SPEAKERS CONTENTS INSERTS
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24–133PS
2006
THE INVESTIGATION OF THE WORLD TRADE
CENTER COLLAPSE: FINDINGS,
RECOMMENDATIONS, AND NEXT STEPS
HEARING
BEFORE THE
COMMITTEE ON SCIENCE
HOUSE OF REPRESENTATIVES
ONE HUNDRED NINTH CONGRESS
FIRST SESSION
OCTOBER 26, 2005
Serial No. 109–28
Printed for the use of the Committee on Science
Available via the World Wide Web: http://www.house.gov/science
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COMMITTEE ON SCIENCE
HON. SHERWOOD L. BOEHLERT, New York, Chairman
RALPH M. HALL, Texas
LAMAR S. SMITH, Texas
CURT WELDON, Pennsylvania
DANA ROHRABACHER, California
KEN CALVERT, California
ROSCOE G. BARTLETT, Maryland
VERNON J. EHLERS, Michigan
GIL GUTKNECHT, Minnesota
FRANK D. LUCAS, Oklahoma
JUDY BIGGERT, Illinois
WAYNE T. GILCHREST, Maryland
W. TODD AKIN, Missouri
TIMOTHY V. JOHNSON, Illinois
J. RANDY FORBES, Virginia
JO BONNER, Alabama
TOM FEENEY, Florida
BOB INGLIS, South Carolina
DAVE G. REICHERT, Washington
MICHAEL E. SODREL, Indiana
JOHN J.H. ''JOE'' SCHWARZ, Michigan
MICHAEL T. MCCAUL, Texas
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VACANCY
VACANCY
BART GORDON, Tennessee
JERRY F. COSTELLO, Illinois
EDDIE BERNICE JOHNSON, Texas
LYNN C. WOOLSEY, California
DARLENE HOOLEY, Oregon
MARK UDALL, Colorado
DAVID WU, Oregon
MICHAEL M. HONDA, California
BRAD MILLER, North Carolina
LINCOLN DAVIS, Tennessee
RUSS CARNAHAN, Missouri
DANIEL LIPINSKI, Illinois
SHEILA JACKSON LEE, Texas
BRAD SHERMAN, California
BRIAN BAIRD, Washington
JIM MATHESON, Utah
JIM COSTA, California
AL GREEN, Texas
CHARLIE MELANCON, Louisiana
DENNIS MOORE, Kansas
C O N T E N T S
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October 26, 2005
Witness List
Hearing Charter
Opening Statements
Statement by Representative Sherwood L. Boehlert, Chairman, Committee on Science, U.S. House of Representatives
Written Statement
Statement by Representative Brad Miller, Member, Committee on Science, U.S. House of Representatives
Written Statement
Statement by Representative Vernon J. Ehlers, Chairman, Subcommittee on Environment, Technology, and Standards, Committee on Science, U.S. House of Representatives
Written Statement
Prepared Statement by Representative Jerry F. Costello, Member, Committee on Science, U.S. House of Representatives
Prepared Statement by Representative Eddie Bernice Johnson, Member, Committee on Science, U.S. House of Representatives
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Prepared Statement by Representative Russ Carnahan, Member, Committee on Science, U.S. House of Representatives
Prepared Statement by Representative Sheila Jackson Lee, Member, Committee on Science, U.S. House of Representatives
Prepared Statement by Representative Dennis Moore, Member, Committee on Science, U.S. House of Representatives
Panel I:
Ms. Sally Regenhard, Chairperson, Skyscraper Safety Campaign
Oral Statement
Written Statement
Panel II:
Dr. William Jeffrey, Director, National Institute of Standards and Technology (NIST)
Oral Statement
Written Statement
Biography
Ms. Nancy McNabb, Director, Government Affairs, National Fire Protection Association
Oral Statement
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Written Statement
Biography
Dr. James R. Harris, President, J.R. Harris and Company; Member, American Society of Civil Engineers
Oral Statement
Written Statement
Biography
Mr. Glenn Corbett, Assistant Professor of Fire Science, John Jay College of Criminal Justice; Member, NIST National Construction Safety Team Advisory Board
Oral Statement
Written Statement
Biography
Mr. Henry L. Green, President, International Code Council
Oral Statement
Written Statement
Biography
Discussion
Appendix 1: Answers to Post-Hearing Questions
Dr. William Jeffrey, Director, National Institute of Standards and Technology (NIST)
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Ms. Nancy McNabb, Director, Government Affairs, National Fire Protection Association
Dr. James R. Harris, President, J.R. Harris and Company; Member, American Society of Civil Engineers
Mr. Glenn Corbett, Assistant Professor of Fire Science, John Jay College of Criminal Justice; Member, NIST National Construction Safety Team Advisory Board
Mr. Henry L. Green, President, International Code Council
Appendix 2: Additional Material for the Record
Statement by The American Institute of Architects
Letter to Chairman Boehlert from James A. Thomas, President, ASTM International, dated January 11, 2006
An Analysis of the NIST Report on the Collapse of the World Trade Center Towers for potential recommendations and impacts on ASTM standards, prepared on behalf of ASTM International by Vytenis Babrauskas, Fire Science and Technology Inc.
Letter to Chairman Boehlert from Ron Burton, Vice President for Advocacy and Research, Building Owners and Managers Association International (BOMA), dated October 26, 2005
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BOMA Comments on NIST Recommendations Contained in the Report on the WTC Disaster
Statement by James G. Quintiere, Professor, Department of Fire Protection Engineering, University of Maryland
Statement by Jake Pauls, CPE, Consulting Services in Building Use and Safety, dated October 26, 2005
Fireproofing Blown Off Twin Towers, article by Michelle Garcia, The Washington Post, Wednesday, April 6, 2005
Staircases in Twin Towers Are Faulted, article by Jim Dwyer, The New York Times, April 6, 2005
3-Year Federal Study of 9/11 Urges Rules for Safer Towers, article by Jim Dwyer and Eric Lipton, The New York Times, Wednesday, June 22, 2005
9/11 Firefighters Told of Isolation Amid Disaster, article by Jim Dwyer and Michelle O'Donnell, The New York Times, September 9, 2005
BUILDING SAFETY: Directing the Herd: Crowds and the Science of Evacuation, article by John Bohannon, Science, October 14, 2005
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THE INVESTIGATION OF THE WORLD TRADE CENTER COLLAPSE: FINDINGS, RECOMMENDATIONS, AND NEXT STEPS
WEDNESDAY, OCTOBER 26, 2005
House of Representatives,
Committee on Science,
Washington, DC.
The Committee met, pursuant to call, at 11:09 a.m., in Room 2318 of the Rayburn House Office Building, Hon. Sherwood Boehlert [Chairman] presiding.
24133a.eps
HEARING CHARTER
COMMITTEE ON SCIENCE
U.S. HOUSE OF REPRESENTATIVES
The Investigation of the World Trade
Center Collapse: Findings,
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Recommendations, and Next Steps
WEDNESDAY, OCTOBER 26, 2005
11:00 A.M.–1:00 P.M.
2318 RAYBURN HOUSE OFFICE BUILDING
Purpose
On October 26, 2005, at 11 a.m., the House Committee on Science will hold a hearing on the key findings and recommendations of the National Institute of Standard and Technology's (NIST) investigation into the collapse of the World Trade Center (WTC), how building and fire code organizations plan to implement the recommendations contained in that report, and what barriers exist to the development and adoption of stronger building and fire codes.
Witnesses
The following witnesses will address the Committee:
Panel I:
Ms. Sally Regenhard, Skyscraper Safety Campaign (SSC), New York, NY. The SSC represents families and survivors of the WTC disaster and supports stronger codes and practices for buildings and first responders.
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Panel II:
Dr. William Jeffrey, Director, National Institute of Standards and Technology.
Ms. Nancy McNabb, Director of Government Affairs, National Fire Protection Association (NFPA). NFPA standards are extensively referenced in the NIST recommendations on the WTC collapse.
Dr. James R. Harris, American Society of Civil Engineers (ASCE). ASCE standards are extensively referenced in the NIST recommendations on the WTC collapse.
Mr. Henry L. Green, President, International Code Council (ICC). The ICC is an association of State and local code officials, building mangers, and other parties that collectively maintain the International Building Code (IBC), the most widely used model building code in the U.S. Many of NIST's recommendations reference the IBC.
Mr. Glenn Corbett, Assistant Professor of Fire Science, John Jay College of Criminal Justice, New York, NY. Mr. Corbett is a member of NIST's National Construction Safety Team Advisory Board.
Overarching Questions
The hearing will address the following overarching questions:
1. What are the most important findings and recommendations of the World Trade Center Investigation report?
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2. Are the NIST recommendations framed appropriately so that they can be adopted into national model building codes?
3. What are the prospects for the adoption of the recommendations by the code organizations? What is NIST doing to promote this process? What are the possible impediments to their adoption?
4. What lessons were learned from this investigation that could be applied to improve future investigations of building failures?
Background
On September 11, 2001, terrorists crashed two fuel-laden Boeing 767s into World Trade Center (WTC) Tower 1 and Tower 2. While both 110-story buildings withstood the initial impact, the subsequent fires weakened the already damaged columns at the periphery and core of the towers, both of which collapsed. More than 25,000 people were safely evacuated from the towers, however 2,749 people were killed in the disaster. World Trade Center 7, a 47-story office building located adjacent to WTC 1 and 2, was damaged during the disaster and collapsed later that same day.
Immediately following the attack, the Federal Emergency Management Agency (FEMA) and the American Society of Civil Engineers (ASCE) began planning a building performance study of the WTC. The week of October 7, as soon as the rescue and search efforts ceased, an ASCE team under contract with FEMA known as the Building Performance Assessment Team (BPAT) went to the site and began their assessment of why the buildings had failed. This was to be a brief effort, as the study team consisted of experts who generally had volunteered their time. In January 2002, FEMA asked the National Institute of Standards and Technology (NIST) to take over the next phase of the investigation of the collapse essentially to build upon the BPAT recommendations and conduct a more thorough investigation of the events leading to the collapse.
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The Science Committee held two hearings in 2002 on the WTC collapse, one on March 6 and the other on May 1. The March 6, 2002, hearing focused on how the Federal Government investigates catastrophic building failures, and what had been learned from the collapse of the WTC 1, 2 and 7. Concerns raised at the hearing included the lack of any specific federal authority, protocols, or funding for investigations of this kind. Concerns were also raised regarding the timing of the BPAT deployment (almost a month after the towers fell), its access to the site and building records, premature disposal of evidence, and FEMA's lack of regular communication with the public about the investigation.
