the response and damage between the 

anticipated design case and actual aircraft impact into each tower.

Task 5—Determine the structural reserve capacity (or margin of safety against collapse) within a 

probability based framework under existing service loads following the loss of exterior and core 

columns and floors due to the aircraft impact. This task will help to determine the mechanism by 

which the towers remained standing immediately after the aircraft crashes and prior to collapse, 

and specifically to evaluate the structural integrity after the crashes.

Task 6—Report preparation. The results of this project will be synthesized into a chapter to 

describe the baseline structural performance of each of the towers under design and service load 

conditions, estimates of damage to the SMA systems due to aircraft impact, and the reserve 

capacity of the structural components under normal design loads, abnormal design loads, and 

subsequent to damage by aircraft impact. The project staff will contribute to drafting the final 

investigation report for review by the Federal Advisory Committee.

Outputs and Estimate of Time-to-Completion:

1. Estimation of the damage to the towers. Models for Boeing 767 and 707 aircraft obtained (4 

months).

2. Reference structural, architectural, and mechanical models of the towers. Third-party review of 

SMA models (6 months).

3. Interim report on estimation of the local and global response of the towers to aircraft impact 

including damage to structural, architectural, and mechanical systems (14 months).

4. Reference structural models of the damaged towers (13 months).

5. Interim report on the baseline performance of the two towers under service and design loads 

(gravity and wind) (16 months).

6. Response analysis of the WTC towers to actual and anticipated abnormal loads from aircraft 

impact (15 months).
7. Interim report on estimation of the structural reserve capacity of the towers under normal 

design, abnormal design loads, and immediately after aircraft impact (17 months).

8. Draft chapter for final report that describes the baseline structural performance of the towers 

under design and service load conditions, and estimates damage to the SMA systems due to 

aircraft impact and the reserve capacity of the components of the tower structures damaged by 

aircraft impact (18 months).

Project #3: Metallurgical and Mechanical Analysis of Structural Steel

Purpose: To analyze structural steel available from WTC 1, 2, and 7 for determining the 

metallurgical and mechanical properties and quality of the metal, weldments, and connections, 

and providing these data to other investigation projects.

Technical Approach: This project is divided into six tasks as follows:

Task 1—Collect and catalog the physical evidence (structural steel components and connections) 

and other available data, such as specifications for the steel, the location of the steel pieces 

within the buildings, and the specified steel properties.

Task 2—Document failure mechanisms and damage based on visual observations of recovered 

steel, especially for available columns, connectors, and floor trusses. Possible factors contributing 

to extreme erosion seen on some parts of the steel columns will be studied. 

Task 3—Determine the metallurgical and mechanical properties of the steel, weldments, and 

connections, including temperature dependence of properties. The grades of steel will be 

identified in the columns, welds, spandrels, trusses, truss seats, and fasteners. The identification 

will include composition, microstructure, mechanical, and impact properties. This project will 

provide steel property data, including models of elevated temperature behavior for relevant 

steels, to estimate damage to the structural steel members from aircraft impact, evaluate 

structural fire response, and study the initiation and propagation of structural collapse in the 

project on Structural Fire Response and Collapse Analysis. 

Task 4—Correlate determined steel properties with the specified properties for construction of the 

buildings. The quality of the steel used in the buildings will be compared with that specified.

Task 5—Analyze the steel metallographically to estimate maximum temperatures reached. It is 

recognized that high temperature exposure before the collapse may be difficult to distinguish from 

exposure during post-collapse fires.

Task 6—Report preparation. The results of this project will be synthesized into a chapter to 

describe the results of the metallurgical and mechanical analysis of the structural steel available 

from the WTC towers and WTC 7. The project staff will contribute to drafting the final investigation 

report for review by the Federal Advisory Committee.

