Flood Gates Protect West Gate Tunnel

The West Gate Tunnel Project is one of Melbourne’s most significant transport upgrades, delivering a second freeway link between the city and the west. This upgrade will ease congestion on the West Gate Freeway and Bridge, improve freight efficiency to the Port of Melbourne, and reduce the number of trucks using residential streets.

As with any major tunnel infrastructure, flood resilience is critical. Tunnel portals and inbound ramps can be exposed to floodwater and intense rainfall run-off, creating a serious risk of inundation, asset damage, and operational disruption. To ensure long-term protection and maintain network reliability during extreme weather events, engineered flood mitigation measures were incorporated into the project’s design.

AWMA was engaged to deliver an active flood protection system for the inbound ramp, providing a flood gate arrangement designed to prevent floodwater ingress into the tunnel. The solution includes a recessed frame system and a set of modular stopboards, which can be deployed when required during major flood events. This system is designed to be installed for short periods during floods between the 50-year ARI and Probable Maximum Flood, protecting the tunnel from inundation and damage caused by floodwater and stormwater run-off.

The stopboards are installed into stainless steel guide channels and stacked to the required height depending on predicted flood levels. A customised bottom stopboard was supplied to accommodate site-specific crossfall requirements, ensuring a reliable seal at the base of the barrier. Integrated compression seals between the boards and frame create a continuous barrier to prevent water ingress when deployed.

To support rapid and safe installation, AWMA supplied a self-engaging lifting frame system (AWMA SELF), allowing stopboards to be raised and lowered using appropriately rated lifting equipment. This lifting frame incorporates additional safety mechanisms to ensure boards cannot unintentionally disengage during installation. Purpose-built storage racks were also provided to enable secure storage, transport, and handling of the stopboards and lifting equipment when not in use.

Effective flood mitigation is essential for protecting critical transport infrastructure, especially tunnels where water ingress can disrupt operations and cause costly damage. AWMA’s collaborative approach to developing water control solutions, including the West Gate Tunnel Project, shows how engineered, deployable flood barriers, designed in close consultation with project partners and stakeholders, deliver reliable protection while keeping key infrastructure safe and fully operational.