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The Trains With Rubber Tires

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The train was one of the game-changing inventions that defined the Industrial Age. No more would humanity rely on tempestuous animals to haul goods and passengers great distances across the land. Fire and steam came along to rapidly increase the speed of travel and transformed the very fabric of society itself.

To this day, the vast majority of train networks rely on the same basic principle—heavy locomotives and carriages running steel wheels on steel tracks. Yet, there is a curious alternative twist on this concept that sees trains of carriages riding on tires instead. But what would possess anyone to build a rubber tired train?

Where The Rubber Meets The Rail

An MP-05 running on the Paris Metro. Credit: Momo Ratp, CC BY-SA 4.0

The first practical rubber-tired train system came about in the wake of World War II. The Paris metro had been poorly maintained during the German occupation, and was in dire need of repair or replacement. The state-owned public transport operator RATP and tire supplier Michelin came to the table, developing a concept wherein vehicles running on pneumatic tires would ride on a flat steel or concrete  “rollway.” The vehicles would also have backup steel wheels that run against a steel rail for safety, keeping the train upright in the case of a tire blowout. Guidance would be provided by extra rubber tires mounted to the wheel bogies on a vertical axis, running against a vertical guideway built into the track, in a manner not dissimilar from later O-Bahn systems.

An MP 89 CC consist running on line 6 of the Paris Metro at Corvisart station. These electric multiple units entered service in 1997. Credit: author

By the 1950s, when the concept was being seriously developed, steel-wheeled railways had been around for well over a century. They were the norm for good reason, but running rubber-tired trains did offer some advantages. The pliable tires would soak up vibrations, which was both good for passenger comfort as well as also virtually eliminating high-pitched squealing noises that are common on steel railways.

The rubber tires, running on concrete or steel surfaces, also offered greatly improved grip. This allowed the rubber-tired metro trains in Paris to climb much greater grades with ease, compared to traditional steel-wheeled railcars. It also aided in early automation efforts on the Paris Metro, as the higher grip level made it easier to ensure locomotives stopped at the right position when entering stations. Rail wear is also greatly reduced compared to steel-on-steel systems.

Note the guidewheels which run against the vertical guideways built into the track. Credit: author

Of course, rubber tires also came with some drawbacks. Tracks were more expensive to build due to the need to incorporate both rollways and guideways, and commonly a steel rail to supply electricity to the trains. Rubber tires don’t last as long as steel wheels, either, aren’t as robust, and are subject to blowouts when damaged. The flexing of pneumatic rubber tires also makes the trains less energy efficient, and generates more heat in operation, which can be a concern in underground operations. As tires break down, they also create particulate pollution which isn’t great for urban air quality or for the people breathing it in.

A bogie from an MP 89 of the Paris Metro, showing the main wheels as well as the guide wheels. Credit: Rama, CC BY-SA 2.0

The Paris Metro found the oddball concept to be of great use, particularly given some of the higher grades faced in certain parts of the network. In time, lines 1, 4, 6, 11, and 14 would all be retooled to the Michelin-designed system with rubber-tired railcars running on 1,435 mm rollways. Various airport routes would later adopt rubber tired services, too, as well as the Toulouse, Lille, Lyon, and Marseille metros as well.

Various rubber-tired metro systems have sprung up around the world. The basic concept is usually the same, though exact implementations differ. This system deployed in Sapporo, Japan, relies on a central rail guidance system, and was built by Kawasaki Heavy Industries. Credit: 出々 吾壱, CC BY SA 3.0

The system was not just limited to France, either. Mexico City found a rubber-tired metro to be the perfect transport solution, as the reduced vibrations were a massive boon given the area’s unstable soils. Other famous examples include the Montreal Metro in Canada, and lines 1, 2, and 5 of the Santiago Metro in Chile. Many other smaller-scale examples can be found around the world, often serving airport routes or shorter-distance lines.

Rubber-tired metros are unlikely to ever fully overtake more traditional steel-wheeled trains in popularity. There are more drawbacks than positives for most typical operations, particularly when it comes to maintenance and ongoing costs. Nevertheless, they have their place, particularly where grip is at a premium, grades are steep, or there is a keen desire to avoid excessive noise and vibration to keep the peace or avoid disturbing the subsurface. These rail-like curios stand out as a weird surprise treat for any railfan visiting Paris, or any of the other similar systems that can be found around the world.

