A Second Chance For The Single Wheel Monorail?

August 16, 2025 by Heidi Ulrich 27 Comments

Lately, this peculiar little single wheel monorail came to our attention. Built by [extraglide1976], all from Meccano. His build started with modest tests: one gyro obviously flopped. Two gyros geared together ran slightly better. But when he adds active gimbal control, things suddenly come to life – the model shudders, catches itself, and carries on. The final green-roofed locomotive, with LEDs signalling ‘system go’, trundles smoothly along a single rail on [extraglide1976]’s deck.

To be fair, it houses a lot of mechanics and engineering which we don’t find in the monorails of today. We do have quite a few monorails in our world, but none of them balance on a single wheel like this one. So, where did this invention derail?

Outside of theme parks, Japan is one of the few countries where monorails are still used as serious urban transport: though Germany’s century-old Wuppertal Schwebebahn, the lesser-known C-Bahn, China’s sprawling Chongqing and Shanghai systems, Malaysia’s Kuala Lumpur line, Brazil’s São Paulo network, the US links in Seattle and Las Vegas, and India’s Mumbai Monorail prove the idea has quietly taken root elsewhere.

The thing you’ll see in nearly all these monorails is how the carriages are designed to clamp onto the tracks. This is of course the most safe option, but it loses out on speed to the ones that sit on top of the tracks, balancing on one wheel. Such a train was actually invented, in 1910, by Louis Brennan. His original monorail promised faster, cheaper transport, even using existing rails. The carriages leaned into turns like a motorbike, without any intervention from the driver. Two counter-rotating gyroscopes kept the carriage upright, cancelling precession forces like a mechanical Jedi trick.

Back then, it failed commercially, but today? With cheap sensors, brushless motors, and microcontrollers, and intelligent software, why not let it make a comeback? It could carry freight through narrow urban tunnels. With high-speed single-rail pods?

Investors killed Brennan’s idea, but we live in a different time now. You could start out with a gimmicky ‘snacks and beer’ highline from your fridge to your garage. Share your take on it in the comments!

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Track Your Circuits: A Locomotive PCB Badge

April 18, 2025 by Matt Varian 7 Comments

This fun PCB from [Nick Brown] features a miniature railroad implemented with 0805-sized LEDs. With an eye towards designing his own fun interactive PCB badge, the Light-Rail began its journey. He thoroughly documented his process, from shunting various late-night ideas together to tracking down discrepancies between the documentation of a part and the received part.

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Push Your Toy Train No More, With This Locomotive!

February 11, 2025 by Jenny List 8 Comments

One of the most popular evergreen toys is also one of the simplest, wooden track with push-along trains. We all know the brand name, and savvy parents know to pick up the much cheaper knock-off because the kid won’t know the difference. But a really cool kid shouldn’t have to push their train around by hand, and thus [Lauri] has given the wooden track a real, powered, locomotive.

In the 3D printed chassis goes a small geared motor driving one axle, with an ESP32 and a motor driver taking care of the smarts. Power comes from an 18650 cell, which almost looks like the right scale for a fake steam boiler. The surprise with this train comes in the front axle, this machine has steering. We’re curious, because isn’t the whole point of a train that the track directs it where it needs to go? Or perhaps a little help is required in the absence of a child’s guidance when it comes to points. Either way, with remote control we guess there would be few kids who wouldn’t want one. We certainly do.

The London Underground Is Too Hot, But It’s Not An Easy Fix

December 4, 2024 by Lewin Day 91 Comments

The London Underground is an iconic piece of Victorian era engineering. What started in 1863 quickly became a core piece of infrastructure that would define the modern character of the British capital. It’s grown and changed immensely in the many years that have passed. Sadly, increasing patronage and more trains have created problems that the original designers never envisaged.

Deep in those London tunnels lies an engineering challenge. The Tube is literally cooking itself. Every day, millions of commuters descend into a network of tunnels that have been absorbing heat since the reign of Queen Victoria. Those clay-lined tubes have been soaking up excess thermal energy like a giant underground radiator, and now they’re giving it back with interest. The tunnels are simply too hot, and cooling them down is inordinately difficult.

The Perfect Storm of Thermal Chaos

The Tube’s heat problem isn’t just about one thing gone wrong – it’s about everything gone wrong at once. When Victorian engineers designed these tunnels, cooling wasn’t a major consideration. The tight, compact tunnels were built deep, nestled in the clay beneath London. In the early days, temperatures in the Underground were considered comfortably low.