The BPAT released its report at the May 2002 hearing. The hearing also reviewed plans for NIST to begin a more comprehensive investigation in view of the criticisms of FEMA, and provided a forum to discuss proposed legislation to give NIST the authorities necessary to conduct such an investigation. The BPAT report highlighted potential reasons for why the two towers, almost identical in design, performed differently under the stresses of the disaster. It also identified critical features that enabled so many to evacuate, and the design elements that may have played a role in the collapse and prevented people above the impacts from being able to exit the buildings. However, witnesses commented that, without a more sophisticated analysis of the evidence, no conclusions could be drawn that could be used to recommend improvements in building and fire codes to prevent future loss of life.
Also at the May 2002 hearing, the witnesses commented favorably on draft legislation being prepared by the Science Committee, based on the authorizing legislation for the National Transportation Safety Board (NTSB) to enhance NIST's existing authority to investigate building failures. On May 9, 2002, the National Construction Safety Team Act (NCST—H.R. 4687) was introduced by Congressman Sherwood Boehlert and Congressman Anthony Weiner. The NCST was signed into law on October 1, 2002. Under the Act, NIST is authorized to appoint a national construction safety team to determine the causes of a building's failure, evaluate the technical aspects of evacuation and emergency response, and ''recommend, as necessary, specific improvements to building standards, codes, and practices based on the findings,'' and propose any research needed to improve building safety and emergency response procedures.'' The law gives NIST subpoena power to ensure that it has access to all evidence to support an investigation, but the results of such investigations cannot be used as evidence in any subsequent litigation.
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On August 21, 2002, NIST announced the appointment of a national construction safety team to investigate building and fire safety in WTC 1, 2, and 7. The project was funded through FEMA, and cost $16 million.
Building and Fire Codes
Building and fire codes are established and enforced by State and local governments, which generally base their codes on national model codes that are written by private non-profit standards development organizations (SDOs). These organizations are generally are made up of members—individuals and groups—that have an interest in construction. Generally make their money through membership payments and selling their codes.
Building and fire codes and standards are technical descriptions of constructions, materials, installations, equipment, or practices designed to achieve specific results, such as safety or strength. Standards are very specific guidelines that describe single elements of construction or safety. For example, a ''fire rating'' is a standard that describes the amount of time a construction element such as a beam can be exposed to a typical fire before it breaks or fails. Other examples of building standards include hallway or stairwell widths deemed necessary to evacuate a certain number of people in a certain amount of time, or the type of steel needed for a beam to support a certain amount of weight. NIST does not write building or fire codes, but does participate in the discussions and provides technical guidance to the standards development organizations.
The most widely-used model building code in the U.S. is the International Building Code (IBC). It is currently the basis of the codes in 45 states and the District of Columbia. The IBC is developed and owned by the International Code Council (ICC). The ICC's members consist of State and local building code officials, building owners and managers, and private sector participants from construction and other industries. ICC's members are concerned with safety, but also with cost and other economic considerations, and these are reflected in the outcomes of the code meetings. The IBC is regularly updated in a deliberative, committee-driven process that takes about eighteen months. The deadline for submitting proposed changes to the IBC, which begins the next eighteen-month cycle, is March 24th, 2006.
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The National Fire Protection Association (NFPA), which develops many standards related to fire safety, recently produced an alternative model building code, NFPA 5000. Experts say that implementing NFPA 5000 may be more expensive than the IBC but may result in a greater level of safety. NFPA's membership is different from that of the ICC, with strong representation by fire protection officials and fire equipment manufacturers. NFPA 5000 has not been widely adopted, but individual NFPA standards are widely used in fire codes.
The NIST Investigation
NIST's Building and Fire Research Laboratory (BFRL) carries out research in fire science, fire safety, structural, mechanical, and environmental engineering. It is the only federal laboratory dedicated to research on building design and fire safety.
The goals of the NIST WTC investigation of the WTC disaster were to investigate the building construction, the materials used, and the technical conditions that contributed to the outcome of the WTC disaster to serve as the basis for:
Improvements in the way buildings are designed, constructed, maintained, and used;
Improved tools and guidance for industry and safety officials for safer buildings and better coordination in emergencies;
Recommended revisions to current building codes, standards, and practices, and
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Improved public safety.
The specific objectives were to:
1) Determine why and how WTC 1 and WTC 2 collapsed following the initial impacts of the aircraft;
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) Assess what procedures and practices were used in the design, construction, operation, and maintenance of WTC 1, 2; and
4) Identify areas in current building and fire codes, standards, and practices that warrant revision.
To meet these goals, NIST assembled a team of in-house experts and outside specialists, totaling about 200 people. The team compiled and reviewed tens of thousands of documents, photographs, and films, interviewed over a thousand people who had been on the scene or who had been involved with the design, construction, and maintenance of the WTC; analyzed 236 pieces of steel taken from the wreckage; performed laboratory tests, and performed computer simulations of the sequence of events that happened from the instant of the aircraft impact to the initiation of collapse for each tower. In addition, NIST held several public meetings in New York City to report on the status of the investigation and solicit comments and additional information that might further the investigation.
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In September, 2005, NIST released its draft Final Report of the National Construction Safety Team on the Collapse of the World Trade Center Towers for public comment. A copy of the executive summary of the report is attached. This report summarizes the findings of the investigation and includes thirty recommendations to improve the safety of tall buildings, occupants, and emergency responders. NIST will publish its final report within the next two weeks.
NIST Findings
The NIST investigation confirmed and expanded upon several of the findings by the initial FEMA BPAT study. When built, WTC 1 and WTC 2 were unlike any other skyscrapers in existence at the time, both in terms of their height and innovative structural features. These consisted of a ''frame-tube'' system of exterior columns on the four faces of the towers, linked to a core of columns by light-weight trusses that supported the floors. In spite of their innovative design, WTC 1 and 2 met or exceeded the requirements of the New York City building codes.
The NIST investigation determined that although the aircraft did considerable damage to the principal structural components of WTC 1 and 2, the towers were inherently robust, and would have remained standing were it not for the dislodged fireproofing which exposed the central columns to the multi-floor fires. In each tower, a different combination of impact damage and heat-weakened structural components contributed to the abrupt structural collapse. The fire safety systems in WTC 1 and 2 met or exceeded current practice at the time the towers fell, but played no safety role on September 11th because the water supplies and electrical systems were damaged by the aircraft impact. In WTC 1, the aircraft destroyed all escape routes, and 1,355 people were trapped in the upper floors when the building collapsed. In WTC 2 where evacuation had already commenced, about 3,000 got below the impact zone before the second plane crashed. One stairwell remained passable for a short period of time and eighteen people evacuated through the impact zone. The remaining 619 people perished. WTC 2 collapsed before WTC 1 because the aircraft did significantly more damage to the central columns and the fires were concentrated on the East side of the building, rather than moving around as they did in WTC 1.
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Major Issues Addressed in the NIST WTC Recommendations
NIST's recommendations fall into eight groups:
Increased Structural Integrity,
Enhanced Fire Resistance of Structures
New Methods for Fire Resistance Design of Structures
Improved Active Fire Protection
Improved Building Evacuation
Improved Emergency Response
Improved Procedures and Practices, and Education and Training.
These recommendations include many references to specific SDOs to modify or, in some cases, completely overhaul those standards that apply to building construction, evacuation, testing, and fire safety. NIST's recommendations also refer to less specific audiences such as building managers, building occupants, property developers, and first responders to develop procedures and best practices to protect building occupants.
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The following highlights some of the key issues referenced by NIST in its recommendations:
Increased Structural Integrity
The NIST investigators found that the existing methods of calculating the effect of wind and other stressors on tall towers produced markedly different results among the different tests, leading them to question whether these tests had a basis in fact and needed to be re-designed. NIST's report also focuses on the concept of ''progressive collapse,'' where the weakening of one structural element contributes to the weakening of others. NIST raises the question of whether the current practice of testing individual building components such as columns and floor trusses gives an accurate estimate of the resilience of an entire building assembly to fire, wind, and other stressors. NIST recommends that a ''structural frame'' approach to fire resistance ratings be developed by the structural standards groups such as ASCE. However, progressive collapse is not well understood, and it may take time for these groups to produce a standard and describe the appropriate tests against which to judge whether structures are prone to progressive collapse.
The recommendations pertaining to structural integrity and design are directed largely at ASCE–7, and specifications developed by the American Concrete Institute (ACI) and the American Institute of Steel Construction (AISC), as well as NFPA, and urge that the latest version of these standards and specifications be adopted by the ICC and NFPA into their model building codes.
Improved Fire Resistance of Structures and Fire Protection
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Over the years, across the United States, there has been a gradual reduction in rigor of building codes of fire rating requirements, i.e., how long something such as a steel column can remain exposed to a fire before breaking or deforming. There has also been a decrease in the compartmentalizing requirements for working and living spaces. Large compartments in buildings allow more air to flow to fires and allow fires to spread faster. Large compartments, however, means more floor area, more tenants, and more rent for the building owner. A lower fire rating requirement allows the use of lighter and less material in construction. The loosening of these restrictions has been compensated for by increasing requirements for sprinkler systems, which have been shown to be effective in quenching typical office fires. On September 11th however, the sprinkler systems were disabled, and even in typical fires, sprinkler systems do not always work. NIST recommends greater redundancy in sprinkler systems, and more compartmentalization to restrict air flow to fires. These recommendations apply to several standards developed by NFPA.
The reduction in fire ratings has also been compensated by the use of spray-applied fire resistive materials (SFRM) on structural components. This was the foam that was applied to the columns and trusses of WTC 1 and 2 as fireproofing. After the 1993 WTC terrorist bombing, it was recommended that the spray-on fire protection on the steel components of the towers be thickened. NIST emphasizes that, were it not for the dislodging of the fireproofing from the structural steel when the aircraft flew into the towers, WTC 1 and 2 would likely have withstood the subsequent fires. The foam on WTC 1 and 2 was shaken or blown off around the cores and peripheral columns on several floors in both Towers on September 11th, meaning the columns reached critical temperatures much faster then they would have normally. NIST recommends that the performance of this type of fireproofing needs to be better understood, particularly its response to shock, aging, and method of application, and new coatings should be developed.
