Hyperloop speed dream held back by tech challenges

Hyperloop speed dream held back by tech challenges

At the start of his first term in 2009, US President Barack Obama endorsed plans for a high-speed rail line between Los Angeles and San Francisco. Given the production costs considered exorbitant (estimated at around 50 to 60 billion dollars at the time), the famous businessman Elon Musk is skeptical. In 2013, he suggested replacing the project with a new system he called “Hyperloop alpha”. Small capsules 2.20 meters in diameter that would circulate on an air cushion in two air tubes, under vacuum, at more than 1,200 km/h with an initial investment estimated at 10,000 million dollars.

Seduced by this futuristic scenario, many start-ups have tried to materialize the idea. Yet nearly a decade later, progress remains limited. Virgin Hyperloop, powered by money from British businessman Richard Branson, has certainly been tested in the Nevada desert, reaching 387 km/h. In November 2020, it even carried passengers for the first time, at 172 km/h, but that was before it announced its conversion to cargo. The section that was going to see the light in 2020 for the Dubai World Expo has not yet come to light.

The contracts, however, multiply. Hyperloop Transportation Technologies (HyperloopTT) signed an agreement on March 21, 2022 to open a line between Venice and Padua, Italy, for the 2026 Winter Olympics. In Canada, TransPod recently managed to raise $550 million to try to connect Calgary with Edmonton. In France, the HyperloopTT test track project in Toulouse is still on hold, but the TransPod project in Haute-Vienne is underway.

Concept of the Hyperloop Cheetah, which is a variant of Elon Musk’s Hyperloop project. It is equipped with wheels, rows of 3 seats and airbags in the ends – RichMacf / Wikimedia CC BY-SA 4.0

Therefore, we are still a long way from the goal, as we explained with Hervé de Trègulode in a recent research article. The effects of the announcement exceed the concrete results because the technical challenges continue to be numerous: that of the rigidity of the tubes installed between pylons in the open air; make sure that the air in the tubes never crosses the sound barrier; compress and cool the sucked air… To the point that François Lacôte, former technical director of Alstom, does not hesitate to speak of Hyperloop as a “tremendous technical-industrial scam”.

To the critical eye of the engineer, we can add some economic considerations questioning the relevance of these “pods” that are sometimes presented as a “fifth means of transport”. Considering physical speed is not enough: it is also necessary to consider economic speed.

money is time

Economists have long demonstrated the benefits of speed gains. In fact, time is money. TGV users are willing to pay more to go faster. But to what extent is the additional cost acceptable? Because money is also time. How much work time will it take to buy speed?

In fact, it is about dividing a journey into two stages. There is the time actually spent commuting and, before that, the time spent working to be able to pay the price of the train or plane ticket. In this first period, it is as if the user is moving at an economical speed.

A scale model pod on a test track in the Netherlands
A scale capsule on a test track in the Netherlands: Jeroen Juumelet/ANP/AFP (via The Conversation)

Let’s take an example. For a Concorde trip twenty years ago (the last flight took place in 2003), the cost was around one euro per kilometer. The net minimum wage at that time was 6 euros per hour, which therefore gives an economic speed of 6 km per hour of work and almost 2000 hours of work for the Paris-New York round trip. In short, nothing “supersonic”.

The observation was also valid for a high salary, for example, 10 times the minimum wage. The economic speed of the Concorde was then only 60 km/h while a subsonic flight costing 10 times less (10 cents per kilometer) corresponded to an economic speed of 600 km/h (and 60 km/h for the smicard).

The commercial failure of supersonic flights has its origin there: the Concorde did not pass the economic speed barrier. Symmetrically, the successes of traditional air transport and even more so of low-cost airlines, whose tickets cost an average of 5 cents per kilometer, are based on the trend increase in their economic speed.