Outputs and Estimate of Time-to-Completion:

1. Catalog of available structural steel and relevant specifications (4 months).

2. Documentation of failure mechanisms and damage from visual observations (4 months).
3. Interim reports on the metallurgical and mechanical properties of the steel and connections, 

including temperature dependence of properties.

a. Data to support model development—identification of steel in the columns, welds, spandrels, 

trusses, truss seats, and fasteners based on composition, microstructure, room temperature 

tensile properties, and impact properties (partial results in 4 months, complete in 12 months).

b. Data to support aircraft impact modeling studies—high strain rate mechanical properties and 

impact properties of columns, spandrels, bolts, and welds on columns (partial in 4 months, 

complete in 14 months).

c. Data to support models of steel frame performance in fire—creep and high temperature tensile 

properties of columns, bolts on columns, trusses, truss seats, and bolts or welds associated with 

truss seats (partial results in 4 months, complete in 12 months).

d. Data to support models of steel during collapse—high strain rate room temperature tensile 

properties of truss seats and associated bolts and welds (partial results in 5 months, complete in 

16 months).

e. Models of elevated temperature deformation as a function of load, temperature and time 

history for relevant steels (some steels in 6 months, complete in 16 months).

4. Estimation of maximum temperatures reached by collected structural steel (complete in 12 

months).

5. Database of microstructural changes with temperature in the various classes of steels for 

future use by building and fire communities (16 months).

6. Comparison of steel properties to applicable material specifications (12 months).

7. Draft of chapter for final report that describes the results of the metallurgical and mechanical` 

analysis of the structural steel available from the WTC towers and WTC 7 (18 months).

Project #4: Investigation of Active Fire Protection Systems

Purpose: To document and evaluate the performance of the installed active fire protection 

systems in the World Trade Center Buildings 1, 2, and 7 and assess their role in fire control, 

emergency response, and the fate of occupants and responders.

Technical Approach: This project is divided into nine tasks as follows:

Task 1—Establish contacts with the Port Authority, Silverstein Properties, their contractors and 

consultants to obtain information relevant to this project.

Task 2—Develop a comprehensive set of questions to collect information from building operators, 

first responders, building occupants, and families of victims on the operation of and damage to 

the fire safety systems on September 11, 2001. These questions will be coordinated with other 

investigation projects, in particular those for building and fire codes, occupant behavior and 

egress, and fire service technologies and guidelines. 
Task 3—Document the performance of active fire protection systems during significant fires in 

WTC buildings 1, 2, and 7 prior to September 11, 2001.

Task 4—Document the design, installation and normal operation of installed active fire protection 

systems, including sprinklers, fire alarm, smoke management systems, pre-connected hoses, and 

communication system for building occupants in WTC buildings 1, 2, and 7. Review available fire 

inspection reports.

Task 5—Document the design and capacity of the water supply to the fire sprinkler systems. 

Review the redundancy and defense-in-depth of the water supply system.

Task 6—Estimate the limits of performance for fully functional sprinkler systems as installed in 

the buildings. 

Task 7—Analyze the design of the active fire protection systems relative to applicable building 

code provisions and standards at the time of installation. The maintenance, modifications, and 

inspection records for these systems will be reviewed. Modifications made after the 1993 

bombing incident will be documented.

Task 8—The information collected in tasks 1-7, along with other information developed in 

projects, will be reviewed and analyzed by NIST staff with the assistance of other fire protection 

engineers with expertise in the operation and capabilities of active fire protection systems. The 

analysis will establish the facts regarding the performance of these systems in WTC 1, 2, and 7. 

NIST staff will interpret and analyze these facts and document the findings. 

Task 9—Report preparation. Synthesize the results of this project into a chapter to describe the 

installed active fire protection systems in WTC 1, 2, and 7, and the performance of these systems 

on September 11, 2001. The project staff will contribute to drafting the final investigation report for 

review by the Federal Advisory Committee.

Outputs and Estimate of Time-to-Completion: 

1. Compilation of information on performance of active fire protection systems in previous fires in 

WTC Buildings 1, 2, and 7 (3 months).