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satadru
9 hours ago
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The Montreal Metro also uses peanut oil and wooden brakes to avoid the aerosolized metal dust that brakes in other subway systems generate!
New York, NY
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Om Malik, 1966-2026

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Om Malik passed away on June 24, 2026, at Stanford Hospital after a long health journey with his heart. He was surrounded by family and friends.

We invite you to share your remembrances of Om in the comments below or by posting and tagging his accounts on X/Twitter, Instagram, Threads, or LinkedIn.

To learn more about Om’s life and work, you can visit his About page or read more on Wikipedia.

— Om’s Family

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satadru
10 hours ago
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RIP Om.
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A Bit of Tedious Drama At Bluesky

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Recently I got suspended for four days from Bluesky for posting this:

My suspension is over now. But I believe that returning after a suspension carries with it an implicit promise that I won’t post that, or something like it, again. I won’t make that promise, so I won’t return to Bluesky.

Regarding Suspension

I’ll talk about what I said and why I meant it. But before that, I have three points about being suspended.

First, I’ll repeat what I’ve said many times: Bluesky and other social media platforms can suspend or ban whomever they want for whatever reason they want. Bluesky’s moderation policies are an expression of its free speech and free association rights, as surely as my decision what to post there (or whom to block there). I may think their expressive choices are stupid, but I think a lot of people’s expressive choices are stupid, and so do you. It’s their right.

Second, I have no idea whether this suspension represented a human being’s decision. Bluesky uses automated moderation because it has to. Bluesky couldn’t use human moderation without charging everyone a ludicrous amount to post on Bluesky. I firmly agree with Mike Masnick’s long-standing rule that good content moderation is impossible to do at scale. A number of twerps and anti-anti-Trump mediocrities pretended to be exercised over the post; there’s a good chance that some sort of mass report campaign resulted in an auto-suspension almost two weeks after the fact. I submitted an “appeal,” which may also have been evaluated by machines, or maybe not. It really doesn’t matter: either humans decided on the suspension, or decided not to lift it, or decided to create the system that imposed it automatically.

Third, I’m not a victim. Don’t cry for me, Bluesky. I said what I said deliberately, knowing the risks. I will miss the parasocial relationships with many cool people, but some of those will be rebuilt elsewhere. It’s social media, not life. Moreover, I’m fortunate. I have lots of channels to express myself. I am in a far better position than the average Bluesky user who gets banned for lashing out — most often, lashing out at transphobia, or racism, or other stuff. Bluesky has a moderation mindset (or at least a moderation AI) that views some rando saying “the world would be a better place if Elon Musk were not in it” as being far worse than Elon Musk and people like him encouraging violence and pogroms. I knew what I was getting into.

Regarding Elon Musk and His Ilk

Now, I’ll address the substance of what I said. I meant every word. Moreover, I was right, and most of the outrage is contrived, dishonest, and in bad faith.

The context for the statement was Elon Musk’s ongoing efforts to use Twitter — his extremely powerful and influential toy, the algorithms of which boost his every thought — to incite racial violence against immigrants in the UK. This is not unusual. Elon Musk regularly encourages, by his own posts or boosting other posts, that the right people should use violence against immigrants and against race-traitor whites.

I could argue this point — try to persuade you — but it’s pointless. The possibilities are these: you already know and you’re appalled, you already know and you support it, or you’ll never be persuaded, any more than a Trump supporter can be persuaded that the 2020 election wasn’t stolen.

The other crucial context is that the current leadership of the United States is increasingly intent on promoting white nationalist hostility and clash-of-civilizations narratives to encourage hatred of immigrants everywhere. Whether it’s Pete Hegseth comparing immigration to the D-Day invasion or Trumpists promoting the noxious Camp of the Saints or the administration turning official social media channels into fonts of Nazi iconography, the Trump Administration supports and promotes the same racial narrative as Musk. Once again: either you know it and hate it, know it and love it, or will never acknowledge it.

Elon Musk is the world’s richest man — a trillionaire, briefly, until a market correction. He and his ideology are also supported by the administration of the most powerful nation on Earth. He is immune to normal social, economic, political, or legal limits. He can use his hugely influential platform to encourage pogroms without social, economic, political, or legal consequences.

It’s simply factual to say, as I did, that the only thing that will stop him is dying. Because my medium was a short Bluesky post, I mentioned him being killed. I suppose it would also stop him if he overdosed on Ketamine or choked on a piece of steak or got ass cancer or crashed one of his vehicles or something. But that would make a long post. Though the post has drawn plenty of criticism, nobody has explained to me how I am wrong about the limited circumstances that will stop him from encouraging racial violence.

