The Building Built on Stilts

by Nickolas Means

In this talk from RubyConf 2016, Nickolas Means presents the story of structural engineer Bill LeMessurier and the Citicorp Center, a 59-story skyscraper in Manhattan that was found to be dangerously unstable under certain wind conditions. The video outlines how LeMessurier's innovative design utilized a lightweight steel skeleton and triangular braces to support the structure while allowing it to sway under wind pressure. Key points discussed include:

Background Context: The building was constructed during a time of economic recession in the 1970s, with Citicorp seeking to establish a presence in New York City through a signature skyscraper.
Design Challenges: LeMessurier faced the unique challenge of cantilevering the building over an existing church with no direct support underneath, leading to the innovative use of triangular braces for structural integrity.
Discovery of a Critical Flaw: A graduate student, Diane Hartley, realized that the building's design was flawed in handling quartering winds, which led LeMessurier to investigate and ultimately uncover significant structural risks due to inadequate welding specifications.
Ethical Response: Faced with the potential failure of the building, LeMessurier chose to disclose the information to Citicorp executives, leading to an urgent plan for reinforcement that included welding additional support plates onto crucial joints.
Collaboration and Solution-Focused Mindset: The crisis was handled through collaboration with Citicorp officials, leading to supportive measures from the New York City Department of Buildings during repairs. LeMessurier and his team approached the situation transparently and focus on solutions rather than blame.
Legacy and Lessons Learned: The talk emphasizes that mistakes are inevitable in engineering and innovation, but addressing them openly can lead to profound improvements in practice and culture within technical teams. Key takeaways include fostering an environment of trust, being solution-oriented, and learning from failure.

Ultimately, the talk underscores the importance of professional ethics, transparency, and teamwork in engineering, using the case of the Citicorp Center to highlight these critical concepts. This event showcases how addressing mistakes can lead to innovation and growth, reinforcing that societal trust can be built when teams communicate effectively during crises.

LeMessurier's experience has since become a teaching example in engineering classes, illustrating how integrity and cooperation can resolve even the most daunting challenges in construction and design.

00:00:15.920 Hey, what's up everybody? How are you all doing? So we're nearly done. I hope everyone has had a fantastic RubyConf and enjoyed all of the talks and the wonderful people you've met.

00:00:22.320 Actually, I have something I would like to ask for your help with real quick before we get started. It was my son's birthday this week, and I wanted to see if you would be so kind as to help me tell him happy birthday. So on the count of three, I would be forever indebted if you would all say, 'Happy birthday, Holden!' Ready? One, two, three—happy birthday!

00:00:34.079 Thank you all! You just blew his mind! He's watching at home on the live stream, so thanks for your help with that. Some of you have seen me speak before, but for those of you who haven't, I'm a storyteller, not a normal conference speaker. I really like telling stories of failure and redemption, and this is one of my favorite stories. It’s the story of a structural engineer named Bill LeMessurier and a building in New York that was built on stilts.

00:00:50.520 Our story starts in the 1970s. I'm sure most of us in this room don’t remember America in the 1970s, but we were in the midst of an economic recession. We had just come out of Vietnam and had spent a ton of money on that war. Additionally, there was an oil embargo that was causing runaway inflation.

00:00:56.199 Because of that, our country was running out of money, and so were our cities. This picture of the New York subway is pretty representative of what public infrastructure looked like in New York in the 1970s. They were so close to bankruptcy that they didn’t even have the money to clean up the graffiti in the subway. The city might have gone bankrupt had it not been for this man, Walter Wriston.

00:01:12.119 Now, Wriston is a businessman, but he’s also very civically minded. In the 1970s, seeing his beloved New York on the verge of bankruptcy, he went to the New York legislature and encouraged them to create something called municipal assistance corporations.

00:01:19.040 Basically, these corporations were set up so cities could sell bonds to finance their ongoing operations during times of financial crisis. He helped the city of New York get that through the legislature and then tried to sell those bonds to people in New York, going around to the big banks and union pension funds.

00:01:36.680 It certainly helped that he was the CEO of one of the banks that was buying up a lot of these bonds—First National City Bank of New York. Now you've all heard of this bank, but you may not know it because they changed their name in the 1970s to Citibank. At that time, Citibank was in pretty good shape despite the recession.

