Because there are limits to how much can be done to eliminate noise emanating from vehicles, it is important that local governments use their authority to mitigate noise impacts at the point where sound is received.

There are three principal ways to minimize noise impacts on humans:

1. Regulating the proximity of noise-sensitive uses to noise sources such as highways and airports.
2. Using site design, building layout and construction techniques to minimize sound impacts.
3. Planning for noise barriers in the form of berms or vegetation.

Regulating the Proximity of Developed Uses to Highways and Airports

A seemingly obvious way to prevent noise impacts is to locate highway facilities away from developed areas. Unfortunately there are some undesirable consequences associated with this approach. First, highway users from the developed area are required to drive farther to access the highway. Development also tends to grow towards the highway facility because of the access benefits it offers. This can result in more open lands being consumed by development than is otherwise needed to accommodate growth. For these reasons, new highway facilities (such as bypasses) are often located relatively close to the edges of communities.

Local zoning regulations play an essential role in preventing noise-sensitive uses from locating near busy arterials and highways. In general, land uses to avoid placing near high traffic roads include residences, schools, churches, day care centers and hospitals. While some advocate placing open space uses between highways and adjacent land uses to act as a buffer zone, this practice is only appropriate if the open space is not intended for recreational use.

Uses which are less noise sensitive and may be appropriate near busy roads include commercial, office, and industrial. Unfortunately, there is often not enough demand for noise-compatible land uses to allow all areas near high volume roads to be zoned for these uses. In this case, communities may decide to permit residential or institutional uses with special requirements for noise barriers, noise sensitive building layouts and special acoustical treatments.

Using Site Design, Building Layout and Construction Techniques

In the event that developed uses will be permitted near highways, there are some techniques available to help reduce noise impacts. Walls facing the highway should be well-insulated and constructed of noise-absorbing materials. Additional wall thickness and special efforts to seal windows can assist to some extent.

When considering site design and layout, open space facilities intended for recreational use should be located on the side of the building farthest from the highway. If residential uses are involved, patios and balconies should be placed on the side of the building opposite the highway.

The layout of interior spaces can also be planned to protect against noise impacts. However, these opportunities are limited, especially for residential uses.

Providing Noise Barriers

Federal Highway Administration regulations do not permit the use of federal funds for the construction of noise barriers in areas near existing highways. Therefore, it is up to local communities to plan to prevent noise impacts.

The effectiveness of vegetation in mitigating sound impacts has been the subject of some debate. A 1971 publication by David I. Cook and David Haverbeke, Trees and Shrubs for Noise Abatement, recommends planting 20 to 50-foot wide belts of trees and shrubs, located 20 to 50 feet from the center of the nearest traffic lane. This may be helpful in urban areas where the main source of noise is the tire-road interaction, but it is less helpful if truck noise predominates. Along high-speed rural facilities, 65 to 100-foot wide belts of trees and shrubs are recommended. Evergreen varieties are recommended where year-round screening is desired.

Another option is to erect manmade noise barriers. This is a costly solution and is only practical when the property developer expects that the market for the land near the highway will bring high enough prices to cover the costs of erecting the barrier.

Summary