How much noise does a road noise barrier block?

Question

I am from The Netherlands, where noise barriers like these are commonly built along motorways:

noise barrier

Now I live in England, where such structures are almost non-existent. In The Netherlands, living 200 metre from a motorway, I experienced far less noise than I do in England, living roughly 1.5 km from a motorway.

How much noise does a motorway noise barrier typically block? I realise the answer will depend on a lot of factors, probably primarily noise barrier design and distance from motorway, and likely others. The extreme case would be to completely bury the motorway, which should reduce noise to essentially zero. Ideally, I would like to have a map like the England noiseviewer where the user can toggle on or off a basic, intermediate, or advanced noise barrier and observe how noise at particular distances gets reduced, although I expect such a map does probably not exist.

Aside from doing a noise survey, there's no good way to quantify the effect other than to say that it does have an effect. I'll try to explain more later when I have some time. — DLS3141, Jun 11 '17 at 15:38
@DLS3141 Why can't we use sound level meters or model the same, then quantify the noise reduction in dB similar to how we can do for ear protection? — gerrit, Jun 11 '17 at 15:43
Those figures are for lab tests, which are great in a lab environment, but have some serious shortcomings when trying to translate them into real world numbers. — DLS3141, Jun 11 '17 at 16:46
@gerrit NRR measurements for ear protection are crappy measurements and completely unreliable. These types of measurements are really hard. — StrongBad, Jul 11 '17 at 18:22

score 4 · Answer 1 · answered Jul 11 '17 at 18:27

The US Federal Highway Administration says:

Effective noise barriers can reduce noise levels by 10 to 15 decibels, cutting the loudness of traffic noise in half.

It goes on to say that a 5 dB reduction is simple to obtain and a 20 dB reduction is nearly impossible to obtain.

Even completely burying a highway does not eliminate the noise. While not a highway, there are many buildings in London where you can feel the tube running underneath them.

How much noise does a road noise barrier block?

1 Answers1