The ribs of the roof, which splayed out like the fronds of a palm leaf, came together like a giant Lego set of 2194 precast concrete segments assembled one by one. They were then glued together with resin, which had the gluey white consistency of condensed milk.

The first of the precast roof segments was lowered into position on 22 November, 1963. For Danish architect Jørn Utzon, who had won the international design competition for the building in 1957, it had taken six years to get to this point. One worker recalls seeing tears in the Dane's eyes when the engineering staff removed the mouldings from the first perfect blemish-free concrete segments. Some of the 10,000 workers from 90 countries – many of them migrants – teared up too.

Then, each rib segment was painstakingly lowered into place using a Hornibrook-devised cradle and positioned with the aid of a steel erection arch conceived by Gore, but designed by a man considered the real genius of the Hornibrook team: Joe Bertony.

Proved his heroism

Bertony was born in Corsica in 1922 and was intrigued by maths from a young age. He went into the French navy to study naval engineering at Saint-Tropez where he was recruited to work as a spy. During World War II Bertony worked as a French agent and was twice captured by the Gestapo and sent to concentration camps to die. He escaped both times; once jumping off a train almost naked surviving in the snow with few clothes and no food for 10 days. He was awarded the Croix de Guerre by the French government for valour for his wartime activities. General Charles De Gaulle said that during both deportations he proved his heroism to France through "courageous discipline". Much like the "courageous discipline" he showed at Bennelong Point, as one of the many migrant workers known then as "new Australians".

Engineer Joe Bertony working on a model of the erection arch used in the building of the Opera House roof. Fairfax Archive

After the war Bertony fled Europe – like so many who built Sydney's famous sails – looking for a better life. In 1952 he arrived in Western Australia, and headed to Rum Jungle, to work in the uranium mines in the Northern Territory. Bertony lived in nearby Bachelor, 100 kilometres south of Darwin, a town that was built pretty much overnight to house workers, mostly single foreign bachelors without work papers like Bertony. With the money he earned there – along with the good references he got for his impeccable problem solving skills – he found himself in Queensland in the early 1960s where he got a job with Hornibrook. He was then asked to go to Sydney to solve the biggest construction problem they had encountered: the Sydney Opera House.

To a significant extent it was Bertony's complex hand-written mathematical equations that made the roof construction possible; it took 30,000 separate equations just to work out how much stress should be applied. The margin of error could be no more than half an inch when putting the segments together; anything more would have thrown the whole thing out of whack. Everything is curved and there is not one flat plane in the entire roof, so the geometry is highly complex.


When Hornibrook wanted to double-check some of Bertony's calculations by computer, he was relieved. It was frightening for him to think that if he had made a mistake no one would find it in all that mass of numbers. So he welcomed the work of a younger colleague, David Evans, who taught himself computer programming to test the calculations.

At that time in Australia there was only one computer large enough to cope with such a job: the IBM 7090 at the Weapons Research Establishment in South Australia. This was part of the Defence Research Centre that tested long-range missiles for the armed services at Woomera.

Stage one of the build was a podium built to resemble a Mayan pyramid. Fairfax Media

So Evans spent one week a month working the night shift in South Australia since that was the only time the computer was free. At no point were Bertony's calculations incorrect. Evans later said of his colleague: "It could be argued that Hornibrook chief Corbett Gore could have found another person, or a team of people, to do what Joe did, but I doubt if there was anyone with Joe's genius to see how to develop the telescopic truss and to build the ribs with it, or to do a dozen other things of importance on that site. It would have taken many minds and many rounds of trial and error, and a much longer time and a much bigger budget, to get those ribs in the air if Joe hadn't been there. Other solutions would have lacked his elegance and genius."

Return to bridge building

After the Opera House Bertony went back to bridge building. His other major engineering feats include Sydney's Roseville Bridge, and the Hume Highway's Pheasants' Nest Bridge across the Nepean River. He's 96 now, a widower still living in his home in the northern Sydney suburb of Hornsby. He drives around in a recently purchased electric car and is working on a wind technology project in Scotland.

Bertony, who owns the copyright to the longhand equations used to design the erection arch, gifted them to the Museum of Applied Arts and Sciences (MAAS) and they are now part of the collection at the Powerhouse Museum. They are beautifully rendered in the neatest of scripts. What astounds him whenever he looks at the sails of the Sydney Opera House today, is that he helped build them with little more than schoolboy geometry.

Helen Pitt is author of The House: the dramatic story of the Sydney Opera House and the people who made it, published by Allen and Unwin on August 15.


One worker recalls seeing tears in the eyes of Danish architect Jørn Utzon when the engineering staff removed the mouldings from the first perfect blemish-free concrete segments. Fairfax Media

The last and highest segment on the roof of the Sydney Opera House is moved into position, 5 April 1967. ? MARTIN BRANNAN

Joe Bertony went on to work on Sydney's Roseville Bridge and the Pheasant's Nest Bridge across the Nepean River. Helen Pitt