Melbourne West Gate Tunnel Project – Eastern Section
Geotechnical Investigation, Design and Construction Support Package includes the construction of two temporary access shafts to facilitate the construction of the north precinct station cavern.
Douglas Partners was engaged as the geotechnical consultant for the eastern section of the West Gate Tunnel Project—a major Victorian infrastructure upgrade connecting the West Gate Freeway to the CBD and port precinct. The eastern works include the Maribyrnong River and Moonee Ponds Creek crossings, elevated freeway structures along Footscray Road, and connections to CityLink, Dynon Road and Wurrndjeri Way.
Project Background
The East Zone occupies a low-lying brownfield area of West Melbourne with a complex history of land use. Historically, the area included salt-flats, swamps, rubbish tips, squatter camps, drainage and reclamation works, extensive rail infrastructure, and the former Melbourne Wholesale Markets.
These past uses—combined with deep alluvial geology—created highly variable ground conditions requiring detailed assessment and robust geotechnical solutions.
The region is underlain by up to 50 metres of Quaternary and Tertiary Yarra Delta sediments, including Coode Island Silt, a very soft, compressible clay known to present significant challenges for foundation design, settlement control and construction risk management.
(Sources: Victorian Geological Survey; GeoScience Australia; West Gate Tunnel Environmental Effects Statement).
Our Role
Douglas Partners provided integrated geotechnical services from investigation through to design and construction support. Our key responsibilities included:
1. Detailed Field Investigations & Ground Modelling
- Extensive site investigations across the East Zone, including boreholes, cone penetration testing (CPT), geotechnical laboratory testing and installation of groundwater monitoring wells.
- Development of a detailed 3D ground model representing deep Yarra Delta deposits and highly variable brownfield conditions.
- Characterisation of Coode Island Silt and other soft ground units to inform settlement, stability and foundation behaviour assessments.
2. Deep Foundation Design for Bridges and Elevated Roads: Douglas Partners undertook advanced geotechnical design for foundations supporting:
- Multi-lane bridges
- Elevated freeway structures and ramps
- Connections to CityLink and local road networks.
Given the depth and variability of the Yarra Delta sediments, a diverse suite of piling solutions was required, including:
- Driven pre-cast concrete piles in large groups
- Steel tubular piles
- Large-diameter bored piles up to 2.18 m
Design considerations included:
- Soft ground performance
- Pile group interactions
- Long-term settlement
- Proximity to existing rail, utilities and road infrastructure
- Brownfield constraints such as undocumented fill and historical industrial land use
3. Construction Support & Temporary Works. Douglas Partners supported the construction team with:
- Assessment of pile capacity and performance under temporary loadings associated with the 1,400-tonne launching gantry used to place elevated precast bridge segments.
- Inspection of bored piles during construction to verify material conditions and ensure compliance with design intent.
- Design of crane hardstands and temporary working platforms.
- Monitoring and assessment of ground movements related to piling in very soft ground to protect surrounding infrastructure and maintain safety.
Outcome
Through detailed investigation, robust geotechnical modelling and responsive construction support, Douglas Partners helped deliver safe and reliable foundation solutions for one of Victoria’s most complex transport infrastructure projects. Our involvement contributed to improved transport capacity, reduced congestion, and enhanced connectivity between Melbourne’s west, the CBD and the Port of Melbourne.