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Colorado’s Forgotten Hover Train

Written by Nicholas Suarez


Trains – the most important invention of the Industrial Revolution. Probably, don’t quote us on that, but it is broadly true that trains made a huge impact on everyday life. It cut travel times, connected places that had originally been separated by vast distances, and facilitated industrial expansion and growth. And all it took was a bit of wheels on a bit of iron or steel.

There’s a saying in the English language: don’t try to reinvent the wheel. It’s a good piece of advice, especially when it comes to creating things, but sometimes the creative types just can’t help themselves. And what better way to reinvent the wheel than by trying to make it obsolete? This is the story of when America tested hovering trains.


The Future is Now

Our story begins in the latter half of the 20th century. If you’ve read some of our posts that talk about nuclear power, or aviation, you know that the 20th century was a wildly optimistic time for scientific progress – concepts like everyone owning personal helicopters, or cars powered by miniature nuclear reactors, those sorts of things. Of course, those lofty dreams didn’t pan out, but sometimes we get a little bit further than just the idea part.

Which brings us to the 1960s. In 1965, America’s federal government passed the High Speed Ground Transportation Act to perform research and investment into high speed passenger railways. To that end, a number of agencies were created, including the Office of High Speed Ground Transportation (OHSGT), which would come to operate a test center in Pueblo, Colorado.

High speed trains, in very general terms, are classified as trains that can travel faster than 155 miles per hour (250 kilometers per hour). Today, that isn’t a big deal; high speed rail exists all over the world, in places that aren’t called the United States. But in 1965, this was actually something of a big deal. The reason for that is because of something called “hunting oscillation”. You see, traditionally engineered trains have a problem, whereby once they start to go faster than 140 miles/hour (225 km/hr), the wheels start to spin so fast that they literally shake the train off of the track. Which would, presumably, be bad.

There’s also some ancillary drawbacks to old-fashioned trains, the most glaring of which is friction. Friction, to put it simply, sucks. A vehicle that’s moving over land is constantly being slowed down by the ground, requiring it to constantly expend fuel to keep moving forward. More fuel means more money, and who doesn’t hate spending extra money? This simple fact of physics is a big reason why transport over water, even today, is cheaper than transport over land, because water has less friction and therefore takes less fuel. But we get off track here. (Get it?)

So, you have trains that can’t go past a certain speed, and a natural phenomenon of physics that’s costing you money. Wouldn’t it be great to kill two birds with one stone, and remove both of these problems at once? Perhaps by making a train that didn’t need wheels at all, but instead hovered slightly off the ground? Is such a concept even possible? Well, yes, but not in the way they imagined. Stay tuned.

For now, let’s talk about the UK. In 1967, the British developed a so-called Air Cushioned Vehicle, or ACV, for use in marine environments, as well as a land-based counterpart, the Ground Effect Machine, or GEM, a rare example of both the acronym and the actual name being cool to say out loud.

These designs were early versions of what we would today call a hovercraft – a vehicle that can glide over land and/or water, using an air cushion between the vehicle and the ground. Importantly, these vehicles did actually work, and the tests were only cancelled when Britain got a new government with different priorities. But during those tests, the OHSGT in Colorado was keeping track of their progress. And, asking themselves those same questions from earlier, they started to get an idea – what if hovercraft, but for a train? And so it was.


Hover Hands

In 1971, after a period of studies and reviews to see if the project was actually feasible, the OHSGT formally asked numerous private companies to submit bids for testing their prototypes. They also contacted government agencies like NASA, and even got the universities of MIT and Princeton to pitch in and help. Incidentally, the fact that NASA was involved was the reason why all the prototypes looked a little bit like the Space Shuttle.

Eventually, there were three candidates selected for the project: Garret AiResearch[NS1] , a division of The Garrett Corporation responsible for making plane engines; Rohr Industries, which also made plane engines, but branched out into making railcars, too; and Grumman Aerospace Corp, which you’ve probably heard of and can probably guess what they do. There may be something to be said about using primarily aerospace companies to design trains, but it makes at least some sense, I suppose.

And they did have expertise. All three companies came up with vehicles to test: the Garrett LIMRV, the Rohr TACV, and the Grumman TLRV. Welcome to acronym hell, by the way.  Let’s start with the vehicle that came first, the Garrett LIMRV. That stands for Linear Induction Motor Research Vehicle, and it was, get this, a vehicle built to research the Linear Induction Motor. Venomous sarcasm aside, what exactly is a linear induction motor? The very simple explanation is that, by running electricity through a coiled wire, a magnetic field is created which pushes any metal away from the wire. That’s the “induction motor” part, and they are extremely common. But with a bit of ingenuity, this magnetic repulsion can be redirected, and used to push a vehicle forward. That’s the “linear” part.

In the case of the Garrett, as we’ll call it, the motor also required a special third rail called a “reaction rail”. It ran down the middle of a traditional railroad track, with the air cushion being between it and the underside of the vehicle. Meanwhile, some standard train wheels were used to support the vehicle. So, not quite a hovercraft, in the purest sense of the word, but probably close enough.

And, as far as important things go, the Garrett did well during testing, which began in early 1971. Despite limited funding meaning that the company could only have about 6 of the 10 miles of track they wanted, the vehicle reached speeds of 255 miles per hour, a record for “wheel-on-rail” vehicles that actually remains unbroken to this day. It ran on electric power, and to supply that electricity, they added a turbine from a NASA plane that had crashed during testing for an unrelated project. Efficiency, people.

