Ground freezing for the Suburban Rail Loop in Melbourne

Ground Freezing – Interview with Simon Klösges | CDM Smith

Simon Klösges

Project Manager

An Innovative Method to Challenging Infrastructure Projects

The Suburban Rail Loop, or SRL for short, is one of Australia’s largest and most ambitious infrastructure projects. The plan is to build a rail line around 90 kilometres long, which will run in a loop around Melbourne and connect numerous densely populated suburbs. In this interview, Simon Klösges, project manager at CDM Smith SE, explains why ground freezing is being used on the project and what makes the method particularly environmentally friendly.

Read the Full Interview with Simon:

CDM Smith

Why is ground freezing being used on the project and what is CDM Smith’s role in this?

Simon Klösges

In the eastern section of the Suburban Rail Loop – known as the Suburban Rail Loop East – the line will be constructed entirely underground. Two parallel tunnel tubes are being built there, connected at regular intervals by cross-passages. These cross-passages serve, among other things, as escape routes. Due to the challenging ground conditions, these connections must be constructed safely. This is where ground freezing comes into play. It enables the ground to be temporarily stabilised and prevents groundwater from entering the excavation – and this is done exclusively from within the existing tunnel tubes, without any intervention at the surface. CDM Smith is responsible for the planning and design of the ground freezing for this project and is providing technical support throughout its implementation. Originally, ground freezing was only intended for one cross-passage. However, due to its compelling advantages, the concept was extended to a total of 29 cross-passages.

CDM Smith

What specific soil and groundwater conditions in the project area were decisive in the decision to opt for ground freezing?

Simon Klösges

The project area consists predominantly of water-bearing unconsolidated soils. This combination of soil with low bearing capacity and nearby groundwater poses a considerable challenge during the construction of the cross-passages. Ground freezing allows the excavation area to be selectively stabilised and, at the same time, made watertight by freezing the water contained within the ground. The freezing process is carried out from within the existing tunnel tubes. A stable frozen mass forms between the two tunnel tubes, creating a protected zone in which the cross-passage can be safely excavated. The key advantage is that no surface intervention is required. Traffic, built-up areas and public life remain unaffected.

CDM Smith

What makes ground freezing particularly environmentally friendly compared to other methods?

Simon Klösges

Ground freezing does not require any permanent alterations to the ground or groundwater. No substances are injected, and no additional excavation pits or surface installations are required. Once the work is complete, the ground thaws again, groundwater returns to its original conditions, and only the steel pipes of the freezing system remain underground. The system operates in a closed circuit: the refrigerant circulates continuously and is neither consumed nor replenished. The main energy input consists of electricity for the freezing units. Depending on the local energy mix, the method can be operated in a correspondingly climate-friendly manner. Furthermore, the early integration of ground freezing enables the optimisation of structures and processes. This leads to reduced material usage, particularly of concrete, and thus to a significant reduction in CO₂ emissions.

CDM Smith

The project has won the ISGF’s World First Award. What is special about this award?

Simon Klösges

‘World First’ recognises the outstanding achievements in project sustainability. The ISGF (International Symposium on Ground Freezing) has defined the criteria for this award. The primary aim is to minimise the carbon footprint of the entire project through the early optimisation of structures and processes. In the case of ground freezing, this includes, for example, the electricity consumption of the freezing systems or the design optimisation.

Curious to Learn More?

When you’re ready to apply this method, we can help.

Person in dark suit and light blue shirt standing in a modern indoor setting.

Simon Klösges

Project Manager

Project manager for national and international infrastructure projects, specialising inshaftand tunnel construction and ground freezing.

Ground Freezing for the Suburban Rail Loop in Melbourne

Ground Freezing for the Suburban Rail Loop in Melbourne

Practices

Markets

Priorities

An Innovative Method to Challenging Infrastructure Projects

Read the Full Interview with Simon:

Practices

Markets

Priorities

Spotlight on Ground Freezing

Ground Freezing Services

Ground Freezing Lab

Curious to Learn More?

Simon Klösges

More Resources on This Topic

Geotechnical Field Investigations

Building Resilience to Heavy Rainfall

Geophysical Explorations