>> [MUSIC]
On September 11th, 2001,
terrorists flew two airplanes
into the World Trade Center towers.
By the end of the day,
nearly 3,000 people had perished,
including over 400 emergency responders.
The three tallest buildings
on the site collapsed,
and numerous nearby buildings
were damaged or destroyed.
As the nations sought to come to
terms with this tragedy,
NIST scientists and engineers
were called upon for their expertise.
>> After 911,
Congress recognized that there was
no federal agency with
the authority to conduct
technical building failure investigations.
Congress through the National Construction Safety Team Act,
asked NIST to conduct
a technical investigation,
including how and why the building collapsed,
the evacuation and the emergency response.
NIST's work investigating
the World Trade Center building collapses
was extensive.
During the investigation, NIST interviewed
116 emergency responders and
more than 1,000 survivors.
Thoroughly examined evidence,
including hundreds of
steel building components,
7,000 video segments,
more than 7,000 photographs,
emergency responder recordings,
and published accounts of
evacuations from 400 survivors.
NIST also created detailed computer models
to simulate the complex collapse sequence,
including the airplane impacts,
spread of fires,
and thermal weakening,
and conducted live-fire experiments
to build the models and
validate the computer simulations.
>> NIST did not undertake
this work by itself.
NIST had over 200 individuals,
including world-class scientists and
engineers from NIST industry and academia,
who were involved in investigation.
We also had an advisory committee
of highly respected scientists and
engineers who were involved.
>> Over the course of the investigation,
NIST held 23 public briefings
and issued draft reports for public comment.
The recommendations in
NIST's final reports resulted in
more than 40 major changes to
US building and fire safety codes.
These changes
primarily focused on tall buildings
include: additional stairway capacity
with hardened enclosures,
increased fire-resistance rating
for structural frames,
improved water supply
for building sprinklers,
and more robust radio
communications coverage within
buildings for emergency responders.
>> The tragedy of 911 revealed
significant issues with
public safety communication systems,
and contributed to the deaths
of first responders that day.
NIST responded by leading
critical cutting edge research to
enable public safety interoperability,
and to ensure access to
communication systems and networks
during times of emergencies.
>> NIST's work also contributed to
major advances in
the field of forensic science.
A NIST scientist developed a new DNA test,
that allowed medical examiners to identify
human remains from
highly fragmented DNA samples.
Today, that DNA test is still
being used in challenging investigations.
NIST's fire research continues to examine how
structures and building materials
respond to fires,
and NIST teams deploy to
study building failures around the country.
From Joplin, Missouri to Surfside,
Florida to make people
safer and communities more resilient.
Learn more by visiting
wtc.nist.gov [MUSIC].