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NIST notes in its report that both the IBC and NFPA 5000 model building codes have since changed their fire rating requirements for buildings over 420 feet from two hours to four. The report also says, however, that the technical basis for fire ratings is not strong, particularly since the typical contents of offices, and construction materials, have changed in the last 100 years. NIST recommends a comprehensive review by all fire-related SDOs of fire testing procedures to ensure that fire ratings are meaningful. Structural fire resistance is closely tied to the outcomes of work on the structural frame approach for large buildings, which NIST advocates in its report while recommending an extensive re-evaluation by national building code committees (ICC and NFPA) of the dynamics of fire, evacuation, and emergency response for skyscrapers to determine what fire ratings are needed for tall buildings. In the case of re-evaluating the tests steel and concrete assemblies, this could be an expensive proposition. A typical full-scale fire test costs $30,000 or more per test, and to validate a new test, experimental tests must to be run several times. It is not clear who should be conducting these tests.
Full Evacuation of Large Buildings
After the 1993 terrorist bombing of the WTC site, it took four hours to evacuate everyone from WTC 1 and WTC 2. The standard evacuation plan for skyscrapers does not usually anticipate such a mass egress: fire-related evacuation plans assume that occupants ''evacuate in place'' to higher and lower floors while first responders fight the fire. Although this approach may change as a result of the events of September 11th, it may still be the most practical and safe procedure for typical skyscraper fires. Skyscraper elevators in the U.S. are not generally fireproof, nor are they intended to be used for mass evacuation. Full evacuation via stairwells takes a long time. On September 11th, with all elevators out of commission, it would have taken hours for firefighters to ascend to the affected floors to fight the fires, or assist survivors down the stairs. This fact has provoked some re-thinking of how elevators should be designed and used for emergency purposes.
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WTC 1 and 2 had three stairwells each, centered at the core of the buildings. When the aircraft crashed, these stairs were destroyed. The NIST investigation found that about six percent of the people in the towers had health problems or disabilities that made taking the stairs difficult. Overall, it was found, people evacuate buildings twice as slowly as generally thought. NIST recommends structural hardening of elevators for use in large-scale emergencies, and that stairwells be spaced further apart, although it does not say by how much. NIST also recommends that stairwells should be widened to allow more people to descend as well as to allow counter flow from first responders going up the stairs. Most of the recommendations apply to NFPA 101, and the National Model Building and Fire Codes of the ICC.
Communications and Emergency Response
For the approximately 1,000 emergency responders on the site on September 11th, this was the largest disaster they had ever experienced. Communications networks at the site were destroyed, and portable communications devices such as walkie-talkies and cellular phones were overwhelmed as dozens of first responders attempted to talk at the same time. Walkie-talkies performed inadequately, or otherwise failed to function inside the steel-concrete construction of the towers. There was no inter-operability between the New York Police Department and the New York Fire Department equipment. Although there had been significant upgrades to the fire monitoring and communications infrastructure in the WTC Complex after the 1993 terrorist bombing, incident command centers established inside the two towers by first responders were still unable to provide a sufficient assessment of the situation, or monitor and relay information to other first responders at the site for proper coordination of their activities. First responders commented later that viewers watching the disaster on television had a better grasp of the scope and nature of the crisis than did anyone at the WTC site.
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NIST's recommendations on improved emergency response apply mostly to NFPA standards, but also extend to the Department of Homeland Security, and state and local jurisdictions, and first responders. NIST emphasizes that systems need to be effective for large-scale emergencies and able to function in ''challenging radio frequency environments.'' NIST also states that better procedures are needed for integrating information from multiple sources and coordinating a unified response among different agencies and departments.
Additional Issues
Follow-up funding is limited
In many instances, NIST has recommended research and testing to determine whether and how changes in building codes should be made. It is not clear this effort will receive the commitment for funding it requires. In order to implement many of NIST's recommendations, a lot of research and collaboration with SDOs and stakeholders will have to be done to provide a scientific and technical basis for the standards changes needed to meet those recommendations. NIST requested $2 million in additional funds for FY 2006 for codes and practices for buildings and first responders, but the FY 2006 appropriation has not yet been finalized. If adequate funding for NIST's research efforts is not provided, it is unclear what progress will be made on implementing those recommendations that need scientific research to be implemented.
Future building investigations
It is unclear what role NIST will play in investigating future building failures. FEMA received heavy criticism at the Science Committee hearing March 6, 2002, for shortcomings in the way in which it conducted the investigation of the collapse of the World Trade Center. The passage of the National Construction Safety Team Act was supposed to address these shortcomings by creating the authority to investigate building failures at NIST and providing NIST with subpoena power to obtain whatever evidence it needed to complete investigations. However, in the years since September 11th, although several building failures have occurred, Hurricane Katrina being the most recent event causing structural failures, NIST has not invoked the NSTC Act to launch investigations, but rather has been called in under another agency: FEMA in the case of Katrina. NIST does not have a source of funding dedicated to pay for such activities and is apparently reluctant to act independently. Outside observers note that NIST is a research institution and may not be culturally suited to conduct investigations as does the NTSB, upon which the NCST Act was based, or the Chemical Safety and Hazards Investigation Board.
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Questions for the Witnesses
Ms. Sally Regenhard, Skyscraper Safety Campaign
I invite you to open the hearing with a five-minute statement that outlines the views of the Skyscraper Safety Campaign on the investigation, its findings and the next steps that should be taken.
Dr. William Jeffrey, Director, National Institute of Standards and Technology
In your testimony, please briefly describe the most important findings and recommendations of the NIST investigation of the World Trade Center collapse and answer the following questions:
1) What specific steps is NIST taking to ensure that its recommendations are incorporated into model and local codes? What barriers has NIST confronted or does it expect to confront as part of that process and how do you plan to overcome those barriers? What past successes can NIST draw on as part of this effort?
2) Some experts have criticized the recommendations—some arguing that they are too general and therefore hard to translate into codes, and others arguing that they are too detailed and will needlessly increase building costs. How do you respond to these criticisms?
3) What lessons have you learned in carrying out this investigation that could be applied to future investigations, including the ones being undertaken in the wake of Hurricane Katrina?
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Ms. Nancy McNabb, Director of Government Affairs, National Fire Protection Association (NFPA)
In your testimony, please briefly describe the process by which NFPA writes codes and answer the following questions:
1) Does NFPA support the recommendations of the NIST study? Why or why not?
2) What specific steps will NFPA be undertaking to determine whether and how to incorporate the NIST recommendations into its codes? How long should that process take? What will be the greatest barriers in the process?
3) What specific actions should NIST be taking to help code organizations incorporate its recommendations? Are the recommendations framed in a way that facilitates their adoption by code organizations or are they too general or too specific?
Dr. James R. Harris, American Society of Civil Engineers (ASCE)
In your testimony, please briefly describe the process by which ASCE writes codes and answer the following questions:
1) Does ASCE support the recommendations of the NIST study? Why or why not?
2) What specific steps will ASCE be undertaking to determine whether and how to incorporate the NIST recommendations into its codes? How long should that process take? What will be the greatest barriers in the process?
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3) What specific actions should NIST be taking to help code organizations incorporate its recommendations? Are the recommendations framed in a way that facilitates their adoption by code organizations or are they too general or too specific?
Mr. Henry L. Green, President, International Code Council (ICC)
In your testimony, please briefly describe the process by which ICC writes codes and answer the following questions:
1) Does ICC support the recommendations of the NIST study? Why or why not?
2) What specific steps will ICC be undertaking to determine whether and how to incorporate the NIST recommendations into its codes? How long should that process take? What will be the greatest barriers in the process?
3) What specific actions should NIST be taking to help code organizations incorporate its recommendations? Are the recommendations framed in a way that facilitates their adoption by code organizations or are they too general or too specific?
Mr. Glenn Corbett, Assistant Professor of Fire Science, John Jay College of Criminal Justice, New York, NY
1) What are the most important findings and recommendations of the NIST World Trade Center Investigation report?
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2) Some experts have criticized the recommendations—some arguing that they are too general and therefore hard to translate into codes, and others arguing that they are too detailed and will needlessly increase building costs. What is your view of these criticisms?
3) What are the prospects for the adoption of the recommendations by the code organizations? What should NIST and the code and standards groups be doing to promote this process?
4) What lessons were learned from this investigation that could be applied to improve future investigations of building failures?
Attachment
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Chairman BOEHLERT. Good morning. This hearing is open, and we are pleased to welcome back one who strayed from the fold, Mr. Weiner of New York, who was a very valued Member of this committee, and has gone onto other pursuits, but still, fortunately, within the Congress of the United States. Mr. Weiner, welcome back.
I want to welcome everyone to this important hearing, the Committee's third on the tragic collapse of the World Trade Center. But it won't be our last. I want to promise and perhaps warn everyone at the outset that this committee will be closely monitoring the followup to the National Institute of Standards and Technology report on the events of September 11.
That means we will be watching what NIST does, what other federal agencies do, and what the code writing organizations do. We are obviously not technical experts, but we will be making sure that their recommendations are considered fully and thoroughly, that NIST is doing everything necessary to back up those recommendations, and that any decisions are fully justified by the facts.
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The issues raised in NIST's report go far beyond a single horrific terrorist incident, and indeed, beyond terrorism as a phenomenon. The report raises fundamental questions about what we know about the behavior of buildings and their contents, what we know about the behavior of individuals in emergencies, and about whether buildings are well enough designed for any large emergency. This is not about making every building strong enough to survive a plane crash.
That said, NIST's conclusion that the Trade Center buildings could have survived even the massive insult of a plane crash if the fireproofing had remained in place, is at once both chilling and promising, chilling because the massive loss of life was not inevitable, promising because it is an indication we can do more to protect lives in the future.
This committee will be asking hard questions of all of our witnesses today, to make sure we do take all reasonable steps to protect lives. We will be looking into whether NIST's recommendations are written in a way that will facilitate the adoption by code groups. It appears that they do not. We will be probing whether code groups are prepared to fully and fairly review the recommendations. On that, while the initial indications in today's testimony are promising, the jury necessarily is still out.
But our tough questions should not obscure the debt of gratitude we owe to NIST. NIST took seriously the mandate from this committee, and Mr. Weiner, I want to thank you for your assistance in that, and the Nation gave it in the National Construction Safety Team Act, and assembled an impressive group of experts that produced a comprehensive and impressive report. But our focus now has to be on whether everyone is doing enough to translate the report into specific, concrete steps that will prevent future tragedies.
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The protection of life is the highest responsibility of public officials, and our hearing today is about that responsibility, just as much as any hearing on the military or homeland security would be. But the process in this case is far more complex, because of the way it involves the private sector and every level of government. But complexity is not an excuse for inaction.
Before I turn to the minority, I want to give a special welcome to Bill Jeffrey, who is making his first appearance before this committee. I say first public appearance, because Dr. Jeffrey has long been a valued advisor to this committee in his work at the Office of Science and Technology Policy, someone we have admired for his intelligence, open-mindedness, and candor.
