The debates mainly covered topics such as:
One of the proposed solutions to future attacks is the underground construction of buildings. For example, there have been proposals to expand the city of Amsterdam with a futuristic and massive underground network of activities. This paper seeks to examine the construction lessons learned from the WTC attacks and the possibility of considering underground construction as a way of avoiding attacks situations similar to the one of the WTC.
The twin towers were designed and constructed five decades ago as new way of building skyscrapers in which they were to be very light in weight and involved modular methods of construction meant to reduce costs and accelerate the building schedule. They were constructed using an egg-crate design having extra columns that would hold the building standing in case one or two columns were to be lost (Eager & Musso, 2001). This design made the towers to be some of the most resilient buildings ever constructed and it is no wonder their collapse was that astonishing and generated so much speculations and debates among knowledgeable structural engineers (FEMA, 2002; National Institute of Science and Technology, 2008)).
Prior to the WTC attacks, security in design was not all that an important concern to engineers, architects or builders (Bazant and Cedolin, 1991). Security was normally only considered a design priority when designing and constructing specific types of projects such as consulates, government facilities and prisons and State Department embassies. Following the attacks, security has become of absolute importance in virtually all types of construction including educational, healthcare, commercial, residential and institutional.
The drastic change in the construction environment, which occurred virtually overnight, makes it important that all suitable technology and security safeguards are incorporated into the initial