DAVID FAWCETT | INTERVIEW


Above left: David cycling in the Lake District recently Above right: While retired, David Fawcett continues to work internationally as a tunnelling and project consultant


rock. So if you are digging a tunnel and take out good rock and replace it with a concrete lining – is that really sensible? I can understand why we do it, but it still seems a bit odd to me. “And a hydro tunnel, where people do


not go – building it unlined is a lot cheaper, and if one in ten of them has a collapse and costs three times the original amount to repair, then the savings on the other nine tunnels more than covers it. The insurer pays the bill in any case. Insurance premiums rise to pay for it, of course, but it still works out a lot cheaper overall – and a lot cheaper for society – because no one client has ten tunnels that collapse. The risk is spread, and that is a good use of insurance. It levels out the risk cost across projects and saves society money.” He has done a fair bit of tunnel collapse


investigations. What is the usual cause? “The mistakes are usually very simple.


They are all mess-ups.” (Actually the word he used begins with a ‘C’). “Someone didn’t spot something they should have spotted, didn’t attend to something they should have known about. He investigated a case in South America.


“It was an unlined headrace tunnel through Karst limestone, and it had failed dramatically where a small (thought to be irrelevant?) fault zone connected to a cave system. When I got home I rang my mother


and told her what I had been doing. ‘But limestone has holes in it,’ she said. And I said, ‘Yes, mother, it does.’ “You get this huge file about a collapse or


something and you think ‘How on earth did they do that?’ You cannot believe it. And, you like to think that you wouldn’t have done it yourself – though of course you might have. I have driven tunnels through faults myself (and only realised the next day when the thing failed), though in much less dramatic circumstances. “And it is worth remembering that nobody


actually just builds a tunnel. You build a railway, or a road, or a water conduit or a sewerage system. That’s where the benefit to society comes from, not from a hole in the ground. The Channel Tunnel wasn’t a tunnel project – it was a railway project. It happens to use tunnels over much of its length but of the billions of pounds that it cost to make it three-quarters was spent on things that were not tunnels.


“To me rock tunnelling is not just


understandable, it is instinctive. I did geology as part of my course; I do understand the calculations; but I don’t need them. I can look at a rock face and know what its strengths and weaknesses are.” Did that come from experience or was he


born with it? “I don’t know the answer to that. I


remember walking through the Kielder Tunnel with John Hudson, who became Professor of Rock Mechanics at Imperial College, London. We were looking at the walls and he was saying how to put all this into some programme to work out where it needed strengthening and I said, ‘Yes, but you can see that you need a rock bolt there.’ He said, ‘Your brain can see that. Most people can’t.’ “So there is some instinct there. I’ve not


put a lot of effort into thinking about it. I have just been me.” And, lest any reader become too big-


TO ME ROCK TUNNELLING IS


NOT JUST UNDERSTANDABLE, IT IS INSTINCTIVE.


headed about his or her profession, hear these words from a man who has spent a lifetime in that profession and has been hugely successful in it: “Most tunnelling isn’t a lot of hard work: it’s just a hole in the ground.” Really? “People make a right fuss about it but


that’s all most of it is: a round hole in the ground. I’m not kidding.”


May 2026 | 39


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