Pushkin. Henry Petrotski was, and I mean this as a most sincere compliment, a nerd. This is a man who wrote a four hundred page history of the toothpick and even managed to get that book reviewed in the New York Times, even if the reviewer did tell him to knock it off. I never read the Toothpick book, I have to admit, but I did read other books by Dr Petrowski, and I love them. His history of the pencil is amazing. Now, we economists have a strange relationship with pencils because a classic essay in economics titled Eye Pencil is kind of an autobiography of a pencil, which explains the decentralized genius of the free market economy. But Petrotski went way deeper into pencils, where they came from, how we overlook them, even how they get the lead into the middle of the pencil. He meditated on their erasability so indispensable to designers and engineers. Ink is the cosmetic that ideas will wear when they go out in public. He wrote, Graphite is their dirty truth. Exhibit A in Overlooking the Pencil is Henry David Threau, the great nineteenth century American essayist. He once made a comprehensive list of supplies for an excursion, specifying obvious items such as a tent and matches, adding string, old newspapers, a tape measure, and a magnifying glass, also including paper and stamps to make notes and write letters. But as Petrotski points out, isn't it strange that he omitted to mention the very pencil with which he was making the list. Well maybe not, you think, until you realize that Threau and his father made their money by manufacturing high quality pencils. For row was big pencil. As for that perennial question about the pencil lead, and by the way, it's not lead, and it's never been lead. Pencil leads are made from graphite. When they first discovered graphite in the English Lake district underneath the roots of an old tree that was uprooted in a storm, well they didn't know what it was and they called it black lead. But I digress. How do they get the graphite inside the wood? The trick is to take a slim slab of kiln dried wood and saw a row of grooves into the top surface. Originally the grooves were square easier to cut by hand, now their precision machined with a semi circular cross section. Once the cylindrical rods are laid into the grooves, you glue another grooved slab on top, this time with the grooves in the bottom. Then all you have to do is cut the whole graphite sandwich into sticks parallel to the graphite rods. Those sticks are unformed, pencils, plane, varnish, and the chops done. And that is what you learn if you read Henry Petrowsky. But Petrotski was not only a toothpick and pencil guy, not at all. He was an engineer, and a particular kind of engineer. He was fascinated by failure. You can understand why I'm such a fan of the man, He once told The New York Times. Successful engineering is all about understanding how things break or fail. One of his books, Success Through Failure, explored the way that engineers often advanced the field by building more and more ambitious buildings, till eventually they exceeded what was possible and something broke a bridge, a wall, a concrete multi story car park. The engineers learned, adapted, and moved on. That was one of the inspirations for my own book, adapt and Petrovsky was really really thoughtful on the subject of engineering failure. In nineteen eighty one, two skywalks at the Kansas City Hiatt Regency hotel collapsed, killing one hundred and fourteen people. Dr Petrowski's neighbor asked him, how on earth could that happen? Did engineers really not understand how to build a simple structure like a walkway hanging from a ceiling? And so Petrotski thought about that and went on to write some of the most interesting analysis of the disaster. His writing really helped me think through the catastrophe at the Hiatt Regency, and it helped me think through a lot more. Henry Petrowski died in June twenty twenty three at the age of eighty one. He leaves behind a shelf full of insightful books. Whether you're inter engineering failure, or into pencil, or even Heaven forbid, into toothpicks, Petrosky is your man. We'll be back in two weeks with another brand new episode of Cautionary Tales, but this week we're going to rerun a classic death on the dance floor. It's a harrowing story about the collapse of the Kansas City Skywalks. But like the best of our cautionary tales, it's also a story that will, I hope, make you think. Henry Petrowski made me think long and hard about the skywalks. I hope something of that spirit has rubbed off on the podcast. Friday Night at the Hyatt Regency one of Kansas City's most popular dates since the hotel opened just a year earlier. There are cues at the lobby bar. The place is buzzing. It's the summer of nineteen eighty one, but the orchestra is belting out the big band sounds of the forties and fifties. Dance contestants with numbers pinned to their backs are doing the Mambo and the East Coast Swing. But while the music is nostalgic, the hotel lobby is distinctly space age. It's big and airy, with a glass wall letting in the light and three walkways skywalks crossing the space on the second, third, and fourth floors. They're suspended from the ceiling so that the lobby itself is unobstructed by columns, all the more room for dancing Cindy Paulson briefly looks down from the terrace rest to see if she can see her father out on the dance floor the restaurant. On a large mezzanine overlooking the lobby provides the perfect view, but the lobby floor is packed and she can't pick him out of the crowd. After a moment, she goes back to work. Cindy's a college student, her family live in town. Being a hostess at the Hyatt is her summer job. It's five past seven in the evening. Cindy will always remember that because she glances across the lobby, out through the floor to ceiling glass wall, and sees the time on the clock on the bank just across the street. Then, as a sharp crack, clearly audible even above the music and the loud buzz of conversation, Cindy's eyes refocus from the distant clock to the sky walks in front of her, but she can't believe what she's seeing. I'm Tim Harford and you're listening to cautionary tales. Dr Joseph Wackerley got the call almost immediately from emergency dispatchers. We need you at a hiat he grabbed a stethoscope and scrubs and ran to his car. Wackerley, just thirty five years old, had already served as the director of Kansas City's emergency medical system. He rushed to the scene. When Wackley arrived at the hyat, it was lit by the flashing lights of ambulances. Amid the crowd. There were dozens of injured people. Some were bleeding, others had broken bones. Some were lying on stretchers. Wackley sprang into action, checking who needed assistance most urgently. Then a paramedic grabbed him. You're in the wrong place, he said. The real casualties are inside the hotel. You need to get inside. The lobby was no longer airy and bathed in evening sunlight. It was coated in concrete dust. The skywalks no longer levitated across the atrium. Two of them had fallen, crunching onto the busy dance floor. Voices were calling out for help. Electric cables were swinging loose arcs of electricity, sending flashes of light across the dim space. Somewhere high above, a pipe had fractured and water was gushing onto the lobby floor. It was six inches deep. Or ready and threatened to submerge those who were trapped if anyone had survived the impact. That is, Wackerley could see arms and legs sticking out of the rubble. Dr Wackerley took charge of the medical operation. It was bolstered by a huge voluntary effort, with taxis, buses, and private cars helping the ambulances to get injured people to hospitals. Locals were doing whatever they could to tend to the walking, wounded, free the trapped, and comfort families. Among them was Cindy Paulson, the restaurant hostess. She'd helped evacuate the diners at the restaurant, but then she'd return to the lobby. Somewhere in the middle of that mess was her father. She moved through the lobby, doing what she could. She