Last flight of the Concorde between New York and London on October 24, 2003: according to the economist, there was nothing supersonic about it
Concorde’s last flight between New York and London on October 24, 2003: in the eyes of the economist, it was nothing supersonic – Nicolas Asfouri / AFP (via The Conversation)

High physical speed is, in fact, irrelevant when economic speed is low. Because, when two speeds are combined (to calculate a “generalized speed” here), it is always the slower one that weighs more in the calculation.

Take the example of a cyclist climbing a pass in the Alps at 10 km/h and descending at 60 km/h to reach his starting point. His average speed is not 35 km/h (the sum of the two speeds divided by two) but 17.1 km/h. For most mathematicians, it is a harmonic mean and not an arithmetic mean. The curious reader will be able to calculate that even descending the port at the speed of light, the cyclist barely reaches 20 km/h.

It’s kind of the same when you combine economic speed and physical speed. The first corresponds to ascent, the second to descent.

What time savings and for whom?

By projecting ourselves into Jules Verne’s imagination, the quest for speed makes us dream. It is implicitly seen as a sign of progress, but sometimes at the risk of running counter to common sense if the economic speed remains low for most.

The wide spread of rail transport, then by road and air, was possible because they made it possible to increase the speed of travel. But the greatest success of these modes of transport is their democratization, which has only been possible through a general increase in economic speed.

Even with a liter of gasoline at 2 euros, the hourly minimum wage today allows you to travel about 100 km with a small car compared to just 30 km in the early 1970s. In 1980, a round-trip plane ticket a Tunisia required 123 hours of work at minimum wage compared to 15 in 2020.

Gains in physical speed are of no interest if they cannot be democratized. However, Hyperloop-type projects will have great difficulty in offering travel costs that are accessible to as many people as possible due to their low potential return.

By flow we mean the number of passengers that can be transported on an axis in one hour. Today, in a TGV train with two elements and two floors, we can fit between 1,000 and 1,200 passengers. With modern signaling systems, it is possible to pass 15 trains per hour and therefore between 15,000 and 18,000 passengers per hour.

TGV trains can carry up to 18,000 people per hour on one axis: it seems very difficult for 20-seat pods to match this performance
TGV trains can carry up to 18,000 people per hour on one axis: it seems very difficult for 20-seat pods to match this performance – Philippe Lopez / AFP (via The Conversation)

In Hyperloop-type capsules, with a capacity for 20 people, it would be necessary, to achieve the same result, one exit every four seconds. The problem seems insoluble technically but above all in terms of security. In the event of a problem for a capsule, how to prevent a certain number of the following from not being embedded in it?

Focusing on physical speed is useless if performance is low, even if the investments required are gigantic. How can infrastructure worth tens of billions of euros be justified if it only benefits a privileged minority?

It could be objected that the construction of the railway network also required very important investments. In the 19th century, a kilometer of rail cost fifteen times more than a kilometer of road. But the railway has made it possible to increase traffic in such a way that we have been able to amortize the costs of building the infrastructures. In the 1970s, the engineer Michel Walrave showed that the same thing happened with the first high-speed line projects.

Therefore, the question of performance is crucial because it determines public and private costs. Next, we touch on issues of a profoundly democratic nature. If the State finances the construction of infrastructure, how can we justify the mobilization of taxes from all at the service of a privileged minority? It is a bit like deciding to subsidize the space travel of billionaires (for whom the economic speed is, by the way, 100 meters per hour for a minimum wage).

For Hyperloop, even if a democratization were someday possible, let us not forget that the search for speed structurally faces diminishing returns. By doubling the speed of trains between Paris and Lyon, travel time has been cut in half, from 4 to 2 hours. But by doubling the speed again (from 250 to 500 km/h), we would gain only one hour and only half an hour by multiplying it again by two (1000 km/h). The time gain would be more and more minimal to the point where the question would arise: is the game worth it? This is also the question that Hyperloop-type projects face.

This analysis was written by Yves Crozet, Professor Emeritus at Sciences Po Lyon and Transport Economist at Lumière Lyon 2 University.
The original article was published on the site of The conversation.

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