The Old Coat hanger The Sydney Harbour Bridge

“The Old Coat hanger” The Sydney Harbour Bridge - J. J. C. Bradfield & Ralph Freeman -

Harbour Bridge -1, 650’ Steel Arch Main Span - Worlds broadest roadway: 8 lanes, 4 rail lines, 2 walkways - World’s 2 nd longest arch bridge when completed - Bayonne Bridge main arch span: 1, 675’ - Connects northern Sydney to the southern urban center - Considered Sydney’s most famous landmark 2 nd to Opera House - Average traffic per day: ~ 160, 000 Vehicles

Sydney Harbour

Other Proposals for the Crossing

Design bids by Ralph Freeman with Dorman Long & Co. Design Main Span Cost * Cantilever 1, 600’ $22, 200, 000 Cantilevered Arch 1, 650’ $18, 200, 000 Arch 1, 650’ $17, 100, 000 * Pounds Sterling converted to American dollars by £ 1 = $4. 8665 Table and illustration from April 1932 Civil Engineering

Sydney Harbour Hellgate

Upper Chords - Upper Arch Chord provides virtually no load bearing capacity, only stiffness - Originally designed for upper chord to end within towers as at Hellgate - Architectural consultants decided that visually separating the upper chord from the towers conveys sense of structural independence from the masonry towers

Upper Chord Differences

Construction -Each Arch half anchored to abutment. . . …then cantilevered out with use of “creeper cranes” that traveled along the upper arch chord

Deck Construction

Bridge Opening - Bridge opened on Saturday March 19, 1932 by J. T. Lang, Prime Minister of New South Wales - Estimated 300, 000 to 1 million people in attendance - Public allowed to walk across roadway deck, an event only repeated on the 50 th anniversary of opening - Capt. Francis De Groot of the paramilitary group the New Guard on horseback charged and slashed the ribbon before the bridge could be declared open

Bridge Climb! - Thousands of people take guided “bridge climbs” every year. - In order to make the Bridge Climb you must: - pay around $150 - Remove all loose articles (including cameras) - Be in good physical health and not be pregnant - pass a breathalyzer test.

Summary – The 3 S’s - Social: The public interacts with structure through pylon museum & bridge climb. Bridge tolls payback construction and maintenance costs (current bridge toll $2). Arch form cheapest solution. - Scientific: Largest & 3 rd longest steel trussed arch (1650’ span). Load tested with 96 steam locomotives in various configurations. Load transferred to abutments entirely through lower arch chord. - Symbolic: Imitative of Hellgate, but on much larger scale. Massive structural form visually separated from purely decorative masonry towers. An Elegant representation of Sydney’s unity and perseverance through financial depression.