comforted one couple pinned under the wreckage. After firefighters were able to free them, Cindy kept looking for her father. Two hundred and fifty miles away in Saint Louis, Jack Gillum and his wife arrived home to find the telephone ringing. The call was from one of the architects at the Hyatt Regency Hotel. There's been a collapse at the Hyatt. Jack Gillum was stunned. He was the structural engineer of record for the Hiatt Regency Hotel's construction. That meant he was the one who had signed off on all the designs, certifying that they were safe. And now Gillam was being told that those elegant walkways across the hotel lobby had fallen out of the sky and smashed into the crowd of people below. Jack, the rescue teams are trying to get equipment that can move the fallen sections of walkway. They need to know how heavy the sections are reeling. Gillam could hardly think. He stammered out an approximate answer. Each of those airy looking skywalks weighed over thirty tons. A single walkway section weighed about eight tons. They were going to need cranes. Gillham managed to charter a plane and fly over, arriving a few hours into the rescue effort. Whatever he expected to see, the disaster was worse, But his job now was to try to figure out how the structure had failed. This was a brand new building. It looked bold, but the engineering was simple enough. Somehow the structure had failed catastrophically. Somehow they'd missed something. But what Three skywalks had spanned the atrium of the highest regency, flat decks of steel and concrete with glass balustrades hanging on steel rods from the roof. The third floor skywalk hung by itself and was undamaged, but the second floor skywalk had hung directly beneath the one on the fourth floor. When Cindy Paulson had gazed absently over the lobby at a clock across the street, her attention had been caught by the sound of both skywalks lurching downwards a few inches. There were a few people on the upper skywalk and more on the lower one, fifty sixty maybe, but there wasn't time for them to react. A moment later, both skywalks simultaneously tore free of one of the supporting ceiling rods. The extra load was suddenly transferred to nearby rods, ripping the skywalks free of those connections too. From the nest and the next the skywalks simply unzipped themselves from the ceiling rods, and the skywalks no longer more than sixty tons of steel and concrete fell onto the dancers below, spraying bystanders with deadly glass shrapnel. The entire chain reaction took seconds. Dr Joseph Wackerley and the other rescuers were now trying to deal with the aftermath. One man was half buried, his legs crushed by a piece of skywalk. Wackerley told him he wouldn't survive unless they could amputate. The man said no. Others didn't get the choice. Medics were forced to tell people, we can't get you out in time. You'll die before they get the cranes in here. All we can do is give you something to ease the pain. Then they moved on to the next patient. Family members were on the scene almost immediately, begging the medics and the fire crews to help. Wackerley was trying to decide who most urgently needed care, with the spouses and parents and children of the victims right there crying, pleading, screaming. As he did it, he went back to the man who had turned down the amputation. I've changed my mind, Doc, he said, you can take my legs off. I just want to live. Wackley beckoned over a surgeon with a chainsaw to perform the amputation. They got him out, but in vain. He didn't survive the night. Cindy Paulson was outside looking for her father, hoping he'd been able to walk away, and deep deep under the rubble was a man called Mark Williams. Williams was an old school friend of Joseph Wackerley. While Wackerley hurried around directing the medical response, Williams was doing his best to contribute. He was trapped in an eighteen inch pocket of air underneath a section of fallen skywalk. His legs had been slightly askew when the skywalks fell and were wrenched into the splits and beyond. Both his legs were dislocated. His left foot was up beside his right ear, but other trapped people could hear his voice, calmly talking to them, trying to reassure everyone that help was on the way, that they'd get through this. But with his face pressed against the floor and water seeping through the rubble all around him, Williams realized that after surviving over sixty tons falling on him, he was now all too likely to drown. While the medics and the fire fighters worked through the night, the structural engineer Jack Gillum wasn't getting any sleep either. He was the man who'd officially declared the skywalks were safe to build. What had gone wrong was a very simple and surprising mistake. Gillam spent some time doing some calculations to confirm his suspicions. Then he went to bed, staring at the ceiling of his hotel room until the morning. Meanwhile, the rest of the world was left to speculate. One popular theory was that the skywalks were overcrowded with people dancing, and that their rhythmic movements had set up dangerous resonances which destroyed the structure. But the numbers didn't add up. The people on the skywalks would have had to have been phrenetically go go dancing, not gently nodding along to big band swing, and the weight of the people was small compared with the weight of the skywalks themselves. There were sixty three people on walkways that, by coincidence, weighed sixty three tons. Kansas City building codes demanded that the skywalks could have carried nearly ten times as many people, more like five hundred people than sixty three. Then talk turned to the quality of construction, had someone tried to save money by using cheap materials A reasonable guess, but no. Within days, the world had figured out the skywalk's fatal flow thanks to a young engineer, a telephoto lens, and the Kansas City Star. I relied on reporting from the Kansas City Star for the eyewitness accounts of the disaster, but the newspaper also won a pull its surprise for its investigation into exactly why the skywalks collapsed. After loud protests about a cover up, the press were allowed to visit the hyat's shattered atrium. The Star sent its best reporters and at the last minute persuaded a young structural engineer named Wayne Lishka to join them. The visit was a shock. Wayne Lishke and his wife had spent evenings dancing in the hotel lobby. The disaster seemed unnervingly close, but it was also frustrating. Journalists were only allowed the view that the hostess, Cindy Paulson, had had looking down at the lobby floor from the elevated restaurant. It wasn't close enough to see March, unless, of course, Lishka asked the Stars photographer to use a long zoom lens even from a distance, Lishka could point out the details he wanted to see up close. Take a shot of that, he said, and that and that. When the photographs were developed, they showed the end of the vertical rods uselessly hanging from the ceiling down to the fourth floor. Lishka could see clearly that the rods were basically undamaged. They hadn't thinned or stretched. The rods hadn't failed the skywalks had fallen off them. Examining a few more photographs, Lishka and the Kansas City Star had their answer, and on the front page of the newspaper they published technical drawings highlighting a tiny detail of the design, a tiny detail that had been overlooked with the most appalling consequences. The detail concerned the connection between the long vertical rods and the horizontal beams that supported the walkways. These steel beams were hollow, big square steel pipes. The vertical rods pierced each horizontal beam, and the beam was supported by a steel nut threaded onto each rod. The beam wouldn't slide down the rod because the nut was in the way. That might sound flimsy, but in fact, a well designed steel nut could support a huge weight. Now Here comes the fatal detail. The original drawings for the skywalks showed both of them suspended from the same long rods. The fourth floor skywalk was supported by nuts