Two weeks ago, on the 2 October, Gladesville Bridge celebrated its 50th birthday.
When it was completed in 1964, the bridge was the largest concrete arch bridge in the world, a record that stood until 1980. It was also one of the first to be designed by computer, by a young engineer called Tony Gee working for the engineering firm G Maunsell & Partners in London.
The bridge replaced an earlier steel truss bridge built in 1883. This bridge was one of several built in the 1870s and 1880s to take road traffic across the various rivers and coves as you head west from the city, replacing punts and ferries on the way. Its nearest neighbour, Iron Cove Bridge (still standing) was completed two years before.
The original low steel bridge went across the Parramatta River at a narrow section at Huntleys Point. The last span on the western side was a swing span that could be opened to allow boats to pass through, heading up or down river. A number of jams in the mechanism in the 1920’s and afterwards however stretched the public’s patience. The sandstone piers at either end of the bridge, joining it to the land are still in place today.
By the mid-1950s the old bridge was past its use by date. As a single lane each way, the bridge could no longer cope with the increasing amount of vehicle traffic and traffic jams became increasing common. The County of Cumberland scheme, a new planning scheme for Sydney released in 1951 had suggested the need for new bridges and freeways, with Gladesville Bridge as one of the proposals.
The first plan was for another steel bridge until Maunsell’s idea for a concrete span was accepted. The idea of a concrete bridge of the scale required was a bold and innovative plan for the 1950s, and had not been tried before. Tony Gee, just 22 and recently graduated, was sent out to manage the project. He suspected that the company thought getting the job was a long shot so they sent the cheapest employee.
Gee wrote and designed computer programs to design the massive structure and work began in December 1959. The arch consisted of four concrete box arches constructed independently, which share the load of the road deck equally. Each arch was built in sections and transported to the site where they were constructed on formwork, in the same basic style of traditional stone arch bridges. When each arch was finished, the concrete load acted to lift the arch from the formwork which was then moved sideways so the next section could start.
It seems Sydney had a thing for innovative, cutting edge concrete design that no-one else was quite confident or crazy enough to take on at this time. Just down the harbour a bit the start was being made on the other concrete engineering masterpiece, the Sydney Opera House.
As with any large scale construction in Sydney, especially its inner suburbs, the construction resulted in demolitions of many houses along its route and the route of its two associated bridges, the Fig Tree Bridge and Tarban Creek Bridge. However, it had been planned to be part of the northwest freeway which was abandoned due in part to protests about the proposed demolitions of hundreds of houses in Glebe.
The bridge was opened on 2 October 1964 by visiting Royal Princess Marina, Duchess of Kent.
There is plenty more on the Bridge here, with videos of its construction and opening.