“The Underground’s the only spot for comfort when the days are hot; it is cooler below.” – London Underground poster, 1926

Originally, the clay surrounding the tunnels sat at around 14°C, acting as a heat sink for the network. However, over the years, with more trains coming and going and more heat pouring in, the temperature has risen. It now typically sits anywhere from 19° to 26 °C. That’s just the earth around the tunnels, though. Air temperatures are worse—hitting as high as 47°C during a 2006 heatwave. The problem has been a continual bugbear of the beloved Tube, with concerns that future heatwaves could see temperatures rise ever higher. Continue reading “The London Underground Is Too Hot, But It’s Not An Easy Fix” →

Train Speed Signaling Adapted For Car

September 11, 2024 by Bryan Cockfield 33 Comments

One major flaw of designing societies around cars is the sheer amount of signage that drivers are expected to recognize, read, and react to. It’s a highly complex system that requires constant vigilance to a relatively boring task with high stakes, which is not something humans are particularly well adapted for. Modern GPS equipment can solve a few of these attention problems, with some able to at least show the current speed limit and perhaps an ongoing information feed of the current driving conditions., Trains, on the other hand, solved a lot of these problems long ago. [Philo] and [Tris], two train aficionados, were recently able to get an old speed indicator from a train and get it working in a similar way in their own car.

The speed indicator itself came from a train on the Red Line of the T, Boston’s subway system run by the Massachusetts Bay Transportation Authority (MBTA). Trains have a few unique ways of making sure they go the correct speed for whatever track they’re on as well as avoid colliding with other trains, and this speed indicator is part of that system. [Philo] and [Tris] found out through some reverse engineering that most of the parts were off-the-shelf components, and were able to repair a few things as well as eventually power everything up. With the help of an Arduino, an I/O expander, and some transistors to handle the 28V requirement for the speed indicator, the pair set off in their car to do some real-world testing.

This did take a few tries to get right, as there were some issues with the power supply as well as some bugs to work out in order to interface with the vehicle’s OBD-II port. They also tried to use GPS for approximating speed as well, and after a few runs around Boston they were successful in getting this speed indicator working as a speedometer for their car. It’s an impressive bit of reverse engineering as well as interfacing newer technology with old. For some other bits of train technology reproduced in the modern world you might also want to look at this recreation of a train whistle.

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A map of the US showing the potential changes to passenger rail service due to the Corridor ID Program

A New Era For US Passenger Rail?

July 31, 2024 by Navarre Bartz 115 Comments

Here in the United States, we’re lagging behind the rest of the world when it comes to shiny new passenger rail, despite being leaders in previous centuries. The Federal Railroad Administration (FRA) has just released a story map of how the US could close the gap (a little).

The Corridor Identification and Development (CID) Program is a way for FRA to provide both funding and technical assistance as corridor sponsors (mostly state Departments of Transportation) evaluate either new intercity service or expansion of existing services. While it isn’t a guarantee of anything, it is a step in the right direction to rebuilding passenger rail capacity in the US.

Some cities would be getting rail service back for the first time in decades, and perhaps even more exciting is that several of the routes being studied are for high speed rail “primarily or solely on new trackage.” As any railfan can tell you, vintage rails aren’t the best for trains going fast (sorry, Acela). With recent polling showing strong public support for the build out of high speed rail, it’s an exciting time for those who prefer to travel by rail.

We don’t think you’ll be able to ride a gyro monorail, nuclear-powered, or jet train on these proposed routes, but we do hope that Amtrak and FRA are looking to the state-of-the-art when it comes to those high speed alignments. While you’re eagerly awaiting new passenger service, might we recommend this field guide to what all those different freight cars going by are for here in North America?

Crank-Powered Train Uses No Batteries Or Plugs

April 12, 2024 by Kristina Panos 5 Comments

The prolific [Peter Waldraff] is at back it with another gorgeous micro train layout. This time, there are no plugs and no batteries. And although it’s crank-powered, it can run on its own with the flip of a switch. How? With a supercapacitor, of course.

The crank handle is connected a 50 RPM motor that acts as a generator, producing the voltage necessary to both power the train and charge up the supercapacitor. As you’ll see in the video below, [Peter] only has to move the train back and forth about two or three times before he’s able to flip the switch and watch it run between the gem mine and the cliff by itself.

The supercapacitor also lights up the gem mine to show off the toiling dwarfs, and there’s a couple of reed switches at either end of the track and a relay that handles the auto-reverse capability. Be sure to stick around to the second half of the video where [Peter] shows how he built this entire thing — the box, the layout, and the circuit.

Want to see more of [Peter]’s trains and other work? Here you go.

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