halfway up each rod, and the second floor skywalk was fixed by nuts at the bottom of the same rods. But that is not what was built. Instead of hanging from the same long steel rods, the upper skywalk hung from shorter rods, and the lower skywalk hung from rods which were attached to the upper one. Describing it, that change seems trivial, and if I were to show you a technical drawing, the chances are you'd still say that the change was trivial. It seems hard to see why the change makes a difference. So picture this. Imagine that you and a friend are planning to swing on a rope hanging from a high tree branch. You'll hold on to a knot in the middle of the rope and your friend will hold on to a knot near the bottom. But then you realize you don't have a long enough piece of rope. You've only got two shorter lengths. No problem, says your friend. She ties one length of rope knotted at the bottom around the tree branch. You swing from that rope, she says. Then she ties the other length firmly around your waist. I'll swing from this one. That isn't going to work, is it. Your grip was strong enough to support your own weight, but it's not strong enough to support both of you. It won't be long before your clasped hands lose their grip, slipping around the knot, and because your friend is hanging from a rope attached to you, when you've shield fall. Two, The apparently trivial design change to the skywalks had the same fatal effect. Instead of two walkways hanging from the same set of rods, now the upper walkway was supporting its own weight and the weight of the lower skywalk two. For a year, the steel strained under double the intended weight, absolutely at the limit. What makes this an engineering tragedy rather than an engineering curiosity was how finely balanced the skywalks were. Any weaker than they would have collapsed during construction, any stronger than they might have lasted indefinitely, but they were just strong enough to stay aloft until one busy, buzzing Friday evening in the summer of eighty one, when hundreds of people danced underneath the skywalks, and a few dozen more came to stand on them and watch. The first responders to the disaster were weeping in frustration as they tried to pry up the huge concrete slabs. People underneath were begging for help, but the standard rescue equipment was all but useless. As the words spread across Kansas City of what was happening at the Hiat, construction workers began to arrive at the site, bringing jackhammers and oxyo settlin torches, portable generators and lights. The deputy fire chief used to work part time at a construction crane operator just down the street. He made the call, and before long, the huge cranes were on their way to the scene. Cindy Paulson was outside, still looking for her father, when across the chaos she saw her mother instead. The two rushed towards one another. How did you get here, asked Cindy, Your father called her mother replied he was perfectly safe. He'd left the hotel before the skywalks fell and only heard about the accident on the radio. He'd called home to reassure his family and Cindy's mother had rushed to the scene to reassure Cindy. Cindy told her mother to head home without her, she was going back in to help. From time to time, Dr Wackerley would whistle as a signal for the rescue effort to fall silent. The rescuers, hundreds of them, would listen as trapped people called out their names from under the rubble. The rescuers did their best to mark the location of each one. After the first hour or so, there wasn't much good news. Most of the survivors were out. Most of those who remained were beyond help, but there was the occasional moment to lift the spirits. At two o'clock in the morning, a man, a woman, and a boy were pulled alive from an air pocket under the wreckage. Mark Williams, his legs wrenched around his ears, was still waiting. The water around him had receded, but the voices of those buried nearby had also fallen silent. At three in the morning, two massive cranes smashed through the atrium's beautiful glass wall, showering the shards across the blood and the dust on the floor. Those all two heavy concrete slabs were lifted a little, letting rescuers call in and shine their torches. The excited rescuers were now very close to Mark Williams, which posed new and unexpected risks. He could hear a jackhammer getting ever closer. Its chisel tip his ribs, then stabbed down near his cross. Shut the jackhammer off, you idiots, he yelled during a brief pause. They did, and a few minutes later Mark Williams, twisted like a pretzel, but very much alive, was pulled out of the rubble. After that, there would be no more miracles. The rescuers had spent the night cutting through dead bodies to reach the living, trying to stabilize people with catastrophic injuries, digging out the spouses who died together as they danced, eighteen married couples, and finding the body of eleven year old Pamela Coffee, the only child to die in the collapse. Dawn had broken when the cranes lifted the final fallen section of skywalk. For some of the rescuers, it was the moment when the long struggle became too much to bear. There were thirty one people underneath, every single one of them was dead. Over the years, engineers have found a horrid fascination in the skywalk collapse. It's been a case study in a thousand engineering classes, a kind of logic puzzle. Spot the floor in the innocuous, seeming design change. It's because the error is so surprising, so easy to overlook, and then so obvious in hindsight. Letting the lower skywalk hang off the upper skywalk was the simple fatal error, so clear only when you imagine swinging off a rope and trying to bear the weight of someone swinging off you. The steel crossbeams couldn't bear the double weight focused to that small nut on the steel rod. The beams buckled and slipped around the nut and off the rods, and disaster followed almost instantly. After the tragedy, there was plenty of commentary in places such as the letters page of the Engineering News Record. Some pointed out that it was no surprise that the original design concept had been modified. That concept secured the upper skywalk by resting it on nuts halfway up the vertical steel rods. Simple until you think about it. How does each nut get there? One possibility is to machine fifteen feet of each rod with a fine screw thread and hope that those threads remain undamaged while these six rods were installed in a busy construction site, or perhaps custom made rods slightly slimmer at one end than another, so that the nut can slide along until it reaches the thread in the middle. There are other ways to get a nut onto the middle of a long rod, but the original design doesn't acknowledge that there's even an issue. No wonder the contractor suggested a change. As one engineer commented, a design that begs a change cannot be completely without blame when the change is made. The letter's page was filled with clever alternative solutions, but it's not hard to find a solution once you clearly understand that switching to an upper and lower rod posed a problem in the first place. Nobody did I worry that in focusing on the skywalk collapse as a flaw in engineering design, we risk losing sight of the real problem. Engineers will forevermore pay close attention to the design of rod girder connections, But this isn't really about the structure of a steel connection. It's about the structure of a project. What failed wasn't just a beam. What failed was a process turn away from the powerful eyewitness reporting of the Kansas City Star and pick up instead a special May two thousand symposium in the Journal of Performance of Constructed Facilities. In that symposium, numerous engineers, including Jack Gillum himself, analyze what went wrong. Gillum listed seventeen different factors contributing to the error. The project was rushed, details weren't checked by external reviewers, Senior people resigned from the engineering company halfway through, important jobs were outsourced. Gillum himself