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Interview - Tristram Carfrae: “I’ve had luck all my life"

Arup deputy chairman, engineer for the Garden Bridge and designer of the Beijing Olympic Aquatic Centre Tristram Carfrae picked up his Gold Medal from the Institution of Structural Engineers last month. Jackie Whitelaw went to meet him.

Tristram Carfrae is unique among structural engineers in being able to say one of his projects has been judged more desirable even than lipstick and high heels. That scheme was the Beijing Olympics Aquatic Centre – the Water Cube – and in 2008, women’s magazine Marie Claire placed it in top spot in its list of the world’s 101 most sexy things.

It is an accolade he is incredibly proud of because the beauty of structural engineering received mainstream recognition and because it demonstrated that the right design can resonate positively with the public, something which he believes all engineering design should be doing.

“I was chosen apparently because I knew about steel and lightweight structures rely on steel. But all I had said was that I knew nothing about concrete.”

As he said when his Gold Medal award was announced: “The next decade will be full of opportunity for structural engineers; engineering will become more relevant to ordinary people’s lives as we respond to challenges like climate change and sustainability, designing the new, resilient structures required for increasingly challenging environments – while also attempting to to make a better built environment.”

The Beijing Aquatic Centre, he says, is his best engineering solution to date.

“We did something then that no one had ever done before,” he says. “We got the engineers to tell the architects what the perfect swimming centre would look like.” That included the acoustic engineers saying they didn’t want a glass box as it reflects sound but the mechanical engineers saying they needed a glasshouse to keep the costs of heating the water down. Out of that came the solution to use ETFE plastic that let the sound out and the light in. 

“The right engineering solution led to the right structure” as Carfrae says and the deep blue box of bubbles became for the public the enduring symbol of the 2008 Games, more even than Arup’s other triumphs, the Bird’s Nest stadium and the CCTV tower.

The Aquatic Centre was, excuse the pun, something of a watershed moment for Carfrae himself. Use of ETFE, if you look back over his career, was inevitable given that he had pioneered and developed lightweight structures since the early 1980s. “But up until Beijing all my structures had been about efficiency. Afterwards I became more poetic,” he says.

“But I was incredibly fortunate to be part of the first generation using computer design. I know we haven’t fully explored its use yet, but there won’t be the same vertical curve."

Singapore’s Marina Bay double helix bridge, the AAMI Park Stadium in Melbourne and 111 Eagle Street Brisbane are all late flowering Carfrae designs.

Carfrae is now 55 and has spent his whole career with Arup which he joined fresh from a Cambridge degree in mechanical sciences. 

His decision to study engineering was the result of seeing his mother at work as an architect. “I remember clearly saying to my mum at 16 that I fancied being an architect. She took one look at me and said no,no,no! You are not arty enough but you could be an engineer and work with a firm like Arup who collaborate well with architects. I’d forgotten that until I joined Arup and then it all came back to me.”

His whole career, he says, has hinged on what happened in the first week at Arup in 1981. In those days all the new graduate employees gathered together for a residential two week induction. “Someone stood up during that and talked to us about lightweight structures,” Carfrae remembers. “A week later they asked who wanted to join and I was one of about 15 who put their hand up. 

“I was chosen apparently because I knew about steel and lightweight structures rely on steel. But all I had said was that I knew nothing about concrete. In fact I knew nothing about either!”

"I found a colour VDU sitting idle – no one had worked out what to use it for – and managed to make it draw lightweight structures."

Starting out in a whole new field suited him down to the ground. “There were no codes of practice, no regulations, you had to work everything out from first principles. And we were just moving from physical models to using computer analysis so I became a computer programmer. I helped write something then that I am still using now – the Fablon non linear analysis program. That was just a list of numbers to start with, numerical co-ordinates for the structure, fine for engineers but not good for explaining the structure to clients and architects. 

“But I found a colour VDU sitting idle – no one had worked out what to use it for – and managed to make it draw lightweight structures. Then I photographed the screen with a polaroid camera on a tripod under a black sheet like a Victorian. Even then, I could only get an image by taking the photograph after dark with the lights off.”

Carfrae spent a year with lightweight structures but with no live projects moved on to join the team on the Richard Rogers Lloyds of London building. 

It was his first spell working with Sydney Opera House roof engineer Peter Rice who with John Thornton was leading the Lloyds engineering. Carfrae helped design the steel for the atrium using U-frame theory for the stability of the out- stand truss chords, as he says “a common enough technique for bridge design then but rarely used in buildings”.

