HMAS Stirling is the Royal Australian Navy’s primary base on the west coast and is located on Garden Island, 5km off the WA coast. The 305m low level bridge is located at the mainland end of the causeway which links the island to Point Peron.
The bridge comprises a reinforced concrete deck supported by a steel structure on steel piles, providing a two lane roadway. The abutments are reinforced concrete and steel sheet piling. There have been various repair works conducted since its commission in 1972, including most recently in 2007/2008.
Duratec and DDR were engaged to perform repairs due to the accelerated deterioration of the structural steel under the bridge deck. The scope of works included repairs to:
- Structural steel supporting the deck (beams and piles).
- Steel sheet piling.
- Reinforced concrete abutments including cathodic protection.
- Reinforced concrete deck soffits.
- Reinforced concrete deck edges.
- Expansion joints at abutments and bents.
- Also included was the removal of existing coal tar epoxy coatings from the underside of the bridge which required a fully encapsulated work area for the safe management of a hazardous material in a full working environment, including a negative air pressure filter and HEPA filters.