2. Comprehensive set of questions for collecting information on the operation of and damage to 

fire safety systems on September 11, 2001 (3 months).

3. Interim findings on the design, installation, and maintenance of and modifications to active fire 

protection systems present in WTC 1, 2, and 7 (6 months).

4. Completion of estimates of the performance limitations of fully functional sprinkler systems of 

the type and capacity installed in the WTC buildings (8 months).

5. Synthesis of collected information that will be used to establish the facts and analyze the 

performance of the active fire protection systems (12 months).

6. Draft of chapter for final report that describes the installed active fire protection systems in 

WTC 1, 2, and 7, and evaluates the performance of these systems on September 11, 2001 (18 

months).
Project #5: Reconstruction of Thermal and Tenability Environment

Purpose: Reconstruct, with assessed uncertainty limits, the time-evolving temperature, thermal 

radiation, and smoke fields in World Trade Center Buildings 1, 2, and 7 for use in evaluating the 

behavior and fate of occupants and responders and the structural performance of the buildings.

Technical Approach: This project is divided into seven tasks as follows:

Task 1—Develop guidance on the initial conditions for modeling the fires, the rates of fire spread, 

and the floors on which the structural collapses appear to have begun through the acquisition of 

available and relevant photographic and video images of damage to the three buildings, review of 

accounts from occupants and responders (via project #7), and the cataloging and analysis of 

such images and accounts.

Task 2—Gather data on the internal construction materials, furnishings and contents to 

characterize the types of combustibles and estimates of the mass loading and to compare them 

with data from prior surveys of similar occupancies. Other fuel sources in WTC 7 will be identified 

and documented. The extent of the dispersed aviation fuel in WTC 1 and 2 will be estimated 

based on input from the Baseline Structural Performance and Aircraft Impact Damage Analysis 

project.

Task 3—Compile existing data on the fire performance of floor, wall, and ceiling systems and on 

the nature of openings (ducts, shafts, etc.), complemented by additional measurements as 

needed, to determine air access for combustion, to identify fire paths for intercompartment fire 

spread, and to identify those paths that were capable of contributing to the collapse of the 

buildings. 

Task 4—Determine the thermal properties of the structural insulation systems and the effects of 

vibration, impact, and shock on their thermal performance. Use this information to estimate the 

thermal environment on the outside surface of the protected structural members. Also included 

will be the extent to which the coatings were in place on September 11 and any indication of 

whether chemical interaction between the insulation materials and the steel at elevated 

temperatures could have contributed to degradation of structural performance in the time 

available.

Task 5—Extend the capabilities of NIST's Fire Dynamics Simulator (FDS), using knowledge 

gained from the previous tasks, to reconstruct the temperature, thermal radiation, and smoke 

fields within the three buildings (including floor spaces and stairwells) as a function of time and 

location. Reduced-scale experiments will be used to guide and evaluate the accuracy of key FDS 

sub-models. 

Task 6—Use FDS to simulate fully involved fires in the three buildings, with and without the initial 

damage from the aircraft or incident debris, for evaluating the extent that damage affected the 

thermal environment experienced by the structure. Parameter variations in the re-creation of the 

fires will enable characterization of (as appropriate to each of the three buildings) the mode and 

locale of fire ignition; the roles of jet fuel and building contents, ventilation system, compartment 

damage, pressurized core, and fire protection system on growth and spread of fire; the rate and 

extent of fire spread; and the extent of hot, smoky, and toxic conditions. Uncertainty will be 

estimated for the results of the analyses. The effectiveness of compartmentation in controlling fire 

spread in these buildings will be analyzed.
Task 7—Report preparation. The results of this project will be synthesized into a chapter to 

describe the time-evolving temperature, radiation, and smoke fields in WTC 1, 2, and 7, the 

effectiveness of compartmentation in controlling fire spread in these buildings on September 11, 

2001, and the associated uncertainties. All experiments, model assumptions and operations, and 

reconstructions will be documented. The project staff will contribute to drafting the final 

investigation report for review by the Federal Advisory Committee.

