Highway Noise Barrier Walls

Highway Traffic Noise Abatement Walls

Numerous studies have indicated that the most pervasive noise sources in our environment today are transportation-associated. Highway traffic noise tends to be a dominant noise source in the environment.

In 1970, public outcry led to Federal legislation that authorized the use of Federal-aid highway funds for measures to abate, mitigate, and control highway traffic noise. The measures included the construction of highway noise abatement walls and sound mitigation projects.

What Is A Noise Barrier?

Noise abatement walls are solid obstructions made of precast concrete installed between the highway and the communities along a highway. Noise abatement walls do not completely block all noise, they only reduce overall noise levels. Effective highway noise barrier walls typically reduce noise levels by 5 to 10 decibels (dB), cutting the loudness of traffic noise by as much as one-half. For example, a barrier that achieves a 10-dB reduction can reduce the sound level of a typical tractor-trailer pass-by to that of an automobile.

When Are Noise Barriers Required?

Federal requirements for noise abatement walls and noise barriers can be found in the U.S. Code of Federal Regulations, Title 23, Part 772, “Procedures for Abatement of Highway Traffic Noise and Construction Noise”. The U.S. Department of Transportation has stated that “noise barriers are not always required at locations where an absolute threshold is met”. To clarify, there is not an “industry standard number” which requires the construction of a noise barrier.

Federal Highway Administration noise regulations apply only to projects where a State transportation department has requested Federal funding for participation in the improvements. The State Department of Transportation must determine if there will be traffic noise impacts when a project is proposed for (1) the construction of a highway in a new location or (2) the reconstruction of an existing highway to either significantly change the horizontal or vertical alignment or increase the number of through-traffic lanes. If the State DOT identifies potential impacts, it must implement abatement measures. This can include the construction of noise abatement walls or sound barriers, where feasible and reasonable.

Federal law and Federal Highway Administration regulations do not require State transportation departments to build noise abatement walls or sound barriers along existing highways where no other highway improvements are planned. They may voluntarily do so, but they are solely responsible for making this decision.

• Can reduce the loudness of traffic noise by as much as half
• Do not completely block all traffic noise
• Most effective within 61 meters (200 feet) of a highway (usually the first row of homes)
• Must be designed to be visually appealing
• Must be designed to preserve aesthetic values and scenic vistas
• Do not increase noise levels on the opposite side of a highway
• Reduce noise levels for people living next to highways.

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