Sunday marks the 15th anniversary of the September 11 attacks on the United States, when the extremist group al-Qaeda carried out a series of terrorist attacks by flying two highjacked commercial airplanes into the World Trade Center buildings and another into Pentagon. A fourth plane presumably headed toward Washington, D.C. crashed in Pennsylvania.

The devastating events claimed the lives of nearly 3,000 people and left more than 6,000 injured. They resulted in at least $10 billion in property and infrastructure damage, according to the Institute for the Analysis of Global Security, and $3 trillion in total costs, according to the New York Times.

Looking Back

October 2001 issue of USGlass magazine

USGlass magazine covered the aftermath of the event extensively in the October 2001 issue. As Scott Haddock of the Protective Glazing Council (PGC) said at the time, no amount of protective glazing could have mitigated the damage to the World Trade Center towers. “In that case, I think it’s more of a question of tightening security so something like this could not happen again,” he said.

Fifteen years later, this still rings true. “The 9/11 attacks that brought down the Twin Towers and resulted in the deaths of thousands mostly changed the security measures around travel and the emergency evacuation of people,” says Valerie Block of Kuraray, a current member of the PGC, which today is a part of the Glass Association of North America.

Block says the security glazing wake-up call was the bombing of the Alfred P. Murrah Federal Building in Oklahoma City in 1995. “The General Services Administration took the lead in developing standards for building security that were shared with other government agencies,” she says.

In the October 2001 USGlass article, Lee Evey, a program manager involved in renovation work at the Pentagon prior to the attacks, said the area of that building struck by the plane had blast-resistant windows, two inches thick and 2,500 pounds each. “[They] stayed intact during the crash and fire,” said Evey. Ron McCann of Viracon says Viracon and Physical Security had re-glazed that section of the building within a year before the attack.

Looking Forward

Evey predicted at the time that the magnitude of the event would have a short and long-term impact on the industry “with increased interest in protective glazing not just in the federal [sector], but in the private sector, too.”

This, too, has transpired. “Generally the performance requirements and what’s expected out of security glazing has improved dramatically,” says Thomas Niziolek of Covestro. “Everyone is much more conscience of protecting not only public buildings but private buildings.”

“We’ve developed more advanced test methodologies, both on the government levels and with independent test laboratories,” he adds. These factors, he says, have led to the advances in the concept of various glazing constructions. McCann agrees that the biggest development in protective glazing in recent years has been overall awareness, and that the combination of glass products with polycarbonate has become much more prevalent.

Another Lesson

The type of glazing used in the Twin Towers couldn’t have prevented the damage it sustained. However, the effect a blast event has on surrounding structures was a major consideration brought to light by the buildings’ collapse.

“When the [Twin Towers] came down, the debris and the shockwaves impacting all the surrounding glass storefronts and buildings caused a massive amount of damage to the interior of these buildings,” says Liz Grimes of Curbell. Grimes says if the glass in these buildings had been laminated or reinforced by some kind of safety or security glazing measure, contents inside the buildings may have been saved.” Other events such as the Boston Marathon bombing in 2013, she notes, have also drawn attention to this.

Niziolek agrees, adding that more attention has been given to the idea that if a particular building or property is using or considering security glazing for blast reasons, nearby structures should also be taken into account.

“In commemorating these sad events, it’s also very important to learn lessons from them,” says Niziolek. “They’ve affected the way people design buildings, the way people occupy them and secure them.”