Outputs and Estimate of Time-to-Completion: 

1. Acquisition and analysis of photographic and video images of damage to WTC buildings 1, 2, 

and 7 (3 months).

2. Compilation of data on construction materials and systems, furnishings and contents, and other 

fuel loads (4 months).

3. Evaluation of the thermal performance of structural insulation system(s) (8 months).

4. Completion of experiments to guide FDS sub-model development (10 months).

5. First prediction of the fire dynamics in one of the WTC towers (12 months).

6. Evaluation of pathways for fire ventilation and for compartment-to-compartment fire growth in 

the three buildings (14 months).

7. Completion of reduced-scale demonstration experiments (15 months).

8. Final predictions, with uncertainties, of the time-varying temperature, thermal radiation and 

smoke fields in WTC 1, 2, and 7 (16 months).

9. Draft chapter for final report that describes the time-evolving temperature, radiation, and smoke 

fields in WTC 1, 2, and 7 and the effectiveness of compartmentation in controlling fire spread in 

these buildings on September 11, 2001 (18 months).

Project #6: Structural Fire Response and Collapse Analysis

Purpose: To determine the response of structural components and systems to the fire 

environment in WTC 1, 2, and 7, and to identify probable structural collapse mechanisms.

Technical Approach: This project is divided into seven tasks as follows:

Task 1—Evaluate the response of floor and column systems under fire conditions. The following 

sub-tasks will be performed:

a. Develop structural model of floor truss and slab system including supports (i.e., connections to 

columns). Obtain information from project on Baseline Structural Performance and Aircraft Impact 

Damage Analysis.

b. Develop structural model of both interior (core) and exterior column system for the floors of 

interest. Obtain information from project on Baseline Structural Performance and Aircraft Impact 

Damage Analysis.
c. Obtain thermal environment time-histories. Consider both standard fires (e.g., ASTM E-119 

and ASTM E-1529) and real fires based on fire dynamics simulations.

d. Obtain thermal and mechanical properties of steel truss and connections as well as steel 

columns sections at elevated temperatures.

e. Obtain thermal insulation properties of spray-on fire proofing.

f. Estimate, using transient thermal analysis, the time-temperature relationship for the floor truss 

and column systems. Consider both unprotected and protected steel.

g. Evaluate, using thermal-mechanical analysis, the time-dependent structural response of the 

floor truss system using the thermal environment time-histories determined in "c", including 

support reactions (connection forces), and the column system for the estimated service and fire 

loads.

Task 2—Evaluate the response of the WTC towers under fire conditions, without and with aircraft 

impact damage. The following sub-tasks will be performed:

a. Develop structural model of floors of interest (location and number of floors to be determined) 

to evaluate the response of the WTC towers without aircraft impact. Obtain information from 

project on Baseline Structural Performance and Aircraft Impact Damage Analysis.

b. Develop structural model (including aircraft damage) of floors of interest (impact floors and 

floors above that are involved in fire). Obtain information from project on Baseline Structural 

Performance and Aircraft Impact Damage Analysis.

c. Obtain thermal environment time-histories. Consider both standard fires (e.g., ASTM E-119 

and ASTM E-1529) and real fires based on fire dynamics simulations.

d. Estimate, using transient thermal analysis, the time-temperature relationship for the structural 

components for the estimated service and fire loads. Consider both unprotected and protected 

steel.

e. Evaluate, using thermal-mechanical analysis, the time-dependent structural response of the 

floors of interest using the thermal environment time-histories determined in "c". Include the effect 

of load transfer from damaged zones to the remaining structural elements, the composite floor 

system, and the connection of the floor system to the columns.

f. Identify components critical to collapse initiation. Estimate the nominal safety margin for each 

critical component as a function of time.

