It’s Getting Busy at the BORR and Bussell Highway Interchange

The BORR / Bussell Highway interchange now has its Mechanically Stabilised Earth (MSE) retaining walls up and in place marking the next milestone in this innovatively Y-shaped interchange’s road to completion.

Published: 14 December 2023, Updated: 14 December 2023

Sometimes, it’s Y that marks the spot. Or at least it’s the Bussell Highway Y-interchange that marks the spot where the new Bunbury Outer Ring Road (BORR) and Bussell Highway meet.

So what is so special about MSE walls?

It’s the construction methodology that makes this process interesting. Firstly, the facing panels are pre-cast concrete and are trucked to site. To get these walls up, the panels are tilted into position by crane and then propped up with temporary struts until they are permanently secured into place. Great care must be taken to ensure that no damage is done to the panel structures while they are transported and erected.

MSE panels being lifted into place by crane

After they are propped into place, during the backfilling process, metal straps are attached horizontally, at regular intervals to provide stability to the batter (that’s the slope behind the bridge). The combination of the walls, straps and backfill technique provides the required structural integrity for the bridge.

An example of the cross-section of the strapping process

For this bridge, if you look carefully you can see recessed shapes in the panel walls giving us a glimpse of the art design that will be featured at the interchange. This artwork, designed by local South West artist Ian Mutch, will showcase the native species of Banksia found in the region and capture the beautiful aesthetic of the flora during the cool Makuru season, which lasts throughout June and July.

Visualisation of Ian Mutch’s artwork design

As construction at the BORR and Bussell Highway interchange continues, it’s exciting to see the innovative structure take shape. The Y-shape of the interchange facilitates free-flowing traffic from the north and south, reducing stoppages and making for a safer and more efficient road network.

“The MSE panels going up at the Bussell Highway Y-interchange is an exciting milestone,” said Michael Kakulas, Area Lead and Structural Bridge Engineer at the South West Gateway Alliance. “This innovatively designed interchange is a first for Western Australian country roads and will be a great landmark for people travelling north onto BORR or south off of BORR.”

Wall panels installed and ready with recessed artwork visible

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