In 1983 he was back working on lightweight structures, this time on a real project, Michael Hopkins research laboratory for Schlumberger in Cambridge which was the first major use of PTFE coated woven glass fibre fabric in the UK. “That was very exciting; I wrote the program to calculate the cutting patterns.”

“That’s the advantage of moving place; you don’t have a whole history burdening you. People thought I was more experienced that I was and I took the chance offered.”

It was a startling first three years of career in hindsight. Are there the same opportunities for young people now? “That’s difficult to answer,” Carfrae says. “Arup was a smaller place and scale changes culture whether you like it or not. You could move about more freely but we are by no means stolid now.

“But I was incredibly fortunate to be part of the first generation using computer design. I know we haven’t fully explored its use yet, but there won’t be the same vertical curve.

“That said what is changing is that engineers are able to work faster. Ove Arup always said that if architects, engineers and builders could talk to each other more there would be better buildings. The problem in the past has been that engineering calculations take a long time and we were out of the loop. Now we have become faster we can get more involved.”

Carfrae’s next opportunity came when he moved to Australia. “Almost as soon as I landed Arup won Sydney Football stadium with architect Philip Cox and they needed me to sort out the roof so I was given a fantastic project on a plate.

“That’s the advantage of moving place; you don’t have a whole history burdening you. People thought I was more experienced that I was and I took the chance offered.”

My most formative job in Australia was the Brisbane Convention and Exhibition Centre,” Carfrae says. “It introduced me to the way construction is done. A lot of major public jobs are tendered for design and construct so the biggest and most reputable contractors all compete and their reputation depends on them doing a good job. They get their architects and engineers involved right from the start and it’s all about speed, efficiency and cost control. 

“I’ve had luck all my life and here is where I understood that."

“For Brisbane we decided to do a hyperbolic paraboloid steel shell and I committed to using only 50kg/m2 of steel.

“I’ve had luck all my life and here is where I understood that. I had specified T50 steel reinforcement to economically increase the tensile capacity of some steel tubes. But then I was told they didn’t make those in Australia. They used Y’s and at 40mm maximum. Before I had time to say anything to the contractor he had called to say he’d found a stockpile of T50s that he’d bought cheap and he wanted to use. So I was seen as supremely clever.”

For a two year interlude he came back to the UK in 1998 to help run Arup’s architectural practice, Arup Associates, “which had just won the Manchester Commonwealth Games stadium and the roof was mine.”

“Working with Arup Associates changed my approach to design,” Carfrae says. “I was interested in what all the different engineers in the team did. I moved from being  a technical structural engineer to an integrator, picking up an understanding of all the other disciplines. Back home in Sydney, Khalifa stadium for the Asian Games 2006 was soon on the books and then it was on to the heights of Beijing and groundbreaking projects like the Helix bridge.

In 2007 Carfrae was promoted to be global leader of the building sector practice and in 2011 he came back to the UK to be at the centre of the Arup business.

“I found that a difficult transition,” Carfrae says. “I hadn’t realised how much a part of the Sydney industry I had become. In London I had 2,500 people working with me but I was unknown to them and think I was slightly unwelcome.

“Three years and more on its becoming good and now I am deputy chairman I am out of people’s everyday hair. The developing relationship with Thomas Heatherwick has been a particular pleasure for Carfrae. “I saw his work on the British pavilion at the Shanghai expo – the best space that I have ever been in – and wanted to work with him after that. The bridge is going to be the most beautiful environment. I’m working with Mike Glover, another Gold Medal winner, and the only niggle is that Thomas came up with structural layout before we were involved which is slightly frustrating,” he says, smiling.

"Now we can represent accurately every element of the end product we will effectively be manufacturing. So will builders become manufacturers or will manufacturers become builders?"

Carfrae will ultimately probably return to Australia but has at least ten years in which to make even more of a mark at Arup. “What do I want to achieve? I want to spend half my time on projects with clients to demonstrate that though we are a very large firm, Arup can still be led by people practising professionally. 

“I am intrigued by the mechanisation of the industry too. Now we can represent accurately every element of the end product we will effectively be manufacturing. So will builders become manufacturers or will manufacturers become builders? And if we will be employing less of the “wet” trades, how will that affect the economy, education and training?

“And I am fascinated by the potential of timber. The more timber we put in buildings the more carbon dioxide we lock up. Construction is the only place to put it that will lock it away for 50 to 100 years. 

“Our focus as an industry and a profession could change to being carbon positive! The potential is enormous.”

This article first appeared in The Structural Engineer