Bridges

The Sydney Harbour Bridge was completed in 1932 and at that time carried six road lanes and two rail corridors on each side. The rail corridor on the eastern side was used for trams and was replaced by a roadway in the late 1950ís. The rail corridor on the western side is supported by timber transoms on steel stringers and carries the North Shore Line which remains an integral part of the Sydneyís rail network.

The timber transoms and decking require continual ongoing maintenance. A deck design was required which would: reduce the frequency and costs of future maintenance, improve safety, reduce stringer stresses and improve their load carrying capacity.

Following extensive investigation, the breakthrough in the design came with the adoption of precast concrete deck panels and Ultra-High-Performance Fibre-Reinforced Concrete (UHPFRC) for the stitching of adjoining panels and the composite connections between these panels and the steel stringers. The use of UHPFRC enabled rapid strength gain that achieved adequate composite action to suit weekend possessions as well as simplified shorter reinforcement laps in the stitch pours connections between the panels.

The design was further refined with collaboration between Jacobs, Sydney Trains and their Subcontractors and Transport for NSW. This refinement included a novel shear stud design and a flexible installation system for rapid installation of the precast panels and the UHPFRC. The system is currently being successfully installed using a series of weekend track possessions.

The paper covers the design development and construction planning and implementation.