While many Tasmanians have heard the story, some people may not realize that there is an important piece of history next to the Tasman Bridge as they travel between Hobart’s eastern and western coasts.
Most important points:
Nearly 50 years after the Tasman Bridge disaster, CSIRO and an engineering group have produced the first complete 3D model of the wreck, bridge, riverbed, and shoreline. Road sections that fell into the river during the incident The impact of Lake Illawarra lie next to the Tasman Bridge, where more than 70,000 vehicles cross every day.
SS Lake Illawarra lies at the bottom of the River Derwent after it crashed into several bridge pylons on Sunday, 5 January 1975, killing 12 people.
Although the 140-meter bulk carrier is popular with divers, most of us have a hard time imagining what the wreck of Lake Illawarra looks like.
That is, until now.
Nearly 50 years later, CSIRO and Jacobs Engineering Group have produced the first complete 3D model of the wreck, bridge, riverbed, and shoreline.
“It gives a much more detailed and accurate representation of what’s on the seabed, and of course the wreck and piers themselves,” said Jacobs survey technical director Paul Digney.
The crash, around 9:30 a.m. on a Sunday, killed 12 people, with one man never found. (ABC)
The project took four days to complete, using multi-beam sonar and a terrestrial laser scanner to map features above and below the waterline.
“We [CSIRO and Jacobs] have been able to improve the resolution of the data so you can see more detail of the wreckage,” said CSIRO hydrographic surveyor Craig Davey.
“Now we have a full seafloor and bridge dataset, which is interesting”.
The impact of SS Lake Illawarra caused three unsupported bridge spans and 127 meters of roadway to collapse. (Tasmanian Archives and Heritage Office)
The new map also gives a clearer picture of the exact position of the wreck, revealing that the ship’s bow sits next to the third tower on the east bank of the bridge, and the boat is at a 45-degree angle to the center the bridge—The river points.
The wreck lies 125 meters offshore in approximately 35 meters of water and at its highest point about 15 meters below the waterline.
Craig Davey of the CSIRO mapped the wreckage. (ABC News: Luke Bowden)
The new data has been presented to the state government as it prepares for the Tasman Bridge’s first major upgrade since its repairs in 1975.
“We’ve informed the Department of State Growth that this data is available, and we’re optimistic it will be of some value. It certainly gives a much clearer picture of everything they’ve had in the past,” Digney said.
The wreck lies in approximately 35 meters of water. (Supplied: CSIRO)
The new high-resolution map of the Lake Illawarra wreck also offers the opportunity to compare the data with a 2014 study, track any deterioration of the impact, and assess whether it has moved during that time.
“The wreckage poses no risk to the bridge, but without the ability to measure that, there’s always a concern that something is going on that isn’t being considered,” Digney said.
The new mapping gives a clearer picture of the exact position of the wreck under the bridge. (Supplied: CSIRO)
Over 1,000 shipwrecks in Tasmanian waters
A maritime archaeologist said the state has a fascinating history, with over 1,000 shipwrecks in Tasmanian waters.
“It’s not unusual for a shipwreck to be so close to a city, as it was an important point of contact between sea and land transport,” said Emily Jateff of the Australian National Maritime Museum.
“Most shipwrecks are the result of an accident and capture the world at that exact moment.”
M.s Jateff said there were many shipwrecks around Tasmania. (included)
While all wrecks are an important part of our history, many have a connection to the Lake Illawarra story.
“There is a lot of interest not only in the tragedy of the wreck but also in the social impact,” said John Wadsley of the Maritime Museum of Tasmania.
“Hobart was cut in half, and it caused such a big change in how the city operated.”
Maritime experts hope the stunning images will give people a new appreciation of what happened to Lake Illawarra and how the Tasman Bridge disaster shaped the city of Hobart.
“The East Bank became much more developed… it completely changed transport patterns in Hobart,” said Mr Wadsley.
Mr. Wads. ley said the accident had changed Hobart. (ABC News: Liz Gwynn)
Now, work is underway to find more of these sunken ships that capture important historical moments.
“One of the things we’re doing now is working with CSIRO, and they’re using their advanced onboard surveying equipment to search for shipwrecks while doing other scientific research, so that’s a real help,” said Ms. Jateff.
“But some wrecks are graves… so you may not want to find them at all.”
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