The US Army Planned a Nuclear Version of Its Already Crazy Off-Road Land Train

The U.S. Army’s midcentury off-road trains were wild enough. So of course, there were serious plans to make them nuclear-powered, too.

byPeter Holderith| PUBLISHED May 18, 2022 4:03 PM
The US Army Planned a Nuclear Version of Its Already Crazy Off-Road Land Train
U.S. Army, Getty
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The frigid peaks of the Cold War were defined by the east and west coming up with ever-more advanced, ever-more unbelievable technology to stay one step ahead in a potential global conflict. The terrible possibility of nuclear war loomed over everything, driving national priorities on both sides, draining defense budgets, and defining the lived experiences of hundreds of millions of people.

And also, it nearly gave the world a 572-foot-long, 54-wheel-drive, nuclear-powered overland train.

You see, defending an area as large as North America from a first strike attack by the Soviet Union was a massive logistical undertaking that spawned a slew of unconventional solutions. One of them was the U.S. Army's overland train—literally, an off-road train, unbound by rails. Designed by prolific American engineer R.G. LeTourneau in the mid-1950s, these gargantuan machines were built to ferry building materials and supplies to remote military outposts in the Canadian Arctic and Greenland that were otherwise unreachable by air, sea, or conventional trucks at the time. Comprised of a control cab and any number of cargo trailers, they stretched on for hundreds of feet, rolling through the wilderness with an immensely powerful diesel-electric drivetrain, innovative all-wheel-drive system and gigantic tires.

LeTourneau's land trains are worth an entire article in their own right, and in fact, we've written that story. Today, we're adding a new chapter, one that somehow takes an already unbelievable subject to new heights of absurdity. By the late 1950s, it seems the Army wasn't satisfied with the train's diesel-electric setup. It saw unrealized potential. Suitable for the atomic age, it wanted a new version of these earth-rumbling monsters driven by nuclear power.

The VC-22 Sno-Freighter. Getty

Compact Reactors

Overland trains were originally built in the 1950s by LeTourneau to deliver supplies and building materials to the Distant Early Warning Line far in northern Canada. The so-called DEW Line was meant to be the first section of western watchtowers scanning for Soviet nuclear bombers, betting on the assumption that formations of the doomsday-ushering aircraft would take the shortest possible route to North America; straight over the Arctic Circle. This world-ending air raid never happened, of course, but the DEW Line was maintained all the way up until 1993, just in case.

One important feature of the DEW Line to understand is just how remote it was. Absolutely everything to build these stations, sustain life and keep watch for the Soviets had to be delivered to the various arctic outposts, including fuel for power and heat. Sea ice and harsh weather at many of these stations made supply runs by ship or aircraft unreliable, which is why the unstoppable land trains, developed by LeTourneau, made sense to the U.S. Army. Also keep in mind that heavy-lift helicopters were still in their infancy.

Given all that hassle, you can see why a localized, consistent power supply like a compact nuclear reactor would be a logistical boon. Many of the outposts were already in coastal areas which had ready access to cooling water, and without the need to constantly deliver fuel to the stations the Army would reduce the risk of being unprepared for a potential attack. Land-portable or barge-mounted reactors, the Army Corps of Engineers thought, could be key for the DEW Line as well as other similar installations. They just had to be developed. 

Starting in the mid-1950s, research began on such a family of portable fission reactors. This program, known as the Army Nuclear Power Program, was ambitious. Beyond just supplying the DEW Line, a group within the Army Corps of Engineers thought it was possible to replace the mountain of diesel generators the Army currently operated everywhere with a far smaller amount of cleaner, quieter, and far more efficient nuclear systems. The largest of these land-portable power plants, the MM-1 was expected to produce 2,500 kilowatts and be fully operational by 1968. It would need a massive machine to haul it around, though.

A rendering of a nuclear-powered land train completed for the U.S. Army. U.S. Army

In a now-declassified document titled "MOBILE NUCLEAR TOWER PLANTS 1960-1970" originally published in November of 1960, the Army lays out the concept of the nuclear overland train as a solution to this problem. "The Military Compact Reactor [MM-1] is being developed to provide a compact, lightweight mobile source of power for a variety of military applications, including propulsion of the overland train," the document reads.

Prepare for the Ridiculous Stuff

The most reasonable purpose the Army had for the MM-1 reactor was what we've laid out so far; to power and supply strictly logistical things like the DEW Line. Hospitals, POW camps, refrigeration warehouses, relay stations, radio transmitters, they're all on the table. Shortly after this conventional list of potential uses, though, things have the slightest indication of starting to get off the rails. 

The next thing it's suggested the MM-1 could power is mobile nuclear missile batteries, primarily ones equipped with the upgraded Nike-Hercules, Redstone, and other future weapons in the then-growing American ballistic arsenal like the Pershing. The document states these are all "Field missile systems with high power requirements," and as such, a mobile nuclear reactor would be ideal to keep them operational. It also notes that missile systems designed to intercept incoming ICBMs would need uninterrupted electricity. This is assumedly in the case of a power cut triggered by a nuclear war, which the document does not care to mention. 

American Senator Stuart Symington and Lt. General James M. Gavin examine models of the country's ballistic missiles, including the Redstone and Nike., Getty

A strong hint of the increasing absurdity to come is then dropped on page A-48, under a section labeled "FUTURE RESEARCH AND DEVELOPMENT AREAS." A subsection referred to as "Vehicular Propulsion" notes that, yes, the nuclear overland train is one of the admittedly few vehicles even a compact reactor could power. However, it notes, distributing the energy of this powerplant to a slew of other vehicles, not just fixed installations, seems pretty promising, too. "Indirect application of nuclear power to propulsion through use of stored energy appears to offer the greatest possibility of achieving positive savings," it explains. The document then lays out ways to distribute energy from a nuclear reactor to something like an entire company of tanks. First, it considers making the tanks battery-powered but quickly comes to the realization that the battery technology of the day isn't up to the task. It's actually best to use the reactor, it goes on, to create hydrogen for a fleet of fuel cell-powered combat vehicles. 