00:01:49.560 They had diversified their investment portfolio and spread out their loan portfolio. They still had plenty of money on hand; they weren't hurting at all. The only problem they really had was that they were out of room at their headquarters at 399 Park Avenue. If you or I had encountered this problem, we would have gone to the building next door and leased a couple of floors.

00:02:00.600 But you and I are not Walter Wriston. Wriston wanted to make two statements: number one, he wanted to show everyone that Citicorp was still in great shape despite the recession. They still had plenty of money. And second, he wanted to show Citicorp's commitment to the city of New York. Despite the recession, Citicorp was there to stay.

00:02:11.840 When you're a man with ambitions the size of Walter Wriston, the best way to do this is to build a signature skyscraper on the New York skyline. So they started buying up property, a whole city block, in fact. Their headquarters were at 399 Park, and they started buying the block right across from them.

00:02:28.560 However, they ran into a problem. The good people of St. Peter's Evangelical Lutheran Church liked their church right where it was. And it stood right here at the corner of 54th and Lexington, right on the prime corner of Citicorp's block.

00:02:39.880 Now Citicorp owned all the rest of the land on this block; the only holdout left was St. Peter. They knew exactly how strong their hand was and decided to play it. So they went to Citicorp and said, 'Yeah, we’ll sell you our land, but you have to build us a new church.'

00:02:53.440 Citicorp said, 'Sure, we can build you a new church. Where do you want it? Right where it is?' They didn’t really have an option. St. Peter’s wasn’t compromising on their demands. There wasn't enough money to make them move, so they had to figure out how to build this church on the corner of their lot and still erect this signature skyscraper.

00:03:06.159 Walter Wriston went to this man, Hugh Stubbins, his architect for the project, and said, 'Hugh, here's the deal. We've got this church that isn't moving; it's got to be on the corner of the lot. Not only that, but they've insisted that we can't have any support structures going through the church or any adjoining walls.' It had to be a freestanding structure, but we can build over the church.

00:03:18.960 This was actually the first air rights transaction in New York real estate history. It’s pretty common now. Stubbins had an idea; he thought maybe they could cantilever one corner of the building over the church. He brought his structural engineer in to consult on this and see if it might be feasible. This man was William LeMessurier.

00:03:35.280 Stubbins tells Bill his idea, and Bill said, 'Sure, I imagine we can figure that out.' They could cantilever one corner. Stubbins thinks about it a little more and says, 'You know what? It would be really nice if we could cantilever two corners; it would make for nice symmetry.' LeMessurier said, 'Well, that's going to be harder, but I'm sure I can come up with a plan to do that.'

00:03:46.960 Then Stubbins got greedy. He went to LeMessurier and said, 'Bill, we could build this building with a ton of open space at the base; it'd be dramatically appealing if we could cantilevered all four corners.' And that’s just what they did. You can see St. Peter’s Church tucked under one corner of the building, and the building itself sits atop ten stories on those skinny little columns.

00:04:03.680 Now, it doesn’t look like those columns would be enough to support that giant building, but that was the genius of Bill LeMessurier’s design. Like most great ideas, this one came about from a napkin sketch. Bill LeMessurier was sitting at his favorite Greek restaurant next to his office in Cambridge, Massachusetts, when he conceived of these triangular braces down the side of the building.

00:04:18.920 Let me explain how this works. Now, in most buildings, the bulk of the structural load is carried by columns going down the corners of the building, which are the strongest parts. But what happens to that load when the columns don’t go all the way to the ground? This was the problem LeMessurier had to solve: how to support the building without normal weight-bearing members.

00:04:37.680 You can kind of see the start of his design on this napkin sketch with these triangular braces running down the sides of the building to direct the load to the columns at the base. To explain a little more how this works, there are six triangular Chevron braces, each eight stories tall, that go down the side of Citicorp Center.

00:04:54.920 Let’s take this floor right in the middle of one of those Chevrons. The load from that floor goes down the corners and the center of the building to the Chevron right below it, and that Chevron directs the load to that center column, where it travels down to the ground. That’s how it handles the structural load.

