Highway Sound Insulation

Driving on the motorway, through Chiba Prefecture in Japan (on my way to the Highway Conference in Kuala Lumpur) I couldn't help noticing the structures used there to insulate surrounding buildings from the noise of motorway traffic...

The exceptions were the industrial areas. They had no sound insulation....

But this sort of treatment was common. Solid barriers for sound waves, with some added greenery to soften the visual impact (for traffic), and also along the top in many places to soften the visual effects from buildings...

In areas of denser residential development the sound insulation barriers curve inward - like this - to further direct sound waves vertically and to protect residential dwellings from transport noise.

This treatment must have used heavy glass blocks to get the sound insulation level needed, but also provided for reduced visual effects - both from the point of view of vehicles and buildings.