We could not be more delighted with his appointment as the Director of NIST, and we very much look forward to continuing to work with him. Hopefully, after today, he will still feel that way about us. This isn't, perhaps, the topic any of us would have chosen for his maiden hearing, but there is none of greater importance, and this hearing underscores the importance of NIST and its need for greater funding. But I won't get started on that subject now; we have more than enough to deal with today.
And I also want to welcome back someone who has been so invaluable to this committee as counsel, Sally Regenhard, Chairperson of the Skyscraper Safety Committee. She is emotionally and intellectually involved in our proceedings in so many different ways, and she has been a source of strength and inspiration to us, and she is dogged in her determination, and I commend her for that. People will often ask me, ''When you go to Washington, I bet you meet with lobbyists.'' And I say ''Sure, I meet with lobbyists. Every single day. Lobbyists are people who advocate for something.'' And there is one of the best lobbyists in this town today in Sally Regenhard. What she is advocating for involves the protection of life.
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So, with that, let me turn to Mr. Miller for any statement he might care to make, and then we will have our first panel of one, Ms. Regenhard.
[The prepared statement of Chairman Boehlert follows:]
PREPARED STATEMENT OF CHAIRMAN SHERWOOD L. BOEHLERT
I want to welcome everyone to this important hearing, this committee's third on the tragic collapse of the World Trade Center, but probably not our last. I want to promise (and perhaps warn) everyone at the outset that this committee will be closely monitoring the follow-up to the National Institute of Standards and Technology (NIST) report on the events of September 11.
That means we will be watching what NIST does, what other federal agencies do, and what the code writing organizations do. We are obviously not technical experts, but we will be making sure that the recommendations are considered fully and thoroughly, that NIST is doing everything necessary to back up those recommendations, and that any decisions are fully justified by the facts.
The issues raised in NIST's report go far beyond a single, horrific terrorist incident, and indeed beyond terrorism as a phenomenon. The report raises fundamental questions about what we know about the behavior of buildings and their contents, what we know about the behavior of individuals in emergencies, and about whether buildings are well enough designed for any large emergency. This is not about making every building strong enough to survive a plane crash.
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That said, NIST's conclusion that the Trade Center buildings could have survived even the massive insult of a plane crash if the fireproofing had remained in place is at once both chilling and promising—chilling because the massive loss of life was not inevitable; promising because it is an indication we can do more to protect lives in the future.
We could not be more delighted with his appointment as the Director of NIST, and we very much look forward to continuing to work with him. Hopefully, after today, he will still feel that way about us. This isn't perhaps the topic any of us would have chosen for his ''maiden'' hearing, but there is none of greater importance. And this hearing underscores the importance of NIST, and its need for greater funding. But I won't get started on that subject now; we have more than enough to deal with today. Mr. Gordon.
Mr. MILLER. Thank you, Mr. Chairman. I want to join Chairman Boehlert in welcoming everyone to this morning's hearing.
On the surface, today's topic may sound dry and technical. However, what we are talking about here really is saving lives. The sole purpose of the National Construction Safety Team Act is to save lives by investigating and understanding building collapses, and then improve building codes, emergency response, and evacuation procedures.
The National Institute of Standards and Technology's, NIST's, World Trade Center investigation and their recommendations are the first real result of the Act. The NIST report is a good first step, but really a lot remains to be done. We need to know what is required to translate these NIST recommendations into improved buildings and emergency response and evacuation procedures. Those changes will improve public safety, and otherwise, we would have nothing to show, except another government report sitting on a shelf. That is going to require continued oversight by this committee as the process moves forward.
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I also encourage the witnesses to give us their assessment of the work that NIST has done during the last two years, and what they think could be improved. And I want to mention that I am not only interested in the subject from the Science Committee perspective, but also how it relates to the Terrorism Risk Insurance Act, TRIA, which is now pending before the Financial Services Committee, and whether we should consider the NIST recommendations as part of private sector preparedness, and how that affects TRIA.
Now, I would like to yield the balance of my time to a former Member of the Science Committee, Anthony Weiner. Mr. Weiner has no small interest in NIST's work on the World Trade Center investigation, both as a Member from New York City, but also, he was the co-author, along with Chairman Boehlert, of the National Construction Safety Team Act.
Mr. Weiner, welcome back.
[The prepared statement of Mr. Miller follows:]
PREPARED STATEMENT OF REPRESENTATIVE BRAD MILLER
I want to join Chairman Boehlert in welcoming everyone to this morning's hearing.
On the surface, today's hearing topic may sound dry and technical. However, what we're really talking about is saving lives. The sole purpose of the National Construction Safety Team Act is to save lives by investigating and understanding building collapses and then improve building codes, emergency response and evacuation procedures.
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The National Institute of Standards and Technology's (NIST) World Trade Center (WTC) investigation and recommendations are the first case of implementation of the Act. The NIST report is a good first step, but much work remains to be done. We need to know what is required to translate the NIST recommendations into improved building codes, and emergency response and evacuation procedures. It is these changes that will improve public safety, otherwise we will have nothing more than another government report sitting on a shelf. This will also require continued oversight by the Science Committee as the process moves forward.
I'm also encourage the witnesses to give us their assessment of what NIST has done during the past two years and what they feel could be improved. I also want to mention that I'm not only interested in this subject from a Science Committee perspective, but also how it relates to Terrorism Risk Insurance from my work on the Financial Services Committee.
Now I would like to yield the balance of my time to a former Member of the Science Committee, Anthony Weiner. Rep. Weiner not only has a parochial interest in the NIST's WTC investigation, but he was a co-author, with Chairman Boehlert, of the National Construction Safety Team Act.
Mr. WEINER. Thank you, Mr. Miller. I appreciate it, and thank you, Mr. Chairman, for continuing to keep the effort alive that was one of the ones that emerged after September 11 that truly drew consensus in this Congress. I want to welcome back, also, Sally Regenhard, who if it was the Boehlert-Weiner Bill, it really should have been the Boehlert-Weiner-Regenhard Bill, because she acknowledged and called all of our attention to the notion that we all agree upon now, that before September 11 and until the passage of this legislation, there was no effort by government to do any kind of forensic examination of why buildings collapse, how we make them stronger, and how we make sure that they never happen again.
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That is just one of the things I think we agree upon at this point. We also agree, and from learning, from reading the report and from hearing the stories of those that were inside, and those that were engaged in the largest civic rescue in our nation's history, there were some tragic flaws in the design of the World Trade Center. There were also some remarkable design achievements that allowed the buildings to stand despite remarkable stress.
But we also, after getting the report back now, I think there is an emerging consensus on a couple of other issues as well. One is that the study doesn't go far enough. The study doesn't include the level of specificity that would truly make the report a handbook for those seeking to come up with building codes in the future. The City of New York is involved in something it hasn't done in a generation, which is rewriting its building codes. If I were to send this report to the City of New York, and they wanted to go to a reference and say, well, how do we follow up on the NIST recommendation that we improve standards for fire resistance testing. Is there a standard in this report? And the answer is no. If they want to follow up on the NIST recommendation that fire protection and suppression redundancy be built into buildings, is there a specific standard that they can take from this report? The answer is no. So, I think that we have fallen short, NIST has fallen short of making this a true reference manual for future protection of big buildings. And for those of us in New York City and other big cities, and frankly, even medium sized cities that are building buildings of greater than twenty stories, it falls short.
And I also think something else. You know, we in government have a certain tolerance for the slow pace of things. This took too long. It took too long for NIST to produce a report that really doesn't get us anywhere past the 50 yard line here. We are not in the Red Zone. We are not getting close to the place that we need to be. And I am prepared to introduce legislation, hopefully with the support of this committee and its great chairman, to say okay, let us take the next step. Let us take these general recommendations. Let us take the general forensic examination that was done on the World Trade Center. Let us take the general propositions that are suggested herein. Let us assume they are correct, but let us take the next step. Let us produce a document that truly has some fairly specific standards. Let us incentivize, but not require—I don't believe we should have a Federal Buildings Department—that incentivizes cities, states, and localities to adopt these things, and also, allows families, allow legislators when considering things like TRIA or building codes in Skokie, Illinois or Brooklyn, New York, to have a reference guide that they can use. Only then will the true goals of our original legislation have been fulfilled, and I think that that is something that we should point towards in the future.
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And I thank you again, Mr. Chairman, for allowing me to sit in. I want to thank all of the professionals at NIST. Mr. Jeffrey, I am sure by now you have gotten to know the Chairman. You and I haven't gotten to know one another. I am sure you have gotten to know Members of this committee. You would be wise to get to know Sally Regenhard very well, because whether you would like to or not, you are going to have a very big file with her name on it, and she has shown us one thing, you know, for those of us that have lost loved ones, there are many ways that people express their grief. The way Sally Regenhard and many of her friends and neighbors have expressed their grief is by making sure that there are no such disasters like this again in the future, and doing everything we can to prevent it. That is something that Chairman Boehlert and I are committed to. I know the professionals at NIST are committed to that. Now we have to go and finally get that job done.
And I thank you, Mr. Chairman.
Chairman BOEHLERT. Well, welcome back, and just let me say how pleased I am that you are finally getting to meet Dr. Jeffrey, because to know him is to like him, but more importantly, to know what he is all about and his mission and his approach to the job is to know he is determined to follow through, as we are.
This is just another hearing. This is not the final chapter in a drama about a horrific incident. We are determined to follow through, as is Dr. Jeffrey and the people at NIST working with the National Institute of Building Sciences. This is, by no means, the final chapter. This is another chapter, but we are determined to go forward working together, and we welcome you back as part of the team.
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With that, let me present the first witness, and I—Dr. Ehlers.
Mr. EHLERS. Thank you, Mr. Chairman. I appreciate you calling this hearing, and am very pleased to see the results that have been achieved. It is a little known facet of NIST responsibilities to do this sort of thing, and I am very pleased with the work they have done. And I think is providing a very strong base on which to build for the future.
I want to thank all our witnesses for coming here today. In particular, I want to congratulate Dr. Jeffrey, the new NIST Director, on his first appearance before this committee, and on NIST's latest Nobel Prize for Physics, announced this month to Dr. Jan Hall, a former colleague from my days as a researcher at NIST's Joint Institute for Laboratory Astrophysics, better known as JILA at the University of Colorado. And I have known Dr. Hall for years, and he is certainly deserving of this honor. This increases Nobel Prizes to three, demonstrating that NIST continues to be a world leader in research and theoretical work. I might also add that now that a physicist is heading the organization, I expect the output of Nobel Prizes will increase, and so, I will leave that to you as a challenge. I also wanted to congratulate Mr. Henry Green, a resident of my home State of Michigan, on his prestigious new position as President of the International Code Council, and I have had the pleasure of meeting with Mr. Green, and I am very impressed with him and his ability. I look forward to great things from him and his work on that Council.
