Bridges

Opened in 1940, the Birkenhead Bridge over the Port River has a double leaf bascule opening central span. The bridge provides a critical road connection between Port Adelaide and Birkenhead while allowing shipping to access the inner harbor and its importance is recognized by the bridge being a State Heritage item [1]. The bascule span consists of steel trusses, cross girders and stringers supporting a timber deck and plywood surfacing. Over time, deterioration of the deck and surfacing resulted in an increased maintenance effort, roughness for traffic and, following a localized failure, the imposition of a load limit.

A new lightweight replacement deck made from Fibre Reinforced Polymer was designed and installed on the bascule spans of the bridge. Other work included the replacement of a plywood surfaced footpath with aluminium, cleaning and painting of steelwork directly under the deck and placing bitumen resurfacing.

The installation of the new deck was completed over 3 months in 2020. Contingencies were made to address potential issues that could be encountered during construction including unknown condition of the steelwork directly under the deck, securing the bascules while they were unbalanced with the deck removed and ensuring the bascules were balanced at handover. The paper will detail the history of the timber bascule deck and its surfacing and the management of ongoing issues, the investigation of alternative decking and selection, design, and construction of the new Fibre Reinforced Polymer deck.