Updated: Jul 2, 2020
The order of events in the Bridge's collapse
Around 11.00 am that morning the Section Engineer contacted Jack Hindshaw, the Resident Engineer, and advised that things were not going well. Hindshaw arrived on site and was instantly aware that a potentially dangerous situation was imminent and decided to get further advice, making a phone call to Gerit Hardenber, a Senior Representative of WSC Melbourne.
The last words that Hindshaw was heard saying were "Shall I get the bods off?" (referring to all the workers). It was then, at 11.50 am, that span 10 -11 collapsed, taking the lives of 35 men, Jack Hindshaw among them.
Two years into the construction of the bridge, at 11:50 am on 15 October 1970, the 112-metre (367-foot) span between piers 10 and 11 collapsed and fell 50 metres (164 feet) to the ground and water below.
Thirty-five construction workers were killed and 18 injured, and it remains Australia's worst industrial accident to this day. Many of those who perished were on lunch break beneath the structure in workers' huts, which were crushed by the falling span. Others were working on and inside the span when it fell.
The whole 2,000-tonne (4,400,000 lb) mass plummeted into the Yarra River mud with an explosion of gas, dust and mangled metal that shook buildings hundreds of metres away. Nearby houses were spattered with flying mud.
The roar of the impact, the explosion, and the fire that followed could be clearly heard over 20 kilometres (12 mi) away.
The Engineering fault that caused the collapse
On the day of the collapse, there was a difference in camber of 11.4 centimetres (4.5 in) between two half-girders at the west end of the span which needed to be joined. It was proposed that the higher one be weighted down with 10 concrete blocks, each weighing 8 t (8.8 short tons), which were located on-site.
The weight of these blocks caused the span to buckle, which was a sign of structural failure. The longitudinal joining of the half-girders was partially complete when orders came through to remove the buckle. As the bolts were removed, the bridge snapped back and the span collapsed.