Ian Firth: How Do Engineers Balance Risk And Beauty In Design?

Nov 8, 2019
Originally published on November 8, 2019 11:51 am

Part 4 of the TED Radio Hour episode Risk.

About Ian Firth's TED Talk

As a bridge designer, Ian Firth is responsible for building safe, reliable bridges. But he also manages the risk involved with designing bridges that are beautiful — not just functional.

About Ian Firth

Ian Firth is a structural engineer and bridge designer based in the UK.

His projects range from smaller structures, like the Bridge of Aspiration in London's Covent Garden to the large Messina Strait Bridge in Italy.

Firth is Chairman of the British Group of the International Association for Bridge and Structural Engineering. He is an Honorary Fellow of the Royal Institute of British Architects.

Firth holds a BSc in civil engineering from Bristol University, and an MSc in structural steel design from Imperial College London.

Copyright 2020 NPR. To see more, visit https://www.npr.org.


It's the TED Radio Hour from NPR. I'm Guy Raz.


RAZ: When I say the word risk, what comes to mind?

IAN FIRTH: Uncertainty - the word risk and the word uncertainty are connected in my mind because everything I do is uncertain, in a way.

RAZ: This is Ian Firth.

FIRTH: Basically, I'm a designer. I love to design bridges big and small.

RAZ: And when Ian says that, he's being kind of modest. He's actually one of the world's leading bridge engineers.

FIRTH: But risk also implies responsibility and reliability. You know, I need to be able to apply a responsible, professional approach to managing that risk.

RAZ: And that sense of responsibility is always at the top of Ian's mind because thousands of people in cars and trucks and on bikes and trains cross his bridges every single day. I mean, you think about cities like London or New York or Istanbul...

FIRTH: Definitely.

RAZ: They could not function without bridges.

FIRTH: I know.

RAZ: Like, we don't think about that. Bridges have enabled those cities and many around the world to become what they've become.

FIRTH: Absolutely right. Just about every city in the world - you know, almost every capital city and many, many other cities - owe their existence entirely to a bridge across a river because, you know, that tends to be the place - certainly when they were establishing those things many hundreds of years ago - that people could get to by boat. Materials, trade, all the kind of transportation and trafficking around the world would come there by boat in some shape or form, so bridges became the thing to do.

So in London, of course, the Romans built a bridge across the River Thames. And, you know, every big city owes their existence to a bridge of some sort. And very often also, that bridge has become iconic - I mean, certainly in the Bay Area, you know, the Golden Gate Bridge. I mean, which one do you choose? I suppose you have to say Brooklyn Bridge in New York would be the sort of iconic structure that then defines the place, the spirit of the place, even. And without it, the place doesn't even function.

RAZ: Ian Firth continues his idea from the TED stage.


FIRTH: It's hard to imagine a civilization without bridges because they're so essential for growth and development of human society. But they're not just about a safe way across a river or an obstacle. Bridges are enormous features in our landscape - not just enormous. Sometimes, they're small ones. And they are really significant features. And I believe we have a duty to make our bridges beautiful.

But technological change happens relatively slowly in my world, believe it or not. And the reason for this can be summarized in one word - risk. Structural engineers like me manage risk. We are responsible for structural safety. That's what we do. And when we design bridges like these, I have to balance the probability that loads will be excessive on one side or the strength will be too low on the other side - both of which, incidentally, are full of uncertainty usually. And we have to make sure that there's an adequate margin for safety between the two, of course.

But innovation is vital. It's - as an engineer, it's part of my DNA. It's in my blood. I couldn't be a very good engineer if I wasn't wanting to innovate. But we have to do so from a position of knowledge and strength and understanding. There's no good taking a leap in the dark, and civilization has learned from mistakes since the beginning of time, no one more so than engineers.


RAZ: Because you don't want a bridge to just be functional. You want it to be beautiful and innovative, right?

FIRTH: Definitely, yeah.

RAZ: I mean, when bridge design began, was beauty a part of - was it baked in as a design element? Or was it just a functional thing in the early days?