protested that we requested from the architect, owner and construction manager on three separate occads, that we be permitted to provide full time inspection during the construction, yet each time we were denied. Of course Gillan was pleading his own case there, but the overall impression is clear. It was a complicated project with lots of ins and outs, lots of people coming and going. It's easy to see how things could get missed. What's unnerving about this is that, well, every big building is a complicated project. We have to trust the project managers to cope. In his book The Checklist Manifesto, The Surgeon at All Gowande looks at how to prevent accidents in modern medicine. It's all so complicated these days, he argues, there are large medical teams, complex medical procedures, lots of ways in which things can go wrong, often because of a simple oversight. Gonde makes a compelling case that this complexity can be tamed with checklists, agree a list of what has to be done, everything from a surgical team introducing themselves to each other, to ensuring that there are the right supplies and spares on hand, to making sure that you have the right patient on the operating table in front of you. Checklists sound absurdly simple, but in many cases they've been proved to work. But what's striking to me is where Atulgoande originally got the inspiration for this idea. It was talking to the team who were building an eleven story extension to the hospital where he worked. Three thousand, eight hundred and eighty five tons of steel, thirteen thousand cubic yards of concrete, nineteen air handling units, sixteen elevators, one cooling tower, and one back up emergency generator, and to make sure nothing was missed. Checklists, lots of checklists. Checklists for schedules, checklists for communication, checklists for checklists. But when it came to building the highatt regency in Kansas City, some vital boxes never got ticked. There's one pivotal moment worth highlighting. It happened early in January nineteen seventy nine, two and a half years before the disaster. At the time, it didn't seem like much, and that was the problem. It was simply a phone call, which was a common enough way of communicating in the days before email. A manager at the steel fabricator phoned the structural engineer's project manager and suggested that fateful switch from the long single rods to the shorter pairs of rods. The structural engineer thought it through while still on the phone, but missed the critical realization that the change would double the load that the upper beams were supporting. He said that the check change sounded fine, but asked the steel fabricator to submit the request through formal channels. That formal request was never made. Do you see why I say this was a process error as much as a failure of structural engineering design. Someone makes a phone call with a request, someone else says it sounds okay, but put it in writing. It never gets put in writing. Nobody follows up. This sort of thing happens all the time in offices all over the world. Meeting notes are unclear or nonexistent, or lost emails disappear down into the depths of an overloaded inbox. People agree that some task needs to be done, but it's not quite clear who's responsible, and so in the end nobody is. We've all seen it happen. It's just that usually when someone's a bit sloppy with their to do list, nobody dies. This time, people did, a lot of people. Jack Gillum, the structural engineer with overall responsibility for the project, explained the connection that failed was never designed. The original detail of the connection as shown on the contract structural drawings was only conceptual in nature. Neither the original detail nor the double rod connection as built was designed, so not a failure of design, an absence of design because of a failure of process. When the official investigation was completed by the National Bureau of Standards, it concluded that, yes, the switch from long single rods to short double rods was probably the difference between the skywalks staying up and the skywalks falling. But it also concluded that even the original design wasn't strong enough to meet the requirements of Kansas City's building code. The original design would almost certainly not have collapsed, which of course is the important thing, But the original design was still too weak. Nobody ever, seems to have checked that, and nobody had noticed, not the structural engineers, not the steel fabricators, not the building inspectors. In the arguments and legal disputes that followed, the attorney representing the state Licensing Board said it wasn't a matter of doing something wrong, They just never did it at all. Nobody ever did any calculations to figure out whether or not the particular connection that held the sky walks up would work. It got built without anybody ever figuring out if it would be strong enough. It just slipped through the cracks literally true, of course, under the tremendous weight of two skywalks. The nut ripped through the weakest point of the box beams, a welding scene that cracked open metaphorically true as well. In between the tooing and throwing, the resignations, and the outsourcing, everyone assumed that someone had designed and checked the steel joint, nobody had it slipped through the cracks. One hundred and fourteen people died in the disaster, almost two hundred were injured. No criminal charges were filed, but Jack Gillum and one of his colleagues lost their license to practice in Missouri. Gillam spent his twilight years retelling the story of the collapse as a cautionary tale for other construction professionals. He often spoke to engineers about the disaster, hoping to scare the daylights out of them. The buck stops with me, he would tell them, that was my engineering seal on the plans. Student hostess Cindy Paulson spent that night at the hyat helping with the rescue effort. It took a toll on her her grades. Once outstanding started to fall, she took time out of her studies to try to reset, but that didn't help either. She was later diagnosed with depression, but she got on with life and found a career selling real estate. She tries not to think too much about the hyat, but she can't help but get nervous on walkways. Mark Williams, the last person to be pulled out of the rubble alive, spent two months in hospital, much of it on dialysis because his kidneys had given up under the strain. He spent a further two years learning to walk again, a little unevenly, but not too bad. He gave an upbeat assessment to The Kansas City Star. We don't know what we can accomplish, what we can withstand until we're tested. As a slogan for life, it's a good one, but it was never supposed to be a principle of engineering design. We rely on engineers to get things right on the drawing board. We don't expect to find out the hard way that sixty tons of steel and concrete are floating in the sky on a joint that nobody designed and nobody checked. A key source for this episode was Donna McGuire's reporting for The Kansas City Star in two thousand and one. For a full list of references, check out the show notes. It's Timharford dot com. Cautionary Tales is written by me Tim Harford with Andrew Wright. It's produced by Ryan Dilly with support from Courtney Garino and Emily Vaughan. The sound design and original music is the work of Pascal Wise, Julia Barton edited the scripts. It features the voice talents of Ben Crowe, Melanie Gutteridge, Stella Harford, and rufus Wright. The show also wouldn't have been possible without the work of Mea LaBelle, Jacob Weisberg, Heather Faine, John Schnaz, Carli Migliori, Eric Sandler, Royston Basserv Maggie Taylor, Nicolmrano, Daniela Lakhan, and Maya Kanigg. Cautionary Tales is a production of Pushkin Industries. If you like the show, please remember to share, rate and review, and if you want to hear the show, add free and listen to four exclusive Cautionary Tale shorts. Then sign up for Pushkin Plus on the show page in Apple Podcasts or at pushkin dot fm, slash plus

