A landmark elevated motorway project founded on large-diameter CFA pile groups in highly variable ground conditions, requiring innovative foundation engineering, constructability planning and verification to deliver Australia’s first major road project adopting CFA piles as the primary foundation solution.
Client
Urban Superway JV
Location
Adelaide, South Australia
Sector
Infrastructure & Transport
Services Delivered
Constructability AdviceEmbankment DesignFoundation Anlaysis & DesignFoundation VerificationGround ImprovementPile TestingTemporary Works Design
The challenge.
The South Road Superway involved the construction of approximately 2.8 km of elevated roadway as part of a major transport infrastructure upgrade in Adelaide. The structure was supported on deep foundations founded within highly variable ground conditions comprising alluvial deposits overlying the heavily overconsolidated Hindmarsh Clay Formation, which contains variable sand lenses and localised changes in material properties. These conditions created challenges in predicting foundation performance and developing a design that could be applied consistently across the alignment.
In addition to the complex subsurface conditions, the elevated roadway imposed significant lateral loading and displacement compatibility requirements on the foundation system. At the time, the use of large-diameter Continuous Flight Auger (CFA) piles as the primary foundation solution for a major Australian road project was unprecedented, requiring a robust technical justification and careful consideration of construction methodology, performance requirements and verification procedures.
The approach.
FSG provided geotechnical and foundation engineering services throughout the tender, detailed design and construction phases of the project. A detailed review of geotechnical investigation data, including CPT testing and trial piling results, was undertaken to develop a comprehensive understanding of the site stratigraphy and the behaviour of the proposed foundation system. This information was used to refine the geotechnical model and support the development of an innovative CFA pile solution.
Working closely with the structural design team and project stakeholders, FSG designed groups of 1050 mm diameter CFA piles extending to depths of approximately 30 m. Around 700 CFA piles were ultimately adopted across the project. In addition to foundation design, FSG provided constructability reviews, geotechnical certification, pile testing and verification services, ensuring that foundation performance requirements could be reliably achieved while maintaining construction efficiency.
The outcome.
FSG’s foundation solution was successfully adopted and became a key component of the project’s delivery strategy, helping establish CFA piling as a viable solution for large-scale transport infrastructure projects in Australia. The approach provided a practical and cost-effective alternative to more conventional foundation systems while satisfying the demanding structural and geotechnical performance requirements of the elevated roadway.
By combining rigorous geotechnical analysis with a strong understanding of construction methodology, FSG delivered a foundation solution that was technically robust, readily constructible and capable of supporting the project’s programme and commercial objectives. The result was a reliable, high-performing foundation system that contributed to the successful delivery of one of South Australia’s most significant road infrastructure projects.