Yes, the Army wanted to use a compact nuclear reactor to propel an overland train, and then, once it arrived in a combat area, have it act as a mobile hydrogen generation point to power a group of fuel cell-powered tanks. It really does sound like something a group of especially bright nine-year-olds would come up with. 

An official Army illustration of the vehicle., U.S. Army

The most absurd part of this is that the idea was actually expanded on outside this document, with two separate Army research and development magazines from May and January of 1961 detailing the concept. A short piece titled "Nuclear Power Planned For Overland Train" in the January issue of Army Research and Development—again with the crazy names—explains that indeed the Army is developing compact nuclear reactors and yes, the rumors you heard at the water cooler are true. "One of the promising potential applications of the plant is to provide power for the Army's new Overland Train, now under construction by R. G. LeTourneau, Inc." It then notes that "When available, nuclear power is expected to give the train almost unlimited cruising range," and, also, oh yeah, this thing is gonna be 560 feet long with 54-wheel drive

A later issue of the same magazine from May 1961 delves into the somehow more outlandish land train gas station concept, and it's in a very 1960s in an asbestos sort of way. It starts by going into the limitations of compact reactors in terms of powering terrestrial vehicles. "The optimum form, an integrated fuel-power system as an integral part of a vehicle, is speculative. Unfortunately, the extent to which nuclear plants can be miniaturized appears to be limited—and the cost of reactors is still too high." The Army didn't just give up after realizing that, though. "Yet, we can approach the optimum if we utilize a nuclear-powered, cross-country vehicle comparable to the overland train as a mobile supply point." Imagine saying that with a straight face. Yes, the optimum solution we've come up with is a nearly eighth-mile-long off-road land train with 54 wheels powered by a nuclear reactor. And it's a gas station. 

"Several cars of the train would be equipped to manufacture certain chemicals, perhaps ammonia or hydrazine from water and air, and liquefy it for convenient storage and handling. The heat and power for the process equipment would be provided by the nuclear plant, which also would propel the train." For those who don't know, ammonia and hydrazine are both toxic chemicals that can be used as fuels in a fuel cell. "The ammonia or hydrazine, in turn, would be furnished from this mobile service station to combat vehicles equipped with fuel-cell propulsion engines, or to stationary fuel cells providing electrical power for other applications." The article then goes on to claim that such a station on an overland train could produce the equivalent of 500,000 gallons of gasoline... per day. Now you might understand why this idea was considered at all. 

As a side note, this same magazine has a short story about a 9-year-old boy named Kenneth Connelly from Philadelphia who "conceived the notion of a gun to be fired by radar." It goes on to note that, "with the help of his 13-year-old brother, Thomas, an 8th grader, Kenneth put his idea down on paper and offered it to scientists at the U.S. Army Ordnance Corps' Frankford Arsenal in Philadelphia." Like what, he just walked in? The short snippet then states that the Army encourages the duo to "continue using their imagination and to apply themselves at school, keeping in mind the possibility of someday designing guns for their country's defense as future Army scientists." I love a happy ending. 

Too Many Big Problems

Needless to say, this idea never worked out and, ironically, it's likely for a litany of reasons all stated in the original declassified proposal document from November of 1960. In a nutshell, making the Army even partially nuclear-powered would be a huge logistical undertaking that would quickly spiral out of control, and plus, the reactors never actually worked. Some testing was done with a small reactor called the ML-1 which was theoretically capable of providing a constant output of 400 kW (536 horsepower) wherever it was pulled by a truck. In fact, the Army went as far as to build a towable mockup in an attempt to prove the concept was feasible, but the reactor never functioned properly. By comparison, the larger MM-1, the focus of much of this development, was never even built.

The ML-1 mockup being towed around the National Reactor Testing Station in Idaho during the 1960s., Wikimedia

Yes, you can theoretically use a mobile nuclear reactor to create a hydrogen-based fuel to propel combat vehicles, even aircraft. However, the Army had no such fuel cell-powered machines when this idea was considered, and indeed never developed any in that era. The alternative to this fuel cell plan was to figure out a way to distribute this electrical power directly over a wide area—without storing the energy chemically—but that too required significant technological advancements that have never occurred. The document states "Beam Power Transmission," yes, that's exactly what you think it is, could be a solution to this problem. Long-range wireless power transmission has of course never been developed, though. That unfortunate roadblock was another nail in the coffin for the idea.

The document goes on and on stating the possible applications of the tech, however in the very same pages it also backs down and refutes its own points. Heating, electrical power, hydrogen fuel production, all of these things would require the Army to turn itself inside out to accommodate this new nuclear energy source.

Nuclear power would be considered at the DEW Line at least once more during the 1980s, however we never got the off-road nuclear land train the Army wanted. To have gotten multiple land trains at all seems like a miracle to me, though. These behemoths worked and worked well, but their operational life was short; a fact often attributed to the development of advanced heavy-lift rotorcraft.

Real life, as usual, turns out to be pretty boring, but when the alternative to conventional logistics is incorporating nuclear power into a wheeled vehicle longer than a football field, perhaps it makes sense. It doesn't make me any less disappointed that we didn't get to see one of these fission-fueled monsters tearing up the countryside, though.

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