Pushkin. Henry Petrotski was, and I mean this as a most sincere compliment, a nerd. This is a man who wrote a four hundred page history of the toothpick and even managed to get that book reviewed in the New York Times, even if the reviewer did tell him to knock it off. I never read the Toothpick book, I have to admit, but I did read other books by Dr Petrowski, and I love them. His history of the pencil is amazing. Now, we economists have a strange relationship with pencils because a classic essay in economics titled Eye Pencil is kind of an autobiography of a pencil, which explains the decentralized genius of the free market economy. But Petrotski went way deeper into pencils, where they came from, how we overlook them, even how they get the lead into the middle of the pencil. He meditated on their erasability so indispensable to designers and engineers. Ink is the cosmetic that ideas will wear when they go out in public. He wrote, Graphite is their dirty truth. Exhibit A in Overlooking the Pencil is Henry David Threau, the great nineteenth century American essayist. He once made a comprehensive list of supplies for an excursion, specifying obvious items such as a tent and matches, adding string, old newspapers, a tape measure, and a magnifying glass, also including paper and stamps to make notes and write letters. But as Petrotski points out, isn't it strange that he omitted to mention the very pencil with which he was making the list. Well maybe not, you think, until you realize that Threau and his father made their money by manufacturing high quality pencils. For row was big pencil. As for that perennial question about the pencil lead, and by the way, it's not lead, and it's never been lead. Pencil leads are made from graphite. When they first discovered graphite in the English Lake district underneath the roots of an old tree that was uprooted in a storm, well they didn't know what it was and they called it black lead. But I digress. How do they get the graphite inside the wood? The trick is to take a slim slab of kiln dried wood and saw a row of grooves into the top surface. Originally the grooves were square easier to cut by hand, now their precision machined with a semi circular cross section. Once the cylindrical rods are laid into the grooves, you glue another grooved slab on top, this time with the grooves in the bottom. Then all you have to do is cut the whole graphite sandwich into sticks parallel to the graphite rods. Those sticks are unformed, pencils, plane, varnish, and the chops done. And that is what you learn if you read Henry Petrowsky. But Petrotski was not only a toothpick and pencil guy, not at all. He was an engineer, and a particular kind of engineer. He was fascinated by failure. You can understand why I'm such a fan of the man, He once told The New York Times. Successful engineering is all about understanding how things break or fail. One of his books, Success Through Failure, explored the way that engineers often advanced the field by building more and more ambitious buildings, till eventually they exceeded what was possible and something broke a bridge, a wall, a concrete multi story car park. The engineers learned, adapted, and moved on. That was one of the inspirations for my own book, adapt and Petrovsky was really really thoughtful on the subject of engineering failure. In nineteen eighty one, two skywalks at the Kansas City Hiatt Regency hotel collapsed, killing one hundred and fourteen people. Dr Petrowski's neighbor asked him, how on earth could that happen? Did engineers really not understand how to build a simple structure like a walkway hanging from a ceiling? And so Petrotski thought about that and went on to write some of the most interesting analysis of the disaster. His writing really helped me think through the catastrophe at the Hiatt Regency, and it helped me think through a lot more. Henry Petrowski died in June twenty twenty three at the age of eighty one. He leaves behind a shelf full of insightful books. Whether you're inter engineering failure, or into pencil, or even Heaven forbid, into toothpicks, Petrosky is your man. We'll be back in two weeks with another brand new episode of Cautionary Tales, but this week we're going to rerun a classic death on the dance floor. It's a harrowing story about the collapse of the Kansas City Skywalks. But like the best of our cautionary tales, it's also a story that will, I hope, make you think. Henry Petrowski made me think long and hard about the skywalks. I hope something of that spirit has rubbed off on the podcast. Friday Night at the Hyatt Regency one of Kansas City's most popular dates since the hotel opened just a year earlier. There are cues at the lobby bar. The place is buzzing. It's the summer of nineteen eighty one, but the orchestra is belting out the big band sounds of the forties and fifties. Dance contestants with numbers pinned to their backs are doing the Mambo and the East Coast Swing. But while the music is nostalgic, the hotel lobby is distinctly space age. It's big and airy, with a glass wall letting in the light and three walkways skywalks crossing the space on the second, third, and fourth floors. They're suspended from the ceiling so that the lobby itself is unobstructed by columns, all the more room for dancing Cindy Paulson briefly looks down from the terrace rest to see if she can see her father out on the dance floor the restaurant. On a large mezzanine overlooking the lobby provides the perfect view, but the lobby floor is packed and she can't pick him out of the crowd. After a moment, she goes back to work. Cindy's a college student, her family live in town. Being a hostess at the Hyatt is her summer job. It's five past seven in the evening. Cindy will always remember that because she glances across the lobby, out through the floor to ceiling glass wall, and sees the time on the clock on the bank just across the street. Then, as a sharp crack, clearly audible even above the music and the loud buzz of conversation, Cindy's eyes refocus from the distant clock to the sky walks in front of her, but she can't believe what she's seeing. I'm Tim Harford and you're listening to cautionary tales. Dr Joseph Wackerley got the call almost immediately from emergency dispatchers. We need you at a hiat he grabbed a stethoscope and scrubs and ran to his car. Wackerley, just thirty five years old, had already served as the director of Kansas City's emergency medical system. He rushed to the scene. When Wackley arrived at the hyat, it was lit by the flashing lights of ambulances. Amid the crowd. There were dozens of injured people. Some were bleeding, others had broken bones. Some were lying on stretchers. Wackley sprang into action, checking who needed assistance most urgently. Then a paramedic grabbed him. You're in the wrong place, he said. The real casualties are inside the hotel. You need to get inside. The lobby was no longer airy and bathed in evening sunlight. It was coated in concrete dust. The skywalks no longer levitated across the atrium. Two of them had fallen, crunching onto the busy dance floor. Voices were calling out for help. Electric cables were swinging loose arcs of electricity, sending flashes of light across the dim space. Somewhere high above, a pipe had fractured and water was gushing onto the lobby floor. It was six inches deep. Or ready and threatened to submerge those who were trapped if anyone had survived the impact. That is, Wackerley could see arms and legs sticking out of the rubble. Dr Wackerley took charge of the medical operation. It was bolstered by a huge voluntary effort, with taxis, buses, and private cars helping the ambulances to get injured people to hospitals. Locals were doing whatever they could to tend to the walking, wounded, free the trapped, and comfort families. Among them was Cindy Paulson, the restaurant hostess. She'd helped evacuate the diners at the restaurant, but then she'd return to the lobby. Somewhere in the middle of that mess was her father. She moved through the lobby, doing what she could. She