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Walk This Way: The History of the Moving Sidewalk

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Authors like H.G. Wells, Isaac Asimov, and Robert Heinlein have long envisioned a future where the automobile gives way to massive, high-speed moving walkways. Some of them merely zoom commuters around cities, while others, like Heinlein’s "mechanized roads,” could take people from Cleveland all the way to Cincinnati.

The moving sidewalk is familiar to travelers in the real world, too, but smaller and limited to controlled environments like airports and train stations. They lack the grandeur and the game-changing status that futurists once envisioned, but that isn’t to say that people haven’t tried for larger, longer, faster moving sidewalks. Inventors had very real plans for the moving sidewalk that rivaled anything Wells dreamed up, but were undone by technical limitations and wary politicians and riders that science fiction authors could simply write their way around.

A Walking Tour of Moving Sidewalks

The history of real-world moving sidewalks goes back to a New Jersey inventor/wine merchant named Alfred Speer, who received the first patent for one in 1871. The first one operated in the U.S. was built for the 1893 World's Fair in Chicago. Operated by the Columbian Movable Sidewalk Company, which charged 5 cents for a ride, it ran almost the entire length of the 3,500-foot pier that many guests arrived at after taking a scenic steamship trip from downtown to the fairgrounds. Riders could stand or walk on the first platform, which traveled at about two miles per hour, or step up onto a second parallel platform, which ran at four miles per hour and had benches. Running at full capacity, the walkway could ferry 31,680 passengers per hour. Its life was short, though, and it was destroyed by a fire the following year.

The wooden moving pavement ('Trottoir Roulant') at the Exposition Universal in Paris, 1900 /

In the early years of the next century, Speer and Max Schmidt, who designed a moving walkway for the 1900 Exposition Universal in Paris, both proposed their own versions of the moving sidewalk in Manhattan to relieve some of the foot traffic on New York City’s crowded streets. Speer’s plan called for an elevated system of three parallel walkways running along Broadway that would move passengers at up to 19 mph. Speer’s system had one stationary platform for boarding and two moving ones where riders could either stand, walk or even have a seat in one of a few enclosed “parlor cars” that had drawing rooms for ladies, and space for men to sit and smoke. Despite building a working model and finding support in the city government and state legislature, Speer’s project was repeatedly killed by the governor.

Schmidt’s vision for a Brooklyn Bridge moving walkway consisted of a loop system with four platforms, one for boarding and three others that moved at increasing speeds, the fastest of which ran at 10 mph. Schmidt planned for the system to run constantly, so passengers wouldn’t have to wait to board and no momentum would be lost on stopping and starting the platforms. Schmidt and the individuals and groups who proposed similar systems in Atlanta, Boston, Los Angeles, Detroit, and Washington, D.C., all eventually saw their plans crumble under their own novelty. Maintenance and breakdown concerns, the question of what passengers were supposed to do in the rain or snow, and the familiarity and reliability of buses and subway trains all helped doom the urban moving sidewalk.

Let’s Try This Again

A half-century later, the moving sidewalk reared its head again when smaller-scale versions showed up in sprawling airports and train stations. They’re hardly the stuff of Wells and Schmidt, and are usually just a single platform moving slowly from Point A to Point B just a few hundred yards away.

The first of these simpler sidewalks got moving in May 1954 at the Hudson and Manhattan Railroad’s Erie station in Jersey City, NJ. Built by the Goodyear Tire and Rubber Co., the “Speedwalk’s” 5½-ft wide platform ran 277 feet up an incline used to exit the station, at a top speed of 1.5 mph. It was a relief to many riders used walking up the exit hall, which had earned the nickname “Cardiac Alley.”

While the Speedwalk might have prevented a few injuries, the first moving sidewalk installed at an airport - at Love Field in Dallas in 1958 - infamously caused several. One person was even killed. Early in the sidewalk’s operation, several people got clothing or a foot stuck where the conveyor met solid ground and disappeared into the floor to loop back. A dog suffered a broken leg. A seven-year-old boy got his t-shirt and hand sucked in and lost most of the skin on his fingers. As the boy’s mother tried to free him, her clothing got caught too, and her skirt and slip were pulled clean off. She continued to struggle with her son in nothing but a leather coat until the machine was turned off.

