Client
Midland Junction Alliance
Location
Perth, Western Australia
Sector
Infrastructure & Transport
Services Delivered
Foundation DesignHydrogeology & GroundwaterPile Testing & CertificationRail Subgrade OptimisationSite Investigation & CharacterisationTemporary Works Design
The challenge.
The Midland Station (Cale Street) Project involved the relocation of Midland Station east of its previous location, demolition of the original station and construction of new station platforms, a pedestrian overpass, ancillary buildings, a bus interchange, multi storey carpark, a new level crossing on Cale Street and significant rail corridor works. The site is underlain by variable depths of fill over clayey and sandy soils of the Guildford Formation, which are known for significant lateral and vertical variability. These ground conditions presented challenges associated with excavation stability, settlement performance, bearing capacity and groundwater management, particularly where works interfaced with existing metropolitan and regional passenger rail and freight rail infrastructure.
The approach.
FSG was engaged by the Midland Junction Alliance as the geotechnical designer during the construction phase to provide targeted investigation, design optimisation and construction support. The scope included redesign and optimisation of foundations and retaining structures informed by additional site investigations and staged inspections. Temporary works designs considered short term construction loading to achieve acceptable factors of safety, including the design of working platforms and temporary retention systems where required. This included significant works to maintain safe operation of the Indian Pacific train during foundation works in close proximity to the track. Detailed subgrade and groundwater assessments, monitoring and risk modelling were undertaken to manage weak ground, perched and seasonal groundwater conditions and to address issues related to rail realignment works, eliminating the need for additional subsoil drainage and optimising subgrade preparation works.
The outcome.
The geotechnical and groundwater solutions implemented supported safe and efficient construction of the relocated Midland Station and associated rail infrastructure. Foundation designs were optimised through verification testing, reducing geotechnical risk while meeting performance requirements for rail operations and structures. Groundwater risks were effectively managed, preventing impacts on construction activities and adjacent rail infrastructure. Ongoing site based support enabled practical decision making during construction, minimised over excavation and ensured compliance with design intent, contributing to the successful delivery of a major rail infrastructure project in complex ground conditions.