The Twin Towers are known to the world for their tragic end on September 11, 2001. However geotechnical engineers also know that the foundation design and construction for these landmark structures was particularly complex and interesting. The Geo-Institute has a great blog post from Michael Bennett who has done a phenomenal job of summarizing the design and construction of the foundations for the Twin Towers and of course, the famous slurry or diaphragm walls that survived the collapse of the towers. Had they failed, the site and portions of the New York Subway system would have been inundated by the Hudson River!
A few years ago, my wife and I had the privilege of visiting the 9/11 Memorial Museum. The entire experience is a hallowed one. But for a geotechnical engineer, it was especially moving to walk at the foundation level and see the original grillage footings, the preserved portion of the slurry wall, and other geotechnical features that are probably lost on the general public but hold great significance for us engineers. Here are a few photos I took from the Museum that others may find interesting.