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13 November 2014

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You are in: London > London Local > Greenwich > Work and Money > University learning lessons of 9/11

9/11 attacks

9/11 attacks

University learning lessons of 9/11

Survivors of the terrorist attacks on the World Trade Center have helped researchers from Greenwich; to learn about how buildings can be evacuated quickly in an emergency.

They were the tallest buildings in Manhattan, and together they formed one of New York's most recognisable views.

When hijackers flew aircraft into the twin towers on the morning of the 11th September 2001 it started a series of events which later led to both skyscrapers collapsing within hours.

271 survivors interviewed

Seven years on and survivors of the two towers have been interviewed by a team of researchers from the Universities of Greenwich, Ulster and Liverpool.

Remains of the WTC after the 2001 attack

Remains of the WTC after the 2001 attack

The three and a half year study into the evacuation of the twin towers included face-to-face interviews with 271 survivors of the attacks.

6,000 pages of 'first hand accounts' were recorded, with the data being used to help save lives in the future.

Computer simulations

Greenwich researcher's preliminary findings included the fact more than half the occupants stayed in the buildings to carry out tasks before they evacuated the towers.

Occupants of the buildings who sought information about what was going on outside took between 1.5 and 2.6 times longer to exit the buildings, than those who simply left.

Computer simulations of the North Tower being evacuated suggested 7,592 people would have died - had the skyscraper been fully occupied.

"I mean we were running down for the first five stairs, "Boom, boom, boom, boom, boom," two stairs at a time sometimes."

WTC Survivor testimony

Skyscraper design

Sally Regenhard, from the Skyscraper Safety Campaign and mother of a firefighter lost at the WTC has welcomed the University of Greenwich research.

She says: "designers of high rise buildings and their evacuation procedures are architects of destiny for millions around the world."

"When I see a new skyscraper, I want to know that the deadly mistakes of 9/11 have been corrected."

Safety measures

Survivor details have been entered in a database known as the High-rise Evacuation Evaluation Database (HEED).

It's hoped the findings of the report will improve the safety of high rise buildings around the world.

WTC collapsing after the attacks

WTC collapsing after the attacks

Professor Ed Galea of the University of Greenwich said: "together these personal stories paint a comprehensive picture of what happened and why."

"What influenced evacuees' behaviour? What was going through their minds when they made key decisions? This is a hugely important body of data in itself."

He continued: "we will be making the HEED database available to bone fide researchers all over the world, so that it can become a valuable international resource for others to use."

Staircase congestion

Already the data has shown that engineers had failed to accurately predict the speed at which people would evacuate from the 110 storey buildings.

Survivors travelled more slowly down the staircases than had been predicted.

One survivor told Greenwich researchers: "we stopped at [floor] 55, right there, because there was obviously a lot more people.

They continued: "I mean we were running down for the first five stairs, "Boom, boom, boom, boom, boom," two stairs at a time sometimes. When we got to 55, we couldn't do that because we would plough into people."

World Trade Center before the attacks

World Trade Center before the attacks

Evacuation model

Eighty-two percent of those interviewed said they had stopped at least once as they tried to leave the buildings, with many having to stop because of congested stairwells.

Prof Galea said: "for such buildings, additional evacuation provision will need to be provided, for example through the use of specially designed lifts/elevators."

The University of Greenwich is already exploring the use of lifts for evacuation of high-rise buildings using their building evacuation model.


The project was funded with a £1.6 million grant from the UK Engineering & Physical Sciences Research Council.

As a thank you to the survivors the three Universities have donated a total of $5,420 to the World Trade Center Survivor's Network.

  • Now the University of Greenwich are asking for your help in working out how humans behave when leaving buildings. You can take part in the University's questionnaire - look for the link in the top right of this page.

last updated: 11/09/2008 at 12:51
created: 10/09/2008

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