Because dreams of speed are slowed by technological and economic challenges

Because dreams of speed are slowed by technological and economic challenges

Because dreams of speed are slowed by technological and economic challenges

Beginning 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 around 50-60 billion dollars), the famous businessman Elon Musk is skeptical. In 2013 he suggested replacing the project with a new system which he called “Hyperloop alpha”. Capsules of 2.20 meters in diameter that would circulate on an air cushion in two air tubes, under 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 make the idea come true. Almost a decade later, however, progress remains limited. Virgin Hyperloop, powered by the money of British entrepreneur Richard Branson, was certainly 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 announcing its conversion to freight. The section that was supposed to see the light in 2020 for the Dubai Universal Exposition has not yet come out of the ground.

Contracts, on the other hand, 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 to Edmonton. In France, the HyperloopTT test track project in Toulouse remains at a standstill, but the TransPod one 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 airlock at the ends
Concept of the Hyperloop Cheetah, which is a variant of Elon Musk’s Hyperloop project. It features wheels, rows of 3 seats and airlock at the ends – RichMacf / Wikimedia CC BY-SA 4.0

We are therefore still very far 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 remain numerous: that of the rigidity of the pipes installed between the open-air pylons; make sure that the air in the pipes 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” which are sometimes presented as a “fifth means of transport”. It is not enough to consider physical speed: economic speed must also be considered.

Money is time

Economists have long shown the benefits of speed gains. Indeed, time is money. TGV users are ready 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 gain speed?

In fact, it is a question of dividing a journey into two stages. There is the time actually taken to travel and, before that, the time spent working to be able to afford the price of the train or plane ticket. In this first period it is as if the user moves at a low speed.

A pod, scale model, on a test track in the Netherlands
A scale model 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 was in 2003), the cost was close to the euro per kilometer. The minimum net wage at the 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 also applied to 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 lower (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 here: the Concorde has not crossed the barrier of economic speed. 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 to Concorde between New York and London on 24 October 2003: according to the economist there was nothing supersonic about it
Last flight to Concorde 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)

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

Let’s take the example of a cyclist who climbs a pass in the Alps at 10 km / h and descends at 60 km / h to reach the 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 going down the pass at the speed of light, the cyclist barely reaches 20 km / h.

It’s a bit the same when economic speed and physical speed are combined. The first corresponds to the ascent, the second to the descent.

What time saving and for whom?

Projecting ourselves into Jules Verne’s imagination, the pursuit of speed makes us dream. It is implicitly seen as a sign of progress, but sometimes it runs the risk of going against common sense if economic speed remains low for the majority.

The wide spread of rail, then road and air transport was possible because they allowed for an increase in travel speed. But the greatest achievement 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, the minimum wage of one hour now allows you to travel around 100 km in a small car compared to just 30 km at the beginning of the 1970s. In 1980 a one-way flight ticket back to Tunis required 123 hours of work at the minimum wage compared to 15 in 2020.

Physical speed gains don’t matter if they can’t be democratized. However, Hyperloop-type projects will have great difficulty in offering affordable travel costs to as many people as possible due to their low throughput potential.

Flow is defined as the amount of passengers that can be transported on one axis in one hour. Today, in a two-element, double-decker TGV train, we can accommodate between 1000 and 1200 passengers. With modern signaling systems it is possible to make 15 trains pass per hour and therefore from 15,000 to 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, which carry 20 people, it would take, to obtain the same result, a start every four seconds. The problem seems insoluble technically but above all in terms of safety. If there is a problem with a capsule, how do you prevent a number of the following from being incorporated into it?

Focusing on physical speed is useless if throughput is low, even if the investments required are gigantic. How to justify infrastructures that cost tens of billions of euros if only for the benefit of a privileged minority?

It could be argued that the construction of the railway network also required very large investments. In the 19th century, a kilometer of railroad cost fifteen times more than a kilometer of road. But the railway has made it possible to increase traffic in such a way as to be able to amortize the costs of building infrastructure. In the 1970s, engineer Michel Walrave proved that the same was true of early high-speed line designs.

The issue of throughput is therefore crucial because it determines private and public costs. We then touch upon issues of a profoundly democratic nature. If the state finances the construction of infrastructure, how to justify the mobilization of taxes by all in 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 per hour for a minimum wage).

For Hyperloop, even if democratization were possible one day, let’s not forget that the search for speed is structurally confronted with diminishing returns. By doubling the speed of trains between Paris and Lyon, the journey time was halved, from 4 to 2 hours. But by doubling the speed again (from 250 to 500 km / h), we would only gain an hour and only half an hour by multiplying it again by two (1000 km / h). The time gain would be increasingly minimal to the point that the question would arise: is the game worth the candle? This is also the question faced by Hyperloop-type projects.

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 website of The conversation.

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