Report on Trade Center Collapses Emphasizes Damage to Fireproofing
By TIMOTHY WILLIAMS
Published: April 5, 2005
World Trade Center towers may have remained standing even after they
were struck by aircraft if the impact had not dislodged fireproofing
and if office furniture had not extended the life of the fires sparked
by the jet fuel, a federal report released today concluded.
report by the National Institute of Standards and Technology said its
findings support the fact that the World Trade Center towers withstood
the initial aircraft impact and "that they would have continued to
remain standing indefinitely, but for another significant event such as
the subsequent fires."
The agency was charged by Congress two
years ago with investigating various aspects of the World Trade Center
attacks on Sept. 1, 2001, including evacuation and rescue procedures,
the quality of the buildings' steel, and how and why the buildings
The group did not issue recommendations in its report
today. It is scheduled to release the draft of its final report in
June, followed by a final report with recommendations in September. The
investigation has produced more than 10,000 pages of data, according to
The conclusions are in line with previous analyses
that cited the intense heat of up to 800 degrees Fahrenheit as a
central reason for the collapse - heat that would have been tempered if
the fireproofing had not been stripped. But the report also said that
while the architects of the towers had tested the impact of a Boeing
707 passenger jetliner crashing into the 80th floor of one of the
buildings in 1964, they never envisioned the intense fires that
engulfed the towers after the planes struck them.
released today concluded that there were about 8,900 people in the
first World Trade Center tower and about 8,500 in the second tower.
About 87 percent of the people were able to evacuate safely. The report
found that of the approximately 2,567 victims, "20% or more ... may
have been alive in the buildings just prior to their collapse."
only two of 198 elevators were working inside the towers after the
jarring impact of the jet liners, those who had the best chance of
safely evacuating from the floors not directly impacted were able to
leave their offices relatively quickly, to find stairwells, and were in
good enough physical shape to exit without resting between floors.
the analysis determined that in the first tower, the average surviving
occupant spent 48 seconds per floor descending the stairwell - 50
percent slower than the slowest speed predicted for non-emergency
evacuations presented in a standard fire engineering text. Because of
the slow pace of evacuation, the analysis said that had each of the
towers been full -- or had about 25,000 employees in each -- the
evacuation would have taken four hours and about 14,000 people would
The report also found that the World Trade Center's
high rise communication repeater was working properly, a finding that
contradicts claims by some rescue workers.
The analysis found
that while the impact of the planes destroyed and weakened the
buildings' support columns, damaged water supply systems and dislodged
fireproofing, the towers would have remained standing had it not been
for the fires that weakened their support steel.
concluded that most of the fire damage was not caused directly by
dispersed jet fuel from the aircraft, but by combustible office
furniture inside the buildings.
"The jet fuel, which ignited
the fires, was mostly consumed within the first few minutes after
impact," the report stated. "The fires that burned for almost the
entire time that the buildings remained standing were due mainly to
burning building contents and, to a lesser extent, aircraft contents,
not jet fuel."
The fires further weakened the support beams that
caused floors to buckle and the buildings to list to the side. Without
adequate fireproofing, the towers had little chance of surviving, the
"The buildings would likely not have collapsed
under the combined effects of aircraft impact and the subsequent jet
fuel ignited multi-floor fires, if the fireproofing had not been
dislodged or had been only minimally dislodged by aircraft impact," the