The Hyperloop dream of speed held back by technological challenges


At the start of his first term in 2009, US President Barack Obama supported plans for a high-speed rail line between Los Angeles and San Francisco. Faced with production costs considered exorbitant (estimated at the time between 50 and 60 billion dollars), the famous entrepreneur Elon Musk is skeptical. In 2013, he suggested replacing the project with a new system he called “Hyperloop alpha”. Small capsules of 2.20 meters in diameter that would circulate on an air cushion in two air tubes, in a vacuum, at more than 1200 km/h for an initial investment estimated at 10 billion dollars. Seduced by this futuristic scenario, many start-ups have tried to realize the idea. Nearly a decade later, however, 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 freight. The section that was supposed to see the light in 2020 for the Dubai Universal Exhibition is not yet off the ground, but the contracts are multiplying. 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 raised $550 million to trying to connect Calgary to Edmonton. In France, the HyperloopTT test track project in Toulouse remains at a standstill, but the TransPod project in Haute-Vienne is ongoing. 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 airlocks at the ends – RichMacf / Wikimedia CC BY-SA 4.0 So we are still very far from the goal, as we explained with Hervé de Trègulode in a research paper recent The effects of the announcement exceed the concrete results because the technical challenges remain numerous: that of the rigidity of the tubes installed between pylons in the open air; Make sure the air in the tubes never crosses the sound barrier; compress and cool the aspirated 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”. We can add some economic considerations questioning its relevance . of these “pods” which are sometimes presented as a “fifth means of transport”. Considering physical speed is not enough: you also need to consider economic speed.Money is time Economists have long demonstrated the value of speed gains. Indeed, time is money. TGV users are willing to pay more to go faster. But how much extra cost is acceptable? Because money is also time. How much work time will it take to buy speed? In fact, it is a matter of dividing a journey into two stages. There is the time actually spent getting around and, before that, the time spent working to be able to pay the price of a train or plane ticket. In this first period, it is as if the user is moving at an economical speed: a pod, a mockup, on a test track in the Netherlands – example by Jeroen Juumelet / ANP / AFP (via The Conversation). For a Concorde trip twenty years ago (the last flight took place in 2003), the cost was close to one euro per kilometer. The net minimum wage at the time was 6 euros per hour, which therefore gives an economic speed of 6 km per working hour and nearly 2000 working hours 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 salary. The economic speed of the Concorde was then only 60 km/h, while a subsonic flight that cost 10 times less (10 cents per kilometer) corresponded to an economic speed of 600 km/h (and 60 km/h for the smicard ). The failure of supersonic flights has its origin: 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 of increasing their economic speed. Concorde’s last flight between New York and London on October 24, 2003: In the eyes of the economist, there was nothing supersonic – Nicolas Asfouri / AFP (via The Conversation) Physical high speed, in fact, does not has any interest when the economic velocity 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, let’s take the example of a cyclist climbing a mountain pass in the Alps at 10 km /h. and drops back down to 60 km/h to reach its starting point. Its 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 going down the hill at the speed of light, the cyclist barely reaches 20 km/h, somewhat the same when we combine economic speed and physical speed. The first then corresponds to the ascent, the second to the descent. What time saving and for whom? By projecting ourselves into the imagination of Jules Verne, the search for speed makes us dream. It is implicitly considered a sign of progress, but sometimes at the risk of going against common sense if the economic speed remains low for the greater number to increase the speed of movement. 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 petrol at 2 euros, an hour of minimum wage today allows you to travel around 100 km in a small car compared to just 30 km in the early 1970s. In 1980, a round-trip plane ticket to Tunis required 123 hours of work at minimum wage compared to 15 in 2020 of physical speed have no interest if they cannot be democratized. However, Hyperloop-type projects will have great difficulty in offering accessible travel costs to the greatest number of people due to their low potential performance, by performance we understand the amount of passengers that can be transported on a shaft in one hour. Today, in a TGV with two elements and two floors, we can put 1000 to 1200 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 that the capsules 20 places equal this performance. – Philippe Lopez / AFP (via The Conversation) In Hyperloop-type capsules, with 20 people, it would be necessary, to achieve the same result, an exit every four seconds. The problem seems insoluble technically but above all in terms of security. In the case of a problem for one capsule, how to prevent a certain number of the following from being embedded in it?, focusing on physical speed is useless if the throughput is low, even though the necessary investments are gigantic How can infrastructures that cost tens of billions of euros be justified if they only benefit a privileged minority? It could be objected that the construction of the railway network also required very large investments. In the 19th century, a km of railway cost fifteen times more than a km of road. But the railway has made it possible to increase traffic so that we have been able to amortize the costs of building the infrastructure. In the 1970s, the engineer Michel Walrave showed that the same was true of early high-speed line projects, so the question of performance is crucial because it determines private and public costs. Next, we touch on issues of a deeply democratic nature. If the State finances the construction of infrastructures, how can we justify the mobilization of taxes from all at the service of a privileged minority? It’s a bit like deciding to subsidize space travel for billionaires (for whom the economic speed is, by the way, 100 meters/h for a smicard) For Hyperloop, even if democratization were possible one day, let’s not forget that research because speed structurally faces diminishing returns. By doubling the speed of trains between Paris and Lyon, the journey 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 gain in time would be less and less to the point where the question would arise: is the game worth the candle? This is also the question facing Hyperloop-type projects. This analysis was written by Yves Crozet, professor emeritus at Sciences Po Lyon and transport economist at Université Lumière Lyon 2. The original article was published in The Conversation website. 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