00:05:09.000 However, there’s also wind load. At the top of the building, wind can sometimes get high enough that it overcomes the compression strength of the building. Literally, the weight of the building holds it together against the wind, but sometimes there’s enough leverage at the top that it goes beyond that compression strength.

00:05:27.000 So, these angular braces take that wind load on the face of the building and transfer it down to the central column and consequently, to the ground. It was a genius design. LeMessurier took his design to the New York City Department of Buildings, and they determined that it was structurally stable, allowing construction to proceed.

00:05:45.279 Final plans were drawn up, and construction began. Now, Bill LeMessurier, self-confessedly an egotistical man, tried to convince Hugh Stubbins that these structural braces should be on the outside of the building where everyone could see them, but Stubbins insisted on a sleek glass and aluminum facade.

00:05:55.880 He wouldn’t agree to the design, meaning this photo is one of the last where you can actually see these Chevron braces in their entirety during construction.

00:06:00.840 I don’t know about you, but that doesn’t look like a lot of steel to me. The reason it doesn't look like a lot of steel is because it isn’t. The steel structure of this building weighs about 25,000 tons. For comparison, the Empire State Building, which is a little taller than Citicorp Center, weighs 60,000 tons—over twice as much. By reducing the weight that dramatically, it allowed this building to be built on ten-story tall stilts.

00:06:19.760 However, the side effect of this was that because the building was much lighter, it didn’t have a lot of resistance to the wind; this building liked to sway. You may or may not know that all tall buildings sway to some degree.

00:06:32.840 It’s typically much stronger to build a building that has some give to it and can sway in the wind rather than a rigid structure. The wind would blow a rigid building over, but the problem arises when you put humans in the building. You can allow a building to sway considerably and it would still be structurally sound, but as it turns out, humans don’t like that very much.

00:06:45.720 If you and I were on the 59th story of Citicorp Center in the middle of a windstorm, we'd probably be disconcerted by the building moving beneath us and would quickly feel seasick because our eyes couldn't reconcile the motion our bodies were experiencing. In order to construct a building with such a lightweight steel skeleton, Bill LeMessurier installed the first tuned mass damper in a skyscraper in North America.

00:07:05.760 In this case, it was a 410-ton block of concrete, floating on a very thin film of oil, that counteracts the effects of the wind on the building. It reduces sway by about half. Let me show you how this thing works. Here's what it looks like in action: you can see that concrete moving back and forth very subtly. The interesting thing is that the concrete block is the most stable object in this picture; the building is actually moving around the tuned mass damper.

00:07:23.760 As the building shifts out from under this 410-ton block of concrete, it slightly alters the center of balance of the building and reduces the movement caused by the wind by about half. As the building oscillates back and forth, the tuned mass damper stops that motion more quickly than if it weren’t there.

00:07:41.840 There was one more amazing innovation in this building. When it was completed, Citicorp Center was the seventh tallest building in the world at 914 feet and 59 stories tall. It was positively received; The New York Times stated that Stubbins had created one of New York's significant buildings.

00:08:04.160 If you've ever flown into New York City, the bright silver, angled top of this building is easily spotted in the skyline. But Stubbins wasn’t the only one to receive praise—Bill LeMessurier gained widespread acclaim for his structural innovations in this building. He was named a Fellow of the National Academy of Engineering, one of structural engineering's highest honors.

00:08:22.760 That would have been the end of the story had it not been for a Princeton engineering student. She had been encouraged by her thesis adviser to look into LeMessurier’s innovative structure and include it in part of her graduate thesis. The student was Diane Hartley, and in the summer of 1978, Diane placed a fateful call to Bill LeMessurier’s office in New York.

00:08:37.440 She understood most things about how LeMessurier’s structure worked; she grasped how it reacted to wind and how it carried the structural load to those columns at the bottom. But she couldn’t quite figure out the numbers when it came to how the building dealt with quartering winds.

00:08:50.560 The primary force acting on any building day in and day out is the wind, particularly perpendicular wind. Other than an earthquake, this is the strongest force a building will ever encounter. A perpendicular wind hits the building squarely and acts like a sail, exerting extreme force.

00:09:07.360 The building's primary force, as I said, is compression strength, literally its weight. It’s so heavy that the wind can’t blow it over or cause it to crumble. However, at the top of the building, where there’s not as much material stacked on top, where the building isn’t as heavy, sometimes the wind can gain significant leverage.

