the collapse of the World Trade Center It is a seminar project of civil engineering students

1. COLLAPSE OF WORLD TRADE
CENTER

3. BEFORE ATTACK
Something everyone remembers about that day is the sky
didn’t have a cloud in sight, light blue, and crystal clear

4. WHAT HAPPENED…
On September 11, 2001, terrorists attacked the United States. They hijacked
four airplanes in mid-flight. The terrorists flew two of the planes into two skyscrapers
at the World Trade Center in New YorkCity.The impactcaused the buildings to catch
fire and collapse.Another plane destroyed part of the Pentagon (theU.S. military
headquarters) inArlington, Virginia. The fourth plane crashed in Shanksville,
Pennsylvania.
Officials believe that the terrorists on that plane intended to destroy either White
House or the U.S. Capitol. Passengers on the plane fought the terrorists and prevented
them from reaching their goal. In all, nearly 3,000 people were killed in the 9/11
attacks.

5. WHO DID IT
• The people of America banded together in the weeks following the September 11th attacks like
few other times in American history. People responded with donations of blood, effort and money.
The government declared Osama Bin Laden to be the main suspect and sent the military to fight
him and his terrorist organization calledAl Qaeda. The military has been able tocapture numerous
leaders within the terrorist organization but has not been able to capture Bin Laden himself.
• Acontroversy started when President Bush sent troops into Iraq on March 19, 2003 claiming that
the country led by Saddam Hussein was developing weapons of mass destruction and aidingAl
Qaeda operatives.As time passed and no evidence of those weapons were found in Iraq, many in
America were upset by what they felt were unnecessary reasons to get involved in Iraq.

6. TIMELINE OF THE EVENT
7:59
a.m.
All
planes
begin
take
off
8:56 9:05 9:36
a.m. a.m. a.m.
First George Vice
crash, Bush is presiden
9:31
a.m. Bush
makes a
public
announc
-ement
9:03 a.m.
Second
crash,
Flight
175,
south
tower
9:37 a.m.
Flight 77
crashes into
Pentagon
9:59 a.m.
The south
tower
collapses
10:28 a.m.
The north
tower
collapses
5:20 p.m.
The World
Trade
Center
collapses
9:45
a.m.
White
House
and
U.S.capit
ol
are
cleared
10:03
a.m.
The
fourth
plane
crashe
s in
Pennsy
lvania
1:04 p.m.
The air is
cleared
8:30
p.m. Bush
gives
final
address
of the
day

8. MEMORIAL
The National September 11 Memorial is a tribute
of remembrance and honor to the nearly 3,000
people killed in the terror attacks of September 11,
2001 at the World Trade Center site, near
Shanksville, Pa., and at the Pentagon, as well as
the six people killed in the World Trade Center
bombing in February 1993.

9. • FACTS
• On September 11, 2001, 19 men hijack four fuel-loaded commercial airlines bound
for west coast destinations. This terrorist attack on the United States is orchestrated
by al Qaeda leader Osama bin Laden. A total of 2,977 people are killed in New York
City, Washington, DC and outside of Shanksville, Pennsylvania, in the worst terrorist
attack in U.S. history.
• On any given workday, up to 50,000 employees worked in the WTC twin towers,
and an additional 40,000 passed through the complex.
• 9/11 was the single largest loss of life from a foreign attack on American
soil.
• 18 people were rescued alive from the rubble of the WorldTrade Center site.

10. AFTERMATHS
• Other Buildings-
Many of the surrounding buildings were also either damaged or destroyed as the towers fell. 5 WTC suffered a
large fire and a partial collapse of its steel structure. Other buildings destroyed include St. Nicholas Greek
Orthodox Church, Marriott World Trade Center (Marriott Hotel 3 WTC), South Plaza (4 WTC), and U.S.
Customs (6 WTC). The World Financial Center buildings, 90 West Street, and 130 Cedar Street suffered
fires.
Many works of art were destroyed in the collapse.
• Health Effects-
The collapse of the World Trade Center produced enormous clouds of dust that covered Manhattan
for days.It resulted in serious reductions in air quality and is likely the cause
of many respiratory illnesses among first responders, residents, and office workers in lower
Manhattan. Asbestosis is such an illness, and asbestos would have been present in the dust. The
thousands of tons of toxic debris resulting from the collapse of the Twin Towers
contained more than 2,500 contaminants, including known carcinogens.

11. • Clean-up:
The cleanup was a massive operation coordinated by the City of New York Department of
Design and Construction. On September 22, a preliminary cleanup plan was delivered
by Controlled Demolition, Inc. (CDI) of Phoenix, Maryland. It involved round-the- clock operations,
many contractors and subcontractors, and cost hundreds of millions of dollars.The large pile of debris left on the
site burned for three months, despite efforts to extinguish the blaze until the majority of the rubble was finally
removed from the site.By early November, with a third of the debris removed, officials began to reduce the
number of firefighters and police officers assigned to recovering the remains of victims, in order to prioritize
the removal of debris. This caused confrontations with firefighters. In 2007, the demolition of the surrounding
damaged buildings was still ongoing as new construction proceeded on the World Trade Center replacement, 1
World Trade Center.

12. FUTURE PREPAREDNESS’
The tragedy of 9/11 resulted in awareness that our country needed to be prepared for a terrorist
attack. Since 2001 there have been significant advances in emergency response for large-scale events.
• Improvements to hospital preparedness since 9/11 include surge capacity, better preparedness for
chemical/bioterrorist attack, emergency drills with local agencies and employee training.
• Pre-9/11 there was limited or no capability of first responders from different jurisdictions to communicate
with each other. Since fiscal year 2003 the Department of Homeland Security (DHS) has provided
approximately $3 billion for communications interoperability initiatives.
• There were no risk-based security funds pre-9/11. Today 100% of Urban Area Security Initiative
(USASI) funds are awarded based on risk and effectiveness.
• Pre-9/11 no critical infrastructure was in place. Following 9/11 DHS crated the National Infrastructure
Plan (NIPP), “a historic and unprecedented public/private partnership to identify and protect the
Nation’s critical infrastructure and key resources.”
• Since 2004, September has been declared as National Preparedness
• Month. Sponsored by the Federal Emergency Management Agency, the focus is on personal and
community preparation. We remember the loss of 9/11 and we share in the responsibility of preparedness.

14. CONCLUSION
In the past, designers had no need to accommodate for terrorist attacks from
the air, but now that this threat is a reality, designers are looking for
reasonable ways to protect our high-rises.It appears that to truly be safe, a
building must be able to withstand a great impact without losing structural
integrity, as well as defend itself against fires and explosions. Perhaps
buildings can be made more resistant with redundant systems in which the
structure will not collapse if a few columns are destroyed by an impact or
explosion. Perhaps high-rise buildings should have backup fire protection
systems in case the primary system is disabled for some reason. Ultimately
buildings will have to focus more on robust construction and emergency
precautions and less on aesthetic appeal. Of course, if the World Trade Center
is going to be rebuilt, which many say it will, the new buildings will have to be
as aesthetically pleasing as their predecessors; they will be replacing the two
most famous buildings in the infamous New York skyline.

15. THANK YOU