15 October marks 50 years since one of Australia’s worst accidents. 35 people were killed when the West Gate Bridge in Melbourne collapsed during construction. The tragedy came just a few months after a similar accident in Milford Haven, South Wales, when the Cleddau Bridge also collapsed during construction, killing four people.
Both bridges used a relatively new technology, steel box girders. These had developed rapidly in the 1960s and were being applied by many bridge designers. With dozens of similar bridges being planned or built in the UK alone, there was an urgent need to establish what had gone wrong.
Not long after another tragedy occurred. In November 1971 a steel box-girder bridge across the River Rhine near Koblenz in Germany collapsed killing 12 people.
Investigating the disasters
The British government responded by setting up the Merrison Committee of Inquiry. It was tasked with investigating the design and construction methods of box-girder bridges. It was also asked to make recommendations for change.
The committee was made up of some of Britain’s most respected civil and structural engineers. It quickly produced an interim report in June 1971, with a final report (Inquiry into the basis of design and method of erection of steel box-girder bridges) following in February 1973. The report set out radically new design and workmanship rules for bridges.
A similar investigation in Australia led to the publication in 1971 of the Report of the Royal Commission into the Failure of West Gate Bridge
The two reports remain essential reading for bridge engineers. While the technical lessons have been incorporated into modern codes of practice, leading to safer designs today, the procedural lessons are still every bit as relevant.
When presenting the committee’s conclusions, the chairman noted:
"No amount of writing of design codes and writing of contracts can in the end be guaranteed to prevent the results of stupidity, carelessness or incompetence. But one can do a great deal to discourage these vices and that must be done."
Sir Alec Merrison
West Gate Bridge collapse. Image credit: Public Record Office Victoria