Confidence in tall buildings sky high five years after 9/11

An American tall buildings group has claimed confidence in skyscrapers has been rebuilt five years after terrorists attacked and destroyed the World Trade Centre in New York.

The Council on Tall Buildings and Urban Habitat (CTBUH) said lessons had been learnt after the attacks, making such buildings safer and more secure and the market for them thriving.

A statement by the body listed seven main areas where changes had been made to the design of new skyscrapers, such as building evacuation, elevators, communciation and building management.

CTBUH chairman David Scott, also a structural engineer at Arup said: "Tall building design moved out of the technical domain and into the public domain. Though it is neither practical nor feasible to design buildings to withstand every forseeable extreme event, safety concerns have led building owners, developers and occupants to demand more robust building designs, and that demand has been answered.”

Scott added that not every building required the same level of security or additional design. "Threat and risk assessment can provide a suitable framework for developing a robust, cost-effective design solution, but there is little point in spending large sums of money on protection systems that may offer little extra benefit to the safety of building occupants or firefighters," he said.

"It is more appropriate to look at these issues in the context of reasonable risk, based upon identified risks, rather than preparing for worst case scenarios across the board. Additional mitigating measures, based on client requirements and cost-effectiveness, can be developed where appropriate.

"These new approaches and heightened awareness will help prevent future catastrophic building collapse and have helped to rebuild confidence in high-rise buildings," Scott said. "This is perhaps one explanation for the recent worldwide boom in high- rise construction."