FIRTH: You know, I hope that human beings throughout time have considered beauty to be something to be celebrated. You know, don't you? I like to think that even the very earliest Homo sapiens - you know, the earliest people - would have appreciated beauty. And therefore, when they made something which they felt wanted to be beautiful and didn't just need to be utilitarian, they would shape it and form it in some way. You look at some of the great stone arches that the Romans built. They have a majesty about them. They have an elegance about them. And so yes, you know, society demands elegance and beauty around them.

RAZ: Yeah. I mean, but sometimes - right? - you can take a risk on design that totally backfires. Like, you mentioned the collapse of the Tacoma Narrows Bridge...


RAZ: ...In 1940. And I remember seeing the videos of that - just - from your talk. I'm just trying to remember, that - was it an earthquake?

FIRTH: No, no. It was wind...

RAZ: It's wind.

FIRTH: ...1940...

RAZ: Of course, yeah. What...

FIRTH: ...A strong but not extreme wind which set up this oscillation in the bridge deck. It was a super light bridge. And, you know, designer Leon Moisseiff really sort of pushed the boundaries too far.

RAZ: Yeah. I mean, there's this just infamous video of this bridge, right? And it was super narrow, and you could literally see it swaying back and forth before it collapsed. It was basically this moment where, I guess, primarily, like, designers looked at this and said, OK. We need to rethink how we accept risk, right? I mean, because the designer, Moisseiff, was taking a huge risk here, right?

FIRTH: Yeah, so Moisseiff was no stranger to long-span bridge design. He had worked on them before. But here at Tacoma, he was taking that risk of, you know, can I make it that much more slender? Obviously, he'd done some analysis. He'd done some calculations. But at that time - 1940 - it was a great shock. Everybody was saying, what on Earth went wrong? And for 10 years, there was a complete dearth; no big, long bridges built anywhere.

RAZ: When most people are on a bridge, they don't think about the possibility that that bridge could collapse. They're just driving across it. And...

FIRTH: Right.

RAZ: We take it for granted. I mean, the bridge is going to be there probably forever, at least in our minds. But how much does the risk or risks involved with a bridge factor into how you even approach a blank sheet of paper when you're thinking about where to begin?

FIRTH: So the question of risk is very closely associated with reliability and confidence. If you like, confidence and risk are sort of two sides of the same thing - that I design - when I design something - and it's based very largely on a knowledge of what works. And that's born out of experience. And that experience has involved working through calculations and analysis and so on. So most engineers don't actually ever think about it because all they're doing is applying those formulae. But if they were actually to stop and think about it, everything they deal with in the design of a bridge is uncertain - everything. And so the ending structure, of course, has got a whole lot of uncertainty in it. But collapse - let's be honest. OK, bridge collapse is very rare.

RAZ: Yeah.

FIRTH: But everything we design is based on some uncertainty.

RAZ: I mean, even with all of those equations and the testing that's involved, zero risk doesn't exist. This is something that we should all, I guess, accept; that there is no such thing as a perfectly foolproof bridge.

FIRTH: Absolutely. There is no such thing as zero risk, whether we're talking about bridges or anything else (laughter).

RAZ: Yeah, right.

FIRTH: People like to think of it. You know, they say, I don't want to - any risk on this project, you know? And, you know, you have to say, well, actually what you mean is you want the risk to be manageable and low enough to be acceptable, you know? So what we have to do is to make sure that it's sensible.


FIRTH: Our bridges need to be functional, yes. They need to be safe, absolutely. They need to be serviceable and durable. But I passionately believe they need to be elegant. They need to be beautiful. Our bridges are designed for a long time. We tend to design for a hundred years-plus. They're going to be there for an awfully long time. Nobody's going to remember the cost. Nobody will remember whether it overran a few months. But if it's ugly or just dull, it will always be ugly or dull.


FIRTH: Beauty enriches life, doesn't it? It enhances our well-being. Ugliness and mediocrity does exactly the opposite. And if we go on building mediocre, ugly environments, it's something like a large-scale vandalism, which is completely unacceptable. Thank you.


RAZ: That's Ian Firth. He's an engineer and bridge designer. You can see his full talk at ted.com.

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