The National Construction Safety Team Act, which originated in this committee, gave NIST specific authorities necessary to complete the monumental task of understanding the collapse of the World Trade Center towers. Today's hearing will give the Science Committee the chance to learn about NIST's findings and recommendations, and obtain comments from the witnesses about these recommendations and the process by which they will be implemented.
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The publication of the NIST report may signal the end of the investigation itself, but it launches a new phase in that process which I hope will result in safer buildings. NIST's recommendations indicate that there are opportunities to make buildings safer and more resilient to fires and other incidents, to improve evacuation routes and procedures, and to improve emergency response. However, the task of amending the building codes is in the hands of the private sector and the State and local officials. NIST's role now becomes technical advisor to the code development process. Congress needs to understand this process, and must support the research and testing required if any of NIST's recommendations are to become common practice. Congress also needs to understand what challenges may exist in implementing NIST's recommendations. Finally, I hope we hear from NIST about how it plans to use the National Construction Safety Team Act in the future, because I am certain we will have other occasions that this has to be called into action.
I want to thank NIST for the good work that you have done. Keep this up as we continue to work together to make buildings safer, both during and after disasters. I will have to apologize, because I will be in and out of this committee meeting, mostly out, because I have two other committee meetings simultaneously, and we are marking up bills, so my presence is required for votes. And I apologize to the Members testifying, the witnesses testifying, and also to the Chairman, but I will be here as much as I can.
[The prepared statement of Mr. Ehlers follows:]
PREPARED STATEMENT OF REPRESENTATIVE VERNON J. EHLERS
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Thank you, Chairman Boehlert.
I want to thank all our witnesses for coming here today. In particular, I want to congratulate Dr. William Jeffrey, the new NIST Director, on his first appearance before this Committee, and on NIST's latest Nobel Prize for Physics, announced this month to Dr. Jan Hall, a former colleague from my days as a researcher at NIST's Joint Institute for Laboratory Astrophysics (JILA) at the University of Colorado. This increases NIST's Nobel Prizes to three, demonstrating that NIST continues to be a world leader in research and theoretical work. I also want to congratulate Mr. Henry Green, a resident of my home State of Michigan, on his prestigious new position as President of the International Code Council (ICC).
The National Construction Safety Team Act (NCST), which originated in this committee, gave NIST specific authorities necessary to complete the monumental task of understanding the collapse of the World Trade Center Towers. Today's hearing will give the Science Committee the chance to learn about NIST's findings and recommendations, and obtain comments from the witnesses about these recommendations and the process by which they will be implemented.
The publication of the NIST report may signal the end of the investigation itself, but it launches a new phase in a process that I hope will result in safer buildings. NIST's recommendations indicate that there are opportunities to make buildings safer and more resilient to fires and other incidents, to improve evacuation routes and procedures, and to improve emergency response. However, the task of amending the building codes is in the hands of the private sector and state and local officials. NIST's role now becomes technical advisor to the code development process. Congress needs to understand this process, and must support the research and testing required if any of NIST's recommendations are to become common practice. Congress also needs to understand what challenges may exist in implementing NIST's recommendations. Finally, I hope we hear from NIST about how it plans to use the National Construction Safety Team Act in the future.
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Thank you to NIST for the good work you've done. Keep this up as we continue to work together to make buildings safer both during and after disasters.
Chairman BOEHLERT. Well, now that you are making some admissions, in the interest of full disclosure, while we are all very proud of that Nobel Prize in physics for NIST, in the interest of full disclosure, Dr. Ehlers is a physicist, and so, he is particularly proud.
[The prepared statement of Mr. Costello follows:]
PREPARED STATEMENT OF REPRESENTATIVE JERRY F. COSTELLO
Good morning. I want to thank the witnesses for appearing before our committee to discuss the findings and recommendations of the National Institute of Standard and Technology's (NIST) investigation into the collapse of the World Trade Center (WTC).
This committee has held two hearings in 2002 on the WTC collapse that focused on how the Federal Government investigates catastrophic building failures and the lessons learned from the collapse. Concerns raised at the hearing included the lack of any specific federal authority, protocols, or funding for investigations of any kind. As we have learned from the catastrophic damages of Hurricane Katrina, coordination among federal agencies is critical for gauging our preparedness and responding to national disasters. In order to address these concerns, it is my understanding that NIST issued a draft report for public comment that summarizes the findings of the investigation and includes thirty recommendations to improve the safety of tall buildings, occupants, and emergency responders. However, for NIST's plans to be effective, they must be implemented by standards organized and adopted by State and local authorities that set building codes and standards. I want to know how NIST intends to implement its research and recommendations for improved building codes, emergency response and evacuation procedures.
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I welcome our witnesses and look forward to their testimony.
[The prepared statement of Ms. Johnson follows:]
PREPARED STATEMENT OF REPRESENTATIVE EDDIE BERNICE JOHNSON
Thank you, Mr. Chairman and Ranking Member.
The events of September 11, 2001, changed our lives forever. That day changed how we Americans prepare ourselves against terrorism.
Building codes and safety regulations play a critical role during a disaster—natural or otherwise. Smart construction can mean the difference between life and death.
During an attack, the weight of collapsing building materials and heat of fire challenge even the best building designs.
The National Institute of Standards and Technology has come today to report on its findings and recommendations following its investigation into the collapse of the World Trade Center.
I hope today's discussion will underscore this key report and help the Committee understand how building and fire code organizations plan to implement the recommendations contained in that report.
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I would like to extend a warm welcome to our witnesses today. Thank you, Mr. Chairman.
[The prepared statement of Mr. Carnahan follows:]
PREPARED STATEMENT OF REPRESENTATIVE RUSS CARNAHAN
Mr. Chairman and Mr. Ranking Member, thank you for hosting this important hearing.
I am eager to learn more about the National Institute of Standards and Technology report recommendations. The World Trade Center collapse was a horrific episode for our nation and this report is another appropriate measure that revisits the events and permits us to learn from the tragedy.
Building safety and emergency evacuation are issues that go well beyond the subject of terrorism. This terrible hurricane season is demonstrating all too well the effect natural disasters have on man-made structures and our communities.
I represent a congressional district in St. Louis City that runs south along the Mississippi river. Our region is near the New Madrid earthquake center, which struck the area from 1811 to 1812. These sequences are the most powerful earthquakes ever to have been felt on the North American continent. The New Madrid Fault System remains a threat to our region, and thus, I am eager to learn more about the steps our community needs to take to better prepare our structures for a possible earthquake.
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To the multiple witnesses that appear before us today, thank you for your time and your efforts. I look forward to hearing your testimony.
[The prepared statement of Ms. Jackson Lee follows:]
PREPARED STATEMENT OF REPRESENTATIVE SHEILA JACKSON LEE
In looking at what are the next steps in terms of building codes and building structures and integrity, we must unfortunately review what took place on that dreadful day know as September 11th. Like most building collapses, these events were the result of a combination of factors. While the buildings were able to withstand the initial impact of the aircraft, the resulting fires that spread through the towers weakened support columns and floors that had fireproofing dislodged by the impacts. This eventually led to collapse as the perimeter columns were pulled inward by the sagging floors and buckled. According to reports, each aircraft severed perimeter columns, damaged interior core columns and knocked off fireproofing from steel as the planes penetrated the buildings. The weight carried by the severed columns was distributed to other columns. Subsequently, fires began that were initiated by the aircraft's jet fuel but were fed for the most part by the building contents and the air supply resulting from breached walls and fire-induced window breakage. These fires, in combination with the dislodged fireproofing, were responsible for a chain of events in which the building core weakened and began losing its ability to carry loads. The floors weakened and sagged from the fires, pulling inward on the perimeter columns. Floor sagging and exposure to high temperatures caused the perimeter columns to bow inward and buckle—a process that spread across the faces of the buildings which as a result caused the entire structure to collapse.
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As a Member of the Committee on Homeland Security, I am very interested in hearing the testimony of our witnesses today. While there have been many theories, no one really knows when, where and if another terrorist attack will take place. It is due to this uncertainty that we must do our best to be prepared in all possible aspects of homeland security. It is my understanding that the September 20, 2005 report released by NIST includes a detailed technical analysis of the root causes of the building failures as well recommendations to improve the safety of tall buildings, occupants and emergency responders. I believe these recommendations fall into eight categories of thirty recommendations. Loosely categorized these are: 1) increased structural integrity, 2) enhanced fire resistance of structures, 3) new methods for fire resistance design, 4) improved active fire protection, 5) improved building evacuation procedures, 6) improved emergency response, 7) improved procedures and practices in the design, construction and operation of buildings; and 8) upgrading the education/training of building and fire safety professionals. In closing, I look forward to the statements and recommendations of our witnesses as they lay out a road map as to how to protect our nation's structures.
[The prepared statement of Mr. Moore follows:]
PREPARED STATEMENT OF REPRESENTATIVE DENNIS MOORE
More than four years after the devastating terrorist attacks of September 11, 2001, we still remember too well the horrible images of that morning: the citizens of New York and Washington D.C. running in fear and confusion from the site of the attacks, firemen and other safety personnel bravely ushering men and women out of harms way, and the skeletal remains of the Twin Towers silhouetted against the bright September sky.
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Within hours of the attacks themselves, the Twin Towers collapsed, killing thousands of individuals trapped inside.
While there were many factors that contributed to the catastrophic loss of human life our country suffered on 9/11, an issue that demands careful scrutiny by this committee is the circumstances that contributed to the collapse of the Towers themselves.
As co-chair of the Congressional Hazards Caucus, ensuring that our buildings are properly designed and constructed to handle destructive forces, whether they are terrorist attacks, hurricanes, or tornadoes is of utmost importance to me.
I appreciate the willingness of the panel to share their opinions with the Members of the Science Committee on the findings of the National Institute of Standard and Technology's (NIST) report on the collapse of the World Trace Center and look forward to working with you in the future to ensure the continued safety and security of not only our buildings, but of the American people.
Chairman BOEHLERT. Now, with that, and no further opening statements, let me present, welcome back to the Committee, Ms. Sally Regenhard, Chairperson of the Skyscraper Safety Committee. Ms. Regenhard, the floor is yours, and she will have a very interesting statement, and so much of the commentary in her statement will lead us to provide questions to the panel that will follow.
So, Ms. Regenhard, the floor is yours.
