Land Use Planning

 

The FAR Part 150 of the Federal Aviation Regulations helps to identify noise sensitive land uses at and around airports.

To do this, FAR Part 150 provides the standards and procedures for voluntary development of:

  • Noise Exposure Maps (NEM) ] - These maps show the noise levels around the airport in 5 dB increments (65, 70, and 75 DNL). The airport operator uses these maps to identify noise-sensitive land uses in the contours.
  • Noise Compatibility Programs - This study proposes measures the airport operator can take to reduce noncompatible land uses and for preventing additional noncompatible uses within the area covered by the NEM.

Noise Exposure Maps

Noise Exposure Maps help to show how much airport noise reaches each location around an airport. When each area's noise levels are known, it is easier to prevent structures from being built in incompatible areas.

What goes into making the map?

Maps must show a standard and accurate representation of noise levels around an airport. Therefore, the FAA places restrictions on what is shown on the map and how the map is created:

  • The sound data used in the map must be taken with an instrument using an A-weighted decibel scale. This ensures that the sound data obtained more closely mirrors what would be perceived by human hearing.
  • The sound data and many other measurements that affect sound levels are put into a computer program called the Integrated Noise Model (INM). This data includes:
    • The lengths of runways
    • The number of airplanes that take off in both the daytime and the nighttime
    • The elevation and average temperature of the airport

This INM computer program is the only one accepted by the FAA. It produces noise exposure contours on the map. Noise exposure contours are lines on the map that only pass through places of equal noise levels as measured by the yearly day-night average sound levels (DNL). The FAA requires that maps show lines for the 65, 70 and 75 DNL contours.

  • The map must also show relative distances between sound sources and sound-sensitive features or structures. Therefore, a map must include such things as:
    • Locations of runways
    • An outline of the airport boundaries
    • Locations of noise sensitive buildings such as schools and hospitals
    • Estimates of the number of people inhabiting areas within the 65, 70 and 75 dB contours.

It must also show any incompatible land uses within the different noise contours, such as a school without sound insulation inside the 65 dB contour or a zoo within the 70 dB contour line.

Compatibility is determined by a table in the FAR Part 150 that includes different types of land uses and the sound levels with which they are compatible.

The following video illustrates a noise footprint for an aircraft departure using different flight tracks. The noise impact can be reduced by using flight tracks that fly over compatible open space land us.

To watch the video Track Changes, click here.

For more information on Noise Exposure Maps, click here.

Noise Compatibility Programs

After an adequate Noise Exposure Map has been made, a Noise Compatibility Program is developed. This program has three purposes:

  • To help the airport operator to:
    • understand the impact of airport noise on the community
    • understand the benefits and costs of noise reduction
    • find ways to reduce or prevent incompatible land uses
  • To bring together those affected by airport noise and those affected by airport operations. This helps the airport operator to consider the needs of everyone involved.
  • To create a plan to keep noises outside the airport boundaries at or below acceptable levels. This includes recommending measures to prevent future incompatible development near the airport.

In meeting its purpose, the Noise Compatibility Program must not cause excessive strain on aviation operations. For example, the Program must not:

  • Cause a burden on interstate or foreign commerce
  • Reduce safety
  • Affect the efficiency of the Navigable Airspace and Air Traffic Control System

In summary, FAR Part 150's Noise Exposure Maps help to identify noise compatibility problems. Its Noise Compatibility Programs help to solve those problems and prevent problems from arising in the future.

References:

For more details, see the Federal Aviation Administration site at: "Part 150-Airport Noise Compatibility Planning."

Glossary Words:

Air Traffic Control, A-weighted decibel scale, day-night average sound levels (DNL), FAA, Far Part 150, Federal Aviation Regulations, Integrated Noise Model, Noise Compatibility Program, noise exposure contours, Noise Exposure Map, noise, runway, sound insulation, sound level

For definitions of words used in this section go to the NoiseQuest Glossary of Terms.