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Before the 760mph Hyperloop dream, there was the atmospheric railway

Megan Geuss

“A view looking from within the tunnel into the station.”(1872)
“Interior of the pneumatic passenger-car.” (1872)
“General plan, showing the arrangement of the machinery, the air-flue, the tunnel, and the mode of operating the pneumatic passenger-car.” (1872)
Flight Rail Corp built a small prototype of a modern atmospheric railway system.

A while back, a reader e-mailed me about a Hyperloop article I had written. He said the article reminded him of an experimental railway system—called an “atmospheric railway”—that was constructed in London in the 1840s. The system essentially connected a train to a piston which lived inside a semi-sealed tube placed along the length of the track, between the track’s two rails. A pumping station at the end of the train’s route pumped air out of the tube while air was allowed into the tube at the other end. This created an atmospheric pressure differential in front of and behind the piston that moved the piston—and the train connected to it—down the rails.
I was intrigued. Running trains through tubes using unconventional methods of propulsion is hardly an idea unique to the Hyperloop, but the handful of atmospheric railway systems built in the mid-19th century prove that humans have been trying to manipulate contained atmospheres for transportation purposes for centuries.
You can see how the idea feels similar to a Hyperloop, which also relies on creating low atmospheric pressure along the length of the rail. As CEO of SpaceX and Tesla Elon Musk imagined it, a Hyperloop would involve shooting pods down long tubes whose internal pressure has been lowered to 1/6th of the pressure of the atmosphere of Mars. Many Hyperloop designs since then have tried to reduce friction even further by mounting concept pods on magnetic skis that repel the pod from the rails.
By the way, Ars will be attending a Hyperloop Pod competition near SpaceX Headquarters in Los Angeles on Sunday—check back later this week to see pictures and reporting from the 30 college and university teams that have built Hyperloop demo pods.
But hopefully Sunday’s pod competition on a nearly-mile-long test track will be unfazed by the woes that afflicted at least one of the few atmospheric railways built in 19th-century Europe. To seal off the railway’s pressure tube as the train moved down the track and the piston moved through the tube, the tube depended on a flap of leather coated with tallow. The leather was often connected to a piece of metal that lay on top of it, so the leather wouldn’t get sucked into the tube while the pump station was pumping air out of the tube. As the piston moved through the tube, an arm above the pressure tube pushed the leather flap back into place.
The problem was, “leather rubbed with tallow” is not a bad meal for some of England’s murine residents. When the leather flap is destoryed, the vacuum in the railway's tube is destroyed, too. The Ars reader who contacted me, Roy MacDonald, wrote in his e-mail that he had toured the Croydon railway’s station when he lived in London. He remembered that the leather seals and tallow created “a problem with rats” that the railway never solved. MacDonald recounted, “Every time they ran the pumping stations, large quantities of rats were expelled from the system.”
While searching for information on how atmospheric railways of the 19th century worked, I came across the 1841 document “A Treatise on the Adaptation of Atmospheric Pressure to the Purposes of Locomotion on Railways” (PDF) by Joseph Samuda. He had worked on early atmospheric railway prototypes along with his brother Jacob and gas engineer Samuel Clegg. He was also later instrumental in helping build the Croydon atmospheric railway.
In his 1841 work, Samuda describes contemporary atmospheric railways like the Great Western Railway, which had an atmospheric section that was a half mile in length and depended on a tube with a 9-inch internal diameter. Samuda claimed that cars on this railway generally traveled between 18 and 30 miles per hour, depending on how loaded the cars were. He suggested that on a longer railway, pump houses should be spaced two and a half to three miles apart.
Atmospheric railway travel had several advantages. Trains on such a system neither carried fuel, nor did they need to hold heavy motors to propel them. This often meant that atmospheric systems were able to push trains up inclines more effectively than steam engines could.
An example of this was an atmospheric railway that was constructed outside of Paris in 1847. An 1852 article in the New York Times describes a railway of about five and a half miles, “the last half mile with an ascent of about three and a half percent.” The incline “was too great to be overcome by an engine in all weathers,” the paper reported, but the atmospheric railway easily made the ascent.
Ultimately, the atmospheric railways across Europe met the same fate but for different reasons. They were phased out because they were too difficult to keep up, or investors lost interest, or they were replaced by steam engines.
But all is not lost for the atmospheric railway. A few decades ago, Aeromovel built atmospheric railways at Porto Alegre Airport in Brazil and in Jakarta, Indonesia. Today, a company called Flight Rail Corp is working on an atmospheric system from their offices in Ukiah, CA. That company has already built a 1/6th-scale working prototype in Mendocino County called Vectorr. It expects to be able to build a system that can reach 200mph with vacuum pump stations located as much as 50 miles apart. John Rearden, a spokesperson from Flight Rail Corp, told Ars in an e-mail that the secret, perhaps like the Hyperloop concept, is magnets:
In the early systems, the tube had a slot on the top, and the piston was connected directly to the cars. As the piston traveled through the tube, it would open a continuous flap which sealed the slot ahead of it. This flap seal proved problematic. Our Vectorr system uses a power tube that is not slotted. Rather, the cars on top are connected to the piston and the assembly inside the tube through a proprietary magnetic coupling. This allows us to use vacuum ahead and, if necessary, air pressure behind the piston for a push-pull effect for considerably more thrust without having to use high pressure or strong vacuum.
Rearden added that the Vectorr train can handle inclines of 10 percent or more. It could also have wheels on independent bearings so that the train can handle curved tracks easily.
So, everything old is new again. Vectorr and the much-hyped Hyperloop have some striking similarities with 170-year-old efforts to solve problems with rail travel. Now the question is: will today's iterations take off? Or will they end up in the annals of transportation oddities a couple of centuries from now?

Before the 760mph Hyperloop dream, there was the atmospheric railway Reviewed by Chidinma C Amadi on 7:18 PM Rating: 5

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