10 reasons why digging a tunnel under London is an epic endeavour

The BBC has a nice documentary on Crossrail, a £15 billion project to build a new 120-km train line passing through central London. I knew that this is a great engineering challenge, but I did not appreciate the scale of difficulty the engineers faced. You can watch the three one-hour episodes here (need UK access), or here’s the summary of the interesting points illustrated with pictures (credit: BBC, Wikipedia):

1. The project is using eight specially made tunnel-boring machines (shown below), each with a female name, such as Elizabeth, Mary and Victoria.

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2. One of the biggest challenges has been tunnelling under Tottenham Court Road station. It is where the tunnel-boring machine needed to pass through very crowded space. The tunnellers have labelled it “the eye of the needle”. There the 900-tonne tunnel-boring machine has had to pass through a space where 30cm above it was a live escalator and 85 cm underneath was the active Northern Line.

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3. When drilling under London, tunnellers need to ensure that all the buildings above ground remain as they were. This is tricky because during the operation, there is every possibility of disturbing the earth beneath some ancient buildings, causing them to tilt or, worse, crash down. To monitor the balance, they have installed laser sensors which measure any movement. When the building starts sinking, the alarms ring.

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4. The building then needs to be brought back to its previous stable state, which is done by injecting grout just at the right place to fill up any spaces that are causing the sinking. To do that, they have created 22 massive shafts throughout London, which have small pipes originating from them spreading through the ground beneath as a spider web. Whenever there is a disturbance that the laser monitors spot, they insert a tube through the right pipe that goes under the building and pumps grout in that area, which we are assured stops the building from sinking. Some shafts operators spend 16 hours a day doing this.

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5. The Thames river is the first river in the world to have a tunnel built underneath it. That first 400m tunnel, opened in 1843, needed 16 years of work to build. The design of the boring machine built then by Marc Isambard Brunel is still in use. In the modern version the actual digging work is done by robotic arms rather than people. The tunnel under the Thames near Woolwich of about the same length as the 1843 one took only 8 months.


6. Despite nearly two centuries of expertise boring under the tunnel, it’s still quite a challenge. One of those difficulties is a tunnel near the Custom House station. Where they had to block the river, drain the area and work on expanding an already existing tunnel to fit the wide Crossrail trains.

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7. When tunnellers use the word “breakthrough” they are literally breaking through something. And when they use the phrase “seeing the light at the end of the tunnel”, they actually see light at the end of the tunnel.

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8. The Crossrail’s Canary Wharf station (shown below) is going to cost £500 million. Similarly, the new Farringdon station’s cost is £440 million.

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9. Station constructions have 22-week period allowed for archaeological investigation, if an opportunity shows up. In an old city, it almost always does. Shown here is the remain of someone who died from bubonic plague, or Black Death, in the 14th century. More than 20 other such bodies were found in the same spot near Farringdon station.

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10. Underground trains form an almost perfect air seal, pushing all the air in front of it at the same speed as it travels. Each underground station has to build ventilation systems to accommodate the pressure such pushed air can create. So next time you see a ventilation shaft outside a station, remember that is built not built to keep you cool underground but to make sure the air pressure created by trains doesn’t break things.

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Welcome to Curious Bends

A few years ago, I formed a group of science enthusiasts. Our goal was to fix the problem of poor science communication in India. There only existed a handful of science publications and fewer among them did the work that was so critical to a democracy with the potential that India has. We discussed many ideas but couldn’t implement them.

After all these years, science communication in India hasn’t changed much. But the problem kept nagging me all along. So now, with fellow nerd Vasudevan Mukunth, I’ve started a weekly newsletter to address that problem in a small way. The aim of the weekly newsletter would be to become a place where you can come to find interesting stories from global publications covering science, technology and data that have their focus not on the West.

Here is this week’s edition (our second). If you enjoy it, you and your friends can subscribe here.


1. Warheads at supersonic speeds… on the ground
India’s defence research organisation has installed five 4-km long rails at a research lab in Chandigarh for propelling missile warheads at supersonic speeds. Could this be useful for India’s space programmes, too? The timing is suggestive. In July this year, the space agency is slated to launch an unmanned “Orbital Vehicle” that is at the heart of India’s human spaceflight program. The rails can be used to simulate re-entry of crew capsules. (3 min read)

2. In the unfortunate event that New Delhi is nuked…
On the Doomsday Clock, which is a countdown to global catastrophe, the world has come 12 minutes closer to midnight since 1991. Recently, Nitin Gadkari, now a minister in the new Indian government, was exchanging nuclear threats with a Pakistani analyst on TV. This spurred a journalist to look at the government’s emergency plans to deal with a nuclear fallout. Hint to civilians: “To begin with, nothing that can be dug without the help of E. Sreedharan—the Metro Man—is likely to be deep enough.” (8 min read)

