Is Seattle Still Too Noisy?

I don't have any skin in this arena but I picked up a couple of pointers reading about Newton and corpuscular versus waveform light. The wavelengths for audible sound vary from a couple of centimeters to twenty meters. A barrier needs to be at least equal to the wavelength to throw a shadow, even then, the shadow diminishes with distance. Think of sea waves coming to a pole in the water, it throws no shadow; a stone jetty throws a shadow, but only so far, the waves spread back again.

Hmm? The express lanes are on the lower deck of the bridge; did they box it in?

How could one get a controlled comparison? Who's to say the traffic loudness was the same before and after installing the panels?

In taking sound levels in an iron ore processing plant some 25 years back I realized not many know much about sound levels and how sound can best be handled.

The plant had an maximum 80 decibel weighted average guarantee outside of areas where you had to wear ear protection. After considerable searching I finally found a location where that could be achieved - a couple of hundred meters from the from the plant and behind two immense ore piles.

As the years went by I came to the conclusion the best option was to design to deflect the sound waves upward. Seemed to be the only practical solution.

Providing a wall for the sound to bounce off of probably drove the sound levels on the roadway even higher.

I've thought that too. They have put these vertical barriers along some of our limited access roads. I think they should lean to deflect upward.

I've seen that in industrial plants - the last thing you want is a wall to make sound bounce back as it becomes worse than ever.

Sometimes we used louvers to redirect the sound up and away.

Russ