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The satellite view of this overpass (on Google Maps) shows some banded earthworks.

enter image description here

When driving by, you can see that each band is an elongated triangular shape (street view):

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My guess is that these earthworks act as a wind break by making the wind turbulent, so as to minimise the force of cross winds on the overpass.

Is that what they're for? What are they called?

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  • $\begingroup$ They could be just a means of hiding the excess... otherwise what happens if the wind changes direction? Ie along the bands... $\endgroup$ – Solar Mike Jan 31 at 5:43
  • $\begingroup$ @SolarMike There may be a very prevailing wind direction to the area. I do prefere he decorative approach of storing excess fill. $\endgroup$ – Forward Ed Jan 31 at 6:20
  • $\begingroup$ When I first looked at these they reminded me of miniature landfills. However when looking at them from the side they are much too small to be this. They may just be simple landscaping shapes that someone put in to make the area more interesting. $\endgroup$ – Forward Ed Jan 31 at 6:22
  • $\begingroup$ Almost certainly not relevant, but interesting nonetheless: youtube.com/watch?v=7dlLmeage2U $\endgroup$ – Jonathan R Swift Jan 31 at 9:29
  • $\begingroup$ @SolarMike If the wind passes through the bands it is at ground level, so the wind isn't as strong. The overpass runs parallel to the bands. The wind at the level of the overpass is stronger simply because it's higher. $\endgroup$ – CJ Dennis Jan 31 at 9:33
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Visually appealing, natural shaped barriers to decrease noise and light from a heavy use freeway.

From: Peninsula Link - Information Sheet

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The landscape design also includes major shaped earth features, sometimes known as land-forming, at the Bungower Road and the Mornington-Tyabb Road interchanges.

Along with providing interesting visual features along the roadway these land forms also act as natural barriers to light and sound.

The view from Mornington-Tyabb access ramp at is more representative of the actual barrier.

enter image description here


From Penisula Link - Managing road traffic noise

Managing traffic noise on the freeway is a key aspect of the Peninsula Link design.

Where the acoustic model for Peninsula Link predicts that the noise limits in this policy are likely to be exceeded, noise mitigation measures such as noise walls and earth mounds will be applied to reduce traffic noise.

The choice of noise mitigation measure depends on the space available, aesthetics, visual impact and the practicality of building noise walls within the road reserve.

The height and location of the noise walls and earth mounds on Peninsula Link have been determined using the acoustic model.

They had space available, so they used shaped earth mounds to block noise and light from the expressway from the surrounding countryside. Better than unsightly noise walls.

View from Bungower overpass from 2013 showing tent-like structure of earth-works. They clearly tower over freeway blocking view and sound of freeway from access roads (and surrounding countryside).

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The earth mounds appear to be all the same shape, same angles, same peak to peak distance, parallel to intersecting road, with increasing number of planted trees off of mound peak. They are seeded with ground cover, no trees or bushes. Both intersecting roads are overpasses, which would cause amplification of sound as vehicles pass underneath.

This is too specific. If you take what they say as guidance. They ran acoustic models of noise levels that would be produced and this is the solution to cancel out the prominent frequencies that would be produced by traffic.

A noise wall is just a noise wall. They have used them all over the expressway in residential areas. Mounds shaped as triangles is unique. They even have an artistic rendition of the Bungower mounds. This is some highway engineer's pride and joy. Something they can show their grand-kids. Their signature.

It would be easier to flatten out the land and plant trees. That would block noise and visual impacts. This is used of other areas of the road.

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  • $\begingroup$ I'd like to say [citation needed], but for the claims in the original reference material, not for your answer. How does the land-forming act as a natural barrier to light and sound? Also, I've only seen land-forming in rural/semi-rural areas, not in suburban areas, so noise (and light) would seem less of a problem. $\endgroup$ – CJ Dennis Feb 1 at 1:46
  • $\begingroup$ @CJDennis ROFL So human oriented. Cows are people too! The triangle wedges are perpendicular to and above main highway. I'd go with them being more visually appealing than a solid barrier. $\endgroup$ – StainlessSteelRat Feb 1 at 1:57
  • $\begingroup$ As your image of the Tyabb Rd crossing shows (the next overpass to the south of my image), the land-forming is only between the on/off ramps and the freeway itself. So it's only blocking noise and light between those two parts of the road? No cows there (hopefully)! $\endgroup$ – CJ Dennis Feb 1 at 2:01
  • $\begingroup$ If you Google Bungower Road and Mornington-Tyabb, you will see 2019 development plans for the area. $\endgroup$ – StainlessSteelRat Feb 1 at 2:23
  • $\begingroup$ Those plans are always dumbed down for public consumption. I want to know how they work, since we've found out they're more than just decorative. Why are they that particular shape? How does that make them work? $\endgroup$ – CJ Dennis Feb 1 at 2:25

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