'No lack of engineering expertise in India': 2023 Silkyara tunnel collapse rescue expert Arnold Dix

Arnold Dix, 61, is International Tunnelling and Underground Space Association president (2022-25). (Image: X)

Sixteen days after a section of the Telangana Srisailam Left Bank Canal (SLBC) tunnel collapsed trapping eight workers on February 22, rescuers have recovered the first body, and work is on to find the others. At the start, the tragic collapse had drawn hopeful comparisons with the Silkyara Bend-Barkot tunnel collapse rescue. By February 24, a team of rat miners who had helped in the Silkyara rescue had been called in to work with the SLBC rescue team.

To be sure, there are some similarities in the two cases—with rescue efforts taking more than two weeks in each case, and the soft rock and previous collapses making the work trickier in both locations—but there are also some major differences. The biggest of them: no one died in the Silkyara tunnel collapse of 2023. In the SLBC tunnel rescue, mud and water inside the tunnel also impeded progress in the early days. Another way in which the Silkyara rescue was different from the SLBC tunnel collapse is that by the second day, rescuers at Silkyara were able to repurpose a 12-cm pneumatic air pipe to transport water, food and medicines to the workers trapped inside, but getting them out of there would take another 15 days.

Here’s a quick recap of what had happened at Silkyara: At roughly 5:30 am on November 12, 2023, 41 workers got trapped around 250 meters from the entrance of the under-construction Silkyara Bend-Barkot in Uttarakhand. Early rescue efforts ran into one problem after another. Equipment flown in to drill an 80-cm hole through the debris ended up getting destroyed by the torn metal and heavy machinery that was mixed in with the rubble. Add to that, soft rock in this section of the Himalayas threatened further collapse. As with the SLBC tunnel, there were signs of previous catastrophic collapses. On November 16, 2023, Rahul Gupta, National Highways Authority of India chief engineer and in-charge of the Silkyara tunnel project, connected PMO to the president of the International Tunnelling and Underground Space Association—an Australian by the name of Arnold Dix. Dix was in Slovenia at the time for work. After the call, he hopped on planes—flying through Slovenia, Dubai, Mumbai, Delhi and Dehradun before being escorted to Silkyara in an Army helicopter.

Arnold Dix’s book about the Silkyara tunnel rescue mission—nicknamed Operation Zindagi—was released in January this year. In it, Dix compares cutting a tunnel through a mountain to balancing an elephant on an egg. He writes that the job of the tunnel engineer is to trick the mountain using physics and redistribute the weight around the tunnel. And if the trick isn’t good enough, the mountain will reclaim that empty space. Under-construction tunnel collapses, of course, can and do happen in many parts of the world. But techniques and technologies are getting more sophisticated to prevent more mishaps.

Over a video call from his home office near Melbourne, Dix explained why building tunnels in young mountains like the Himalayas is trickier than in the older mountains of, say, Australia. Dix simulated snoring noises to indicate how old mountain ranges in Australia respond to tunnelling versus the energy and movement in young mountains like the Himalayas. Dix also spoke about the difference between the Indian Himalayas and the mountains on the Chinese side, and how India has 20 exciting years of building massive infrastructure projects including tunnels and underground rail connections ahead. Edited excerpts:

Is it true that you have a tiny piece of the rock from Silkyara with you to date?

I actually have it here in my office. Look, I've got it here (it's a grey-black jagged piece, about the size of a hockey puck). Whenever I'm telling the story, I like to touch it because it reminds me of the rescue.

You don't have to be a geologist or rock expert to see that this is a soft sedimentary rock that probably breaks off easily. In one place in the book you explain that the Himalayas are a young mountain that were formed when India and China collided into each other, ripping up the ocean floor—which is why mountaineers have found seashells near Mt Everest. You also explain that the mountains are almost soapy rock and very fragile. As somebody who has studied mountains and underground spaces around the world, could you give us a sense of exactly how the Himalayas are different from some of the other older mountain ranges that you have seen or underground spaces that you have seen around the world? And does this present any special challenges while undertaking tunnelling work here? You also mention the ongoing Zojila project that you write is even trickier than Silkyara in some ways...

Yeah, well, there are other places with new mountains as well. Japan, Korea, China, Italy... they've also got new mountains. But like Australia, I'll do a simulation of Australian mountain... Zzzz (makes a deep snoring sound). It's like completely fast asleep; almost dead. It's just been there so long and it's old and it's tired. And when you drill a hole through it, it's just like, yeah, whatever. You feel it when you're building your tunnels in it. But the Himalayas, it's like it (the rock) is alive and it feels alive. It's hard to explain it because it I'm not talking like a geologist or scientist (now). But for me, it's a live mountain. Not just alive, but like a childish alive mountain. It's got a lot of energy and it's sort of bouncing around and it's badly behaved and everything. So that's quite different to the more ancient mountains which have calmed down and are in a sort of a greater sense of balance.

