Refinery Interchange - Piling
Client: Haw & Inglis
Engineer: SMEC
Main Geotechnical Contractor: Terrastrata
Pile Type: Pre-augered DCIS piles, 610mm diameter
Project Period:
Phase 1: Nov 2021 – Feb 2022
Phase 2: Dec 2022 – Mar 2023
This large-scale infrastructure upgrade involved replacing the existing single-span bridge over the N7 at the Refinery Interchange with a new dual-span bridge, as well as widening the adjacent railway bridge. Fairbrother Geotechnical Engineering was subcontracted by Terrastrata to carry out the installation of all foundation piles at the bridge abutments and piers—specifically pre-augered DCIS (Driven Cast-In-Situ) piles.
Scope of Work:
Scope of Work:
Two piling campaigns with approximately 85 piles per phase
Installation of vertical and 1:6 raked piles at bridge abutments
Vertical piling for five central piers located in the median islands of the N7
Much of the piling was executed on narrow median islands between live traffic lanes. Rig transfers between abutments and piers were carefully coordinated and performed at night with the assistance of traffic authorities.
Site Challenges:
At Abutment 2, Phase 2, high groundwater levels and unstable saturated soils caused repeated auger-hole collapses. With SMEC’s approval, Fairbrother implemented drilling polymers to stabilise the holes. Additionally, we performed localised dewatering, allowing successful pile completion and enabling Haw & Inglis to construct the pile cap without flooding.
This project reflects Fairbrother’s ability to deliver technically complex piling solutions in constrained, high-risk transport corridors with adaptive problem-solving.