Task 3—Conduct tests of structural components and systems under fire conditions. In the course 

of the investigation, it may be necessary to physically re-create the predicted thermal 

environment in the buildings and measure the structural response of components such as floor 

truss seat connections, floor truss assemblies, and exterior prefabricated column-spandrel 

elements. Such tests would be used to validate analytical models and to provide response data 

that are otherwise unavailable. 

Task 4—Evaluate failure hypotheses for the WTC towers. The following sub-tasks will be 

performed:
a. Identify candidate hypotheses for initiation and propagation of collapse.

b. Evaluate hypotheses for collapse initiation and propagation, including the role played by floor 

diaphragms, connections, and transfer trusses and girders.

c. Estimate uncertainty for probable collapse initiation and propagation mechanisms.

d. Identify most probable collapse mechanism(s).

Task 5—Report on the performance of open-web steel trussed joist systems in fire. The past 

performance of open-web steel joist systems in fire will be investigated. This study will include fire 

incident reports, and insurance investigation reports. Test reports (ASTM E119 or others) of steel 

joist systems in fire will be obtained and evaluated. Data obtained both domestically and, where 

possible, internationally will be included in the investigation. The results of this review will be 

compared with the floor system comprised of open-web steel trussed joists used in the WTC 

towers.

Task 6—Analyze the response of WTC Building 7 under fire conditions. The following sub-tasks 

will be performed:

a. Develop model of WTC 7 structural system.

b. Obtain fuel loads for various tenants and internal building operating systems (e.g., power 

generation) from project on Reconstruction of Thermal and Tenability Environment.

c. Obtain thermal environment time-histories. Consider both standard fires (e.g., ASTM E-119 

and ASTM E-1529) and real fires based on fire dynamics simulations.

d. Obtain properties of steel at elevated temperatures from project on Metallurgical and 

Mechanical Analysis of Structural Steel.

e. Estimate, using transient thermal analysis, the time-temperature relationship for the structural 

system.

f. Evaluate, using thermal-mechanical analysis, the time-dependent structural response of the 

structural system, including transfer girder system, for the estimated service and fire loads.

g. Identify most probable collapse mechanism(s), including the role played by transfer girders. 

Estimate the margin of safety for each critical component as a function of time.

Task 7—Report preparation. The results of this project will be synthesized into a chapter to 

describe the response of structural components and systems to the fire environment in WTC 1, 2, 

and 7, and to identify probable structural collapse mechanisms. The performance of open-web 

steel trussed joist systems in fire will be documented. In addition, the role of pivotal components 

such as floor diaphragms, connections, and transfer girders in collapse initiation will be 

documented. The project staff will contribute to drafting the final investigation report for review by

the Federal Advisory Committee.

Outputs and Estimate of Time-to-Completion: 

1. Evaluation of the response of floor system under fire conditions (9 months).
2. Evaluation of the response of column system under fire conditions (12 months).

3. Evaluation of the response of the WTC towers with no aircraft impact under fire conditions (16 

months).

4. Evaluation of the response of the WTC towers with aircraft impact under fire conditions (17 

months).

5. Report on the performance of open-web steel trussed joist systems in fire (6 months).

6. Completion of design, construction, and testing of critical components (16 months).

7. Evaluation of the response of WTC Building 7 under fire conditions (17 months).

8. Draft chapter for final report that describes the response of structural components and systems 

to the fire environment in the WTC 1, 2, and 7, and the probable structural collapse mechanisms. 

The performance of open-web steel trussed joist systems in fire and the role of pivotal 

components such as floor diaphragms, connections, and transfer girders in collapse initiation will 

be documented (18 months).

Project #7: Occupant Behavior, Egress, and Emergency Communications

Purpose: To determine the behavior and fate of occupants and responders - both those who 

survived and those who did not - by collecting and analyzing information on occupant behavior, 

human factors, egress, and emergency communications in World Trade Center Buildings 1, 2, 

and 7, and evaluating the performance of the evacuation system on September 11, 2001. 

