culvert relining on a crane with mainmark technician

Mainmark wins Good Design Award for Toowoomba Bypass project

In 2019 Mainmark embarked on a project in Toowoomba, Queensland, playing an important role in one of the largest infrastructure projects in the state’s history.

The project was the $1.6 billion Toowoomba Bypass, a 41km long dual carriageway and ring road that was designed to improve freight connections to major ports and markets and reduce the number of trucks on Toowoomba’s local roads.

This week, our work on the Toowoomba Bypass received a prestigious Good Design Award Winner accolade in the Engineering Design category, in recognition of outstanding design and innovation.

Our role in the project was to help reline, repair and future-proof seven concrete drainage culverts which were damaged and threatened the structural integrity of the bypass.

Needless to say, it is thrilling to be acknowledged for our contributions to the ground engineering and asset preservation sector. This important project for Queensland challenged our team to think outside the box and deliver an alternative solution to a complex problem. Being recognised for that effort is a great reward for all involved.

This year, the Australian Good Design Awards attracted 933 submissions, which were evaluated by more than 70 Australian and international jurors, including designers, engineers, architects and thought leaders. Each entry was assessed according to a strict set of design evaluation criteria which includes good design, design innovation and design impact. According to Good Design Australia CEO, Dr Brandon Gien, the standard of design excellence represented in this year’s entries were the best he’d seen in 25 years of running the Awards; an encouraging sign that the design sector is flourishing.

The Good Design Awards Jury said, “Mainmark’s solution was a wonderful example of optimising on a range of parameters within constraints. Clearly innovative, this design was clever and had benefits for the project in terms of cost, schedule and quality. This is really impressive design and engineering, and a standout example of good design in this category that deserves to be recognised.”

About the project

During construction of the Toowoomba Bypass, it was discovered that seven reinforced concrete pipe culverts contained at least one damaged barrel while several were compromised in up to five separate remote and isolated locations. These culverts provided drainage from the invert of a valley beneath the fill under the road alignment. Without these culverts, rainwater and other natural events could potentially degrade the valley and the road, making a vital transport route unsafe and unusable.

Mainmark was contracted to repair and reline the damaged culverts, ensuring that they would last for years to come.

Working closely with Nexus Delivery and Roundel Civil Projects Pty Ltd, Mainmark developed an engineered solution using a multi-faceted approach to relining the RCP culverts which involved the insertion of site based custom manufactured corrugated metal pipes (CMPs) inside the damaged RCP concrete culverts and then filling the void (or annulus) between the CMP and the original RCP concrete culverts with Terefil®.

Terefil®, is our proprietary lightweight cementitious grout containing a uniformly distributed matrix of air bubbles generated by mixing cement slurry with stable, pre-formed hydrocarbon foam. This produces a lightweight concrete mix that provides the most suitable fill which does not require maintenance with additional supporting material, energy or resources. Terefil was instrumental in remediating the compromised culverts underneath the bypass, restoring their structural integrity and ensuring suitable drainage for the bypass upgrade.

Terefil is also highly flowable, making its delivery to the project site simple and stress free. This, as well as its high setting strength, allowed the team to complete the work on time and within budget in compliance with specific project requirements set by the Queensland Department of Transport and Main Roads (DTMR).

Since completion in 2019, the bypass has been able to reduce travel time across the Toowoomba Range by up to 40 minutes for heavy commercial vehicles, improve freight connections and redirect trucks away from Toowoomba’s CBD, which enhances liveability in the Toowoomba and Lockyer Valley areas.


Laurie Andrews MainmarkBy Joe Glanville

Joe Glanville is Mainmark’s ANZ General Manager. He has over 15 years’ experience in the Construction Industry, acquiring broad commercial, construction and project management skills.