Project Overview
Located just north of Wellington City, the Whakawhirinaki – Silverstream Pipe Bridge was delivered for Wellington Water as part of a major infrastructure upgrade to strengthen the region’s water supply resilience.
Carrying a bulk new water main that supplies Upper Hutt, Stokes Valley, Porirua and 40% of Wellington City, the bridge also provides a new shared path for pedestrians and cyclists across the Te Awa Kairangi / Hutt River. To improve earthquake resilience, the new pipe was placed on its own structure alongside the cycleway bridge.
Specified by GHD and engaged by our client Brian Perry Civil, Moddex supplied more than 700m of Bridgerail and Tuffrail to deliver a durable, compliant barrier solution protecting pedestrians and cyclists on one side while providing safe maintenance access along the pipe deck.
The Challenge
The fully steel substrate presented complex geometry, irregular gradients and tight alignment tolerances, making a conventional fixed rail system unworkable. The design needed a solution that could adapt precisely to changing slopes while maintaining full compliance with fall and loading standards.
In addition, with bridge fabrication and installation occurring simultaneously, the handrail system had to be designed and delivered in precise stages with fit-first-time accuracy to keep the program moving and avoid rework or delay.
The Moddex Solution
Moddex delivered a custom adjustable top rail design across more than 700m of Tuffrail TR30 and Bridgerail BR40, installed along the bridge length, access ramps and maintenance platforms.
Using advanced 3D modelling and as-built coordination before construction began, the Moddex design team developed a digital model that mapped every slope, curve, and fixing point, which ensured seamless integration and precise installation.
The HDG Bridgerail modular system was chosen for its proven compliance on public access bridges and long term corrosion resistance in the riverine environment. Working with local installers, Moddex staged installation in sync with bridge construction to maintain program flow and minimise disruption.
Client Feedback
“Moddex nailed it. The 3D model and adjustable rail design made a tricky bridge install simple. Everything fit perfectly.”