Speaking of crashing, we found one source stating that the Garrett actually ran off the end of the track during one test, damaging it. We couldn’t confirm this, but that source described the cause of the alleged accident as, “Something about running out of track and having no brakes.” Which… come on, how can we not include that?

The second vehicle to be tested was the Grumman TLRV, or Tracked Levitated Research Vehicle. It was, as the name suggests, mostly designed by Grumman Aerospace Corporation, known for making several well-performing aircraft in World War II, as well as the F-14 Tomcat and the backwards-winged X-29. This design was the closest prototype, in spirit, to an actual hovertrain. That was because, unlike the Garrett, it had no wheels, and no rails – it was designed to move inside of a U-shaped track, floating above the ground like a proper hovercraft.

The Grumman reached the test center in 1972, and was designed to reach speeds of up to 300 miles per hour. Did it reach that? No. The engineers for the Grumman wanted to create a track large enough to test their predictions, but priority was being given to other constructions, at that point. That’s actually a pretty consistent theme throughout this whole episode – too many candidates with too few resources, and so all the projects budged up against each other and got too little to work with to accurately test anything.

Because of the comparatively dinky track that the engineers had to use – 1.5 miles instead of 22 miles – and because of unforeseen design problems and difficulties running the tests, the Grumman only managed 91 mph, less than a third of what had been predicted. Some modifications were made in late 1973, and engineers thought they could definitely get at least 240 miles per hour, if they could just get a little extra track. But the budget was at it breaking point, meaning no new track, and the Grumman had to make do with what it had for the rest of the project. Which must have been frustrating.

The last vehicle that reached the test center was the Rohr TACV, or Tracked Air-Cushioned Vehicle. Interestingly, the TACV was actually the first prototype to be designed, but the last one to be tested. It was first developed in France in 1965 by a man named Jean Bertin, with his company Aerotrain. In 1969, Rohr Industries licensed the technology to make their own designs, just as the OHSGT was getting ready to test high speed transport.


But there was something of an issue. The Rohr vehicle, in contrast with the Garrett and the Grumman, did not have on-board electricity; instead, it had to be supplied power with an extra rail, off to the side of the track. This was expensive, and concerns were voiced about this, since you’ll remember that they were trying to create passenger trains, and that meant they were going to need to build huge lengths of track. So a more expensive train was going to increase any costs exponentially, and, of course, they were already running out of money for testing the things, let alone building them all over the country.

The Rohr didn’t reach the test center until September of 1974, three years after the first design had arrived. But even with the limited resources, it performed reasonably well. Like the Grumman, it had no wheels, hovering slightly above the track, and it managed to reach speeds of 145 miles per hour.

Unfortunately, because the Rohr was so late to the party, the first two designs had taken up basically the entire budget, and new funding was not so forthcoming. And like the other prototypes, it had some blunders during testing; one test actually fried the linear induction motor and melted part of the rail. How this happened is not exactly clear, but one source – the same source that talked about the Garrett prototype crashing off the track – said that a visiting French engineer tried to start the vehicle, did something wrong, fried the motor and the track, and then quietly left, never to be seen or heard from again. Like before, there’s no way to know if that’s true or not, but how can we not include it?

The project effectively came to an end in August of 1975, when the funding finally ran out completely. It had, in any case, become clear that the concept was something of a dead end – the vehicles were electricity hogs, making them expensive to run, and they were all obscenely loud. The project was mothballed, and then cancelled, leaving the hopes for a hovertrain of the future dashed. Or were they?

Remember when we said that the hovertrain concept would work out, just not in the way they expected? Well, it turns out linear induction motors are useful for another kind of train – ones that run on magnetic levitation, or maglev for short. During the time these prototypes were being tested in Colorado, other countries, namely Japan and West Germany, were testing the maglev concept. It wasn’t clear if it would work out; maglev was expensive, it was complicated, and it was believed powerful magnets would interfere with the train’s electronics.

But with time, materials were found which would work, and electronics did what electronics do and vastly improved in a short period of time. Simply put, it was a classic science duel between competing ideas, and at the time it wasn’t clear which would win, despite the outcome seeming obvious to us today. Compared to hovertrains, maglev trains were faster, less complicated (although still very complicated), and crucially, quiet. With these advantages and the end of the hovertrain testing, maglev became the premiere technology for high speed rail, and hovertrains were consigned to the bin of scientific history.

And maglev trains are, right now, some of the fastest trains on the planet, using the same friction-free principle that drove the development of the hovertrains. It’s not the same, really, but it’s good enough.

A Piece of the Past

After the testing ended, the companies who participated found themselves with some basically useless prototypes that they didn’t feel like spending money on to keep in storage. So, they donated them to the city of Pueblo, on the condition that they be displayed in a museum setting. That’s exactly what happened, and today, these vehicles are all held in the Pueblo Railway Museum, whose website supplied a lot of the information we’ve given you today. If it weren’t for them, we probably wouldn’t have been able to make this post, so thank you, Pueblo Railway Museum.

And as we all know, after this project ended, America put its public infrastructure first and redoubled its efforts into creating high speed passenger rail. Right?

 [NS1]“air-research”. I know.

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