comforted one couple pinned under the wreckage. After firefighters were able to free them, Cindy kept looking for her father. Two hundred and fifty miles away in Saint Louis, Jack Gillum and his wife arrived home to find the telephone ringing. The call was from one of the architects at the Hyatt Regency Hotel. There's been a collapse at the Hyatt. Jack Gillum was stunned. He was the structural engineer of record for the Hiatt Regency Hotel's construction. That meant he was the one who had signed off on all the designs, certifying that they were safe. And now Gillam was being told that those elegant walkways across the hotel lobby had fallen out of the sky and smashed into the crowd of people below. Jack, the rescue teams are trying to get equipment that can move the fallen sections of walkway. They need to know how heavy the sections are reeling. Gillam could hardly think. He stammered out an approximate answer. Each of those airy looking skywalks weighed over thirty tons. A single walkway section weighed about eight tons. They were going to need cranes. Gillham managed to charter a plane and fly over, arriving a few hours into the rescue effort. Whatever he expected to see, the disaster was worse, But his job now was to try to figure out how the structure had failed. This was a brand new building. It looked bold, but the engineering was simple enough. Somehow the structure had failed catastrophically. Somehow they'd missed something. But what Three skywalks had spanned the atrium of the highest regency, flat decks of steel and concrete with glass balustrades hanging on steel rods from the roof. The third floor skywalk hung by itself and was undamaged, but the second floor skywalk had hung directly beneath the one on the fourth floor. When Cindy Paulson had gazed absently over the lobby at a clock across the street, her attention had been caught by the sound of both skywalks lurching downwards a few inches. There were a few people on the upper skywalk and more on the lower one, fifty sixty maybe, but there wasn't time for them to react. A moment later, both skywalks simultaneously tore free of one of the supporting ceiling rods. The extra load was suddenly transferred to nearby rods, ripping the skywalks free of those connections too. From the nest and the next the skywalks simply unzipped themselves from the ceiling rods, and the skywalks no longer more than sixty tons of steel and concrete fell onto the dancers below, spraying bystanders with deadly glass shrapnel. The entire chain reaction took seconds. Dr Joseph Wackerley and the other rescuers were now trying to deal with the aftermath. One man was half buried, his legs crushed by a piece of skywalk. Wackerley told him he wouldn't survive unless they could amputate. The man said no. Others didn't get the choice. Medics were forced to tell people, we can't get you out in time. You'll die before they get the cranes in here. All we can do is give you something to ease the pain. Then they moved on to the next patient. Family members were on the scene almost immediately, begging the medics and the fire crews to help. Wackerley was trying to decide who most urgently needed care, with the spouses and parents and children of the victims right there crying, pleading, screaming. As he did it, he went back to the man who had turned down the amputation. I've changed my mind, Doc, he said, you can take my legs off. I just want to live. Wackley beckoned over a surgeon with a chainsaw to perform the amputation. They got him out, but in vain. He didn't survive the night. Cindy Paulson was outside looking for her father, hoping he'd been able to walk away, and deep deep under the rubble was a man called Mark Williams. Williams was an old school friend of Joseph Wackerley. While Wackerley hurried around directing the medical response, Williams was doing his best to contribute. He was trapped in an eighteen inch pocket of air underneath a section of fallen skywalk. His legs had been slightly askew when the skywalks fell and were wrenched into the splits and beyond. Both his legs were dislocated. His left foot was up beside his right ear, but other trapped people could hear his voice, calmly talking to them, trying to reassure everyone that help was on the way, that they'd get through this. But with his face pressed against the floor and water seeping through the rubble all around him, Williams realized that after surviving over sixty tons falling on him, he was now all too likely to drown. While the medics and the fire fighters worked through the night, the structural engineer Jack Gillum wasn't getting any sleep either. He was the man who'd officially declared the skywalks were safe to build. What had gone wrong was a very simple and surprising mistake. Gillam spent some time doing some calculations to confirm his suspicions. Then he went to bed, staring at the ceiling of his hotel room until the morning. Meanwhile, the rest of the world was left to speculate. One popular theory was that the skywalks were overcrowded with people dancing, and that their rhythmic movements had set up dangerous resonances which destroyed the structure. But the numbers didn't add up. The people on the skywalks would have had to have been phrenetically go go dancing, not gently nodding along to big band swing, and the weight of the people was small compared with the weight of the skywalks themselves. There were sixty three people on walkways that, by coincidence, weighed sixty three tons. Kansas City building codes demanded that the skywalks could have carried nearly ten times as many people, more like five hundred people than sixty three. Then talk turned to the quality of construction, had someone tried to save money by using cheap materials A reasonable guess, but no. Within days, the world had figured out the skywalk's fatal flow thanks to a young engineer, a telephoto lens, and the Kansas City Star. I relied on reporting from the Kansas City Star for the eyewitness accounts of the disaster, but the newspaper also won a pull its surprise for its investigation into exactly why the skywalks collapsed. After loud protests about a cover up, the press were allowed to visit the hyat's shattered atrium. The Star sent its best reporters and at the last minute persuaded a young structural engineer named Wayne Lishka to join them. The visit was a shock. Wayne Lishke and his wife had spent evenings dancing in the hotel lobby. The disaster seemed unnervingly close, but it was also frustrating. Journalists were only allowed the view that the hostess, Cindy Paulson, had had looking down at the lobby floor from the elevated restaurant. It wasn't close enough to see March, unless, of course, Lishka asked the Stars photographer to use a long zoom lens even from a distance, Lishka could point out the details he wanted to see up close. Take a shot of that, he said, and that and that. When the photographs were developed, they showed the end of the vertical rods uselessly hanging from the ceiling down to the fourth floor. Lishka could see clearly that the rods were basically undamaged. They hadn't thinned or stretched. The rods hadn't failed the skywalks had fallen off them. Examining a few more photographs, Lishka and the Kansas City Star had their answer, and on the front page of the newspaper they published technical drawings highlighting a tiny detail of the design, a tiny detail that had been overlooked with the most appalling consequences. The detail concerned the connection between the long vertical rods and the horizontal beams that supported the walkways. These steel beams were hollow, big square steel pipes. The vertical rods pierced each horizontal beam, and the beam was supported by a steel nut threaded onto each rod. The beam wouldn't slide down the rod because the nut was in the way. That might sound flimsy, but in fact, a well designed steel nut could support a huge weight. Now Here comes the fatal detail. The original drawings for the skywalks showed both of them suspended from the same long rods. The fourth floor skywalk was supported by