How do the lines they pave on the freeways reduce noise so much?

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And also, how do they hold up so well? I’ve noticed a new trend where all the cement roads have this and they cut down noise *and* seem to last longer.

In: Engineering

The lines have nothing to do with noise reduction. Concrete is much smoother than asphalt. That makes untextured cement fairly slippery so they cut lines into it to improve its traction.

What’s causing the noise reduction is just the cement itself. Concrete absorbs much more noise than asphalt does, which makes it a quieter material for roads. In general, textured concrete is just a better material to make roads out of, its just much more expensive than asphalt so it isn’t used as much.

Could you give an example of “lines they pave” to reduce noise?

I’m familiar with sound *barriers* that run along the outside of the roadway to reduce noise, but I’ve never heard of anything related to *paving* that’s done specifically to reduce noise.

https://canada.constructconnect.com/dcn/news/technology/2015/03/next-generation-concrete-surface-promises-quieter-roads-1006017w

>”In order to get the quietest pavement possible, you first have to develop the smoothest pavement, and the planes on the NGCS are perfectly smooth,” says Kraemer.

>”The grooves were an afterthought, although they help with friction and directional stability if they’re aligned with traffic. With a squared off groove, a tire will typically settle one tenth of an inch into the groove. The grooves also provide channelization for moisture.”

The smoothness of the concrete is what reduces noise. The grooves are cut to help tires grip the road and also avoid water accumulation which can lead to hydroplaning