3. Are tiger poachers really trying to hack radio-collar data in India’s sanctuaries?
The more we resort to technology to protect something, the more its failings become liable for abuse—except when it’s animal poaching. There was a scare about a Pune techie trying to hack into data transmitted by radio-collars around some tigers. It turned out to be false, but not before conservationists reasoned that poachers relied on simpler, ground-based techniques to trap animals, and that’s why they get away. (4 min read)

4. 101 suicides in two months: is Marathwada the new Vidarbha?
Freak hailstorms in March flattened orchard crops in Maharashtra’s Marathwada region. In the two months since, 101 suicides have been reported. The reason? Faulty agriculture and irrigation policies have driven farmers to orchard farming that is submissive to failing, because of the time and capital investment it requires. (5 min read)

5. Call for action to prevent millions of “invisible” deaths
More than 780,000 babies less than 28 days old die every year in India. The cost of preventing these deaths is a meagre $1.15 (₹ 68) per person. Why then aren’t these deaths prevented? Because these are “invisible deaths”. Parents don’t seek to register their child’s birth or death because they don’t think it can make a difference. This silence perpetuates the myth that newborn deaths and stillbirths are inevitable. (6 min read)

6. Video: Putting hardy small millets back on the menu
Decline in food diversity is driving malnutrition around the world, and the hardy millet is one casualty. This cereal crop can be cultivated in a variety of ecosystems, from coastal areas in South India to mountainous terrain in the Himalayas, but it has become a niche crop. A Canadian agency wants to redress this imbalance in India, Nepal and Sri Lanka, and to put women farmers in the centre of its approach. (5 min watch)

Chart of the week

If you divide China into two, one half will have 94% of its population (nearly 20% of world’s population). This geographic divide hasn’t changed in last 80 years despite the population tripling. In 1935, a Chinese geographer noticed the divide and drew an imaginary line, called Heihe–Tengchong Line, that no one seems have crossed over to settle. Yet, what this map hides is the fact that China has recently seen the largest migration in human history: 160 million people have moved from rural areas to urban ones in the last 30 years, no doubt within Eastern China.

Please email curiousbends@gmail.com with suggestions or feedback. We’d love to hear from you. For more such stories, find curators Vasudevan Mukunth and Akshat Rathi on Twitter. Enjoy the week!

An attempt at setting the information balance right

The problem is not that there is too much information, but that there is too little of the right kind

In his brilliant book, A Short History of Nearly Everything, Bill Bryson shows through many examples how history often credits the wrong person. They show how being in the right place at the right time or publishing your ideas in the right publication so that the right people notice them is some times more important than having the idea.

For instance, today the great astronomer Edward Hubble is credited to have discovered that we live in an ever-expanding universe. However, it was an astronomer with the cheerily intergalactic name Vesto Slipher who should have got the credit.

Carl Scheele (Credit: Wikimedia)

Or take the example of Carl Scheele, a Swedish chemist, who discovered eight new elements—oxygen, nitrogen, chlorine, fluorine, manganese, barium, molybdenum and tungsten—and received credit for none of them. His work was either overlooked or made it late to publication after someone else had made the same discovery independently. The credit instead went to chemists of the English-speaking world.

And, if you’re still not convinced, try Josiah Willard Gibbs, who Bryson calls the “most brilliant person that most people have never heard of”. Between 1875 and 1878 he produced a series of papers on the thermodynamic principles of nearly everything but published them in the Transactions of the Connecticut Academy of Arts and Science, a journal that “managed to be obscure even in Connecticut”. Although Gibbs was recognised later in life, most of the work he did remained hidden for too long at great cost to the scientific enterprise.

Information games

The reason I am telling you all this is not just because it is interesting, but also because there is a lesson we can learn from these examples. All three scientists who got scooped lived in the age when information was scarce and the fastest it travelled was at the speed of a moving vehicle. 

We live in the age of information excess and the fastest it travels is the fastest it will ever travel (ie at the speed of light). However, we are still stuck with one problem that those gentlemen of the 19th century faced and perhaps it has become worse—who receives what information matters even more today. With the internet throwing up interesting things on our screens every day, are we getting the information we really need?

I’ll explain the problem with two examples. The first comes from how we learn history. This came to my attention during my first months in Oxford. Ask any non-Indian what they thought about British colonisation of India and you got a view that was quite different to what I was taught in school in India.

Partisan views

Most people acknowledged that there was imperial excess. They bemoaned the human cost of the partition between India and Pakistan, for instance. But they, particularly British friends, also praised how the British gave Indians railways, law and order, the English language, and, some even suggested, the Indian identity. Most importantly, they saw Indian independence as British leaving India. This was a time, one said, that Britain was relinquishing control of other colonies too following the troubles that World War II had caused for Britain domestically.

Sardar Patel. Credit: Govt of India
Sardar Patel. Credit: Govt of India

This wasn’t what I was taught in school. Indian textbooks glorify the independence struggle, it seemed. I was surrounded by some of the smartest people I had ever met, and instead of questioning them I had to go back and read history. What I realised soon though was that neither my British friends nor I had quite the balanced view that one ought to have of this important period in world history.

