Here is National Nine News coverage of the West Gate Bridge disaster on 15 October 1970 in Melbourne, with voice-over from reporter John Bailey.
On 14 October the West Gate Bridge was nearing completion when an 11 cm gap was reported between two spans.
The solution was to use kentledge weights, often employed as ballast in ships and as counterweights in cranes, to push down the structure and realign the girders. However, by all accounts too much weight was used, causing the bridge to buckle.
On 15 October, attempts to straighten the buckle failed. Soon before midday, a 112-metre span between two piers, weighing 2,000 tonnes, plummeted 50 metres into the mud of the Yarra River.
You can learn more about West Gate Bridge disaster in this article.
Notes by Adam Blackshaw