How can we make the hyperloop a reality?

Contestants at the SpaceX Hyperloop competition in Hawthorne, California, on 29 January 2017. Image: Getty.

Across Europe and parts of Asia, travellers can enjoy some of the fastest rail services in the world. From Málaga to Madrid, Tokyo to Osaka, high-speed electric trains condense the travel times between major hubs by racing along at some 300kph. The fastest commercial service in the world is the Shanghai maglev – short for magnetic levitation, the method of propulsion it uses to glide along its tracks as rapidly as 430kph.

Of course, air travel is still much faster: an Airbus A380 aircraft has a cruising speed of over 1,000kph. But at a time when reducing emissions is a top priority across the globe, there’s an urgent demand for cleaner, more energy-efficient alternatives – especially in the US, which is by far the world’s biggest user of air travel, with almost 800m passengers each year. Enter, the Hyperloop – a train-like technology which has the potential to match air travel for speed.

Hyperloop is the brainchild of US business magnate Elon Musk. First proposed in 2013, the Hyperloop system consists of “pods”, which are suspended inside a tube by magnetic levitation and propelled using a linear electric motor. The environment inside the tube is almost a complete vacuum, allowing the pods to travel at great speeds without being slowed by air resistance. The tubes themselves can be placed underground, or run above ground, elevated by columns.

The race begins

Musk originally intended the Hyperloop to cover the 600km route from Los Angeles to San Francisco at an average speed of about 960kph, reducing what’s currently a 12-hour train journey to just 35 minutes. Although funding has since been channelled into a bullet train service for this route, the idea of the hyperloop has attracted interest elsewhere.

The wealthy city-state of Dubai has agreed to conduct a feasibility study for a 150km link with Abu Dhabi. There’s also a proposal to connect Vienna with Budapest and Bratislava. And US start-up Hyperloop One recently announced a shortlist of 35 potential hyperloop test projects, which included proposals for routes linking Sydney with Melbourne, London with Edinburgh and Mumbai with Delhi.

While these developments have sparked much excitement, some remain sceptical about whether they can work in the real world.


Too fast to function?

Hyperloop pods are designed to reach their top speed of 1,220kph (slightly less than the speed of sound) in about 70 seconds, when accelerating at 0.5G (the “G” refers to “G-force”, which is how we measure acceleration).

To put this in context, at 1G we are pushed into the back of our seat with a force equal to our body weight – it would be uncomfortable. But the acceleration of an aircraft during takeoff is typically around 0.4G, and most people are happy with that.

We also experience G-forces when we go around a curve. This “centrifugal force” is what flings you from side to side on fairground rides. Again, about 0.5G is the limit for comfort. Travelling at speeds of 1,220kph sets the minimum curve radius to about 23km, which means that the track has to be pretty straight. It must be very level, too, because vertical hills and bumps also give rise to G-forces.

With the right site, these constraints could be manageable. The real challenge for hyperloop will be dealing with earth movements. In all large-scale engineering, allowances are made for thermal expansion, ground water and seismic activity – things that make the ground shift around. Normally, these aren’t too much of a problem. There are expansion joints in bridges and pavements, and even when subsidence causes cracks to appear in a wall, we shrug our shoulders and say, “so what?”.

But movement in the hyperloop track could cause real problems, when the pods are travelling at such high speeds. That’s why Musk favours a track on columns, so that it can be adjusted and realigned in the event of ground movement. Indeed, we already do this kind of realignment with conventional railway tracks: the rails on sleepers are loosely supported on ballast and regular “tamping” ensures that the track is kept straight.

With such demanding specifications, actually constructing a hyperloop will not be cheap. But the days of aircraft and ships are numbered, unless we can find a way to power them with electricity or hydrogen fuel. Perhaps we could even learn to live with nuclear-powered ships. Hyperloop offers a novel vision of the future of long-distance travel – one that might just catch on.The Conversation

If you'd like to know more about the hyperloop, check out our recent podcast.

Hugh Hunt is reader in engineering dynamics and vibration at theUniversity of Cambridge.

This article was originally published on The Conversation. Read the original article.

