The flexibility in noise abatement decision making is reflected by data indicating that some states have built many noise barriers and some have built none. Nine states and the District of Columbia have not constructed noise barriers to date. The table below lists the ten states that have constructed the most noise barriers. Effectiveness Noise barriers can be quite effective in reducing noise for receptors within approximately 61 meters of a highway. The table below summarizes barrier attenuation.
Barriers do have limitations.
For a noise barrier to work, it must be high enough and long enough to block the view of a road. Noise barriers do very little good for homes on a hillside overlooking a road or for buildings that rise above the barrier. Openings in noise walls for driveway connections or intersecting streets greatly reduce the effectiveness of barriers. In some areas, homes are scattered too far apart to permit noise barriers to be built at a reasonable cost. Public Perception Overall, public reaction to highway noise barriers appears to be positive.