Spanning 345 metres and boasting 120-metre tall diamond-shaped pylons, Sydney’s Anzac Bridge proudly stands tall over Johnstons Bay connecting Glebe Island and the inner suburbs of Pyrmont and Darling Harbour.
Designed and built between 1989 and 1995, the eight-lane reinforced concrete, cable-stayed bridge is the longest of its kind in Australia and serves as an integral piece of the harbour city’s road infrastructure network.
Its genesis, in part, can be credited to world-renowned civil engineering alumnus Ken Wheeler who headed the design team at the Roads and Traffic Authority (now Roads and Maritime Services).
“I felt honoured to be given the responsibility for leading the design team for a major bridge incorporating new technology,” says Ken, who graduated with a Bachelor of Engineering (Civil) from the Faculty of Engineering and Information Technologies in 1976.
“We were a small group tasked with designing a new form of bridge incorporating innovative structural concepts and employing state-of-the-art methods of construction.”
The Anzac Bridge had been intended to replace the existing Glebe Island Bridge, which was built in 1901 but proved inadequate in dealing with traffic flows by the 1990s.
Unbeknownst to Wheeler, designing Sydney’s newest bridge would not be straightforward.
“The initial preferred design option was a 200m main span-balanced cantilever, concrete box girder bridge with the two main V-shaped piers in the water,” explains Ken.
“However, the alignment of the bridge was close to a set of submarine high voltage electrical cables which crossed Blackwattle Bay and serviced Sydney’s CBD.
“It was determined that the integrity of these submarine cables was at an unacceptable risk should there be a ship collision with the main bridge piers. We decided to move the piers out of the water, lengthening the span beyond the range of a balanced cantilever bridge and into the range of a cable-stayed bridge.”
As Ken and his team soon discovered, there were many challenges associated with this decision to design what would now be the first modern day cable-stayed bridge in Australia.
The team then needed to incorporate new technologies such as analysis methods and stay cable technology (materials, corrosion protection, installation methods) into the mix.
They also had to understand the learnings from what had and had not previously worked well on similar international projects, such as the effects of rain and wind vibration of the stay cables which became a real issue near the end of construction.
“Under conditions of moderately light winds with coincident rain, the stay cables started to vibrate and the movement of the cables could be alarming to the bridge user,” explains Ken.
“This was a phenomenon only recently observed in some Japanese bridges and we needed to quickly understand the causes and how this could be controlled.
“Nowadays this vibration can be simply controlled by adding dampers to the cables or incorporating a spiral bead on the outside of the cable ducting to drain away the rain. Both of these solutions have since been successfully incorporated on the Anzac Bridge.”
Now semi-retired, Wheeler’s 40-year career has seen him lead the bridge design of such prominent projects as the Bolte Bridge in Melbourne, the main spans for the Gateway Bridge in Brisbane, and the ASEAN Bridge in Sarawak, Malaysia.
He also managed the construction engineering for the cable-stayed Centennial Bridge over the Panama Canal and the Phu My Bridge in Vietnam, and leading the multi-disciplined design team for Bangladesh’s Padma Multipurpose Bridge, currently under construction.
Ken was recently awarded Engineers Australia’s 2017 John Connell Gold Medal, a prestigious accolade for structural engineers. He also helped develop the Australian Bridge Design Code AS5100 and has represented NAASRA, Austroads and Consult Australia on Standards Australia committees for steel structures, composite structures and bridge design.
It’s the culmination of a career that started with his decision early in life to study at the University of Sydney. Aside from his civil engineering degree, Ken also completed a Bachelor of Science in 1974 and Master of Engineering Science in 1984.
“As a young boy I always had a keen interest in building things and solving problems and growing up, the University of Sydney was highly regarded for engineering, so it was there that I wanted to complete my studies,” reveals Ken.
“Their engineering courses provided a sound technical background to my career, for which I am grateful. Engineering qualifications from the University of Sydney are highly regarded internationally, particularly in South East Asia, and this has been of great assistance in being accepted by clients in these countries.
“I am pleased that there have been a number of opportunities where we have been able to recommend the University academic staff as corroborators or ask them to confirm our technical approach in specific engineering areas, such as during the detailed design of the Anzac Bridge and the Gateway Bridge.”