Bridges

The West Gate Tunnel Project is one of Australia's largest infrastructure projects currently under construction and will give Melbourne an alternative to the West Gate Bridge.

The scope includes:

• Two three-lane road tunnels,
• Widening of the West Gate Freeway (WGF) from eight to 12 through lanes, including substantial new bridge work, along with widenings and strengthening
• A second crossing of the Maribyrnong River
• A significant viaduct and interchange linking the tunnel with the Port of Melbourne and Citylink
• A 2.5km raised cycle 'Veloway'
• Additional tie ins with Dynon Road and an elevated viaduct that links to Wurundjeri Way.
• 14km of new and upgraded cycling and walking paths and 9ha of new open space and wetlands.

In all, there are more than 22 km of bridge structures on the West Gate Tunnel Project meaning that it is one of Australia's largest bridge projects. The project includes the widening and strengthening of many existing bridges and the provision of numerous new bridges, along with several significant structures. The bridge forms range from super-t girder bridges to precast segmental bridges to long span (up to 100m) curved structural steel trapezoidal box girder bridges. These bridges posed significant challenges, including being in a brownfield site with tight project boundaries, accommodation of significant volumes of existing traffic, and complex interfaces between new and existing freeways. The construction staging and camber requirements of the steel bridges were intricate and required constant iterations and modifications based on the construction and temporary works requirements. Due to the scale of the site, the ground conditions varied significantly. Soft Coode Island Silt is predominant in the eastern zone, which contains the most significant bridges on the project. The paper will present an overview of the bridges on the project along with key design and construction challenges.