 
 
 
 

Mayor Marvin Rees' hope for Bristol: A more equitable city that can 'live with difference'

“I call on everyone to challenge racism and inequality in every corner of our city," Bristol Mayor Marvin Rees says. (Matt Cardy/Getty Images)

When the statue of 18th century slave trader Edward Colston was torn from its plinth and dumped in Bristol’s harbour during the city’s Black Lives Matter protests on 7 June, mayor Marvin Rees was thrust into the spotlight. 

Refraining from direct support of the statue’s removal, the city’s first black mayor shared a different perspective on what UK home secretary Priti Patel called “sheer vandalism”:

“It is important to listen to those who found the statue to represent an affront to humanity,” he said in a statement at the time. “I call on everyone to challenge racism and inequality in every corner of our city and wherever we see it.”

48 year-old Rees, who grew up in the city, has since expanded on his approach to the issue in an interview with CityMetric, saying “wherever you stand on that spectrum, the city needs to be a home for all of those people with all of those perspectives, even if you disagree with them.”

“We need to have the ability to live with difference, and that is the ethnic difference, racial difference, gender difference, but also different political perspectives,” he added. “I have been making that point repeatedly – and I hope that by making it, it becomes real.” 


What making that point means, in practice, for Rees is perhaps best illustrated by his approach to city governance.

Weeks after the toppling of Colston’s statue, a new installation was erected at the same spot featuring Jen Reid, a protester of Black Lives Matter. However, the installation was removed, as “it was the work and decision of a London-based artist, and it was not requested and permission was not given for it to be installed”, Rees said in a statement.

Bristol may appear a prosperous city, logging the highest employment rate among the UK’s “core cities” in the second quarter of 2019. But it is still home to many areas that suffer from social and economic problems: over 70,000 people, about 15 percent of Bristol’s population, live in what are considered the top 10 percent most disadvantaged areas in England. 

In an attempt to combat this inequality, Rees has been involved in a number of projects. He has established Bristol Works, where more than 3,000 young people from economically disadvantaged backgrounds are given work experience opportunities. And is now setting up a commission on social mobility. “Launching a Bristol commission on social mobility is not only about social justice; it [should not be] possible for a modern city to leave millions of pounds worth of talent on the shelf, just because the talent was born into poverty,” he says.

The mayor is also a strong supporter of the UN’s Sustainable Development Goals (SDGs), explaining that SDGs offer a way to talk about sustainability within a framework of many issues, ranging from climate change and biodiversity to women’s issues, domestic violence, poverty and hunger.

“What we want to achieve as a city cannot be done as a city working alone,” he insists. “We don’t want to benefit only people inside Bristol, we want to benefit the planet, and the SDGs offer a framework for a global conversation,” suggesting that a vehicle should be launched that allows cities to work together, ideally with organisations such as the UN, the World Bank and the International Monetary Fund involved. 

Greater collaboration between cities would be “beneficial in terms of economies of scale,” he argues, “as cities could get more competitive prices when buying materials for building houses or ordering buses, rather than each city acquiring a few of them at a higher price.”

In an attempt to focus on the long term, Rees launched One City Plan in January 2019, setting out a number of goals for Bristol to achieve by 2050.

Investing in green infrastructure to meet 2030 carbon emission targets spelled out in the SDGs is a key area here, with the mayor noting that transport, mass transit and energy are important sectors looking for further investment and government funding: “The sooner we meet our targets, the sooner we will benefit from them, and invest in sectors that will provide people with jobs.”

Jobs, especially following the outbreak of Covid-19, are of paramount importance to Rees. Bristol’s council wants to ensure that any government money given to the city will be quickly passed on to businesses to help prevent redundancies, he says, though given that mass job losses seem inevitable, reskilling options are also being looked into, such as through a zero-carbon smart energy project called City Leap.

Another important area for investment in Bristol is affordable housing, with 9,000 homes already built under Rees’s term of office. “People could build a base for life with affordable housing, [and this would mean] their mental health would be better because they have a safe place,” he explains. “Children in families that have a home that is affordable are more likely to able to eat and to heat, [and they are more likely to enjoy a] better education.”

Taken in the round, Rees’s agenda for Bristol is its own blueprint for shaping history. The Colston statue now lies in safe storage, with a local museum likely to play host to the controversial monument. But the Black Lives Matters protestors were fighting for a fairer, more equal future, and it is here where Rees is determined to deliver.

Sofia Karadima is a senior editor at NS Media Group.