Behind the construction of ‘Australia’s greenest freeway’

(Photo by Markus Spiske from Pexels)

Melbourne’s Mordialloc Freeway has been called ‘Australia’s Greenest Freeway’ for its unique design features and high percentage of recycled material. Roads & Infrastructure speaks to the team at Alex Fraser, one of the project’s key suppliers. Tom O’Keane reports.

The delivery of the new Mordialloc Freeway in Melbourne’s eastern suburbs by McConnell Dowell, Decmil Group and Major Road Projects Victoria (MRPV) in November last year marked the completion of one of Australia’s most sustainable freeway constructions.

The project was one of the six selected by the Australian Constructors Association and Engineers Australia as finalists to compete for the prestigious 2022 Australian Construction Achievement Award (ACAA), with the winner due to be announced in May.

The project delivered nine kilometres of dual carriageway between Mornington Peninsula Freeway and the Dingley Bypass, eight kilometres of shared walking and cycling paths and six new bridges, including four with new freeway entry and exit ramps.

Construction of the project commenced in October 2019 and was completed four weeks earlier than scheduled, on 21 November 2021.

The Mordialloc Freeway construction was firmly focused on sustainability, using large volumes of recycled materials and emission reduction initiatives.

Hundreds of tonnes of plastic waste was reused in the noise walls and the drainage pipes, and thousands of tonnes of kerbside glass and construction and demolition waste was recycled into the green pavement.

MRPV also put strategies in place to minimise the project’s impact on local wildlife and the environment. As a result, more than a million plants, grasses, shrubs and indigenous and native trees were planted along the freeway and 44 per cent of the energy used during the construction was sourced from green energy providers.

This emphasis on sustainable practices extended to the project’s suppliers, who were tasked with delivering innovative sustainable and recycled materials to lower the carbon footprint and broader environmental impact of the project.

Use of green materials

The nine-kilometre section of newly developed arterial features more than 150,000 tonnes of recycled asphalt and over 193,000 tonnes of recycled roadbase material supplied by Alex Fraser, one of Melbourne’s leading manufacturers of sustainable construction materials. Alex Fraser also provided its paving expertise to the iconic freeway project.

The project chose to use Alex Fraser’s ‘Green Roads’ roadbase and asphalt products, containing volumes of recycled content, including concrete, brick, rock, reclaimed asphalt products (RAP) and waste glass fines. Alex Fraser worked with project leads from McConnell Dowell Decmil Joint Venture to innovate their asphalt supply resulting in unprecedented carbon savings on the pavement build for a project of this type.

The supplier introduced a Green Roads asphalt mix design, incorporating much higher volumes of RAP, which in itself contains quantities of aged, high viscosity bitumen. As a result, significantly less new bitumen was required to bind the mix, and was added at a lower viscosity. This high recycled content asphalt was designed to meet VicRoads’ General Registration, and delivered a boost for the project’s sustainability outcomes with big cost and carbon savings.

All up, the use of Green Roads roadbase and asphalt in the Mordialloc Freeway project directly diverted more than 249,739 tonnes of recyclables from landfill; saving close to 1,432,166 kilograms in greenhouse gases, when compared to the use of conventional construction materials and methods. The recycled glass incorporated into the pavement amounted to the equivalent of 204 million glass bottles, or approximately 512,511 yellow wheelie bins.