Technical Approach: This project is divided into six tasks as follows:

Task 1—Gather baseline information on the evacuation of the WTC buildings on September 11, 

2001 through a comprehensive, systems-oriented, and interdisciplinary data collection effort 

focused on occupant behavior, human factors, egress, and emergency communications 

(including instructions given, interpretation of instructions, and response to instructions). This will 

involve the collection of new data from people affected by the WTC attacks (e.g. building 

occupants, building operators, and first responders via direct accounts from survivors and families 

of victims), especially those who had to evacuate the buildings. Experts in human behavior and 

statistical sampling will be used to develop a data acquisition strategy that considers various data 

collection methods such as interviews and questionnaires. Inputs and suggestions will be 

obtained from groups with an interest in the content of the data collection effort. Additionally, 

written accounts, transcripts of (emergency) communications, published accounts, and other 

sources of egress related information will be obtained, in coordination with other data collection 

efforts for the investigation.

Task 2—Collect archival records from prior WTC evacuation incidents (e.g., 1975 fire, 1977 

blackout, 1980 bomb scare, 1990 power outage, and 1993 bombing) and practice evacuations, 

including oral history data from floor wardens and fire safety directors. These records will be 

compared and contrasted with the September 11th incident evacuation. Changes made to the 

evacuation procedures following the earlier incidents and in recent years will be evaluated in the 

context of the experience on September 11, 2001.
Task 3—Document pre-event data for WTC Buildings 1, 2, and 7. This information includes, but 

is not limited to, physical aspects of building egress components, such as stairs (width, number, 

location, vertical continuity), evacuation lighting, back-up power, elevators (number, operational 

before and after impact, role in evacuation), and active fire protection systems (sprinklers, manual 

suppression, fire alarms, smoke control). Building plans, emergency plans, type and frequency of 

evacuation drills, occupancy level and distribution on the morning of September 11th, and 

communications will also constitute pre-event data. This information will provide a baseline for 

evaluating the performance of the egress system. 

Task 4—Store the information collected in task 1 in a database. Additionally, information from 

third-party sources, such as television interviews and newspaper articles, as well as other 

relevant published material will be analyzed, examined, and assembled in the database. 

Task 5—Analyze the data to study the movement of people during the evacuations, decisionmaking and situation awareness, and issues concerning persons with disabilities. A timeline of 

the evacuation will be developed using the results of these analyses together with other data 

sources. This timeline will be compared with the timeline of the structural response, the 

development of the interior conditions (fire and smoke), as well as activation of the active fire 

protection systems. The characteristics of the WTC evacuation designs and protocols will be 

evaluated, including the performance of stairs and elevators, emergency communications, and 

the temperature and smoke conditions. The designs will also be compared with building code 

requirements and practices for tall buildings in other major cities worldwide. The observed 

evacuation data will be compared with results obtained using alternate egress models to better 

understand occupant behavior and identify needed improvements to existing egress models. In 

addition, the evacuation experience will be compared with previous evacuation incidents in these 

buildings. The results of the analyses will be reviewed in the context of occupant protection 

practices for tall buildings, including the consideration of full evacuation and phased evacuation 

strategies.

Task 6—Report preparation. The results of this project will be synthesized into a chapter to 

describe the occupant behavior, egress, and emergency communications in WTC 1, 2, and 7, 

and the performance of the evacuation system. The project staff will contribute to drafting the final 

investigation report for review by the Federal Advisory Committee.

Outputs and Estimate of Time-to-Completion: 

1. Completion of data collection strategy (4 months).

2. Collection of archival data and pre-event data (4 months).

3. Completion of data collection effort and database development (9 months).

4. Completion of analysis of occupant behavior, egress, and emergency communications as 

defined in task 5 (17 months).

5. Draft chapter for final report that describes the occupant behavior, egress, and emergency 

communications in WTC 1, 2, and 7 and the performance of the evacuation system (18 months).

