ACCIONA has been internationally recognised for pioneering the world’s first large-scale use of Artificial Ground Freezing (AGF) on the Suburban Rail Loop East project in Melbourne,with the accolade awarded by the International Symposium on Ground Freezing (ISGF) in September 2025.
ACCIONA applied AGF early in the design process to safely construct tunnel cross passages, marking a global first in both scale and methodology.
ACCIONA site engineer Yun Lan Tsai said the recognition from ISGF reflected the ingenuity and technical excellence of its team.
“By integrating AGF into the design phase, we are setting new standards for safety, sustainability and constructability in tunnel infrastructure,” she said.
AGF involves circulating chilled brine, a concentrated saltwater solution, through pipes installed inside the tunnels.
This process temporarily freezes the surrounding groundwater and soil, stabilising the ground to allow for safe excavation.
The technique will be used in 26 of the 54 cross passages along the Suburban Rail Loop East alignment.
The ISGF commended the project for balancing engineering efficiency with environmental responsibility.
By freezing the ground instead of using traditional dewatering or chemical stabilisation methods, AGF reduces groundwater disruption and minimises environmental impact, ACCIONA said.
In addition to the AGF milestone, underpinning works have commenced at Clayton beneath the existing viaduct.
These works involve constructing new foundations under one of the rail line’s piers to support the elevated structure as the tunnel route passes beneath.
The new foundations will redistribute the bridge’s weight, ensuring structural integrity during and after tunnel excavation.