No, mostly people are upset at the more pungent coda — “If only.” I said that because I think the world will be a better place when Elon Musk — sociopathic trillionaire who wants to watch a race war — is dead. I suppose it would be better if he dies from the ketamine thing. Political violence tends to lead to more political violence, political violence tends to hurt the powerless disproportionately, and political violence is destabilizing — though not, I think, as destabilizing as a politically connected trillionaire using his powerful social media platform to urge genocide. Elon Musk is autistic trillionaire Radio Rwanda.

I find the pearl-clutching over this sentiment profoundly unpersuasive. The United States kills people who “need killing” all the time. We’re on a campaign of killing unidentified guys in boats in the Gulf of Dementia because the government claims they’re drug dealers. We execute lots of people, many of whom did what they were accused of, many of whom have IQs above 70. We shoot protesters. We shoot people on the very thin pretense that they were “threatening” police officers. We kill Iranians — military and civilians — and boast about how we’re going to kill more. We killed Yamamoto and it’s a good thing we did. We didn’t kill Hitler but we helped arrange the circumstances where he killed himself, and nobody shook a scolding little finger at anyone for wishing him dead. Our most popular Founding Father’s most popular quote is “the tree of liberty must be refreshed from time to time with the blood of patriots and tyrants."

Now, I think people of good faith can disagree about the morality or utility of wishing other human beings dead. I’ve read a few comments that suggest reasoned opposition. But not many. The loudest cries of outrage are from people who will diagnose you with Trump Derangement Syndrome if you object to the ocean of blood I just described. The reaction is largely contrived, mostly in bad faith, and rarely to be taken seriously. The people landing hardest on the fainting couches are in two groups: pro-Trump people who are thrilled that we are extrajudicially executing fishermen in the Gulf, and professional grifters who don’t necessary like the extrajudicial killings but whose entire gimmick is “aren’t those leftists silly and outrageous.” Look, they need to make a living, and they have to base a personality on something.

Pro-Trump people want you to think this oceans of blood and paeans to genocide are all good and praiseworthy, because those are their values. The anti-anti-Trump crowd wants to mock objections to Trumpism, because their dearest value is grift, and they think cringe is worse than fascism. They both demand to be taken seriously, to be respected. I decline. I said what I said.

Bluesky had the right to suspend me for that. I just think they were petty and dumb to do it.

A Postscript Regarding Honesty And Openness

I’ve made an effort for years to be open and honest about things like depression and anxiety, because I know it’s healthier, and because the social stigma around it should be crushed. This incident resulted, as is often the case, in losers mocking me for being crazy, and slightly more pretentious people obliquely referring to my mental heath. This is how I actually discovered, to my shock and pity, that Twitchy still exists and thinks mocking my mental health is worth two whole posts. Again, these people have to eat, I guess. But here’s my point: it turns out that the only people who do it are assholes, the only people who buy it aren’t worth your time, and it doesn’t really make an impact on your life. So be open and honest about mental health, speak up when you need help, and don’t spare much worry for the rabble. You’ll be better for it.

Now, back to rambling through the Cotswolds.

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satadru
22 hours ago
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New York, NY
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1 public comment
williampietri
15 hours ago
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In crazy times saying sane things get you treated as if you were crazy.

In memory of the man who put red and green squiggles under words

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Every little thing in a graphical user interface that we take for granted today, no matter how small, was thought up by someone, at some point. Case in point: the little red squiggly lines underneath misspelled words. In one form or another, these are everywhere now, and have just become a regular staple of every single text editing field we encounter every single day and don’t stop to think about. Still, they were invented by someone, and we happen to know exactly who that was: Tony Krueger.

In early versions of Word, the Spell Check feature was something that you explicitly invoked, and then you had to sit and wait while the program looked for all your potentially-misspelled words, and then showed them to you one at a time for a decision on what to do for each one. Word did introduce an Auto Spell Check feature to run spell check when the user was idle, so that when you hit the Spell Check button, the results were ready to go. However, the Auto Spell Check was still a blocking operation. As a result, a lot of users turned it off because it always seemed to decide “Now would be a good time to spell-check the document” just as you wanted to do something, forcing you to wait for the spell check pass to complete before you could, say, save and exit.

Tony made the spell checker much more unobtrusive so that it didn’t interfere with your foreground work. And when it found a problem, instead of waiting for you to trigger a spell check, it immediately drew red squiggles under potentially-misspelled words (and later green squiggles under potential grammatical errors).

