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Terrigal Boardwalk - Stainless sets the scene

Terrigal Boardwalk - Stainless sets the scene

The seaside town of Terrigal on the New South Wales’ Central Coast has welcomed a new addition to its foreshore with a scenic walkway using stainless steel.

The long-awaited Terrigal Boardwalk connects the existing pedestrian networks of the Terrigal Beach promenade and The Haven, providing a safe and accessible route around the headland. The new attraction provides social, health and economic benefits for the local community, allowing visitors and tourists to enjoy the public space and ocean front area.

The project was jointly funded by the Central Coast Council ($2.9M) and the NSW Government’s Restart NSW Regional Growth Environment and Tourism Fund ($2.98M). The Terrigal Boardwalk’s construction included a restoration of the adjacent rockpool, a new disability-access ramp and pathway to link the rockpool and boardwalk.

Engineered and designed by Arup, the boardwalk structure has a 50-year design life, demanding a robust design to ensure durability and longevity. The elevated boardwalk is 277m long and 3m wide, and complements the surrounding natural environment with its blackbutt timber decking and stainless steel balustrading.

The construction comprises of a reinforced concrete suspended deck structure, a suspended structural steel viewing platform with fibre-reinforced plastic open mesh, sandstone block revetment and a retaining wall ramp structure. For the bridge deck, 7.5m is the typical span of the precast deck planks between concrete headstocks on steel tubular piles. Solid concrete deck planks were chosen to protect the timber boardwalk above from wave damage and minimise overtopping for users. The boardwalk sits approximately 4.5m above sea level to be just clear of wave crests during strong weather events.

Materials selection was critical to meet the specified design life, with consideration given to the foreshore’s high level weather events and salt exposure. Grade 316L stainless steel was specified for the balustrading on both sides of the boardwalk, ramp handrailing and the rock platform staircase.

While aluminium was considered during the design phase, stainless steel was chosen due to the material’s proven performance, corrosion resistance and durability in a marine environment, and aesthetic benefits in conjunction with the timber decking and handrail specified. In addition, a costing exercise conducted by Arup presented the long-term benefits of using stainless steel outweighing its additional upfront cost over aluminium.

Constructed by Land and Marine Group, the project involved a high level of collaboration between multiple local suppliers and service providers to meet the exacting demands of the specification. 

ASSDA Member Synergy Engineering was engaged to fabricate and install the stainless steel handrails, balustrades and stairs, spotted gum timber railing and the structural steel viewing platform. The project involved the stainless steel fabrication of 247 balustrade panels, 119m of handrail balustrade and an 8-step 1200mm wide staircase with fibre-reinforced treads. TIG welding techniques were used throughout the fabrication and installation process to ensure precision and a clean aesthetic.

ASSDA Member Atlas Steels supplied over 15t of 316L stainless steel, including 3402m of 30x8mm flat bar and 1656m of 70x10mm flat bar. The project was undertaken in the midst of the COVID pandemic, presenting a number of challenges with the supply of imported stainless steel material and shipping lead delays. As a result, Atlas Steels took the initiative to laser cut stainless steel plate to size and engaged ASSDA Member Decoware Australia to polish the material to specification. Starting with a coarse 80 grit through to a 400 grit finish, a surface finish of Ra <0.5 µm was achieved. The resourcefulness of local service and skill assisted in meeting the project program, delivering a resolution for the unprecedented challenges.

A small proportion of material was sourced from ASSDA Member Viraj Profiles, and ASSDA Member Vulcan Stainless supplied an additional 11t of laser cut 5mm, 10mm, 16mm and 20mm 316L stainless steel plate for the project.

Following fabrication, all stainless steel balustrade panels and handrails were electropolished by ASSDA Member Australian Pickling & Passivation Service and delivered directly to site for installation by the Synergy Engineering team.

The beautiful coastal boardwalk features a viewing platform, integrated seating, LED lighting and access to the rock platform. Offering uninterrupted views of the Pacific Ocean and beyond, the Terrigal Boardwalk is certain to meet the performance requirements of its design with its quality construction and use of stainless steel. 

The Terrigal Boardwalk officially opened on 14 April 2021, with its first steps taken by local crowds alongside the New South Wales Premier Gladys Berejiklian, Parliamentary Secretary for the Central Coast, Adam Crouch, Central Coast Council Administrator, Dick Persson, and the Council’s new CEO, David Farmer.
 
    

This article is featured in Australian Stainless Magazine issue 72, 2021.

Tina Belesis