nuts halfway up each rod, and the second floor skywalk was fixed by nuts at the bottom of the same rods. But that is not what was built. Instead of hanging from the same long steel rods, the upper skywalk hung from shorter rods, and the lower skywalk hung from rods which were attached to the upper one. Describing it, that change seems trivial, and if I were to show you a technical drawing, the chances are you'd still say that the change was trivial. It seems hard to see why the change makes a difference. So picture this. Imagine that you and a friend are planning to swing on a rope hanging from a high tree branch. You'll hold on to a knot in the middle of the rope and your friend will hold on to a knot near the bottom. But then you realize you don't have a long enough piece of rope. You've only got two shorter lengths. No problem, says your friend. She ties one length of rope knotted at the bottom around the tree branch. You swing from that rope, she says. Then she ties the other length firmly around your waist. I'll swing from this one. That isn't going to work, is it. Your grip was strong enough to support your own weight, but it's not strong enough to support both of you. It won't be long before your clasped hands lose their grip, slipping around the knot, and because your friend is hanging from a rope attached to you, when you've shield fall. Two, The apparently trivial design change to the skywalks had the same fatal effect. Instead of two walkways hanging from the same set of rods, now the upper walkway was supporting its own weight and the weight of the lower skywalk two. For a year, the steel strained under double the intended weight, absolutely at the limit. What makes this an engineering tragedy rather than an engineering curiosity was how finely balanced the skywalks were. Any weaker than they would have collapsed during construction, any stronger than they might have lasted indefinitely, but they were just strong enough to stay aloft until one busy, buzzing Friday evening in the summer of eighty one, when hundreds of people danced underneath the skywalks, and a few dozen more came to stand on them and watch. The first responders to the disaster were weeping in frustration as they tried to pry up the huge concrete slabs. People underneath were begging for help, but the standard rescue equipment was all but useless. As the words spread across Kansas City of what was happening at the Hiat, construction workers began to arrive at the site, bringing jackhammers and oxyo settlin torches, portable generators and lights. The deputy fire chief used to work part time at a construction crane operator just down the street. He made the call, and before long, the huge cranes were on their way to the scene. Cindy Paulson was outside, still looking for her father, when across the chaos she saw her mother instead. The two rushed towards one another. How did you get here, asked Cindy, Your father called her mother replied he was perfectly safe. He'd left the hotel before the skywalks fell and only heard about the accident on the radio. He'd called home to reassure his family and Cindy's mother had rushed to the scene to reassure Cindy. Cindy told her mother to head home without her, she was going back in to help. From time to time, Dr Wackerley would whistle as a signal for the rescue effort to fall silent. The rescuers, hundreds of them, would listen as trapped people called out their names from under the rubble. The rescuers did their best to mark the location of each one. After the first hour or so, there wasn't much good news. Most of the survivors were out. Most of those who remained were beyond help, but there was the occasional moment to lift the spirits. At two o'clock in the morning, a man, a woman, and a boy were pulled alive from an air pocket under the wreckage. Mark Williams, his legs wrenched around his ears, was still waiting. The water around him had receded, but the voices of those buried nearby had also fallen silent. At three in the morning, two massive cranes smashed through the atrium's beautiful glass wall, showering the shards across the blood and the dust on the floor. Those all two heavy concrete slabs were lifted a little, letting rescuers call in and shine their torches. The excited rescuers were now very close to Mark Williams, which posed new and unexpected risks. He could hear a jackhammer getting ever closer. Its chisel tip his ribs, then stabbed down near his cross. Shut the jackhammer off, you idiots, he yelled during a brief pause. They did, and a few minutes later Mark Williams, twisted like a pretzel, but very much alive, was pulled out of the rubble. After that, there would be no more miracles. The rescuers had spent the night cutting through dead bodies to reach the living, trying to stabilize people with catastrophic injuries, digging out the spouses who died together as they danced, eighteen married couples, and finding the body of eleven year old Pamela Coffee, the only child to die in the collapse. Dawn had broken when the cranes lifted the final fallen section of skywalk. For some of the rescuers, it was the moment when the long struggle became too much to bear. There were thirty one people underneath, every single one of them was dead. Over the years, engineers have found a horrid fascination in the skywalk collapse. It's been a case study in a thousand engineering classes, a kind of logic puzzle. Spot the floor in the innocuous, seeming design change. It's because the error is so surprising, so easy to overlook, and then so obvious in hindsight. Letting the lower skywalk hang off the upper skywalk was the simple fatal error, so clear only when you imagine swinging off a rope and trying to bear the weight of someone swinging off you. The steel crossbeams couldn't bear the double weight focused to that small nut on the steel rod. The beams buckled and slipped around the nut and off the rods, and disaster followed almost instantly. After the tragedy, there was plenty of commentary in places such as the letters page of the Engineering News Record. Some pointed out that it was no surprise that the original design concept had been modified. That concept secured the upper skywalk by resting it on nuts halfway up the vertical steel rods. Simple until you think about it. How does each nut get there? One possibility is to machine fifteen feet of each rod with a fine screw thread and hope that those threads remain undamaged while these six rods were installed in a busy construction site, or perhaps custom made rods slightly slimmer at one end than another, so that the nut can slide along until it reaches the thread in the middle. There are other ways to get a nut onto the middle of a long rod, but the original design doesn't acknowledge that there's even an issue. No wonder the contractor suggested a change. As one engineer commented, a design that begs a change cannot be completely without blame when the change is made. The letter's page was filled with clever alternative solutions, but it's not hard to find a solution once you clearly understand that switching to an upper and lower rod posed a problem in the first place. Nobody did I worry that in focusing on the skywalk collapse as a flaw in engineering design, we risk losing sight of the real problem. Engineers will forevermore pay close attention to the design of rod girder connections, But this isn't really about the structure of a steel connection. It's about the structure of a project. What failed wasn't just a beam. What failed was a process turn away from the powerful eyewitness reporting of the Kansas City Star and pick up instead a special May two thousand symposium in the Journal of Performance of Constructed Facilities. In that symposium, numerous engineers, including Jack Gillum himself, analyze what went wrong. Gillum listed seventeen different factors contributing to the error. The project was rushed, details weren't checked by external reviewers, Senior people resigned from the engineering company halfway through, important jobs were outsourced. Gillum himself