• History
  The first plans for bridging the Derwent close to Hobart date back to 1832. One of these early designs by Captain Jacobs was for a floating structure consisting of short spans in timber bridging between barges anchored across the river. It was not until 1943 that the first bridge was completed, this being a floating arch bridge and lift span.

  Following the completion of the floating arch bridge in 1943 the growth of population on the Eastern bank of the River Derwent was rapid; by 1955 the bridge was unable to carry the number of vehicles required to use it without extreme congestion. In addition after careful examination of the floating part of the arch bridge following a serious storm from the south, it was decided the life of this bridge in its present position was limited.
  

• Towers and Lift Span
  Lift span opening, 180 ft. clear between pier protections.
  Vertical clearance of lift span, 145' 6" at Mean Water Level.
  Weight of towers and lift span, approximately 900 tons.
  Weight of lift span only, 350 tons.
  Weight of steel in lift span towers, 280 tons.
  Weight of steel in lift span, 192 tons.
  Roadway width on lift span, 22 ft.
  Time of opening, 2 minutes.
  
  
• Lift Span Machinery
  Two 50 H.P., 600 R.P.M electric motors in operating house over centre of span. There were also auxiliary motors for opening in case of power failure.
  
  
• Floating Arch
  A floating arch of two reinforced concrete sections anchored to the eastern shore abutmentand lift span. Joined at the centre by one 12 3/4" vertical pin. Each half of arch cast in ten 131' 6" lengths, one 124' 6" and one 138' 6". Average weight of each length is approximately 1,000 tons. Weight of each length is approximately 25,000 tons. Length of roadway on arch is 3,154 ft. Overall width of arch at deck level is 40' 6" including roadway, footway, kerbs and ledges. Total concrete used in arch, 11,000 cubic yards. Total steel used in arch, 3,100 tons.
  

• Miscellanious
  Construction Authority - Public Works Department of Tasmania.
  Designed and patented, A.W. Knight, Esq., Charted Engineer..
  Builders, Timms Bridge Construction Co Pty Ltd, initially, and then Hobart Bridge Company Ltd.
  Length of roadway between shore abutments, 3,807 ft.
  Approximate cost, 500,000.00 pounds.
  Construction Commenced, 1938.
  Arch floated into position, 22nd October 1943.
  Damaged by storm, 4th December 1943.
  Opened to toll traffic, 22nd December 1943.
  Tolls abolished, Midnight 31st December 1948.
  Bridge closed to traffic, 17th August 1964.
  Arch removed and stored, 18th and 19th August 1964.

• Disposal
  In early November 1970, one of the moored half-arches of the Hobart Bridge sank in Geilston Bay. It was successfully raised on 23 February 1971. Each half-arch was cut into three lengths of 161 meters long and weighing 4000 tonnes. The three sections from the raised half-arch were disposed of, two sections on 24 and 25 May 1971 at Betsey Island, and the third section on 16 July 1971 off Droughty Point in Ralphs Bay.

  Two of the three remaining sections from the second half-arch were disposed of by sinking them off Betsey Island on 16 and 17 November 1971. The final section was positioned and sunk at Alonnah for use as a breakwater on 27 June 1972.
  

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Last Update: 05 September 2001