Bridges

The Warringah Freeway Upgrade (WFU) in Sydney is a critical enabling works project for the current Western Harbour Tunnel project. The Warringah Freeway corridor is of critical importance due to its role in providing access for the three harbour crossings, as well as providing the primary bus corridor to and from the CBD. The project will optimise the corridor, improving connectivity, performance and safety by reconfiguring access arrangements, lane configurations and wayfinding improvements.

As part of the project, the Falcon Street interchange is being upgraded. This includes the Bus Lane Entry Ramp Bridge, which provides direct access from Falcon Street onto the southbound bus lane. The bridge is a two-span structure comprised of a pair of steel trough girders.

This paper presents the main considerations for the design and construction of the bridge. A discussion on the final design solution and the options considered to deal with the complex bridge geometry, including reverse horizontal curves, vertical curves, and cross falls, is presented. The variable depth rectangular steel trough girders with permanent precast concrete deck panels spanning one-way between girder flanges was adopted as the most optimal solution. The complex geometry presented challenges particularly when considering the load distribution to the bearings.

The construction sequence and methodology adopted to overcome challenges such as spatial constraints, complex geometries, lifting capacities and construction over and around the busiest road in Australia is also presented. This includes the splicing of the girders with an internal concrete connection whilst supported on temporary towers, and the concrete deck pour sequence. Other matters, including 3D bridge modelling and bridge analysis using Midas Civil, will be presented.