Two years later, an accident resulted in death. On New Year’s Day in 1960, a two-year-old girl, fascinated by the moving sidewalk, broke away from her mother and waddled over for a closer look. Her coat sleeve got caught at the edge, and her left hand, wrist and forearm were pulled below the floor. A police officer rushed to cut off her clothes to release her. He later told newspapers that her coat was pulled so tight around her chest that he couldn’t even get his knife underneath it.

Not So Fast

Designs and safety measures for the moving sidewalk improved, and its use spread to most airports over the next few decades. Some engineers even took another stab at larger, faster versions. Prototype high-speed walkways have been tried out in Paris metro stations in the 1980s and the early 2000s, but both systems were shut down due to mechanical complexity, unreliability, and passenger accidents.

While the idea of quickly floating over the Brooklyn Bridge or across Ohio on a moving walkway is exciting, there seems to be a practical limit to how fast a person can travel on a moving platform without losing their balance and toppling over. Fast, car-less travel over great distances is maybe best left to airplanes and high-speed rail lines. For the shorter moving sidewalks we have now, we don’t necessarily need speed and all the mechanical and safety problems that go with it.

The airport moving sidewalks often slow us down, versus walking normally, because people stand around or block the platform with their bags. The future of the people mover, perhaps, isn’t in a mechanical road that takes us from one town to another, but just an airport moving walkway that isn't treated like a leisure cruise. As Jerry Seinfeld used to say, "It's not a ride!"

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6 Radiant Facts About Irène Joliot-Curie
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Though her accomplishments are often overshadowed by those of her parents, the elder daughter of Marie and Pierre Curie was a brilliant researcher in her own right.


A black and white photo of Irene and Marie Curie in the laboratory in 1925.
Irène and Marie in the laboratory, 1925.
Wellcome Images, Wikimedia Commons // CC BY 4.0

Irène’s birth in Paris in 1897 launched what would become a world-changing scientific dynasty. A restless Marie rejoined her loving husband in the laboratory shortly after the baby’s arrival. Over the next 10 years, the Curies discovered radium and polonium, founded the science of radioactivity, welcomed a second daughter, Eve, and won a Nobel Prize in Physics. The Curies expected their daughters to excel in their education and their work. And excel they did; by 1925, Irène had a doctorate in chemistry and was working in her mother’s laboratory.


Like her mother, Irène fell in love in the lab—both with her work and with another scientist. Frédéric Joliot joined the Curie team as an assistant. He and Irène quickly bonded over shared interests in sports, the arts, and human rights. The two began collaborating on research and soon married, equitably combining their names and signing their work Irène and Frédéric Joliot-Curie.


Black and white photo of Irène and Fréderic Joliot-Curie working side by side in their laboratory.
Bibliothèque Nationale de France, Wikimedia Commons // Public Domain

Their passion for exploration drove them ever onward into exciting new territory. A decade of experimentation yielded advances in several disciplines. They learned how the thyroid gland absorbs radioiodine and how the body metabolizes radioactive phosphates. They found ways to coax radioactive isotopes from ordinarily non-radioactive materials—a discovery that would eventually enable both nuclear power and atomic weaponry, and one that earned them the Nobel Prize in Chemistry in 1935.


The humanist principles that initially drew Irène and Frédéric together only deepened as they grew older. Both were proud members of the Socialist Party and the Comité de Vigilance des Intellectuels Antifascistes (Vigilance Committee of Anti-Fascist Intellectuals). They took great pains to keep atomic research out of Nazi hands, sealing and hiding their research as Germany occupied their country, Irène also served as undersecretary of state for scientific research of the Popular Front government.


Irène eventually scaled back her time in the lab to raise her children Hélène and Pierre. But she never slowed down, nor did she stop fighting for equality and freedom for all. Especially active in women’s rights groups, she became a member of the Comité National de l'Union des Femmes Françaises and the World Peace Council.