00:09:22.080 That’s where the underlying steel structure comes in to support it against winds that the building isn’t heavy enough to resist. But that wasn’t what Diane Hartley was discussing; she was focused on quartering winds—winds that hit the building from the corner.

00:09:41.960 Basic aerodynamics would suggest that this wouldn’t exert nearly as much force because the wind would strike the corner and split, flowing around. Under normal circumstances, this would be true, but Citicorp Center isn’t a normal building.

00:09:56.699 One of LeMessurier’s associates answered Diane Hartley’s questions and happened to relay to Bill LeMessurier that he had spoken to this student. At the same time, LeMessurier was teaching a class on structural engineering to architecture students at Harvard. He thought that maybe if this student found it interesting for a thesis, his class would appreciate a lecture on this building and how its wind bracing worked.

00:10:14.480 So he sat down to do the math and what he realized shocked him. In four of the Chevrons, a quartering wind resulted in a 40% increase in loads on those angled support structures compared to a parallel or perpendicular wind.

00:10:31.480 He initially assumed that because of where the columns were positioned in this building, they were in the best possible place to counter quartering winds, but it turned out that wasn’t true. A 40% larger load than expected on these angled support members normally wouldn’t have concerned him.

00:10:48.640 When it comes to building columns, there’s a substantial safety margin built in; they’re designed to be stronger than necessary to ensure the building doesn't fail. However, LeMessurier had recently attended a meeting in Pittsburgh regarding another building using the same angular support structure from Citicorp Center.

00:11:07.040 He had specified the same welded joints in those angled support members that he had proposed for Citicorp Center, but a potential contractor in Pittsburgh had approached LeMessurier and stated they didn’t believe they required those welded joints.

00:11:23.200 A skilled structural welder can join two metal pieces together so that they're just as strong as a single piece. However, it’s not always necessary for them to be that strong. That was the argument from U.S. Steel; they claimed that bolted joints would be strong enough to support that building.

00:11:41.320 Since welding requires a skilled laborer who is quite expensive and can take a long time, it is often much cheaper to utilize bolted connections when feasible. LeMessurier knew they were using welded joints on Citicorp Center and had not experienced any cost overruns or delays due to that. So, he contacted his New York office for reassurance that the welded joints would be adequate.

00:11:58.160 What he discovered startled him: Stanley Goldstein, the partner in charge of LeMessurier's New York office, informed him that Bethlehem Steel delivered the same message about Citicorp Center. They argued there was no reason to weld these joints; bolting them together would be sufficiently strong.

00:12:07.440 LeMessurier's New York office evaluated and approved this change. They got the new drawings authorized by the New York Department of Buildings. While it wasn't unusual for such changes to happen during the construction of large buildings, LeMessurier didn’t consider it a significant issue at that point.

00:12:24.200 However, two weeks later, upon reviewing the new information about how his building reacted to quartering winds, he wondered if his staff had discovered the same facts when specifying the bolts to secure these joints instead of welding them.

00:12:35.720 He decided to get on a plane and visit New York to assess the situation personally. After arriving at his New York office, he reviewed the building plans and found what he described as a subtle conceptual error that worsened the situation.

00:12:48.040 LeMessurier discovered that when Bethlehem Steel and his New York staff considered the diagonal braces for the switch from welded to bolted joints, they viewed them as trusses, not columns. This distinction is significant because, according to New York building code, a structural column must have a two-to-one safety margin: it needs to be twice as strong as the maximum load it will bear, while trusses have no mandated safety margin.

00:13:01.400 Thus, they had classified these angular support members as trusses rather than columns—meaning who knows how they had constructed them? LeMessurier probed further into the plans and found the detailed bolt diagram outlining how the joints were secured. He noticed far fewer bolts than he expected, and at this point he started to feel increasingly uneasy.

00:13:18.640 Still lacking concrete information, he knew he required exact numbers. So he returned to the boundary layer wind tunnel laboratory at the University of Western Ontario. The boundary layer laboratory is widely regarded as the world’s leading authority on the effects of wind on tall buildings. While designing Citicorp Center, they had conducted a substantial amount of wind tunnel testing.