Having said that, the Himalayas are still old by human terms—millions and millions of years old in human terms. But when you're building in mountains like that, you have to be sensitive to it. It requires you to be a good engineer and to do your job with sensitivity. I think I say it in the book, and it's certainly my experience, there's no lack of engineering expertise in India. The engineers are great, and I know because I work with them all around the world. But I think one of the problems is the way in which the commercial frameworks are put in place for the projects, which means that the engineers aren't able to do their best work because, often, the mechanisms aren't there for them to change the design, for example. So if they've planned on building the tunnel like this, but actually they need to make it like that (for better safety or longevity or integrity of the tunnel), which doesn't look that much different, but it's going to cost more, there's just no way to do that. Therefore, they just leave it the way it is.

In the case of Silkyara, there were 21 prior collapses between where you go in and where the tunnel collapse took place. I mean, it's just awful but it's not the engineer's fault. The mechanism of delivering the infrastructure doesn't have a way within a reasonable time to change things. And I think that's really sad.

Your country (India) is really in transition at the moment, positioning itself to be among the most powerful countries on earth. It's just a bit of adjusting; I think in the past it was 'just build whatever you can and see how we go, because we're lifting the whole country', like the whole country needs a lift. But I think now, it's got this level of maturity to it. There just needs to be some more sophisticated ways for that delivery of the projects. Plus, it's more efficient and I think more fair. So you don't have to spend as much money on the project, and it means there's more money for schools and medicine and other things as well.

So, China would have a similar trajectory as India in terms of building tunnels through the mountains on their side? What's the type of rock there?

It's slightly different geology because you've got the more of the old ocean floor on your side (in India) and they've got more of the granites and things on their side. And I know because also I work in China because I'm apolitical, I'm just technical dude. So I even go to Pakistan. I get to see all the different sides.

So, for your purposes, yeah, it's the same. In the last 15 maybe 20 years, they've gone from very unsophisticated to really leading the world.
And I think India's in the position to take that crown, because you've got so much underground infrastructure to build and you've got such a highly educated and young workforce in all areas, whether it's professional or labour. And they're eager to work. You've got a really good industrial base that you can build upon. You've got a track record where you choose to do something well, like your submarines, your space program, your IT... I think if I was king, which I'm not, but if I was king of India, I'd say make this a (matter of) national pride, national agenda, and within five years you'd see a huge uplift. And within 10 (years), you'd probably be at world leader status - probably to the horror of your neighbours to the northeast.

China's pretty much finished building all its stuff, whereas you as a country have got, I reckon, at least 20 years to go to get all the metros and the high speed rail and the sewerage and the water and everything done. So I'm excited for you.

Following the rescue mission at Silkyara where you were able to extract 41 people alive after 17 whole days, were you asked to give any recommendations on how tunnelling work needs to happen in the Himalayas? If not, would you have any recommendations to share now, given that we continue to dig tunnels through the Himalayas and we continue to build and widen mountain roads. In your book you mention Zojila tunnel—which will provide all-year all-weather road connectivity between Srinagar and Leh, and where the expected completion date has been pushed to 2030 now—is perhaps even more tricky from an engineering point of view than Silkyara... What are some of the do's and absolute don't do's that you would suggest in these areas, based on your years of work in underground infrastructure works and tunnel collapse rescues?

Firstly, the decisions about building the tunnels needs to be based on good science and engineering. That means you really do have to do the necessary work in advance to make sure that your tunnel alignment is a good alignment. And that can take time. And I understand that there are national agendas at play, but you also need to make sure the money that you spend is well-spent. So just a little bit more time to make sure that the science and the engineering is done.

More instrumentation during construction, so that if what we're building isn't performing correctly, we notice it before it collapses. There's technology available, and I think some of it's possibly even developed by Indian companies because of your mining, because your coal mining is such a powerful part of your economy, a bit like Australia. We also use some of the technology from the mining sector so that you get warning if something's not performing how it should be.

Training of your construction workers. So, actually, having some basic requirements for the training of those men just so they have a better appreciation of the risks involved.

On the procurement side, more sophisticated contracts, but (contracts) that suit the Indian environment. I'm not quite sure what that is (entails) because I'm not Indian and because I don't have a detailed understanding of how the local commercial environment works. I'm very respectful that whatever it is, has to be Indian style. It has to work for India. It's no good coming to Australia and just getting an Australian thing or going to Switzerland and getting a Swiss thing. It has to be tailored for India, and that includes the personalities of all the people involved, if there's a practice that I'll call it 'money gets lost along the way', then you need to have a practice which keeps everybody happy enough so that they try and make the new system work. I'm not suggesting corruption, but I am suggesting that it's OK for people to make money. And so let's think about what that might look like.

