Engineers throughout the world use Melbourne’s Westgate Bridge collapse as an object lesson in structural stresses and performance under load, the importance of thorough and complete communication between involved parties, and viable construction practices.
The Royal Commission into the accident concluded that there was no problem with substandard suppliers or materials. The steel substructure of the box girder construction failed because of an untried and ill-advised lifting procedure, and the loading of ten 8-ton blocks onto the deck to, in effect, bend it into place and close the 11.4 cm gap between the two spans. The resulting buckling pressure was worsened by the removal of 30 retaining bolts, some under so much pressure they had to be snapped off. The combined forces of stressed steel, under 80 tons of loading, and sudden release of restraint, led to the violent failure of the span.
Unclear and strained communication between the engineering firms, contractors, and labourers on the project led to incomplete, delayed, and contradictory technical information, which resulted in engineers on the ground making wrong decisions about construction. The general atmosphere around the project was one of distrust and frustration and uncoordinated activity.
The cable-stayed box girder method of bridge building, including the technique of assembling pieces on the ground, required precision monitoring and expertise which was lacking at the site. The collapse of a similar bridge in Wales failed to warn the Westgate parties about the hazards inherent in their project.
The study of the Westgate collapse informs today’s students about the stresses, both human and mechanical, involved in large building projects, and the possible consequences of failure.