00:13:35.520 LeMessurier requested they check his calculations and confirm whether the 40% loading increase figure was accurate. They performed the analysis and found that, indeed, in theory the figure was correct.

00:13:47.280 However, considering the real-world variables in wind direction and intensity, the building could oscillate in such a fashion that the loading increase could rise to anywhere between 60% and 70%. This was worse than he had anticipated.

00:14:03.040 He requested that boundary layer staff analyze every beam and joint in the building, and they provided him with a significant amount of raw data. He wanted to find a place to think through the numbers and the situation, so he retreated to his summer house on a 12-acre private island in Maine, in Lake Seago.

00:14:18.720 As he began to sift through the data, joint by joint and beam by beam, he discovered that the most critical joint in the building was on the 30th floor. Once he realized this, he set out to determine what kind of wind could potentially cause the building to fail.

00:14:37.840 It is essential to note that in this context, the word 'fail' is somewhat of a euphemism. Typically when we envision a building failing, we picture it tumbling straight down, as in videos of buildings being imploded. However, that's not the failure scenario we’re discussing here. If the joint on the 30th floor of Citicorp Center had failed, the upper portion of the building would have toppled over into the building next door, potentially creating a domino effect all the way to Central Park.

00:14:55.680 That’s the worst-case scenario in mind. As Bill LeMessurier faced the data, what he found was absolutely terrifying. It turns out that a 55-year storm could generate winds strong enough to topple this building over.

00:15:10.320 In other words, for every year the building stood, there was a 1 in 55 chance that a storm would occur that would cause the building to fail. But then he realized that wasn’t the worst-case scenario.

00:15:26.480 His calculations included the effect of the tuned mass damper. A 55-year storm is quite severe, bringing strong winds, heavy rain, lightning, and potential flooding, which could lead to power outages. The issue with a power failure is that the tuned mass damper ceases to operate when electricity is lost.

00:15:42.640 As it turns out, without the tuned mass damper, the 1 in 55 figure proved to be exceedingly optimistic. A wind speed of 70 mph blowing for approximately five minutes would have the potential to cause the building to fail, equivalent to tropical storm strength. New York City experiences tropical storms approximately every 16 years.

00:15:58.640 LeMessurier realized that in the time between July and the end of 1978, there was a 1 in 16 chance that a storm strong enough to topple this building could occur. Sitting in his lakeside house in Maine, he faced a choice.

00:16:15.200 If he disclosed this information, he could anticipate a lawsuit. He knew he'd be sued, the damages would exceed his insurance coverage, and it would probably ruin his professional reputation. He considered remaining silent and hoping the odds worked out, rationalizing that there was a reasonable chance a storm this strong wouldn't materialize during his lifetime.

00:16:31.560 He even contemplated driving into a bridge abutment at 100 miles an hour to take the knowledge of this disaster to the grave with him. Ultimately, he decided he couldn't do that; his moral and professional ethics wouldn’t let him stay silent.

00:16:49.600 He resolved to do the only thing he could think of: he called his friend Hugh Stubbins. The very next morning, both he and Hugh were sitting in LeMessurier’s New York headquarters at 515 Madison Avenue, trying to figure out what to do.

00:17:05.560 After calling their insurance company and conferring with their lawyers, they determined the most immediate action was to contact Citicorp and inform them of the building's precarious situation. They attempted to reach Walter Wriston but, of course, failed to penetrate the layers of assistants and secretaries insulating him from the outside world.

00:17:26.640 They sought an appointment with the bank's president's second-in-command, William Spencer, but met the same resistance. However, they finally got through to this man and set an appointment with him: John S. Reed, the senior vice president at Citicorp.

00:17:42.560 Reed succeeded Walter Wriston as chairman of Citicorp and was the third in command. Not only that, but he was also an engineer by training. So, when LeMessurier sat down with Reed and explained the problems concerning Citicorp Center, Reed was well-prepared to understand the implications.

00:17:56.560 This is where Hugh Stubbins saved Bill LeMessurier’s bacon. The solution to the problem was pretty straightforward. Since Stubbins insisted on his sleek aluminum and glass exterior, all of the structural supports in the building had to be concealed.

