Federal Noise Impact Assessment Guidelines and Criteria
 
Many federal agencies have created guidelines for use in determining noise impacts and land-use compatibility. Two commonly used guidelines are those established by the Department of Housing and Urban Development (HUD) and the Environmental Protection Agency (EPA).
 
HUD has established land use compatibility criteria for federally-funded housing projects to help protect public health and welfare from excessive noise. These criteria establish an Ldn range that defines normally acceptable and unacceptable land use for new construction and rehabilitation projects. Table 3 describes the HUD land use compatibility criteria. The HUD criteria are used to determine the land use compatibility of HUD funded residential developments and when noise abatement measures are required and can be funded through HUD.
 
The day‑night average sound level (Ldn) is a 24 hour, weighted average sound level that HUD, EPA, Federal Aviation Administration, Federal Transit Administration, and Department of Defense commonly use for noise impact assessment. The Ldn is derived from hourly Leq values. Studies have shown that additional annoyance occurs during the nighttime since background sound levels are typically at their minimum and many people are noise sensitive while trying to sleep. A 10 dBA nighttime () penalty is therefore added to nighttime Leq values to account for increased noise annoyance during these hours.
 
The EPA has published information which describes noise “cause and effect” relationships for sensitive land uses. These relationships are not standards because they do not account for the cost or feasibility of achieving these levels. These relationships are therefore often considered conservative and are provided for comparative purposes. The EPA cause and effect relationships are presented in Table 4.
 

TABLE 3

HUD Land Use Compatibility

 

 

Ldn Value

 

Land Use Category

Clearly Acceptable

Normally Acceptable

Normally Unacceptable

Clearly Unacceptable

 

 

 

 

 

Residential: single family, duplex, mobile home

Ldn < 60

60 < Ldn < 65

65 < Ldn < 75

Ldn > 75

Residential: multi-family, dormitories

Ldn < 60

60 < Ldn < 65

65 < Ldn < 75

Ldn > 75

Transient Lodging

Ldn < 65

65 < Ldn < 70

70 < Ldn < 80

Ldn > 80

School Classrooms, Libraries, Churches

Ldn < 60

60 < Ldn < 65

65 < Ldn < 75

Ldn > 75

Hospitals, Nursing Homes

Ldn < 60

60 < Ldn < 65

65 < Ldn < 75

Ldn > 75

Auditoriums, Concert Halls, Music Shells

Ldn < 50

50 < Ldn < 60

60 < Ldn < 70

Ldn > 70

Sports Arena, Outdoor Spectator Sports

Ldn < 60

60 < Ldn < 65

65 < Ldn < 75

Ldn > 75

Playgrounds, Neighborhood Parks

Ldn < 55

55 < Ldn < 65

65 < Ldn < 75

Ldn > 75

Golf Courses, Riding Stables, Cemeteries, Water Recreation

Ldn < 60

60 < Ldn < 70

70 < Ldn < 80

Ldn > 80

Office Buildings: professional

Ldn < 65

65 < Ldn < 75

75 < Ldn < 80

Ldn > 80

Commercial: retail, movie theaters, restaurants

Ldn < 65

65 < Ldn < 75

75 < Ldn < 80

Ldn > 80

Commercial: wholesale, light manufacturing, utilities

Ldn < 70

70 < Ldn < 80

80 < Ldn < 85

Ldn > 85

Manufacturing: noise sensitive

Ldn < 55

55 < Ldn < 70

70 < Ldn < 80

Ldn > 80

Livestock Farming, Animal Breeding

Ldn < 60

60 < Ldn < 75

75 < Ldn < 80

Ldn > 80

Agriculture (not livestock), Mining, Fishing

Ldn < 75

75 < Ldn < 95

 

 

Public right-of-way

Ldn < 75

75 < Ldn < 85

85 < Ldn < 95

 

Extensive Natural Recreation Areas

Ldn < 60

60 < Ldn < 75

75 < Ldn < 85

Ldn > 85

Source:  The Noise Guidebook, U.S. Department of Housing and Urban Development, 1980.

 

TABLE 4

EPA Cause-And-Effect Relationships

Type of

Comparison

 

Land Use

 

“Cause”

 

“Effect[1]”

 

 

 

 

Absolute comparison

(Based on overall magnitude of the sound level)

Residences

Hospitals

55 dBA Ldn

(OUTDOORS)

IMPACT THRESHOLD[2]

1.  95% sentence intelligibility (average) at 3.5m (11 ft.), normal voice

2.   Indoors, 100% sentence intelligibility with a 5 dB margin of safety, normal voice[3]

3.  Consistent with available sleep criteria

 

 

65 dBA Ldn

(OUTDOORS)

1. 95% sentence intelligibility (average) at 1m (3 ft.), normal voice

2. Indoors, greater than 99% sentence intelligibility, normal voice3

3.  Above available sleep criteria

 

 

75 dBA Ldn

(OUTDOORS)

1. 95% sentence intelligibility (average) at 0.7m (2ft), raised voice: or at 1.5m (5ft), loud voice

2. Indoors, greater than 95% sentence intelligibility, normal voice3

3. Further above available sleep criteria

 

Educational Uses

55 dBA Leq (24)

(OUTDOORS)

IMPACT THRESHOLD outdoors

IMPACT THRESHOLD, with 5 dB margin of safety, indoors3

Relative comparison[4]

(Based on the difference between existing and project induced sound levels)

Residences

Intruding noise 5 dBA less than background noise, in the absence of the intruding noise

IMPACT THRESHOLD

1. 15% complaints

2. 15-20% highly annoyed

3. Noise essentially least important of various community factors

4. No expected community reaction

 

 

Intruding noise exceeds background by 5 dBA

1. 5% complaints

2. 30-35% highly annoyed

3. Threats of legal action

 

 

Intruding noise exceeds background by 15 dBA

1. 15% complaints

2. 50-55% highly annoyed

3. Vigorous community action expected

 

[1]        All percentages shown are average percentages; specific percentage values depend upon community attitudes towards the noise source, prior experience with similar noise sources, plus other factors not related to the actual noise level.

[2]        “Requisite to protect the public health and welfare with an adequate margin of safety.”

[3] Windows assumed open, resulting in outdoor-to-indoor noise insulation of 15 dBA.

[4] This presentation of EPA conclusions condenses the EPA’s “normalized Ldn,,” to a single IMPACT THRESHOLD tabulation. This condensation is consistent with the following average background noise levels:

  • Quiet suburban or rural community (remote from large cities          50 dBA Ldn

                     and from industrial activity and trucking)

  • Normal suburban community (not located near industrial activity)  55 dBA Ldn
  • Urban residential community (not immediately adjacent to heavily 60 dBA Ldn

         traveled roads and industrial areas)

  • Noisy urban residential community (near relatively busy    65 dBA Ldn

         roads or industrial areas)

  • Very noisy urban residential community                            70 dBA Ldn

 

 Source:         U.S. Environmental Protection Agency, “Information on Levels of Environmental Noise Requisite to Protect Public Health and Welfare with an Adequate Margin of Safety,” Report 550/9-74-004, Washington, D.C., March 1974.