Irène’s extraordinary life was a mirror of her mother’s. Tragically, her death was, too. Years of watching radiation poisoning and cancer taking their toll on Marie never dissuaded Irène from her work. In 1956, dying of leukemia, she entered the Curie Hospital, where she followed her mother’s luminous footsteps into the great beyond.

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ETH Zurich
This Soft Artificial Heart May One Day Shorten the Heart Transplant List
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ETH Zurich

If the heart in the Functional Materials Laboratory at ETH Zurich University were in a patient in an operating room, its vital signs would not be good. In fact, it would be in heart failure. Thankfully, it's not in a patient—and it's not even real. This heart is made of silicone.

Suspended in a metal frame and connected by tubes to trays of water standing in for blood, the silicone heart pumps water at a beat per second—a serious athlete's resting heart rate—in an approximation of the circulatory system. One valve is leaking, dripping onto the grate below, and the water bins are jerry-rigged with duct tape. If left to finish out its life to the final heartbeat, it would last for about 3000 beats before it ruptured. That's about 30 minutes—not long enough to finish an episode of Grey's Anatomy

Nicolas Cohrs, a bioengineering Ph.D. student from the university, admits that the artificial heart is usually in better shape. The one he holds in his hands—identical to the first—feels like taut but pliable muscle, and is intact and dry. He'd hoped to demonstrate a new and improved version of the heart, but that one is temporarily lost, likely hiding in a box somewhere at the airport in Tallinn, Estonia, where the researchers recently attended a symposium.

Taking place over the past three years, the experimental research is a part of Zurich Heart, a project involving 17 researchers from multiple institutions, including ETH, the University of Zurich, University Hospital of Zurich, and the German Heart Institute in Berlin, which has the largest artificial heart program in Europe.


Heart failure occurs when the heart cannot pump enough blood and oxygen to support the organs; common causes are coronary heart disease, high blood pressure, and diabetes. It's a global pandemic, threatening 26 million people worldwide every year. More than a quarter of them are in the U.S. alone, and the numbers are rising.

It's a life-threatening disease, but depending on the severity of the condition at the time of diagnosis, it's not necessarily an immediate death sentence. About half of the people in the U.S. diagnosed with the disease die within five years. Right now in the U.S., there are nearly 4000 people on the national heart transplant list, but they're a select few; it's estimated that upwards of 100,000 people need a new heart. Worldwide, demand for a new heart greatly outpaces supply, and many people die waiting for one.

That's why Cohrs, co-researcher Anastasios Petrou, and their colleagues are attempting to create an artificial heart modeled after each patient's own heart that would, ideally, last for the rest of a person's life.

Mechanical assistance devices for failing hearts exist, but they have serious limitations. Doctors treating heart failure have two options: a pump placed next to the heart, generally on the left side, that pumps the blood for the heart (what's known as a left ventricular assist device, or LVAD), or a total artificial heart (TAH). There have been a few total artificial hearts over the years, and at least four others are in development right now in Europe and the U.S. But only one currently has FDA approval and CE marking (allowing its use in European Union countries): the SynCardia total artificial heart. It debuted in the early '90s, and since has been implanted in nearly 1600 people worldwide.

While all implants come with side effects, especially when the immune system grows hostile toward a foreign object in the body, a common problem with existing total artificial hearts is that they're composed of hard materials, which can cause blood to clot. Such clots can lead to thrombosis and strokes, so anyone with an artificial heart has to take anticoagulants. In fact, Cohrs tells Mental Floss, patients with some sort of artificial heart implant—either a LVAD or a TAH—die more frequently from a stroke or an infection than they do from the heart condition that led to the implant. Neurological damage and equipment breakdown are risky side effects as well.

These complications mean that total artificial hearts are "bridges"—either to a new heart, or to death. They're designed to extend the life of a critically ill patient long enough to get on (or to the top of) the heart transplant list, or, if they're not a candidate for transplant, to make the last few years of a person's life more functional. A Turkish patient currently holds the record for the longest time living with a SynCardia artificial heart: The implant has been in his chest for five years. Most TAH patients live at least one year, but survival rates drop off after that.