00:18:12.720 To fix the building, all they needed to do was to open up the drywall and weld two-inch-thick steel reinforcement plates over all these vulnerable joints. It wasn’t a particularly massive job; they could perform the work at night when the building was vacant.

00:18:24.360 They could bypass the fire alarms triggered by the smoke produced from welding and erect little plywood shacks around the joints to protect tenants’ property. They could complete these welds in a single night, allowing for prompt repairs.

00:18:39.440 John Reed was satisfied with this resolution, but naturally, the only question he had for LeMessurier was how much it was going to cost. LeMessurier estimated it would be around a million dollars. Reed then left to consult with higher-ups.

00:18:55.080 Less than an hour later, John Reed returned to Bill LeMessurier’s office, accompanied by none other than Walter Wriston himself. You could tell just by looking at Walter Wriston that he wasn’t exactly a kind and gentle man, but that day, his focus was centered on saving his building.

00:19:10.480 He was genuinely proud of it and wanted it to withstand the test of time. They began discussing plans to save the building, and somewhere in the process, aware that he would eventually need to issue a press release regarding the repairs they were about to undertake, he asked for something to write on. Someone handed him a yellow legal pad.

00:19:23.120 Walter Wriston chuckled at the pad, looked around the table, and said, 'Gentlemen, every war has been won by generals writing on yellow legal pads.' More importantly than what he said was what he did: he laughed. He diffused the tension in the room.

00:19:39.080 His laughter allowed the team to focus on solving the problem rather than worrying about how he might react. Hours after this meeting, they had not one but two backup generators on-site to ensure the tuned mass damper would remain powered in case of a power failure.

00:19:55.160 The following day, they met with engineers from Carl Coke Construction on an unoccupied floor of Citicorp Center. Carl Coke was the firm contracted to perform the repairs. On this unoccupied floor, they removed drywall from one of the angular wind braces in order to inspect the interior and assess feasibility for the repairs.

00:20:12.520 They discovered just as few bolts as Bill LeMessurier had feared. The situation was indeed as dire as he had suggested, but the good news was that engineers from Carl Coke confirmed the solution was absolutely feasible. Not only that, but they had sufficient 2-inch-thick steel plates on hand to conduct the repairs.

00:20:27.360 Citicorp drew up a contract and as soon as LeMessurier had new drawings made and approved by the city of New York, the repair work would commence. The information remained fairly close-knit through the first week of August, but as mentioned, the repairs required approval from the New York Department of Buildings.

00:20:43.720 On the morning of August 8th, Bill LeMessurier found himself with the New York City Commissioner of Buildings and nine other senior New York City officials, sharing everything that had happened. This was the meeting he feared; he expected to leave it stripped of his professional engineering license.

00:21:01.920 He explained how the situation had transpired, and the city officials posed a few technical questions. They assured him of their support in expediting the repairs as much as possible, and then did something he didn’t anticipate: they commended him for his courage and candor in coming forward with this information.

00:21:16.720 This was the exact opposite of the censure he had anticipated receiving. The Department of Building’s support came in two significant ways: first, Neil Morton, one of the city’s most respected steel inspectors, would remain on-site every night during the repairs.

00:21:32.440 Morton could approve every weld upon completion, allowing the crew to patch the drywall back up before tenants arrived the next morning. More importantly, there was a significant shortage of structural steel welders in New York at that time.

00:21:50.360 The department granted Morton extraordinary authority to conduct and certify welders for structural steel work on-site. Numerous steamfitter welders could complete the structural welding; they just hadn’t passed the city’s welding certification.

00:22:07.720 Second, they collaborated with the mayor's office of emergency management, the New York Police Department, and the Red Cross to strategize an evacuation plan. They decided the building was safe in all but the most extreme wind conditions but wished to be prepared in the event of a storm.

00:22:22.960 Thus, the New York Red Cross dispatched volunteers throughout the surrounding area to gather information on how many people were there during the day and at night, and where they were located, so they could plan for an evacuation.

00:22:39.480 Every night, the building lit up with the welders racing against the unknown. They had no way of predicting if or when a storm strong enough to bring the building down would strike, and thus worked diligently to complete the repairs.

00:22:58.520 They were fortunate until about the first of September when Hurricane Ella churned off the coast and veered towards New York. As a result, LeMessurier convened an emergency meeting with Citicorp officials at 6:30 in the morning, stating, 'The good news is we've fortified the building well enough to withstand a 200-year storm.'

