The hijacked American Airlines Flight 77 that slammed into the west face of the Pentagon that fateful day entered Wedge 1 (of the building's five "wedges"). Fortunately, Wedge 1 had been the first fifth of office space to be renovated under the Pentagon Renovation Program, the first major renovation for the nation's military headquarters since it was built in the early 1940s.
The renovation of Wedge 1, completed in March 2001, included extra measures to enhance safety and security, said Eaton. These enhancements included blast-resistant windows, an interlocking structure of steel tubes and a geo-technical mesh built in behind dry wall inside the Pentagon's outer fa?e. Additionally, automated emergency smoke doors were inconspicuously recessed into corridor walls, and a new sprinkler system - the only one in the Pentagon - was installed overhead.
The blast-resistant windows - at $10,000 a piece installed - along with structural steel reinforcements and Kevlar-like mesh were designed with the intention of protecting people inside the Pentagon from an external explosion. And even though the plane entered the building and exploded from the inside out, the windows and structural reinforcements helped to lessen the impact and prevented the building from collapsing for approximately 30 minutes after impact, said Eaton.
Of the 2,600 people in the immediate area of impact, 125 were killed and more than 100 were injured, according to Eaton. The numbers could have been far worse if not for the structural enhancements. Eaton pointed out that the Pentagon Renovation Program received numerous emails, phone calls and letters of thanks from people who survived the attack.
Lessons learnedAfter September 11, 2001, Pentagon officials determined that even further safety and security improvements were needed, said Eaton. Photoluminescent signage, which requires no electricity to function, will be installed at floor level. These signs will assist victims who in a fire typically have to crawl to safety to avoid smoke inhalation. Concrete masonry units (CMUs) will be incorporated to harden all radial corridors, stairways, elevator shafts and mechanical rooms, increasing the level of fire protection in these areas and making them more resistant to a blast event.
Also, new corridors will be built to create additional avenues of egress. The renovation program is working to improve emergency egress, conducting a time egress analysis. Another improvement will be the installation of additional stand pipes to feed the sprinklers.
In addition, the Pentagon Renovation Program is considering modifications to roads and grounds. Changes would be designed to enhance building security. The program is also looking into the possibility of installing a stand-alone public address (PA) system in every room of the Pentagon.
Another lesson learned from 9/11 involves fire safety training. The Pentagon is planning to train additional area fire wardens and recently hired a full-time fire marshal to manage building fire safety issues and provide training for personnel.