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Panel I:
STATEMENT OF SALLY REGENHARD, CHAIRPERSON, SKYSCRAPER SAFETY CAMPAIGN
Ms. REGENHARD. Okay. Thank you. Good morning, Chairman Boehlert and Members of the House Science Committee. It is truly an honor and a privilege to address you today.
I must first begin by thanking Chairman Sherwood Boehlert and this committee for listening with compassion and concern to the families of the victims of 9/11. When we first came here in March and May of 2002, we were desperately seeking leadership for an investigation of what happened to our loved ones on 9/11. We had sought this on the local level in New York City, but found no one to help us answer the painful questions regarding what happened to our loved ones in the World Trade Center on that dreaded day of infamy.
Chairman Boehlert and the Science Committee, you have redeemed our belief in the system, and renewed our faith in the process of representative government in our beloved country, and for this, we profoundly thank you. The families of the victims as well as the American public remain in your debt for your efforts in authorizing a WTC investigation through the National Construction Safety Team Act.
I must also begin by thanking NIST for interacting with us on a regular basis over the past three years, via conference calls and meetings, with myself and my SSC co-chair, Monica Gabrielle, who is out of the country and cannot be here today. I know that it has not always been easy to deal with me and with other victims' families, but I appreciate the tolerance and respect shown to us by NIST. I also appreciate the vast technical research abilities of this organization and the enormous task of embarking upon the WTC investigation.
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In totality, however, while some very valuable results were achieved, the overall mode and findings of the investigation was not what I had hoped for. I had certain hopes regarding NIST in the investigation, but I and others were somewhat disillusioned regarding what NIST was willing and able to do. I had hoped for more specific and comprehensive recommendations that could easily be translated into code reform and change, but this was not the case. The recommendations, I feel, are very general and lack specifics. I feel that the vagueness of the language was influenced by a need for political correctness and a general reluctance or an inability to investigate, use subpoena power, lay blame, or even point out the deadly mistakes of 9/11 in the World Trade Center.
The following are five areas of concern of the Skyscraper Safety Campaign, and these concerns have been compiled by input from my professional advisors, as well as my own experience during the last four years.
The first area of concern is the role of the Port Authority of New York and New Jersey and its exemptions from immunities and codes. The failure of the NIST investigation to comprehensively examine what role these immunities played in the design, construction, maintenance, and ultimate collapse of the World Trade Center, is of great concern to me.
Secondly, the lack of more intense emphasis on the fireproofing issues, the premature disposal of the steel evidence, the heavy reliance on computer modeling for the fire testing, and the reluctance to focus on cause, blame, and resultant implications are troubling to us.
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Number three, the reliance on the voluntary cooperation of key figures in the investigation to provide needed information, putting the WTC chief structural engineer on the payroll to facilitate his involvement in the investigation, utilizing researchers to the exclusion of true investigators going into the field to obtain evidence is also problematic to me. On this last point, I want to note that I have been married to an NYPD detective sergeant for over 30 years, and I can recognize an investigation when I see one. I feel the inherent character of the NIST as a research rather than an investigative agency was a factor in this situation.
Number four, the lack of focus on evacuation issues of the World Trade Center, such as the remoteness of the exits, the behavior of fleeing persons in the stairwells, and the avoidance of first person accounts of stairwell evacuation, and the length of time it took to evacuate the building was a shortcoming.
Finally, the relative secrecy of the investigation and the withholding of all materials and documents used by NIST to arrive at the study's conclusions is very disturbing. These materials should be made available to professionals to further study and to analyze, and to question and verify the findings according to the scientific method. And they should not be locked away in the National Archives or anywhere else. I certainly hope that I could call on the Science Committee to help unlock this information for the American public in the future.
In conclusion, for these and for other reasons, I feel that government must take a larger role in developing stronger codes and standards for building and public safety, by being a true resource to the code industry. Government representatives should be part of code writing groups, to provide advice and guidance, and to help develop standards and practices. As it stands now, it is largely a battle of the do-gooders, like me and the Skyscraper Safety Advisors, versus the business interests, in a never-ending conflict regarding public safety. The NIST investigation should not be an end. It should be just the beginning of a new era, in which we see the real and meaningful role that government must play in the safety and wellbeing of the American people. In addition to the laudable creation of the National Construction Safety Team Act, this participation can be an additional legacy for the innocent victims of 9/11, including my beautiful son, Probationary Firefighter Christian Michael Otto Regenhard, whose godmother is holding his picture here today. He continues to be the inspiration for the work and the accomplishments of the Skyscraper Safety Campaign.
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I thank you all for this opportunity to speak to you today. God bless you all in your work.
[The prepared statement of Ms. Regenhard follows:]
PREPARED STATEMENT OF SALLY REGENHARD
Good morning Chairman Boehlert and Members of the House Science Committee. It is truly an honor and a privilege to address you today. I must first begin by thanking Chairman Sherwood Boehlert and this committee, for listening with compassion and concern to the families of the victims of 9/11. When we first came here in March and May of 2002, we were desperately seeking leadership for an investigation of what happened to our loved ones on 9/11/01. We had sought this on the local level in NYC, but found no one to help us answer the painful questions regarding what happened to our loved ones in the WTC on that dreaded day of infamy.
Chairman Boehlert and the Science Committee redeemed our belief in the system, and renewed our faith in the process of representative government in our beloved country, and for this, we profoundly thank you. The families of the victims, as well as the American public, remain in your debt for your efforts in authorizing a WTC Investigation through the National Construction Safety Team Act.
I must begin by thanking NIST for interacting with us on a regular basis over the past three years, via conference calls and meetings, with myself and my SSC co-chair, Monica Gabrielle, who is out of the country, and cannot be here today. I know it has not always been easy to deal with me and other victims' families, but I appreciate the tolerance and respect showed by NIST. I also appreciate the vast technical research abilities of this organization, and the enormous task of embarking upon the WTC Investigation.
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In totality however, while some very valuable results were achieved, the overall mode and findings of the investigation was not what I had hoped for. I had certain hopes regarding NIST and the investigation, but I and others were disillusioned regarding what NIST was willing and able to do. I had hoped for more specific and comprehensive recommendations that could easily be translated into code reform and change, but this is not the case. The recommendations are very general and lack specifics. I feel that the vagueness of the language was influenced by political correctness and a general reluctance or inability to ''investigate,'' use subpoena power, ''lay blame,'' or even point out the deadly mistakes of 9/11 in the WTC.
The following are five areas of concern for the Skyscraper Safety Campaign: (While I have an understanding of these issues in concept, for answers to specific, technical questions, I would like to confer with two of my technical advisors who are with me here today.)
1) The role of the Port Authority of NYNJ and its' exemptions from immunities and codes. The failure of the NIST Investigation to comprehensively examine what role these immunities had in the design, construction, maintenance and ultimate collapse of the WTC is of great concern to me.
2) The lack of more intense emphasis on fireproofing issues, premature disposal of steel evidence, the heavy reliance on computer modeling for fire testing, and the reluctance to focus on cause, blame, and resultant implications are troubling.
3) The reliance on the voluntary cooperation of key figures in the investigation to provide needed information; placing the former WTC chief structural engineer on the payroll to facilitate his involvement in the investigation, utilizing researchers to the exclusion of true investigators going into the field to obtain evidence is problematic to me. On this last point, I have been married to a NYPD detective sergeant for over 30 years, and I can recognize an Investigation when I see one. I feel the inherent character of NIST as a research rather than investigative agency was a factor in this situation.
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4) The lack of focus on evacuation issues of the WTC such as remoteness of exits, behavior of fleeing persons in the stairwells, and the avoidance of first person accounts of stairwell evacuation, and length of time it took to evacuate the building was a shortcoming.
5) The relative secrecy of the investigation, and the withholding of all materials and documents used by NIST to arrive at the study's conclusions is very disturbing. These materials should be made available to professionals for further study and analysis, to question and/or duplicate the findings, according to the scientific method, and should not be locked away in the National Archives or anywhere else. I hope I can call on the Science Committee to unlock this information for the American public.
In conclusion, for these and other reasons, I feel that government must take a larger role in developing stronger codes and standards for building and public safety. Government representatives should be part of code writing groups, and help to develop standards and practices. As is stands now, it is a battle of the ''do-gooders'' like me and the Skyscraper Safety Advisors vs. business interests, in a never ending conflict regarding public safety. The NIST investigation should not be an end; it should be just the beginning of a new era in which we see the real and meaningful role that government must play in the safety and well being of the American people. In addition to the laudable creation of the National Construction Safety Team Act, this participation can be an additional legacy for the innocent victims of 9/11, including my beautiful son, Probationary Firefighter Christian Michael Otto Regenhard, who continues to be the inspiration for the work and accomplishments of the Skyscraper Safety Campaign. Thank you for this opportunity to speak today. God bless you all.
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Chairman BOEHLERT. Thank you very much, and you continue to be an inspiration to this committee.
Let me point out that now, the witnesses that will follow. I hope you are going to be able to remain to listen to their testimony, and to listen to the questioning. I think you are absolutely correct in pointing out that I think it is a shared interest in being more specific, rather than vague, in the report, but NIST, I think, has done an outstanding job, and NIST correctly, as you identified in your testimony, is not an investigative agency. It is a research agency. I have found NIST to be most cooperative, but we are going to hold their feet to the fire, and we are going to make certain they follow through in their recommendations.
So, I think, hopefully, some measure of comfort will come to you from the statement of Dr. Jeffrey and his expressed determination to follow through on this. And I think you will be interested in what some of other witnesses have to say. These are people with whom you are familiar. And finally, I just hope it is not the do-gooders versus the business interests. I think we have got to have a partnership here. It is good business to make buildings safer, and that does good in the process. So, we will all work together. Thank you very much.
Ms. REGENHARD. Thank you very much.
Chairman BOEHLERT. The second panel today consists of Dr. William Jeffrey, Director of the National Institute of Standards and Technology; Ms. Nancy McNabb, Director of Government Affairs, National Fire Protection Association; Dr. James R. Harris, President, J.R. Harris and Company, Member, American Society of Civil Engineers; and Mr. Glenn Corbett, Assistant Professor of Fire Science, John Jay College of Criminal Justice, Member of NIST National Construction Safety Team Advisory Board; and for the purpose of an introduction of our final witness, I call on our distinguished colleague, Mr. Schwarz of Michigan.