00:23:15.280 However, the bad news is Hurricane Ella could be a 200-year storm, and there’s no way for us to know how strong it would actually be upon impact. Therefore, we must start discussing our evacuation strategy.

00:23:31.520 They monitored the storm for the rest of the day, and they were merely an hour away from initiating their evacuation plan when Ella decisively turned back out to sea. They all breathed a collective sigh of relief.

00:23:46.760 By September 13th, the crisis was largely resolved; the building was fortified enough to withstand a 500-year storm by that point, potentially making it the strongest skyscraper in existence due to these repairs.

00:24:00.360 But as the crisis receded, the lawsuit that Bill LeMessurier had long dreaded was finally becoming a reality. Citicorp served him notice that they intended to seek recovery of all costs associated with the repairs from him and his firm.

00:24:17.679 However, an interesting situation unfolded: Citibank never filed a lawsuit against Bill LeMessurier. They assembled around a conference table—Bill on one side and two senior vice presidents from Citicorp on the other, without lawyers present.

00:24:36.360 LeMessurier proposed a $2 million settlement. The Citicorp vice presidents expressed that they had been significantly impacted by the situation but did so without conviction; their hearts were not in punishing Bill LeMessurier for the incident.

00:24:55.320 At the next meeting, the only lawyer present was from Bill LeMessurier’s insurance company. The lawyer’s sole purpose was detailing the arrangements to transfer the $2 million to Citicorp. They agreed to hold Hugh Stubbins harmless and to settle with Bill LeMessurier and his associates for the $2 million covered by his insurance policy.

00:25:11.219 Various estimates indicated the repair costs ranged between $4 million and $8 million, depending on how one valued the time contributed by the Citicorp executives involved. And what of Diane Hartley, the engineering student who initially alerted LeMessurier's office?

00:25:29.360 She was completely unaware that any of this even transpired. There have been several interviews with Bill LeMessurier discussing Citicorp Center and how he discovered a problem existed with the building. Invariably, he refers to 'a nice young fellow from Princeton.'

00:25:44.760 Now, most people maintain that LeMessurier never actually spoke directly to this student; he never met Diane Hartley. An associate spoke with her 20 years after the fact. Diane was at home when her husband called out to her, 'Honey, the building you wrote your graduate thesis on is on TV; come watch!'

00:26:05.200 She entered the room just in time to hear Bill LeMessurier refer to this nice young fellow from Princeton and wondered who that could be. Curious, she called her thesis adviser, who clarified, 'Diane, nobody else studied this building; the nice young fellow has to be you.'

00:26:21.360 Diane Hartley never had the opportunity to meet Bill LeMessurier, as he passed away before she learned of this chain of events. Remarkably, nobody knew this series of events occurred until an article in The New Yorker was published 20 years later.

00:26:38.760 It remains one of New York's best-kept secrets, and it’s one of my favorite stories to tell. I’ve read it several times over the years; it’s a fantastic story. This building nearly fell down, but what I love the most about it is something that’s lacking in it: there’s no animosity anywhere in this story.

00:26:57.920 At the end of the day, the building was repaired. Nobody sued anyone, and everyone was satisfied after a couple of conversations. So, in our hyper-litigious society, how does something like that happen?

00:27:13.920 There were actions taken by Bill LeMessurier and Citicorp that led to this outcome. Bill LeMessurier was transparent. The moment he recognized he had made a mistake and understood its magnitude, he owned up to it and came forward.

00:27:30.160 Despite all the fears he had—lawsuits, bankruptcy, and losing his professional reputation—none of those consequences materialized. In fact, the opposite occurred. This story has been used in engineering classes throughout the country as an example of professional ethics in engineering.

00:27:47.000 LeMessurier's story is hailed as a case study featuring the right course of action in challenging situations, ultimately enhancing his reputation.

00:28:01.960 When you find yourself in such dire situations, the instinct is often to focus on all the negative outcomes, which naturally leads us to contemplate the worst-case scenario. When the ramifications of our actions ultimately come to light, we are better equipped to handle them after having prepared for something far worse than the actual reality.

