Designing high-rise buildings: World still learning lessons of 9/11

Professor Ed Galea, from the University of Greenwich, led a three and a half year study into the evacuation of the twin towers, a collaboration between the universities of Greenwich, Ulster and Liverpool.

The project included in-depth interviews with 271 survivors about their experiences of what it was like as they tried to leave the buildings. Their personal stories helped the research team to paint a comprehensive picture of how people acted and what factors influenced their behaviour during evacuation, and assisted in identifying key safety issues that building designers need to address.

"The research is still ongoing and the data we have collected, both on the mechanics of a large-scale evacuation, and on the issues human behaviour, is being shared across the world, as a valuable international resource," Professor Galea says.

Using their buildingEXODUS evacuation software, the Greenwich team analysed the evacuation dynamics of the events of 9/11 and also explored what may have happened if the buildings had been fully occupied. From this work, Professor Galea concluded that, for buildings above a critical population and height, stairs alone were not sufficient for safely evacuating the entire population.

Alongside colleagues Dr Peter Lawrence and Mike Kinsey, at the university's Fire Safety Engineering Group, Professor Galea went on to explore the use of lifts for evacuations in high-rise buildings. As part of their buildingEXODUS software, the researchers have developed advanced human behaviour models, which simulate the choices people make in deciding to use a lift/elevator as part of their evacuation route in an emergency.

"Our studies suggest that buildings should utilise elevators and stairs, in combination," Professor Galea says. "We know stairs alone are not sufficient for full building evacuations, and since 9/11 there has been a trend to use specially designed elevators. But elevators, even fire safe elevators, raise the complex issue of human behaviour, and we know from our studies that many people do not trust using them, or will simply not wait for them, in an emergency.

"So it's vital to consider all aspects when designing new buildings. This means not just the mechanical issues of using elevators to evacuate people, but the whole issue of human behaviour, and this is what we have built into our computer modelling."

Professor Galea, Founding Director of the Fire Safety Engineering Group, warns that, ten years on from 9/11, people need to guard against complacency. "Evacuation drills and training always need to be taken extremely seriously, as successful evacuation depends in part on how quickly people respond," he says. "We found in our research that some people took many minutes to decide to evacuate the towers, while others didn't know where the stairs were, for example. The attacks have also highlighted the need for better information systems in buildings, with proper instructions in an emergency, rather than just an alarm going off.

"We intend that the information we have will help save lives, as it will help improve building design and evacuation procedures."

The original research project, known as HEED (High-Rise Evacuation Evaluation Database), was funded with a £1.6 million grant from the UK Engineering & Physical Research Council (EPSRC).