Metronet Viaduct, Perth

Future-Proof Drainage for Elevated Rail

Case Study Video

Project Overview

The MetroNet Byford Rail Extension is a landmark infrastructure initiative by the Western Australian Public Transport Authority (PTA), designed to enhance public transport connectivity in Perth’s rapidly growing southeastern suburbs. A key feature of the project is the 1.5-kilometre elevated viaduct, which supports dual‑track rail infrastructure between Armadale and Byford Stations.

Constructed by Laing O’Rourke, with hydraulic design by NDY (a Tetra Tech company) and plumbing installation by Altona Group, the project demanded a drainage solution that could meet stringent technical, environmental, and longevity requirements. “HDPE’s ability to naturally accommodate lateral and vertical movement enhances its suitability for dynamic infrastructure environments.” Brent Marsh, Technical Solutions Group Leader Hydraulics, NDY.

The Challenges

Designing and installing a drainage system for an elevated rail viaduct presented a unique set of challenges:

• Design Life: Required to exceed 100 years.
• Environmental Exposure: High UV radiation, extreme temperatures, and potential hydrocarbon spills from rail operations.
• Structural Movement: The viaduct’s dynamic nature required a system that could accommodate both lateral and vertical movement.
• Compliance: Strict adherence to PTA’s earthing and bonding standards.
• Safety & Security: Systems needed to deter vandalism, prevent climbing, and avoid bird nesting.
• Installation Constraints: Elevated work zones and limited space demanded lightweight, easy-to-install materials.

In the early design phase, NDY conducted a comparative assessment of PVC, 316 Stainless Steel, and Geberit HDPE. While 316 Stainless Steel is the PTA’s requirement due to durability, HDPE emerged as the optimal solution due to its:

• Superior adaptability to environmental conditions.
• Resilience to vibration and movement, essential for elevated structures.
• Aesthetic flexibility and ease of integration.
• Three-dimensional movement capacity, critical for viaduct dynamics.

The Solution

Geberit HDPE offered a suite of advantages that directly addressed the project’s challenges:

• Lightweight & Flexible: Simplified handling and installation, especially in elevated environments.
• Prefabrication Potential: Enabled offsite assembly, reducing time and risk on-site.
• Chemical & UV Resistance: Ensured long-term durability in harsh outdoor conditions.
• Movement Tolerance: Naturally accommodates structural shifts without compromising performance.
• Corrosion Resistance: Minimises long-term maintenance and extends system lifespan.
• Bird & Vandal Deterrence: Smooth surfaces and secure fittings reduce nesting and tampering risks.

“HDPE brought significant advantages to the project. It’s lightweight, flexible, allows for prefabrication, and is easy to handle —improving installation efficiency.” Brent Marsh, Technical Solutions Group Leader Hydraulics, NDY.

The success of the drainage installation was underpinned by early and ongoing collaboration between all stakeholders. Geberit provided tailored technical support from the outset, aligning with NDY (A Tetra Company), Altona Group, Laing O’Rourke, and Reece Group to ensure compliance and performance. Altona Group leveraged prefabrication to streamline installation and reduce time spent working at heights. NDY received detailed technical data and installation guidance, ensuring the system met all regulatory and performance benchmarks. “The collaboration with the drainage supplier was professional, responsive, and technically thorough.” Brent said.

The Benefits

The implementation of Geberit HDPE ensures:

• Sustained performance under environmental and structural stress.
• Cost-efficiency through reduced installation time and long-term durability.
• A more sustainable outcome that aligns with modern infrastructure goals.

“HDPE offered a practical, futureproof solution for elevated rail drainage— and that kind of forward thinking is essential in infrastructure like MetroNet.” Cameron Smith, Section Manager, Laing O’Rourke. The MetroNet Viaduct project exemplifies how Geberit HDPE can meet the complex demands of modern infrastructure. Through strategic collaboration, innovative material selection, and a focus on long-term performance, the project sets a new benchmark for elevated rail drainage systems in Australia. “Installing HDPE on a project like this really showcases its benefits. It’s lightweight, easy to handle, and fits well with the movement tolerances of the structure.” Wesley Cox, Team Leader, Altona Group.

FACTS

GEBERIT KNOW-HOW

• Geberit HDPE
• Geberit HDPE Tools

COLLABORATORS