Bridgewater Bridge and Causeway Engineering Heritage National Marker Granton, Tasmania, Australia
By whitewebbs on 12-Sep-20. Waypoint GA17074

Another Engineering Heritage National Marker

While out and about caching I noticed a new Engineering Heritage National Marker had been placed at Granton. (I have tried contacting the previous CO of this series but have had no response, so decided to list the cache myself).

The Bridgewater Bridge and Causeway was recognised by Engineers Australia with an Engineering Heritage National Marker in 2018.

The following was taken from Engineers Australia website:

"The current Bridgewater Bridge (No4) construction commenced in 1938 but was halted during the Second World War, with the bridge opening to limited road traffic in 1942. The full deck was completed in 1944, the lift span in August 1946 and the rail crossing in October 1946. River navigation through the misaligned spans of the three bridges during construction was difficult, so two of the redundant bridges were demolished to aid navigation."

and from the same site from the Nomination for Engineers Australia Engineering Heritage Recognition:

"Rarity

 The Bridgewater Causeway was one of Australia’s largest convict projects and one of the most expensive. Work commenced in 1830, using up to 280 convicts at one time on the site, hand quarrying the stone and then transporting the stone by wheel barrow.

 The first bridge to cross the gap between the causeway and the northern banks of the Derwent River was designed and constructed by Thomson and Blackburn, both convicts that received conditional pardons a few years after their arrival. Work began in 1846, with timber for piles and superstructure sourced from Mt Dromedary some seven kilometres away from the bridge site, also using convict labour. Chutes were built for the timber trunks to slide down from the Mount to the Derwent and floated up to the construction site.

 The current Bridgewater Bridge is the largest surviving lift span bridge in Australia and the only one of its kind in Tasmania.

 The current Bridgewater Bridge may well be the oldest all-welded railway truss bridge and oldest all- welded railway lift span existing in the world.

Representativeness

 The current Bridgewater Bridge is the largest surviving lift span bridge in Australia and the only one of its kind in Tasmania. It has survived for over 70 years and is expected to continue for some 10 years following a recent refurbishment project in 2012.

 The current Bridgewater Bridge may well be the oldest all-welded railway truss bridge and oldest all- welded railway lift span existing in the world."

Please take a photo of yourself or GPSr with the Engineering Marker at GZ.