A 93-Foot Tribute to United 93: The "Tower of Voices" 9/11 Memorial

Honoring the heroes of United Flight 93 takes a whole lot of stainless steel. But you also need some serious computational analysis—and a stiff breeze.

At appropriately 93 feet tall, the Tower of Voices memorial in Somerset County, Penn., will be the world's tallest wind chime tower when it opens this September (though only 8 chimes will be installed for the opening ceremony this Sunday.) This tribute to the 40 heroes of Flight 93 who died on September 11, 2001 was the work of L.A. architect Paul Murdoch. Along with his team of consultants, Murdoch used computer modeling, physical prototyping, and intricate material testing to ensure the tower design provided both a powerful visual and an ear-catching audio display.

Then they had to figure out how to build the thing.

Engineering Sound
The Tower of Voices is perched on a mound overlooking the 2,200-acre site. A lighted stone path winds through the trees to the tower and around the mound, allowing visitors to go inside. The tower not only holds a place of prominence, but pushes the 40 individual wind chimes higher into the air.

The tower itself is 548,000-pound concrete and steel structure consisting of 53 precast pieces varying in weight from 25,000 to 31,000 pounds, includes connecting beams at 40-degree angles to represent the branch angles of hemlock trees surrounding the site. The foundation required 3-inch diameter steel rods grouted inside 7-inch diameter steel casings embedded 15 feet into solid bed rock, some extending 83 feet below the surface of the plaza on a reclaimed mine.

But even with such a robust and artistic form of concrete and steel, the key element remains the 40 wind chimes, each tuned and engineered to provide a pleasant sound.

It wasn’t a simple process.