Tomorrow is a significant birthday for one of Sydney’s bridges. The Gladesville Bridge which spans the Parramatta River is turning 50 years old! The structure was officially opened to the public on 2 October 1964 by Her Royal Highness Princess Marina, Duchess of Kent. The Gladesville Bridge was one of 13 bridges built by the Department of Main Roads during the 1960s, but it is certainly the most spectacular. Other concrete bridges included the Fig Tree Bridge (1963) over the Lane Cove River at Hunters Hill, the Captain Cook Bridge (1965) over the Georges River, and the Roseville Bridge (1966) over Middle Harbour. The Gladesville Bridge replaced an earlier two-lane multi-span lattice iron bridge that had been built in 1881. The first Gladesville Bridge opened up road transport to the city. It remained the only roadway crossing of the Parramatta River to take road transport into the city until the Sydney Harbour Bridge opened in 1932. A horse-drawn bus service started up, offering an alternative to ferry transport. Then in 1910 the tramline was extended through to Gladesville and eventually to Ryde. This reliable transport along the Great North Road, later Victoria Road, encouraged suburban residential subdivision. By the 1950s the two-lane Gladesville Bridge had become a bottle-neck and a major congestion point on Sydney’s roads, particularly in peak hour traffic. The new Gladesville Bridge was an engineering marvel and it claimed two international honours. It was the first large bridge in the world to be designed by computer. The enterprising design was by consulting engineers G Maunsell and Partners of London. At the time of construction, the Gladesville Bridge was the world’s longest concrete arch span, with a clear span of 1,000 feet or 305 metres. The bridge held this honour for 16 years. The arch consists of four concrete-box arches constructed independently and then stressed laterally together. This shares equally the loads from the deck structure above. The placement of each of the concrete-boxes was a slow, precise business. The completed Gladesville Bridge weighs 78,000 tons, almost double the weight of steel in the Sydney Harbour Bridge. Like the Sydney Harbour Bridge before it, the emergence of the span across the Parramatta River captured the imagination of Sydneysiders. Artists sketched the massive structure and sightseers snapped souvenir photographs. A public relations film was commissioned by the DMR to share with the general public the massive engineering enterprise. Each aspect of the construction is narrated in layman’s terms, accompanied by a cocktail lounge music score - you can view the clip here. It is a real retro piece that has been digitised by Australian Screen as part of our audiovisual heritage and the full 30 minute film can be viewed on the Roads and Maritime Gladesville Bridge 50th anniversary page. The Gladesville Bridge connected Gladesville and Drummoyne and was envisaged to form part of the North Western Freeway that would connect the city to Newcastle through Glebe, Annandale, Lane Cove and then connect up with the freeway at Wahroonga. Community protests led the Wran government to abandon the project in 1977. The Bridge’s anniversary is being marked by the unveiling of an Engineering Heritage International Marker. Roads and Maritime have also digitised photographs, programs, oral histories and films associated with the bridge. Happy 50th birthday Gladesville Bridge! References Department of Main Roads, The Roadmakers: A history of main roads in New South Wales, DMR NSW, 1976 Margaret Farlow and Angela Phippen, ‘Gladesville’, Dictionary of Sydney, 2008, http://dictionaryofsydney.org/entry/gladesville  Don Fraser (ed), Sydney: From Settlement to City – an engineering history of Sydney, Engineers Australia Pty Ltd, Sydney, 1989 Roads and Maritime, ‘50 year anniversary of Gladesville Bridge’ website --- If you missed Lisa’s segment with Mitch on 2SER Breakfast this morning you can catch up on the podcast via their website. Don’t forget to listen in next Wednesday morning for more Sydney history brought to you by the Dictionary and 2SER at 8:20am, 107.3