Design & Construction of Mt Henry Bridge

The Mt Henry Bridge is the longest combined road and rail bridge in Western Australia and forms a vital link in the Kwinana Freeway from the Perth CBD to the southern residential suburbs, the industrial and naval precincts of Kwinana and Cockburn Sound. It is also the gateway to the tourist areas and wine growing region of the southwest of Western Australia.

The bridge now comprises two separate side-by-side structures, which overlap without touching, designed and built in separate eras over 20 years apart. Both are conventional post-tensioned concrete box structures, but designed and built by contrastingly and innovative different methods unique to their eras. The first bridge was one of the last major concrete bridges in Australia built using the falsework-supported segmental box construction technique. This involved using temporary falsework supported on the permanent pile caps and by a cable-stayed tower which also served to handle the individual 110 tonne segments. The use of expensive mid-span temporary support piers was thus able to be avoided.

The second bridge was designed and built using the incremental launch technique. For this method, the use of temporary piers could not be avoided, but their size and cost were minimised to carry mainly vertical loading with complex bracing to cater for lateral loads.

The original bridge was also strengthened to upgrade its capacity to support rail traffic.

The completed bridges

Constructing the 1st bridge

Constructing the 2nd bridge

Cross section of the two bridges

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Engineering Heritage Recognition Program

Marker Type	Engineering Heritage Marker (EHM)
Award Date	4 March 2024
Heritage Significance	The two components of Mt Henry Bridge highlight the evolution of bridge design and building technologies in two different eras, over 20 years apart. They serve as a comparison of how far engineering technology advanced and as examples of the innovative and creative methods that were used to design and construct bridges at those times.
Nomination Document	Available here.
Ceremony Booklet Ceremony Report
Plaque/Interpretation Panel	Available here.