As the scope of the World Trade Center (WTC) tragedy came into focus in the hours following the attacks, I wondered what happened to the towers. Why did they come down so quickly? What role did the construction play? What brought the towers down—the planes or the fire? How many people had been evacuated? On and on, the questions kept coming.

This was the largest high-rise fire in American history. This was also the largest structural collapse in world history. I thought that a comprehensive investigation would soon be under way—a master plan, multiple teams of investigators, an army of specialists documenting the scene and securing the evidence. Unfortunately, I was very wrong.

As days turned into weeks and the true magnitude began to be realized, I searched to find out about the investigations taking place. They were disparate, uncoordinated. Certain aspects of the disaster, such as the evacuation, weren’t being examined at all by any official organization.

If there ever was a time for the broadest and most in-depth investigation ever developed, this was it. It wasn’t coming.

A few days into October, I received a phone call from Joe Calderone, a reporter for the New York Daily News. He asked me what I thought about what had happened and if I knew what technical details were emerging about the disaster. I told him that I was concerned that there was no comprehensive investigation taking place. I told him of the critical need to study this disaster. He also spoke with my associate at John Jay College in New York City, Professor Charles Jennings. The result was an article entitled “Two Professors Call for WTC Probe.” This article began my long 11-month odyssey with a group of people dedicated to learning all of the lessons of the WTC disaster.

Within days I received a call from Sally Regenhard, the mother of probationary firefighter Christian Regenhard who was missing at the WTC. She wanted answers as well and asked us to help her find them. Jennings and I agreed to serve as technical advisors to her new organization, the Skyscraper Safety Campaign.

I have learned one very important thing over the past year. It is the “victim groups,” and solely the victim groups, that have had the political horsepower to accomplish major changes and reforms as a result of this disaster. The fire service called for the hiring of 75,000 new firefighters. We’re still waiting. Regenhard and Monica Gabrielle (who joined Regenhard a few months into the disaster) have made a sea change in the way we are handling the WTC disaster investigation and the way we will handle future disasters. It is a shame that our fire service organizations have not solicited their assistance—maybe we would have made greater strides in making tangible improvements to all areas of the fire service since September 11.

Over the months, we have attended numerous meetings, press conferences, and the like. Two congressional hearings were held to inquire about the way in which the WTC disaster was “investigated.” The result: a new $16 million National Institute of Standards and Technology (NIST) investigation and a bill moving through Congress to create a new “National Construction Safety Team,” which will thoroughly investigate future building disasters.

So we are just embarking on a landmark inquiry of the WTC, a watershed event in building disaster investigations. While it is important to learn the lessons, it is equally as important to translate them into positive change. To that end, I have prepared the following random questions that I hope will be addressed during the NIST investigation. I hope we find the answers to these and many other questions and that positive results emerge.


  1. How was the relatively lightweight structural floor system design of the twin towers balanced with the potential fire threat? What kinds of fire scenarios were considered when designing the towers and later upgrades? Besides the impact of a plane, what other disasters were considered?
  2. How would a typical steel frame beam and column “skeleton” building have held up to the plane impact and the subsequent fire?
  3. What were the conditions of the fireproofing before the disaster? How well did it hold up not only to the impact of the planes but to the subsequent fires? If it is true that the planes knocked off the fireproofing (as has been alleged by many people), then how is it that the buildings did not collapse within the first few minutes, given that the steel trusses (which tied the outer columns to the center core structural members) in the building were bare and devoid of fireproofing? How would other fireproofing materials such as ceramics have held up?
  4. How do the fires of 9-11 compare with the time/temperature curve of our fire resistance test standard American Society of Testing and Materials E-119?


  1. How many people were actually in each building at the time of impact?
  2. How many people escaped by way of elevator? How many people were in elevators when the planes hit? How many people died in the elevators overall? (A recent USA Today article estimates this number to be at least 200.) How many people died as a result of hatch locks and door restrictors, which prevented them from forcing their way out?
  3. With regard to the South Tower, what were the evacuation messages given prior to the plane hitting it? How many people ignored the messages? How many people followed the messages? How many people were persuaded to leave because of their experiences during the 1993 bombing? How many people left because they saw what was happening in the North Tower? How many people were ordered to leave by their “bosses,” and how many were ordered to stay?
  4. With regard to the North and South Towers, how much “movement friction” was there between the evacuees going down the stairwells and the firefighters going up?
  5. How did the design of the buildings/ plaza/subterranean areas of the complex aid or hinder the egress once people arrived at the base of the buildings?


  1. When did the extent of damage to the North Tower become clearly established? To what extent was the police helicopter circling above able to assess the structural damage, particularly inside the building? Would an assessment from the roof of adjacent buildings (such as 7 WTC) have been possible/ useful?
  2. Was the public address system in the North Tower functional at all?
  3. What were the conditions of the standpipe systems in the buildings? What are believed to be the closest operable hose outlets to the fire floors in each building?
  4. How dependent were commanders on using “runners” to send and receive messages (prior to the collapses) because of the radio communications problems?


  1. Will future major high-rise fires cause the fire service to focus exclusively on evacuation and the saving of the “savable?”
  2. Are helicopters a viable option for evacuating significant numbers of people off of a roof? Should helicopters be considered for an exterior extinguishment assault on a high-rise fire? For aerial reconnaissance?
  3. Will remote command posts become standard for high-rise fires? How will building fire command stations (fire alarm panels, etc.) interface with a remote command post?
  4. Should we be storing firefighting equipment (hose, forcible entry tools, etc.) in high-rise buildings prior to a fire?
  5. Should new high-rises be developed with enhanced elevator shafts with a higher degree of protection? Should we have “firefighter-only” elevators?
  6. Is the “defend in place” evacuation strategy now dead? Do the areas of refuge provided for disabled people (or others) still make sense in a commercial high-rise?
  7. How much redundancy do we need in terms of passive (for example, fireproofing) and active (for example, sprinkler) protection?
  8. How beneficial will performance-based codes be in dealing with high-rise fire protection for new buildings? Will closely estimating “time to collapse” be part of building design for high-rises?
  9. Should we scrap the “hard-wired” firefighter communication systems (telephones) found in many high-rises and in our current codes? If so, what should take their place?
  10. And finally, the million-dollar question: Can major commercial high-rise building fires today actually be fought successfully?

Are we asking too much?

GLENN P. CORBETT is a professor of fire science at John Jay College in New York City, a technical editor of Fire Engineering, and a captain with the Waldwick (NJ) Fire Department. He previously held the position of administrator of engineering services with the San Antonio (TX) Fire Department. Corbett has a master of engineering degree from Worcester Polytechnic Institute in Massachusetts. He authored two chapters on fire prevention/protection in The Fire Chief’s Handbook, Fifth Edition (Fire Engineering Books, 1995). Corbett has been in the fire service since 1978.

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