How high should a highway noise barrier be?

The height of a highway noise barrier depends on several factors, but generally, the typical range is:

Standard Height Range

8 to 20 feet (2.4 to 6 meters)

What Determines the Right Height?

1.Distance Between Road and Homes

Closer homes usually require taller barriers to effectively block sound.

2.Elevation Differences

If the homes are on higher ground than the road, taller walls might be needed—or walls may be ineffective.

3.Type of Noise Source

Trucks and high-speed traffic create lower-frequency noise, which requires taller and denser barriers.

4.Desired Noise Reduction

A barrier typically reduces sound by 5–10 decibels, but higher walls can offer additional reduction.

5.Line-of-Sight Blocking

To be effective, the barrier must completely block the line of sight between the noise source (tires/engines) and the receiver (homes).

Rule of Thumb

For every 1 foot of added height, noise reduction improves by about 1–2 decibels, up to a point.

Typical Design Example

If homes are:

200 ft away from the road, and

at roughly the same elevation,

a 16 ft tall barrier may be needed for effective mitigation.