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Mr. SCHWARZ. Thank you, Mr. Chairman. It is not frequently that I have the opportunity to introduce a constituent to his testifying before this committee, but in this case, Mr. Henry L. Green not only serves as President of the Board of Directors for the International Code Council, but as an expert in his field, and as a constituent of mine from Delta Township, which is just outside of Lansing, Michigan. In 1989, Mr. Green was appointed Executive Director of the Bureau of Construction Codes and Fire Safety for the Michigan Department of Labor and Economic Growth. Henry, they keep changing the names of the departments. That was what it was when I was in the State senate. He has worked in the Bureau for more than 20 years, serving as Building Inspector, Chief of the Barrier Free Design Division, Chief Building Inspector, and as Deputy Director before assuming his current role. He also serves on the Building Officials Code Administration, BOCA, Board of Directors, serving as President in 1997.
Mr. Chairman, Mr. Green is eminently qualified to testify before this committee, and I am equally delighted that he is here and a constituent of mine from mid-Michigan, from the 7th District. Actually, he is from Spartan Country, not Wolverine Country, but we will forgive him for that.
Chairman BOEHLERT. Mr. Green would join us at the table, and thank you very much for that eloquent introduction. I have had the pleasure of meeting Mr. Green, and I want to welcome you here. I want to welcome all of you here, and I want to thank you for being resources for this committee. I particularly want to welcome Dr. Jeffrey in his maiden public appearance before the Science Committee, in his present capacity.
Dr. Jeffrey, the floor is yours. And I would say to all our witnesses, we would ask that you try to summarize your opening statement in five minutes or so. We are not going to be all that arbitrary, but that will allow more time for questions and interaction between the panel and the Members. Dr. Jeffrey, the floor is yours.
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Panel II:
STATEMENT OF DR. WILLIAM JEFFREY, DIRECTOR, NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY
Dr. JEFFREY. Thank you, Mr. Chairman, and also thank you for your warm welcome remarks.
Mr. Chairman and Members of the Committee, I am pleased to testify on the NIST investigation of the World Trade Center disaster. With your permission, I have a written statement for the record, along with our final report.
Chairman BOEHLERT. Without objection, so ordered. All the statements in their entirety will be part of the official record.
Dr. JEFFREY. And I will now summarize our work to date and our plans for the future. We announced this investigation saying it would be thorough, open, and result in meaningful recommendations.
It was thorough. NIST was able to acquire and test enough steel from the buildings to have confidence in our findings. We acquired more than 7,000 photos and 150 hours of videotape. We interviewed nearly 1,200 survivors and first responders, and we gained access to key information about the building's design and construction.
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It was also open. We sought public comment on our plans even before we began the investigation. We held numerous briefings for the public, published reports on our progress, and solicited comments. We sought input from an advisory committee of outside experts. We established a special liaison with the families of victims, and communicated regularly with the relevant organizations in New York City. This was no academic exercise. We were charged with developing meaningful recommendations, and we have done that. Using the recommendations from this investigation to make improvements in the way people design, maintain, and use buildings has just begun. NIST is working vigorously with the relevant communities to turn the recommendations into action.
The direct link between the terrorist-initiated airplane attacks, the ensuing fires, and the collapse of the towers was established through extensive testing, analyses, and computer modeling. Here, you see a model of the aircraft as it enters Tower 1, and the damage that was inflicted as debris and jet fuel spread over multiple floors. These models helped us to estimate the internal damage to the structure and fireproofing that was not visible in photos and videos taken from the outside.
The egress capacity required by the current building codes is based on evacuating a single floor, not an entire building. Fortunately, the towers were only one third to one half of full capacity that morning, allowing 87 percent of the occupants to evacuate. Had the buildings been full, with about 20,000 occupants each, roughly 14,000 people may have lost their lives. Radio communications were a problem due to three factors: first, the challenging radio frequency environment posed by buildings; second, the scale of operations that overwhelmed the available frequencies and exceeded the limits of the communication protocols; and third, the difficulty of transmissions between different organizations.
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The recommendations we have made call for specific actions. We made our recommendations as specific as we could, identifying the parties that need to help take the next steps. The recommendations do not prescribe specific systems, materials, or technologies. Instead, NIST encourages competition among alternatives that can meet performance requirements. Within these recommendations, NIST has identified 37 specific national model codes, standards, practice guidelines, or regulations that merit consideration through an open and consensus-driven process.
NIST's response plan consists of three parts. First, the building and fire safety investigation. And today, we are releasing the final version of 43 reports documenting this investigation, and plan to release draft reports in the spring documenting our investigation of WTC 7. Second, our research and development program, and third, a dissemination and technical assistance program to facilitate adoption of the proposed changes.
As part of this effort, NIST is aggressively working with the model building code organizations and others representing State and local officials to facilitate this process. Among other things, NIST has held a major conference to focus attention on getting action on these recommendations. We have contracted with the National Institute of Building Sciences to turn the appropriate recommendations into draft code language for submission to the national model code developers, and we have assigned a staff member responsibility for following up on each and every recommendation.
Past NIST investigations have resulted in substantive improvements in building safety. For example, improvements to manufactured homes were made following our work on Hurricanes Andrew and Camille. Improvements in construction safety and inspection resulted from NIST's investigation of an apartment building under construction in Connecticut. There are many more examples of NIST's investigations resulting in improvements to building safety, and we will do everything possible to add the WTC investigation to this list.
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Thank you for your support and this opportunity to update the Committee.
[The prepared statement of Dr. Jeffrey follows:]
PREPARED STATEMENT OF WILLIAM JEFFREY
Mr. Chairman, and Members of the Committee, I am William Jeffrey, Director of the National Institute of Standards and Technology. I am pleased to appear today and testify on the building and fire safety investigation of the World Trade Center disaster carried out by the National Institute of Standards and Technology (NIST).
NIST announced its building and fire safety investigation of the World Trade Center (WTC) disaster on August 21, 2002. (see footnote 1) This WTC Investigation was then conducted under the authority of the National Construction Safety Team (NCST) Act, which was signed into law on October 1, 2002.
The goals of the investigation of the WTC disaster were:
To investigate the building construction, the materials used, and the technical conditions that contributed to the outcome of the WTC disaster after terrorists flew large jet-fuel laden commercial airliners into the WTC towers.
To serve as the basis for:
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— Improvements in the way buildings are designed, constructed, maintained, and used;
— Improved tools and guidance for industry and safety officials;
— Recommended revisions to current codes, standards, and practices; and
— Improved public safety.
The specific objectives were:
1. Determine why and how WTC 1 and WTC 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.
4. Identify, as specifically as possible, areas in current building and fire codes, standards, and practices that warrant revision.
APPROACH
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To meet these goals, NIST complemented its in-house expertise with an array of specialists in key technical areas. In all, over 200 staff contributed to the investigation. NIST and its contractors compiled and reviewed tens of thousand of pages of documents; conducted interviews with over a thousand people who had been on the scene or who had been involved with the design, construction, and maintenance of the WTC; analyzed 236 pieces of steel that were obtained from the wreckage; performed laboratory tests that measured material properties, and performed computer simulations of the sequence of events that happened from the instant of aircraft impact to the initiation of collapse for each tower.
Cooperation in obtaining the resource materials and in interpreting the results came from a large number of individuals and organizations, including The Port Authority of New York and New Jersey and its contractors and consultants, Silverstein Properties and its contractors and consultants, the City of New York and its departments, the manufacturers and fabricators of the building components, the companies that insured the WTC towers, the building tenants, the aircraft manufacturers, the airlines, and the media.
The scarcity of physical evidence that is typically available in place for reconstruction of a disaster led to the following approach:
Accumulation of copious photographic and video material. With the assistance of the media, public agencies and individual photographers, NIST acquired and organized nearly 7,000 segments of video footage, totaling in excess of 150 hours and nearly 7,000 photographs representing at least 185 photographers. This guided the Investigation Team's efforts to determine the condition of the buildings following the aircraft impact, the evolution of the fires, and the subsequent deterioration of the structure.
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Establishment of the baseline performance of the WTC towers, i.e., estimating the expected performance of the towers under normal design loads and conditions. The baseline performance analysis also helped to estimate the ability of the towers to withstand the unexpected events of September 11, 2001. Establishing the baseline performance of the towers began with the compilation and analysis of the procedures and practices used in the design, construction, operation, and maintenance of the structural, fire protection, and egress systems of the WTC towers. The additional components of the performance analysis were the standard fire resistance of the WTC truss-framed floor system, the quality and properties of the structural steels used in the towers, and the response of the WTC towers to the design gravity and wind loads.
Conduct simulations of the behavior of each tower on September 11, 2001, in four steps:
1. The aircraft impact into the tower, the resulting distribution of aviation fuel, and the damage to the structure, partitions, thermal insulation materials, and building contents.
2. The evolution of multi-floor fires.
3. The heating and consequent weakening of the structural elements by the fires.
4. The response of the damaged and heated building structure, and the progression of structural component failures leading to the initiation of the collapse of the towers.
For such complex structures and complex thermal and structural processes, each of these steps stretched the state of the technology and tested the limits of software tools and computer hardware. For example, the investigators advanced the state-of-the-art in the measurement of construction material properties and in structural finite element modeling. New modeling capability was developed for the mapping of fire-generated environmental temperatures onto the building structural components.
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The output of the four-step simulations was subject to uncertainties in the as-built condition of the towers, the interior layout and furnishings, the aircraft impact, the internal damage to the towers (especially the thermal insulation for fire protection of the structural steel, which is colloquially referred to as fireproofing), the redistribution of the combustibles, and the response of the building structural components to the heat from the fires. To increase confidence in the simulation results, NIST used the visual evidence, eyewitness accounts from inside and outside the buildings, laboratory tests involving large fires and the heating of structural components, and formal statistical methods to identify influential parameters and quantify the variability in analysis results.
Combination of the knowledge gained into probable collapse sequences for each tower, (see footnote 2) the identification of factors that contributed to the collapse, and a list of factors that could have improved building performance or otherwise mitigated the loss of life.
Compilation of a list of findings that respond to the first three objectives and a list of recommendations that responds to the fourth objective.
SUMMARY OF FINDINGS
Objective 1: Determine why and how WTC 1 and WTC 2 collapsed following the initial impacts of the aircraft.
The two aircraft hit the towers at high speed and did considerable damage to principal structural components (core columns, floors, and perimeter columns) that were directly impacted by the aircraft or associated debris. However, the towers withstood the impacts and would have remained standing were it not for the dislodged insulation (fireproofing) and the subsequent multi-floor fires. The robustness of the perimeter frame-tube system and the large size of the buildings helped the towers withstand the impact. The structural system redistributed loads from places of aircraft impact, avoiding larger scale damage upon impact. The hat truss, a feature atop each tower which was intended to support a television antenna, prevented earlier collapse of the building core. In each tower, a different combination of impact damage and heat-weakened structural components contributed to the abrupt structural collapse.