The ETH team set out to make an artificial heart that would be not a bridge, but a true replacement. "When we heard about these problems, we thought about how we can make an artificial heart that doesn't have side effects," he recalls.


Using common computer assisted design (CAD) software, they designed an ersatz organ composed of soft material that hews closely to the composition, form, and function of the human heart. "Our working hypothesis is that when you have such a device which mimics the human heart in function and form, you will have less side effects," Cohrs says.

To create a heart, "we take a CT scan of a patient, then put it into a computer file and design the artificial heart around it in close resemblance to the patient's heart, so it always fits inside [the body]," Cohrs says.

But though it's modeled on a patient's heart and looks eerily like one, it's not identical to the real organ. For one thing, it can't move on its own, so the team had to make some modifications. They omitted the upper chambers, called atria, which collect and store blood, but included the lower chambers, called ventricles, which pump blood. In a real heart, the left and right sides are separated by the septum. Here, the team replaced the septum with an expansion chamber that is inflated and deflated with pressurized air. This action mimics heart muscle contractions that push blood from the heart.

The next step was to 3D-print a negative mold of the heart in ABS, a thermoplastic commonly used in 3D printing. It takes about 40 hours on the older-model 3D printers they have in the lab. They then filled this mold with the "heart" material—initially silicone—and let it cure for 36 hours, first at room temperature and then in an oven kept at a low temperature (about 150°F). The next day, they bathed it in a solvent of acetone, which dissolved the mold but left the printed heart alone. This process is essentially lost-wax casting, a technique used virtually unchanged for the past 4000 years to make metal objects, especially bronze. It takes about four days.

The resulting soft heart weighs about 13 ounces—about one-third more than an average adult heart (about 10 ounces). If implanted in a body, it would be sutured to the valves, arteries, and veins that bring blood through the body. Like existing ventricular assist devices and total artificial hearts on the market, it would be powered by a portable pneumatic driver worn externally by the patient.


In April 2016, they did a feasibility test to see if their silicone organ could pump blood like a real heart. First they incorporated state-of-the-art artificial valves used every day in heart surgeries around the world. These would direct the flow of blood. Then, collaborating with a team of mechanical engineers from ETH, they placed the heart in a hybrid mock circulation machine, which measures and simulates the human cardiovascular system. "You can really measure the relevant data without having to put your heart into an animal," says Cohrs.

Here's what the test looked like.

"Our results were very nice," Cohrs says. "When you look at the pressure waveform in the aorta, it really looked like the pressure waveform from the human heart, so that blood flow is very comparable to the blood flow from a real human heart."

Their results were published earlier this year in the journal Artificial Organs.

But less promising was the number of heartbeats the heart lasted before rupturing under stress. (On repeated tests, the heart always ruptured in the same place: a weak point between the expansion chamber and the left ventricle where the membrane was apparently too thin.) With the average human heart beating 2.5 billion times in a lifetime, 3000 heartbeats wouldn't get a patient far.

But they're making progress. Since then, they've switched the heart material from silicone to a high-tech polymer. The latest version of the heart—one of which was stuck in that box in the Tallinn airport—lasts for 1 million heartbeats. That's an exponential increase from 3000—but it's still only about 10 days' worth of life.

Right now, the heart costs around $400 USD to produce, "but when you want to do it under conditions where you can manufacture a device where it can be implanted into a body, it will be much more expensive," Cohrs says.

The researchers know they're far from having produced an implantable TAH; this soft heart represents a new concept for future artificial heart development that could one day lead to transplant centers using widely available, easy-to-use design software and commercially available 3D-printers to create a personalized heart for each patient. This kind of artificial heart would be not a bridge to transplantation or, in a few short years, death, but one that would take a person through many years of life.

"My personal goal is to have an artificial heart where you don't have side effects and you don't have any heart problems anymore, so it would last pretty much forever," Cohrs says. Well, perhaps not forever: "An artificial heart valve last 15 years at the moment. Maybe something like that."


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