Operating for 36 Years I 150+ Years of Experience I 87,000+ Jobs Completed I Iso Accredited I In-house Engineers

Get a FREE Quote Call Us

Search

If you cant find what you’re after please don’t hesitate to contact us.

Select Region

Please select the global region website you'd like to view.

Asia
Japan

Get a FREE Quote

Submit your enquiry using our online form and include a brief message about the issues you are experiencing. A Mainmark expert will contact you within the next 24 to 48 hours, excluding weekends and public holidays.

Hidden
Consent
This field is for validation purposes and should be left unchanged.

Project Profile V16 N16JG013

Rail Tunnel Safely Decommissioned

Sub-industry
Rail
Problems
Subsidence
Location
VIC
Year
2016
Solutions
Void Filling
Technology
Terefil®

The problem

An old rail tunnel under Mercer Street in Geelong, formerly a major transport line for the city, had fallen into disrepair. It had become a shelter for Geelong’s homeless community and was frequently vandalised.

The 6-metre wide, 5-metre tall, 40-metre long tunnel needed to be safely decommissioned to enable construction of a public carpark along the rail corridor.

Mainmark was appointed by Entracon Civil to abandon the tunnel. Using our lightweight Terefil® solution, we quickly and cost-effectively filled the 1,200m3 tunnel in just nine days.

The solution

The council required a fill material that would prevent access to the tunnel by vandals and drug users. The construction methodology had to ensure the safety of the homeless, who were using the tunnel as a shelter, was not compromised. The solution was also required to minimise disruption to the general public and street traffic above.

The Result

The original plan was to fill the void with polystyrene blocks over several weeks, however as polystyrene is highly flammable, the council was concerned a spark in the tunnel may cause a fire. The possibility of a fire was a significant risk to the project and to the members of the public who were using the tunnel as a shelter. The polystyrene system was also unable to bear heavy loads, making it less desirable for the project.

Instead, Mainmark recommended its unique, engineered fill material, Terefil®, as an alternative approach.

The lightweight formula can deliver strengths of between 500 and 6,000 kPA (at 28 days). Ideal for when granular fills or aggregate material options are too heavy, site access is limited, or project schedules are tight, Terefil® is easily-placed, and does not require pre-loading or compaction for settlement mitigation.

The Mainmark team placed Terefil® at a rate of up to 60m3 per hour. The highly-flowable nature of Terefil® made it fast to apply, and the strong material was able to withstand heavy loads, plus the traffic along the road above was not impacted.

By using Terefil®, Mainmark completed the project in just nine days instead of the several weeks it would have taken using the polystyrene method.

Unlike other potential grout injection systems, which would require injection holes and breathers on the road above, Terefil® caused no disruption to traffic because it was pumped directly into the tunnel.

Sean Durston-Ryan, Project Manager at Entracon Civil said, “This was the first time we had used Terefil® and the first time we had worked with Mainmark. The experience was very positive: Mainmark did excellent work and we were able to fill the void as required in a timely fashion. We would certainly choose to work with Mainmark again in the future as we achieved a very strong result for this project.”

Resources

Project Resources & Downloads

Rail Tunnel Safely Decommissioned
Terefil®
Next Project

Safety upgrade of a hazardous weir with Terefil®

Mainmark

© 2025 The Mainmark group of companies. ‘Mainmark®’, ‘Terefil®’, ‘Terefirm®’ and ‘Teretek®’ are trademarks of the Mainmark group of companies.

Mainmark Ground Engineering Pty Ltd
ABN: 51 606 182 503

ISO 9001
ISO 14001
ISO 45001

Solutions

Ground Improvement

Subsidence Repair

Re-Levelling

Void Filling

Slab Lifting

Crack Wall Repair

Sinking Floors

Sinking Foundation Repair

Underpinning Repairs

Locations

Adelaide

Brisbane

Canberra

Hobart

Melbourne

New South Wales

Perth

Queensland

South Australia

Sydney

Tasmania

Townsville

Victoria

Western Australia

Sectors

Commercial

Residential

Infrastructure

Mining

Technologies

Teretek®

Terefil®

JOG

About Us

Our team

Careers

Media & Press

News

Awards

Contact

Locations
Mainmark Sydney

169 Sailors Bay Rd, Northbridge NSW 2063

 

Mainmark Melbourne

Unit 8, 33 Rosalie Street, Springvale VIC 3171

Mainmark South Australia

19 Heath St, Lonsdale SA 5160

Mainmark Queensland

20 Computer Road, Yatala QLD 4207

Mainmark Perth

115 Excellence Dr, Wangara WA 6065

Privacy Policy

Terms and Conditions

Created by Codex

YouTube
Facebook
LinkedIn
Instagram