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In WTC 1, the fires weakened the core columns and caused the floors on the south side of the building to sag. The floors pulled the heated south perimeter columns inward, reducing their capacity to support the building above. Their neighboring columns quickly became overloaded as columns on the south wall buckled. The top section of the building tilted to the south and began its descent. The time from aircraft impact to collapse initiation was largely determined by how long it took for the fires to weaken the building core and to reach the south side of the building and weaken the perimeter columns and floors.
In WTC 2, the core was damaged severely at the southeast corner and was restrained by the east and south walls via the hat truss and the floors. The steady burning fires on the east side of the building caused the floors on that side to sag. The floors pulled the heated east perimeter columns inward, reducing their capacity to support the building above. Their neighboring columns quickly became overloaded as columns on the east wall buckled. The top section of the building tilted to the east and to the south and began its descent. The time from aircraft impact to collapse initiation was largely determined by the time needed for the fires to weaken the perimeter columns and floor assemblies on the east and the south sides of the building. WTC 2 collapsed more quickly than WTC 1 because there was more aircraft damage to the building core, including one of the heavily loaded corner columns, and there were early and persistent fires on the east side of the building, where the aircraft had extensively dislodged insulation from the structural steel.
The WTC towers likely would not have collapsed under the combined effects of aircraft impact damage and the extensive, multi-floor fires that were encountered on September 11, 2001 if the thermal insulation had not been widely dislodged or had been only minimally dislodged by aircraft impact.
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NIST found no corroborating evidence for alternative hypotheses suggesting that the WTC towers were brought down by controlled demolition using explosives planted prior to September 11, 2001. NIST also did not find any evidence that missiles were fired at or hit the towers. Instead, photographs and videos from several angles clearly showed that the collapse initiated at the fire and impact floors and that the collapse progressed from the initiating floors downward, until the dust clouds obscured the view.
Objective 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.
Approximately 87 percent of the estimated 17,400 occupants of the towers, and 99 percent of those located below the impact floors, evacuated successfully. In WTC 1, where the aircraft destroyed all escape routes, 1,355 people were trapped in the upper floors when the building collapsed. One hundred seven people who were below the impact floors did not survive. Since the flow of people from the building had slowed considerably 20 minutes before the tower collapsed, the stairwell capacity was adequate to evacuate the occupants on that morning.
In WTC 2, before the second aircraft strike, about 3,000 people got low enough in the building to escape by a combination of self-evacuation and use of elevators. The aircraft destroyed the operation of the elevators and the use of two of the three stairways. Eighteen people from above the impact zone found a passage through the damaged third stairway (Stairwell A) and escaped. The other 619 people in or above the impact zone perished. Eleven people who were below the impact floors did not survive. As in WTC 1, shortly before collapse, the flow of people from the building had slowed considerably, indicating that the stairwell capacity was adequate that morning.
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About six percent of the survivors described themselves as mobility impaired, with recent injury and chronic illness being the most common causes; few, however, required a wheelchair. Among the 118 decedents below the aircraft impact floors, investigators identified seven who were mobility impaired, but were unable to determine the mobility capability of the remaining 111.
A principal factor limiting the loss of life was that the buildings were only one-third to one-half occupied at the time of the attacks. NIST estimated that if the towers had been fully occupied with 20,000 occupants each, it would have taken just over 3 hours to evacuate the buildings and about 14,000 people might have perished because the stairwell capacity would not have been sufficient to evacuate that many people in the available time. Egress capacity required by current building codes is determined by single floor calculations that are independent of building height and does not consider the time for full building evacuation.
Due to the presence of assembly use spaces at the top of each tower (Windows on the World restaurant complex in WTC 1 and the Top of the Deck observation deck in WTC 2) that were designed to accommodate over 1,000 occupants per floor, the New York City Building Code would have required a minimum of four independent means of egress (stairs), one more than the three that were available in the buildings. Given the low occupancy level on September 11, 2001, NIST found that the issue of egress capacity from these places of assembly, or from elsewhere in the buildings, was not a significant factor on that day. It is conceivable that such a fourth stairwell, depending on its location and the effects of aircraft impact on its functional integrity, could have remained passable, allowing evacuation by an unknown number of additional occupants from above the floors of impact. If the buildings had been filled to their capacity with 20,000 occupants, however, the required fourth stairway would likely have mitigated the insufficient egress capacity for conducting a full building evacuation within the available time.
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Evacuation was assisted by participation in fire drills within the previous year by two-thirds of survivors and perhaps hindered by a Local Law that prevented employers from requiring occupants to practice using the stairways. The stairways were not easily navigated in some locations due to their design, which included ''transfer hallways,'' where evacuees had to traverse from one stairway to another location where the stairs continued. Additionally, many occupants were unprepared for the physical challenge of full building evacuation.
The functional integrity and survivability of the stairwells was affected by the separation of the stairwells and the structural integrity of stairwell enclosures. In the impact region of WTC 1, the stairwell separation was the smallest over the building height—clustered well within the building core—and all stairwells were destroyed by the aircraft impact. By contrast, the separation of stairwells in the impact region of WTC 2 was the largest over the building height—located along different boundaries of the building core—and one of three stairwells remained marginally passable after the aircraft impact. The shaft enclosures were fire rated but were not required to have structural integrity under typical accidental loads: there were numerous reports of stairwells obstructed by fallen debris from damaged enclosures.
The active fire safety systems (sprinklers, smoke purge, fire alarms, and emergency occupant communications) were designed to meet or exceed current practice. However, with the exception of the evacuation announcements, they played no role in the safety of life on September 11 because the water supplies to the sprinklers were damaged by the aircraft impact. The smoke purge systems, operated under the direction of the fire department after fires, were not turned on, but they also would have been ineffective due to aircraft damage. The violence of the aircraft impact served as its own alarm. In WTC 2, contradictory public address announcements contributed to occupant confusion and some delay in occupants beginning to evacuate.
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For the approximately 1,000 emergency responders on the scene, this was the largest disaster they had even seen. Despite attempts by the responding agencies to work together and perform their own tasks, the extent of the incident was well beyond their capabilities. Communications were erratic due to the high number of calls and the inadequate performance of some of the gear. Even so, there was no way to digest, test for accuracy, and disseminate the vast amount of information being received. Their jobs were complicated by the loss of command centers in WTC 7 and then in the towers after WTC 2 collapsed. With nearly all elevator service disrupted and progress up the stairs taking about two min. per floor, it would have taken hours for the responders to reach their destinations, assist survivors, and escape had the towers not collapsed.
Objective 3: Determine what procedures and practices were used in the design, construction, operation, and maintenance of WTC 1 and WTC 2.
Because of The Port Authority's establishment under a clause of the United States Constitution, its buildings were not subject to any state or local building regulations. The buildings were unlike any others previously built, both in their height and in their innovative structural features. Nevertheless, the actual design and approval process produced two buildings that generally were consistent with nearly all of the provisions of the New York City Building Code and other building codes of that time that were reviewed by NIST. The loads for which the buildings were designed exceeded the New York City code requirements. The quality of the structural steels was consistent with the building specifications. The departures from the building codes and standards identified by NIST did not have a significant effect on the outcome of September 11.
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For the floor systems, the fire rating and insulation thickness used on the floor trusses, which together with the concrete slab served as the main source of support for the floors, were of concern from the time of initial construction. NIST found no technical basis or test data on which the thermal protection of the steel was based. On September 11, 2001, the minimum specified thickness of the insulation was adequate to delay heating of the trusses; the amount of insulation dislodged by the aircraft impact, however, was sufficient to cause the structural steel to be heated to critical levels.
Based on four standard fire resistance tests that were conducted under a range of insulation and test conditions, NIST found the fire rating of the floor system to vary between j hour and two hours; in all cases, the floors continued to support the full design load without collapse for over two hours.
The wind loads used for the WTC towers, which governed the structural design of the external columns and provided the baseline capacity of the structures to withstand abnormal events such as major fires or impact damage, significantly exceeded the requirements of the New York City Building Code and other building codes of the day that were reviewed by NIST. Two sets of wind load estimates for the towers obtained by independent commercial consultants in 2002, however, differed by as much as 40 percent. These estimates were based on wind tunnel tests conducted as part of insurance litigation unrelated to the Investigation.
RECOMMENDATIONS
The tragic consequences of the September 11, 2001, attacks were directly attributable to the fact that terrorists flew large jet-fuel laden commercial airliners into the WTC towers. Buildings for use by the general population are not designed to withstand attacks of such severity; building regulations do not require building designs to consider aircraft impact. In our cities, there has been no experience with a disaster of such magnitude, nor has there been any in which the total collapse of a high-rise building occurred so rapidly and with little warning.
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While there were unique aspects to the design of the WTC towers and the terrorist attacks of September 11, 2001, NIST has compiled a list of recommendations to improve the safety of tall buildings, occupants, and emergency responders based on its investigation of the procedures and practices that were used for the WTC towers; these procedures and practices are commonly used in the design, construction, operation, and maintenance of buildings under normal conditions. Public officials and building owners will need to determine appropriate performance requirements for those tall buildings, and selected other buildings, that are at higher risk due to their iconic status, critical function, or design.
The topics of the recommendations in eight groups are listed in Table 1. A complete listing of the 30 recommendations is provided in Appendix A. The ordering does not reflect any priority.
The eight major groups of recommendations are:
Increased Structural Integrity: The standards for estimating the load effects of potential hazards (e.g., progressive collapse, wind) and the design of structural systems to mitigate the effects of those hazards should be improved to enhance structural integrity.
Enhanced Fire Endurance of Structures: The procedures and practices used to ensure the fire endurance of structures should be enhanced by improving the technical basis for construction classifications and fire resistance ratings, improving the technical basis for standard fire resistance testing methods, use of the ''structural frame'' approach to fire resistance ratings, and developing in-service performance requirements and conformance criteria for sprayed fire-resistive material.
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New Methods for Fire Resistant Design of Structures: The procedures and practices used in the fire resistant design of structures should be enhanced by requiring an objective that uncontrolled fires result in burnout without local or global collapse. Performance-based methods are an alternative to prescriptive design methods. This effort should include the development and evaluation of new fire resistive coating materials and technologies and evaluation of the fire performance of conventional and high-performance structural materials.
Improved Active Fire Protection: Active fire protection systems (i.e., sprinklers, standpipes/hoses, fire alarms, and smoke management systems) should be enhanced through improvements to design, performance, reliability, and redundancy of such systems.
Improved Building Evacuation: Building evacuation should be improved to include system designs that facilitate safe and rapid egress, methods for ensuring clear and timely emergency communications to occupants, better occupant preparedness for evacuation during emergencies, and incorporat