↫ Raymond Chen at The Old New Thing

Tony Krueger passed away recently, after, among other things, having worked on an dizzying number of Microsoft Word releases. Imagine coming up with something that seems to basic and elementary to us now, and seeing it spread pretty much everywhere. I wonder what it must feel like to have invented something that seems so simple, most people don’t even realise they use it every single day.

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mareino
12 hours ago
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Washington, District of Columbia
satadru
1 day ago
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New York, NY
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The Warrior-Witches of Ukraine's Resistance

jwz
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An underground intelligence network uses subterfuge and honey traps to direct drone strikes deep inside Russian-occupied territory.

"Serhiy was great at flirting," his commander told me. "Guys in our team started asking him for dating advice." Shortly after Achmad sent that photograph, the coordinates it revealed were struck by a Ukrainian drone. [...]

Any phone purchased inside the occupied territories is useless for resistance work. Devices sold there come preloaded with monitoring software developed by Russian intelligence. That app is called Druge -- Друг -- which means "friend" in Russian.

Druge monitors communications, photographs, and location data, relaying all of it back to Russian intelligence. [...] At checkpoints, Russian soldiers examine every phone. Not having Druge installed is a red flag to them; having an encrypted app, such as Signal, guarantees a phone's owner a trip to the basement. [...]

Few resistance agents have professional training. Most learn on the job. Partisans pass around hard-copy tradecraft manuals to avoid using vulnerable digital channels. Within Kherson's partisan brigade, one of the most sought-after is a Soviet-era handbook describing CIA catfishing tactics in Africa during the Cold War. No online version exists, but a well-worn original circulates among the resistance.

"Your CIA was good at this," Dmytro said. "You bastards knew how to use sex."

Several Ukrainian print shops have developed methods for hiding instruction manuals inside best-selling books. A guard at a Russian checkpoint, thumbing through an artificially tattered paperback, will likely have no idea that some of the pages explain how to kill him.

Previously, previously, previously, previously, previously, previously.

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satadru
1 day ago
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Using Sound Waves To Make Espresso Could Cut Coffee-Brewing Energy Use By 75%

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Researchers developed an ultrasonic espresso process that uses high-frequency sound waves instead of hot water to produce espresso-strength coffee at room temperature. And, not only did coffee drinkers find it comparable to traditional espresso, but the brewing process cut energy use by up to 75%. An anonymous reader quotes a report from The Conversation: We have developed what we call an ultrasonic espresso: a room-temperature brewing process that uses high-frequency sound waves to extract the flavor, oils, aroma and caffeine from coffee grounds. The result is an espresso-strength coffee made in under three minutes, but needing far less energy than the conventional method. Saving up to 75% of energy by not heating the water is a minor benefit for home users or small coffee shops. But for companies making ready-to-drink coffee products at industrial scale, it could be very significant indeed. A concentrated room-temperature coffee could be used directly in bottled drinks, milk-based beverages or cold coffee products. It can also be shipped as a concentrate and diluted later. This would reduce not only energy use, but potentially processing time as well. The key to the new process is ultrasound. These are sound waves above the range of human hearing. In our system, a small metal device called a transducer presses against the side of a traditional espresso basket and makes it vibrate rapidly. Those vibrations move through the water and coffee grounds. This creates a phenomenon known as acoustic cavitation. Tiny bubbles form and collapse in the liquid. When these bubbles collapse near coffee particles, they produce microscopic jets and forces that act a little like scrubbing brushes. They pit and fracture the surface of the coffee grounds, helping flavor compounds, oils and caffeine move into the water much faster than they normally would at room temperature. In other words, ultrasound helps us replace heat with mechanical energy. [...] In earlier work, we used ultrasound to speed up cold brew dramatically. But the challenge in this project was different: could we produce something with the strength, body and intensity of espresso, without heating the water? To do that, we adjusted several variables. Brew ratio was one of the most important: how much water we used for each gram of coffee. Too much water and the drink becomes diluted; too little and extraction becomes difficult. Grind size also mattered. Finer grounds allowed us to extract flavor more rapidly. Finally, we tested how long the ultrasound should be applied. We found the sweet spot was about two-and-a-half to three minutes. Of course, making a concentrated coffee in the laboratory is one thing. The real test is whether people want to drink it. [...] For the espresso samples, participants could not reliably tell the traditional and ultrasonic versions apart. There were no significant differences in aroma, flavor, bitterness or overall liking. For filter coffee, the ultrasound version was actually preferred overall, with participants rating its bitterness more pleasantly.

Read more of this story at Slashdot.

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satadru
4 days ago
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New York, NY
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