protested that we requested from the architect, owner and construction manager on three separate occads, that we be permitted to provide full time inspection during the construction, yet each time we were denied. Of course Gillan was pleading his own case there, but the overall impression is clear. It was a complicated project with lots of ins and outs, lots of people coming and going. It's easy to see how things could get missed. What's unnerving about this is that, well, every big building is a complicated project. We have to trust the project managers to cope. In his book The Checklist Manifesto, The Surgeon at All Gowande looks at how to prevent accidents in modern medicine. It's all so complicated these days, he argues, there are large medical teams, complex medical procedures, lots of ways in which things can go wrong, often because of a simple oversight. Gonde makes a compelling case that this complexity can be tamed with checklists, agree a list of what has to be done, everything from a surgical team introducing themselves to each other, to ensuring that there are the right supplies and spares on hand, to making sure that you have the right patient on the operating table in front of you. Checklists sound absurdly simple, but in many cases they've been proved to work. But what's striking to me is where Atulgoande originally got the inspiration for this idea. It was talking to the team who were building an eleven story extension to the hospital where he worked. Three thousand, eight hundred and eighty five tons of steel, thirteen thousand cubic yards of concrete, nineteen air handling units, sixteen elevators, one cooling tower, and one back up emergency generator, and to make sure nothing was missed. Checklists, lots of checklists. Checklists for schedules, checklists for communication, checklists for checklists. But when it came to building the highatt regency in Kansas City, some vital boxes never got ticked. There's one pivotal moment worth highlighting. It happened early in January nineteen seventy nine, two and a half years before the disaster. At the time, it didn't seem like much, and that was the problem. It was simply a phone call, which was a common enough way of communicating in the days before email. A manager at the steel fabricator phoned the structural engineer's project manager and suggested that fateful switch from the long single rods to the shorter pairs of rods. The structural engineer thought it through while still on the phone, but missed the critical realization that the change would double the load that the upper beams were supporting. He said that the check change sounded fine, but asked the steel fabricator to submit the request through formal channels. That formal request was never made. Do you see why I say this was a process error as much as a failure of structural engineering design. Someone makes a phone call with a request, someone else says it sounds okay, but put it in writing. It never gets put in writing. Nobody follows up. This sort of thing happens all the time in offices all over the world. Meeting notes are unclear or nonexistent, or lost emails disappear down into the depths of an overloaded inbox. People agree that some task needs to be done, but it's not quite clear who's responsible, and so in the end nobody is. We've all seen it happen. It's just that usually when someone's a bit sloppy with their to do list, nobody dies. This time, people did, a lot of people. Jack Gillum, the structural engineer with overall responsibility for the project, explained the connection that failed was never designed. The original detail of the connection as shown on the contract structural drawings was only conceptual in nature. Neither the original detail nor the double rod connection as built was designed, so not a failure of design, an absence of design because of a failure of process. When the official investigation was completed by the National Bureau of Standards, it concluded that, yes, the switch from long single rods to short double rods was probably the difference between the skywalks staying up and the skywalks falling. But it also concluded that even the original design wasn't strong enough to meet the requirements of Kansas City's building code. The original design would almost certainly not have collapsed, which of course is the important thing, But the original design was still too weak. Nobody ever, seems to have checked that, and nobody had noticed, not the structural engineers, not the steel fabricators, not the building inspectors. In the arguments and legal disputes that followed, the attorney representing the state Licensing Board said it wasn't a matter of doing something wrong, They just never did it at all. Nobody ever did any calculations to figure out whether or not the particular connection that held the sky walks up would work. It got built without anybody ever figuring out if it would be strong enough. It just slipped through the cracks literally true, of course, under the tremendous weight of two skywalks. The nut ripped through the weakest point of the box beams, a welding scene that cracked open metaphorically true as well. In between the tooing and throwing, the resignations, and the outsourcing, everyone assumed that someone had designed and checked the steel joint, nobody had it slipped through the cracks. One hundred and fourteen people died in the disaster, almost two hundred were injured. No criminal charges were filed, but Jack Gillum and one of his colleagues lost their license to practice in Missouri. Gillam spent his twilight years retelling the story of the collapse as a cautionary tale for other construction professionals. He often spoke to engineers about the disaster, hoping to scare the daylights out of them. The buck stops with me, he would tell them, that was my engineering seal on the plans. Student hostess Cindy Paulson spent that night at the hyat helping with the rescue effort. It took a toll on her her grades. Once outstanding started to fall, she took time out of her studies to try to reset, but that didn't help either. She was later diagnosed with depression, but she got on with life and found a career selling real estate. She tries not to think too much about the hyat, but she can't help but get nervous on walkways. Mark Williams, the last person to be pulled out of the rubble alive, spent two months in hospital, much of it on dialysis because his kidneys had given up under the strain. He spent a further two years learning to walk again, a little unevenly, but not too bad. He gave an upbeat assessment to The Kansas City Star. We don't know what we can accomplish, what we can withstand until we're tested. As a slogan for life, it's a good one, but it was never supposed to be a principle of engineering design. We rely on engineers to get things right on the drawing board. We don't expect to find out the hard way that sixty tons of steel and concrete are floating in the sky on a joint that nobody designed and nobody checked. A key source for this episode was Donna McGuire's reporting for The Kansas City Star in two thousand and one. For a full list of references, check out the show notes. It's Timharford dot com. Cautionary Tales is written by me Tim Harford with Andrew Wright. It's produced by Ryan Dilly with support from Courtney Garino and Emily Vaughan. The sound design and original music is the work of Pascal Wise, Julia Barton edited the scripts. It features the voice talents of Ben Crowe, Melanie Gutteridge, Stella Harford, and rufus Wright. The show also wouldn't have been possible without the work of Mea LaBelle, Jacob Weisberg, Heather Faine, John Schnaz, Carli Migliori, Eric Sandler, Royston Basserv Maggie Taylor, Nicolmrano, Daniela Lakhan, and Maya Kanigg. Cautionary Tales is a production of Pushkin Industries. If you like the show, please remember to share, rate and review, and if you want to hear the show, add free and listen to four exclusive Cautionary Tale shorts. Then sign up for Pushkin Plus on the show page in Apple Podcasts or at pushkin dot fm, slash plus