I wasn’t expecting my British friends to know about Mangal Pandey or Bhagat Singh, but I thought they would be aware of the Quit India Movement and Jallianwallah Bagh massacre. That they would recognise the importance of the role of freedom fighters, such as Sardar Patel, in accelerating India’s independence. Equally, I suspect my British friends thought I should have more appreciation for the things the British left in India.

The point here is that where the information came from changed how people viewed the world. In this case the topic was a well-studied period of history, and so I was able to educate myself enough to get a balanced view. But what about more recent events?

History’s value

In The Sceptical Patriot, Sidin Vadukut analysed history textbooks used by Indian kids today. He found that none of them devote any space to post-Independence period. Beyond a little bit on the Indian constitution, there is nothing about the wars with Pakistan and China or about the Naxal movement, which is considered the greatest threat to India’s internal security.

Why should Indian kids learn about this stuff? Vadukut’s story might give you an answer:

Sometime in 2002 or 2003, a group of Japanse Hibakusha, or atomic bomb survivors, visited Chennai. The city was a stop on what I think was a global tour to promote peace and condemn nuclear weapons. They decided to visit a primary school and tell the students why the idea of nuclear weapons was a bad one.

I read about the school visit in one of the local newspapers. I don’t recall which one, and no amount of searching online has thrown up the original news report. But the broad details of what happened are seared into my mind.

After the presentation, the Hibakusha asked the children:  should countries go to war? No, they all said in chorus. Should countries use nuclear weapons? No. Should India use nuclear weapons? Never. What if the enemy is Pakistan? Oh, Pakistan is a special case, the kids said, we should totally nuke them.

Every time I retell this story at a public forum, there is an explosion of laughter followed by an awkward silence.

Absence of proper facts

This brings me to the second example, which is closer to me—science journalism. The media landscape of the west is changing. The old media houses are losing audience and revenue at such a pace that it feels like a crisis. The first to lose their jobs in such cases tend to be specialist journalists such as those covering science, environment and health. Sometimes the sections live on, but they shrink in size and depth. The reporting gets done by general reporters instead.

There have been some positive changes with new media organisations trying to fill the gap. And despite all that, even with shrinking newsrooms, western media’s science coverage remains so much better than Indian media’s. A survey I did a few years ago of Indian newspapers gives the same results today—proper science reporting doesn’t exist.

This is a problem. Most of the time if you come across a science story in Indian newspapers, it happens to be one from an international wire service, such as AP, Reuters or The Guardian. Despite the international nature of science, Indian readers are fed the writing of western journalists. The stories become less relevant and thus less interesting. While the hard-science stories are still somewhat valuable, those about the environment, health or even technology aren’t.

This matters because policy depends on the quality of information that decision-makers get. One more example from Vadukut’s book makes that case absolutely clear. In March 2008, Daggubati Purandeswari, the then minister of state for human resource development, when talking about India’s education system, parroted “facts” about Indians abroad, which had been forwarded in a hoax chain email.

“Sir, as rightly pointed out by the honourable member, our students have been placed very well globally. For example 12% scientists in the United States are Indians. We have 38% if the doctors in the US who are again Indians. 36% of NASA scientists are again Indians. So, the students are doing very well, and they are reaching places which again reflects on the quality of education that is being provided to our children in the country.”

All of these “facts” can be easily verified as being false, but the honourable MP did not think she needed to do that. Her words were then reported in Times of India the next day as “facts”. And that is how facts get made up.

Science suffers

That aside, had there been good science journalists writing about the achievements of scientists in India, perhaps Daggubati would not have relied on information from dodgy sources. India’s premier institutes, such as the Indian Institutes of Technology, never figure in the world university rankings. From the information available to the minister today, she won’t be able to figure out whether the absence of IITs in such rankings says something about the poor quality of research or the lack of communication of that research.

There is also another side to this story. In my time at Oxford, whenever there was a paper published in an Indian or Chinese journal, I was explicitly advised not to give it too much value. The suggestion was that research in these journals was not reliable, which in other words means that the researchers were making up data.

This kind of opinion may have been formed by experience. But mostly this opinion was the result of western media reporting negative science stories emerging from China and India, which make academics wary of trusting such research. This, I believe, must lead to missing out on genuinely good research being produced in these countries.

The solution, of course, is one that will require change from the big editorial houses. In my conversations with Indian journalists, I’ve been told many times that there is thirst for good science content but no publication is ready to provide it.

A different solution that a friend and I are pursuing is to collate good science stories from around the web that have their focus on the other side of the world. While this doesn’t solve the need for more science reporting, at least it provides a central place to find good content related to India. Some of it exists, but sadly it tends not to be at one place but spread across different publications. (You can sign up for our newsletter here.)

Those gentlemen in the 19th century suffered personal loss because key information didn’t reach the right audience. Today’s tragedy is the same but the reason is different—key information is not reaching the right audience because either there is too much information and very poor filters or there aren’t enough people to collect and present the information that is so desperately needed.

Lead image: teresaling. Thanks to Deeksha Sharma and Vasudevan Mukunth for reading drafts of this post.