Reading time ~ 4 - 5 minutes.
I am interrupting this weekend’s regularly scheduled program to highlight a story on the 20-year anniversary of September 11th. We will resume wondering about the autumnal season next week.
Leslie Robertson was an upstart 34-year-old structural engineer with no experience in high-rise construction when his Seattle-based firm, Worthington and Skilling, was tapped by Seattle-born architect Minoru Yamasaki1 to help design the World Trade Center in 1962.
The twin towers were marvels of engineering, incorporating several unique elements and setting the record for tallest in the world at 110 stories, 1,368 feet, when the north tower was completed in 1972. Until that time, high-rise buildings were constructed with an internal skeleton of masonry columns separated every 15 feet. Robertson instead created an enormous “space-frame” exoskeleton with prefabricated multi-column panels2 that gave a total of 59 exterior structural columns on each side of the buildings. This “egg-crate” configuration was much lighter in weight with the benefits of lower construction costs and column-free, open office space on every floor. Because of the unprecedented height, Robertson also teamed with scientists to study the amount of subtle motion humans can tolerate before experiencing vertigo, which led him to invent a viscoelastic dampening mechanism to decrease the wind-sway of the buildings.
By 2001, Robertson had established himself as an innovative giant in the field. But despite being praised for novel engineering that altered the way subsequent skyscrapers were built, despite withstanding a 1200-ton bomb that killed 6 people, injured a thousand, destroyed 5 stories and created a 150-foot underground crater in 1993, and despite staying intact long enough for an estimated 14,000 people to evacuate3 after the impact of airplanes loaded with 10,000 gallons of jet fuel, the collapse of these formidable towers tormented Robertson as a personal failure for the rest of his life.
I’ve never stood inside a high-rise contemplating how much wind or what size plane it would take to topple it, nor have I considered how much time I’d need to escape if a fire broke out, but it’s a structural engineer’s job to calculate these things, and Robertson meticulously did just that. Because a B-25 Air Force bomber had crashed into the Empire State Building during a thick fog in 1945, Robertson did not discount that the same could happen with these taller buildings. The twin towers were specifically designed not only to resist hurricane force winds but also to withstand the impact of a 707, Boeing’s first jet and the most common airplane in circulation at the time.4
The World Trade Center engineering was, of course, subject to intense scrutiny after 9/11. Ultimately, forensic analyses concluded there was no fault with the design. Some experts even suggested that the novel exterior columns may have kept the structures standing longer than other traditionally built buildings of that era. Nevertheless, Robertson shouldered the weight of loss, grieving the lives “snuffed out by the collapse of the structures designed by me…it's a big burden. I feel terrible remorse for those who died.”5
But his sense of responsibility did not stop with those who perished at the World Trade Center, he wondered whether he could have altered the aftermath. In his memoir, The Structure of Design, Robertson wrote:
My sense of grief and my belief that I could have done better continue to haunt me…
Perhaps, had the two towers been able to survive the events of 9/11, President Bush would not have been able to project our country into war. Perhaps, the lives of countless of our military men and women would not have been lost. Perhaps countless trillions of dollars would not have been wasted on war. Just perhaps, I could have continued my passage into and through old age, comfortably, without a troubled heart.6
What compels a man to hold himself accountable for an unimagined future—a horrific event nearly 40 years after the project began and almost 30 years after it was finished? He wasn’t at fault for the attack or the decisions that led to the military response in Afghanistan less than a month later. Robertson accomplished what everyone dreams of given a similar situation—presented with a golden opportunity at the start of his career, he didn’t hit it out of the park, he knocked it into the next galaxy.
After September 11th, Robertson received letters of support and letters of hate. He was at times defensive of his design, but he didn’t make excuses or point fingers of blame. He met with families who had lost loved ones when they reached out for clarity and closure. Mostly, he grieved and looked inward to reflect on what he could have done to protect more people—his magnum opus a source of immense heartbreak.
Leslie Robertson died on February 11th at the age of 92. If this was his time for celestial transition, I am relieved for his sake it happened earlier in the year so he did not have to endure the pain and questioning today would have brought.
We are in the midst of another catastrophe right now,7 albeit slower moving, though more deadly. The prevailing responses have been to blame and point fingers, to prioritize self-interest and claims of individual freedom. We would do well to follow Leslie Robertson’s lead: shoulder the burden of responsibility, grieve, and look inward to reflect on what we can do to protect more people.
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Yamasaki was awarded the architectural contract for the World Trade Center in part due to public attention from a previous collaboration with Robertson’s senior partner, John Skilling, that had appeared on the cover of Time magazine—the United States Science pavilion, which was built for the 1962 Seattle World’s Fair. Renamed the Pacific Science Center, it is still a landmark in my city, standing nearby the iconic Space Needle, also built for the fair that year.
https://www.lera.com/leslie-earl-robertson
As this source noted: “The twin buildings…stood long enough for each and every individual who had an unobstructed course to get out.” (Italics added).
The airplanes that were hijacked on 9/11 were Boeing 767s, which weren’t introduced for commercial use until 1982.
Several, actually.
Weekend Wonder 14
So well stated Cara Beth. You are truly a gifted writer. Thank you for your eloquent words that prompt introspection. For my part, I do my best to be kind and courteous to my neighbor, members of my community, and members of communities I visit, here and abroad.