When imagining the materials used to support a road bridge, large white foam blocks aren’t usually what come to mind. But on the northern side of the new Melton Highway bridge, this is exactly what we’re using!
A large drainage culvert runs under the road bridge, and if we’d used traditional earth fill the weight would have been too heavy for the drain. Instead, our engineers came up with the innovative solution of installing lightweight geofoam blocks underneath the road surface.
The geofoam isn’t as light as it sounds – each block weighs about 210kg. But they’re light as a feather in comparison to the equivalent volume of earth, which would weigh more than 14,000kg.
More than 90 geofoam blocks have now been installed, in a process that looked a lot like the piecing together of a giant jigsaw puzzle.
Each piece of geofoam is 5m long, 1.2m high and 1.2m wide, which is around the same size as a large 4-wheel drive.
Over several days workers manoeuvred the huge blocks into place. Smaller blocks were then cut into triangle and rectangle-shaped pieces and slotted in to fill the gaps.
With the puzzle complete, the road surface will soon be laid and the bridge opened to traffic later this year.
