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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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iStock // Ekaterina Minaeva
Man Buys Two Metric Tons of LEGO Bricks; Sorts Them Via Machine Learning
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iStock // Ekaterina Minaeva

Jacques Mattheij made a small, but awesome, mistake. He went on eBay one evening and bid on a bunch of bulk LEGO brick auctions, then went to sleep. Upon waking, he discovered that he was the high bidder on many, and was now the proud owner of two tons of LEGO bricks. (This is about 4400 pounds.) He wrote, "[L]esson 1: if you win almost all bids you are bidding too high."

Mattheij had noticed that bulk, unsorted bricks sell for something like €10/kilogram, whereas sets are roughly €40/kg and rare parts go for up to €100/kg. Much of the value of the bricks is in their sorting. If he could reduce the entropy of these bins of unsorted bricks, he could make a tidy profit. While many people do this work by hand, the problem is enormous—just the kind of challenge for a computer. Mattheij writes:

There are 38000+ shapes and there are 100+ possible shades of color (you can roughly tell how old someone is by asking them what lego colors they remember from their youth).

In the following months, Mattheij built a proof-of-concept sorting system using, of course, LEGO. He broke the problem down into a series of sub-problems (including "feeding LEGO reliably from a hopper is surprisingly hard," one of those facts of nature that will stymie even the best system design). After tinkering with the prototype at length, he expanded the system to a surprisingly complex system of conveyer belts (powered by a home treadmill), various pieces of cabinetry, and "copious quantities of crazy glue."

Here's a video showing the current system running at low speed:

The key part of the system was running the bricks past a camera paired with a computer running a neural net-based image classifier. That allows the computer (when sufficiently trained on brick images) to recognize bricks and thus categorize them by color, shape, or other parameters. Remember that as bricks pass by, they can be in any orientation, can be dirty, can even be stuck to other pieces. So having a flexible software system is key to recognizing—in a fraction of a second—what a given brick is, in order to sort it out. When a match is found, a jet of compressed air pops the piece off the conveyer belt and into a waiting bin.

After much experimentation, Mattheij rewrote the software (several times in fact) to accomplish a variety of basic tasks. At its core, the system takes images from a webcam and feeds them to a neural network to do the classification. Of course, the neural net needs to be "trained" by showing it lots of images, and telling it what those images represent. Mattheij's breakthrough was allowing the machine to effectively train itself, with guidance: Running pieces through allows the system to take its own photos, make a guess, and build on that guess. As long as Mattheij corrects the incorrect guesses, he ends up with a decent (and self-reinforcing) corpus of training data. As the machine continues running, it can rack up more training, allowing it to recognize a broad variety of pieces on the fly.

Here's another video, focusing on how the pieces move on conveyer belts (running at slow speed so puny humans can follow). You can also see the air jets in action:

In an email interview, Mattheij told Mental Floss that the system currently sorts LEGO bricks into more than 50 categories. It can also be run in a color-sorting mode to bin the parts across 12 color groups. (Thus at present you'd likely do a two-pass sort on the bricks: once for shape, then a separate pass for color.) He continues to refine the system, with a focus on making its recognition abilities faster. At some point down the line, he plans to make the software portion open source. You're on your own as far as building conveyer belts, bins, and so forth.

Check out Mattheij's writeup in two parts for more information. It starts with an overview of the story, followed up with a deep dive on the software. He's also tweeting about the project (among other things). And if you look around a bit, you'll find bulk LEGO brick auctions online—it's definitely a thing!

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Cs California, Wikimedia Commons // CC BY-SA 3.0
How Experts Say We Should Stop a 'Zombie' Infection: Kill It With Fire
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Cs California, Wikimedia Commons // CC BY-SA 3.0

Scientists are known for being pretty cautious people. But sometimes, even the most careful of us need to burn some things to the ground. Immunologists have proposed a plan to burn large swaths of parkland in an attempt to wipe out disease, as The New York Times reports. They described the problem in the journal Microbiology and Molecular Biology Reviews.

Chronic wasting disease (CWD) is a gruesome infection that’s been destroying deer and elk herds across North America. Like bovine spongiform encephalopathy (BSE, better known as mad cow disease) and Creutzfeldt-Jakob disease, CWD is caused by damaged, contagious little proteins called prions. Although it's been half a century since CWD was first discovered, scientists are still scratching their heads about how it works, how it spreads, and if, like BSE, it could someday infect humans.

Paper co-author Mark Zabel, of the Prion Research Center at Colorado State University, says animals with CWD fade away slowly at first, losing weight and starting to act kind of spacey. But "they’re not hard to pick out at the end stage," he told The New York Times. "They have a vacant stare, they have a stumbling gait, their heads are drooping, their ears are down, you can see thick saliva dripping from their mouths. It’s like a true zombie disease."

CWD has already been spotted in 24 U.S. states. Some herds are already 50 percent infected, and that number is only growing.

Prion illnesses often travel from one infected individual to another, but CWD’s expansion was so rapid that scientists began to suspect it had more than one way of finding new animals to attack.

Sure enough, it did. As it turns out, the CWD prion doesn’t go down with its host-animal ship. Infected animals shed the prion in their urine, feces, and drool. Long after the sick deer has died, others can still contract CWD from the leaves they eat and the grass in which they stand.

As if that’s not bad enough, CWD has another trick up its sleeve: spontaneous generation. That is, it doesn’t take much damage to twist a healthy prion into a zombifying pathogen. The illness just pops up.

There are some treatments, including immersing infected tissue in an ozone bath. But that won't help when the problem is literally smeared across the landscape. "You cannot treat half of the continental United States with ozone," Zabel said.

And so, to combat this many-pronged assault on our wildlife, Zabel and his colleagues are getting aggressive. They recommend a controlled burn of infected areas of national parks in Colorado and Arkansas—a pilot study to determine if fire will be enough.

"If you eliminate the plants that have prions on the surface, that would be a huge step forward," he said. "I really don’t think it’s that crazy."

[h/t The New York Times]