Project #8: Fire Service Technologies and Guidelines

Purpose: To build upon work already done by the Fire Department of New York (FDNY) and 

McKinsey & Company by: (1) fully documenting what happened during the response by the fire 
services to the attacks on the World Trade Center, up to the time of collapse of WTC 7; (2) 

identifying issues that need to be addressed in changes to practice, standards and codes; (3) 

identifying alternative practices and/or technologies that may address these issues; and (4) 

identifying R&D needs that advance the safety of the fire service in responding to massive fires in 

tall buildings.

Technical Approach: This project is divided into four tasks as follows:

Task 1—Collect emergency response data in cooperation with FDNY to document first responder 

fatalities, command and control procedures, and equipment performance. Records of interest 

include dispatch logs, recorded radio communications, run logs from surviving responding units, 

911 records, data recorded by the FDNY, Port Authority (PANYNJ) operations, and the New York 

City Police Department (NYPD), and fireground positioning of emergency apparatus. Information 

will also be sought on operations and function of communications systems, on-site emergency 

information systems, fire alarm panels, elevator control panels, standpipes and fire hoses, and 

other pre-positioned emergency equipment. In coordination with project #7, oral history data will 

be collected from witnesses, those in control of emergency operations, and surviving first 

responders to the extent their oral history has not already been documented. Technical experts 

will review and conduct a fact-based analysis of the data.

Task 2—Interpret the factual analysis to determine the effect on responder successes of factors 

such as:

the influence of building design (e.g., height, stairways, elevators, smoke control 

systems) on fire service command and control procedures, life saving operations, and 

safety of rescue personnel; 

the influence of aircraft impact damage and fuel run-off on fire service command and 

control procedures, life saving operations, and safety of rescue personnel; 

the impact of systems failures (e.g., communications systems, water supply, sprinklers, 

standpipes) on fire service command and control procedures, life saving operations, and 

safety of rescue personnel; 

building occupant egress as related to fire service operations; 

the ability to fight large fires on the upper floors of tall buildings; 

the impact that the 1993 bombing of the WTC had on codes, standards, and procedures 

that affected first responders in tall buildings; 

pre-planning, training, and standard operating procedures (including command and 

control) at the time of the incident; 

fire fighter accountability, location and tracking, 

fire and emergency response protocols for tall buildings; 

the resources available for initial situation assessment and incident management, and 

practices for determining the possibility of structural collapse; and 

communications and coordination of response activities with other authorities at the 

incident. 

Task 3—Identify alternative emergency response practices and technologies that may advance 

the safety and effectiveness of first responders, such as: knowledge/information systems for 

command and control decisions; elevator use by firefighters; firefighter tracking systems; 

interoperability of communication systems (occupants, firefighters, police, EMS); fire growth and 

smoke hazard prediction; structural safety monitoring, assessment and prediction; and simulation 

tools for training.
Task 4—Report preparation. The results of this project will be synthesized into a chapter to 

describe: the actions of the fire service and performance of their equipment; identify available 

alternatives related to fire service technology, training, and operational procedures; and identify 

R&D needs in support of their capability to protect the public, themselves, and vital physical 

infrastructure during extreme events. The project staff will contribute to drafting the final 

investigation report for review by the Federal Advisory Committee.

Outputs and Estimate of Time-to-Completion: 

1. Documentation of the activities of the fire service and the injuries and fatalities of all emergency 

responders up to the point of the collapse of WTC 7 (8 months).

2. Documentation of the successes of the emergency responders in preserving life and property, 

and the factors that may have limited that success (14 months).

3. Identification of the key factors where R&D may improve the capability of responders to protect 

the public, themselves, and vital physical infrastructure during extreme events (16 months).

4. Draft chapter for final report that describes the actions of the fire service and their equipment; 

identifies available alternatives related to fire service technology, training, and operational 

procedures; and identifies R&D needs in support of their capability to protect the public, 

themselves, and vital physical infrastructure during extreme events (18 months).