The final report from the most detailed examination of a building failure ever conducted was released at a hearing of the House Science Committee on the NIST investigation at which Jeffrey testified. Featured in the report are 30 recommendations designed to improve the safety of tall buildings, their occupants and first responders. It is available online at wtc.nist.gov.
"I have assigned top priority for NIST staff to work vigorously with the building and fire safety communities to assure there is a complete understanding of the recommendations and to provide needed technical assistance in getting them implemented," Jeffrey told the committee.
Jeffrey said that NIST believes its recommendations are realistic, appropriate and achievable within a reasonable period of time. However, he cautioned that improvements would only be realized if they are acted upon by the appropriate organizations. To facilitate this effort, NIST to date has:
Identified specific codes, standards and practices affected by each of the 30 recommendations in the final WTC towers report;
Reached out to the organizations responsible for making changes to expedite consideration of and action on the recommendations (for example, NIST held a major technical conference on the recommendations in September 2005 attended by over 200 people, including representatives from all major standards and codes development organizations); and
Awarded a contract to the non-profit National Institute of Building Sciences to turn many of the recommendations into code language suitable for submission of code change proposals to the two national model code developers, the National Fire Protection Association and the International Code Council.
The NIST recommendations are contained within 43 separate reports (totaling some 10,000 pages) that cover:
- Specific improvements to building standards, codes and practices;
- Changes to, or the establishment of, evacuation and emergency response procedures; and
- Research and other appropriate actions needed to help prevent future building failures.
Based on nearly 500 comments received during the six-week public review period following the release of the draft WTC towers report on June 23, the reports – including some of the recommendations – were amended and clarified. The recommendations are divided into eight groups and summarized as follows:
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. Among the recommendations in this group are:
- Nationwide adoption of standards and codes to prevent progressive collapse;
- More reliable means of predicting the potential for complex failures in structures subjected to multiple hazards; and
- Nationally accepted standards for wind tunnel testing of prototype structures and estimating wind loads for tall buildings.
Enhanced Fire Resistance of Structures: The procedures and practices used to ensure the fire resistance 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; using the "structural frame" approach to fire resistance ratings; and developing in-service performance requirements and conformance criteria for spray-applied fire resistive materials (SFRMs, commonly referred to as "fireproofing").
Among the recommendations in this group are:
- Evaluating, and where needed, improving, the technical basis for determining appropriate construction classifications and fire rating requirements – especially for tall buildings – and making related code changes now by considering a variety of factors (including timely access by emergency responders, full evacuation of occupants and redundancy in fire protection systems critical to structural safety);
- Improving the century-old standard for fire resistance testing of building components, assemblies and systems – including establishing a capability for doing the improved testing under realistic fire and load conditions; and
- Developing and implementing criteria, test methods and standards for measuring the in-service performance and as-installed condition of "fireproofing."
New Methods for Fire Resistance Design of Structures: The procedures and practices used in the design of structures for fire resistance should be enhanced by requiring an objective that uncontrolled fires result in burnout without partial or global (total) collapse. Performance-based methods are an alternative to prescriptive design methods. This effort should include: (1) the development and evaluation of new fire resistive coating materials and technologies, and (2) the evaluation of the fire performance of conventional and high-performance structural materials (such as fire-resistant steels and concretes). Technical and standards barriers to the introduction of new materials and technologies should be eliminated.
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.
Among the recommendations in this group are:
- Enhancing fire protection systems to provide redundancy and accommodate the higher risks associated with tall buildings;
- Developing advanced fire alarms and communications systems that provide continuous, reliable and accurate information on life safety conditions; and
- Developing and requiring real-time secure transmission of data from fire alarm and other monitored building systems for use by emergency responders at any location, and storage of that data off-site or in a black box.
Improved Building Evacuation: The process of evacuating a building 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 incorporation of appropriate egress technologies.
Among the recommendations in this group are:
- Improving occupant preparedness for building evacuations through joint and nationwide public education and training campaigns;
- Designing tall buildings to accommodate timely full building evacuation of occupants if needed – including stairwell capacity and stair discharge door width that accommodates counterflow due to access by emergency responders;
- Maximizing the remoteness of egress components (i.e. stairs, elevators) without making them hard to reach;
- Using pagers and cell phones for broadcast warning systems and Community Emergency Alert Networks; and
- Evaluating for future use such current and next-generation evacuation technologies as protected/hardened elevators, exterior escape systems and stairwell descent devices.
Improved Emergency Response: Technologies and procedures for emergency response should be improved to enable better access to buildings, response operations, emergency communications, and command and control in large-scale emergencies.
Among the recommendations in this group are:
- Installing fire-protected and structurally hardened elevators to improve emergency response activities, the evacuation of mobility impaired occupants – and preferably, all occupants – in tall buildings;
- Installing, inspecting and testing emergency communications systems, radio communications and associated operating protocols to ensure that the systems and their protocols will function in challenging radio frequency propagation environments and large-scale operations, and can be used to track emergency responders within a building; and
- Developing and implementing codes and protocols for ensuring effective and uninterrupted operation of the command and control system in large-scale building emergencies.
Improved Procedures and Practices: The procedures and practices used in the design, construction, maintenance and operation of buildings should be improved to include encouraging code compliance by non-governmental and quasi-governmental entities; adoption and application of egress and sprinkler requirements in codes for existing buildings; and retention and availability of building documents over the life of a building.
Education and Training: The professional skills of building and fire safety professionals should be upgraded through a national education and training effort for fire protection engineers, structural engineers and architects. The skills of building regulatory and fire service personnel also should be upgraded to provide sufficient understanding of what is needed to conduct the review, inspection and approval tasks for which they are responsible.
Along with strongly urging that immediate and serious consideration be given to these recommendations by the building and fire safety communities, NIST also advocates that building owners and public officials evaluate the safety implications of these recommendations to their existing inventory of buildings; and take the steps necessary to mitigate any unwarranted risks without waiting for changes to occur in codes, standards and practices. NIST further urges state and local agencies to rigorously enforce building codes and standards since such enforcement is critical to ensure the expected level of safety.
NIST plans to establish a Web-based system with information on the status of its WTC recommendations that will be available to the public so that progress in implementing them can be tracked.
NIST's investigation of the WTC towers fires and collapses was conducted under the National Construction Safety Team (NCST) Act. The act gives NIST the authority for conducting fact-finding investigations of building-related failures that result in substantial loss of life. NIST has no regulatory authority under the NCST Act.
The NCST Act also states that no part of any report resulting from a NIST investigation into a structural failure or from an investigation under the act may be used in any suit or action for damages arising out of any matter mentioned in the report.