00:28:17.760 However, as a side effect of this mental process, we often shy away from coming forward and admitting when we've made mistakes. It is almost universally the wrong decision to conceal mistakes or attempt to rectify them independently.

00:28:35.640 Attempting to fix a problem by yourself is not beneficial; instead, engaging with colleagues to discuss what has occurred can lead to a more effective solution and create pathways to prevent similar issues in the future.

00:28:52.640 As engineers, we must learn to resist the impulse to conceal mistakes and to ponder worst-case scenarios, as they are seldom productive. Bill LeMessurier also maintained a solution-oriented mindset.

00:29:08.880 When having these important conversations once you've made a mistake, it’s vital to bring a solution with you. Doing so shifts the focus from blame to cooperative problem-solving and future solutions.

00:29:25.320 This approach reassures the individuals involved that you are all on the same team: this was an honest mistake, and it helps advance the discourse forward rather than devolving into a blame game.

00:29:39.720 So, as engineers, you should be transparent and solution-oriented, but what if you find yourself on the receiving end of these mistakes? I’m sure some of you are team leads or managers, often needing to engage in conversations like these.

00:29:55.600 There are valuable lessons that CitiCorp exemplified that can benefit all of us. The first aspect is to keep conversations blameless. Walter Wriston didn't lash out at Bill LeMessurier upon discovering the problems.

00:30:13.720 He certainly could have; being one of the most influential figures in banking, he could have initiated Bill's financial ruin. Instead, he focused on collaborating to address the problem. If you can uphold this approach with those on your team, you can defer discussions about past errors and preventive measures until a calmer atmosphere is present.

00:30:31.960 Once emotions have subsided, you can engage in a rational dialogue instead of panicking and attempting to stave off production in the midst of a crisis. Another crucial thing that Walter Wriston did was demonstrate kindness.

00:30:48.280 Remember how I mentioned earlier how we develop worst-case scenarios in our minds? When somebody brings a mistake to your attention, they're likely expecting certain reactions: they're preparing for reprimands, public embarrassment, or even termination.

00:31:06.760 So, piling onto them while they’re in such a fragile emotional state is neither helpful nor kind. This is a moment where you can build trust; calmly addressing the issue while keeping the atmosphere constructive fosters trust.

00:31:23.080 If you maintain a composed response while acknowledging the problem, you convey to your team that they can trust you to handle mistakes. You're demonstrating that you believe in their intentions. They didn’t make this error purposely; they acted based on their best information at that moment.

00:31:38.640 This approach fosters a trustful environment wherein team members feel empowered to approach you with issues they encounter. Ultimately, your role as a leader or manager is to encourage your team to seek your guidance with problems they’re facing.

00:31:55.720 The overarching truth in this entire story is that mistakes are unavoidable. We operate quickly in our field, constantly adopting new tools and practices, and we build things in new and innovative ways.

00:32:11.680 Bill LeMessurier undertook this before many had done it. He constructed this building with a super lightweight steel skeleton. Engineers previously relied solely on compression strength to support their structures. Nobody had attempted to construct a building of this scale that depended primarily on the underlying steel framework to resist wind.

00:32:27.520 In doing so, he made a substantial mistake, but he also introduced groundbreaking technology into structural engineering that enables us to construct skyscrapers like Taipei 101 and the Burj Khalifa.

00:32:44.720 Without employing lightweight steel skeletons, buildings of that height wouldn’t be feasible, as they would be too heavy for the earth to support and would buckle upon completion.

00:33:01.360 However, because of these lightweight steel skeletons that Bill LeMessurier pioneered, we can construct these towering builds. If he hadn’t pushed the limits of what was possible, we wouldn’t be able to build such super-tall structures.

00:33:16.160 But, as he faced his mistake, nurtured trust in his colleagues, and engaged them for a solution, he moved the state-of-the-art of structural engineering forward. If you, as a software engineer, team lead, or CTO desire to drive software engineering innovation as well, you too must be willing to embrace the possibility of mistakes.

00:33:30.440 Mistakes are inevitable, but by investing your time in learning how to navigate these blunders and treat your team's missteps well, you will be fostering the future of your business and enhancing your capability to innovate.

00:33:47.040 Thank you.

00:34:01.860 You.