And I think huge, huge changes could be made that would make the tunnelling less expensive, more predictable and safer, and actually would accelerate the reforms that the government's trying to achieve. Because at the moment, I think it's time for the country to change gear as it sort of settles into its superpower role.

Three months before you were called in for the rescue at Silkyara, you had gone on this entire refresher course as it were, travelling to different countries, and understanding the ways in which the rock can be different or the ways in which the drilling techniques can be different. Did some of that learning come in handy in your rescue work in the Himalayas?

It doesn't really make sense to me because I'm an engineer, yet a few months before this rescue, for reasons I don't understand, just odd things started to happen. Like I took myself on this world tour of the most extreme underground spaces. I went to South Africa, to the Mepong gold mine, which is the deepest mine on earth and actually looked at the rock collapsing in the gold mine under the pressure, just like I was witnessing in Silkyara later. So I'm actually down in there looking at how they're propping it. This gold mine is in the Guinness Book of Records, the deepest place on Earth.

I went to Finland. And I took part in an ancient ritual. The Finnish people believe in the spirits of the tunnels. When you reach the deepest point in the tunnel, you perform this ritual to keep the mountain spirits at peace.

Then I went across to Germany. I learned about the latest tunnel boring machines, which was in fact the type of tunnel boring machine that that Chris Cooper and his team were launching for the horizontal rescue. It was like the exact (same) company, the exact machines. So I'd done that.

I went to America, to the Colorado School of Mines, and I had explained to me the latest techniques for drilling and tunnel forming that were being developed, of all things, for the moon. And the reason that's important is because on the moon, when you're building a space station for humans, you've got quite limited machinery. Well, that's like what we were doing at Silkyara.

Arnold Dix over video call from his home office near Melbourne in Australia.

What are you working on now?

I am involved in other tunnel disasters at the moment. But as has always been the case previously, no one knows about it and that's how everyone wants it to be.

Could you talk about which tunnel disasters you are working on currently?

No. It's just that people are very sensitive with their tunnel disasters.

But aren't they too large to hide generally?

Well, you'd be surprised. It's always very sensitive because it's always a matter of national pride and national identity and strategic importance and things like that. So, yeah, sorry I have to be bashful and say nothing.

‘The Promise’ reads like it is movie-ready; a thriller about the daring rescue where rat miners made a hole in the mountain just big enough to pull the workers out of the collapsed tunnel. Now out of all of the jobs that you’ve done—including mining, practising law and flower farming—did you also take up a writing job at some point?

No, but I write technical, scientific, engineering and legal papers. So if you research me, I'm an author of academic papers. I've never written a book before. And I think my English teacher, who has passed away now, is probably turning in her grave going, what on earth has happened? How's my little Arnie ended up writing a book? I never thought of myself as a book writer. The publishers reached out to me, and I sort of realized there weren't many nice stories at the moment, like everyone is sort of competing for the worst stories that they can tell and they're all really horrible. And so I thought I'm going to write a truthful story that everyone knows and can be verified and validated. There's no fake news. There's no false news. It's just true.

Do you see yourself as a big reader at least … I can see copies of the Rig Veda and Atharva Veda behind you?

Yes, one of the things that I'm passionate about is the relationship between language and culture and identity. When I was up in the Himalayas, I realized that this is the venue for them (Devbhoomi). So I asked my friends at the temple here in Australia where I could get my hands these (text of the Vedas), and they got them for me. I had to promise that I'd read them. That's when I decided I had to learn Sanskrit. Now, I've got a teacher in India and I have lessons every week. At the book launch, a part of it (my presentation), I gave in Sanskrit. Sanskrit has a sort of a rhythm and a poetry... it's almost like a song. And so I kind of enjoy it. My Sanskrit teacher thinks it's really cool that he's got this really old Sanskrit student who's busy trying to learn Sanskrit. So, you know, check in with me in five years time and see how I am. But my aim is to be able to talk in Sanskrit and to understand it.

When I was in Pune—this again is a very odd thing—before the rescue—and I think it's in the book—my son and a Marathi girl fell in love. She's from a very conservative family. So it's strictly, you know, arranged marriages. The family were really against this marriage. My son was too stupid to understand how serious this was because he's like I'm this lovely Western boy. And I was like, Edward, my God, don't you understand: You are like a disaster for the family. You're the worst possible thing for this girl to bring home.

Anyway, since doing the rescue, our families get on really, really well. So it's all good. Anyway, sorry you weren't asking me about that, I'm a bit of a talker.