_CHANGES TO THE BUILDING CODES FOLLOWING SEPTEMBER 11 ATTACKS ON TWIN TOWERS

I count myself as being very lucky to have had the opportunity to visit the World Trade Centre site in Lower Manhattan in 2000 and to have stood beneath and admired the twin tower buildings. We are all too aware of the shocking events which unfolded the following year which changed the Manhattan skyline forever and which instigated investigations into the existing building standards and codes for high rise structures.

Just over a week before the 10th anniversary of the September 11 attacks in New York, the International Code Council (ICC) published “Building Safety Codes Changed as a Result of 9/11” as a news release. The ICC is a developer of construction industry building safety codes used throughout the United States. The Code Council’s activity heightened when the National Institute of Standards and Technology, a federal agency, released its Report on the Collapse of the World Trade Centre, which contained 30 broad recommendations for the model codes, standards industry, design community and emergency responders.

The news release by ICC follows the completion in May 2010 of several years of rigorous investigations by the International Code Council Ad Hoc Committee on Terrorism-Resistant Buildings. The expert committee was made up of code enforcement officers representing buildings and fire departments, design professionals and fire protection engineers. Gary Lewis, who chaired the committee for several years states “what we have learned from this process is that building vulnerabilities can be addressed in areas where there is clear benefit”.

The ICC initiated code change proposals, many of which were incorporated into the International Code and are outlined below.

• Elevators are required in high-rise buildings more than 120 feet tall so fire-fighters can get to, and fight fires, without walking up from the ground floor with heavy equipment.
• An additional stairwell for high-rises that are more than 420 feet tall.
• In lieu of the additional stairwell, an option to provide enhanced elevators that can be used by the building occupants for emergency evacuation without waiting for assistance from emergency personnel.
• A higher standard for fire resistance in high-rise buildings more than 420 feet tall.
• More robust fire proofing for buildings more than 75 feet tall, which would be likely to be dislodged by impacts or explosions.
• Shafts enclosing elevators and exit stairways that have impact resistant walls.
• Self-luminous exit pathway markings in all exit stairways that provide a lighted pathway when both the primary and secondary lighting fails.
• Radio coverage systems within the building to allow emergency personnel to better communicate with the building and with emergency staff outside the building supporting response.

Rebuilding at the World Trade Centre site has commenced and on September 11 2011 the steel frame of the new One World Trade Centre, now commonly known as the ‘Freedom Tower’, was 80 stories high. The buildings surrounding One World Trade Centre are in various stages of completion.

Following numerous re-workings of the building concept and continual tweaks to the final design, the ‘Freedom Tower’, when finished will stand at 105 stories, a height 1,776 feet, a symbolic feature given that 1776 represents the year America became an independent nation. The ‘Freedom Tower’ is scheduled to be completed in 2013 and scheduled to open in January 2014.