Summary of Noise Barriers Constructed by December 31, 2013

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Updated May 2016

The Federal Highway Administration's (FHWA) highway noise regulation (23 CFR 772.13(f)) requires each state highway agency (SHA) to maintain an inventory of all constructed noise abatement measures. The inventory must include the following:

• overall and unit cost;
• average height, length, area;
• location;
• year of construction;
• insertion loss;
• NAC category(s);
• material(s);
• features;
• foundation; and
• project type.

The inventory, contains the data supplied by 52 SHAs which includes all 50 States plus Washington DC and Puerto Rico. SHAs provided data for the years 1963 to 2013.

Inventory Summary and Tables:
A tool has been developed to view and filter the data within the nationwide noise barrier inventory. This tool allows the user to view all the data, or filter down based on the dropdown menus. An option is provided to create a pdf of the search results. State summaries and selected graphs are also available.

In discussing noise barrier trends, the 1963 to 2013 time frame will be used, with a focus on the period of time from 2011-2013, which is the most recent period collected and the basis for this update.

The 1963-2013 data reflects the flexibility SHAs have in noise abatement decision-making:

• 49 SHAs have built at least one barrier.
• 27 SHAs have each built at least 50 barriers.
• Three SHAs have built no barriers.

The data also shows that from 1963 through the end of 2013:

• Just seven SHAs account for over half of total barrier length in linear miles (51%) and total barrier cost in 2013 dollars (52%).

Available Noise Abatement Strategies:

The FHWA noise regulation (23 CFR 772):

• Allows Federal funding of feasible and reasonable noise abatement associated with certain types of highway projects (Type I projects).
• Allows the purchase of land in order to prevent noise sensitive development adjacent to the highway for Type I projects only.
• Allows the insulation of Activity Category D facilities.
• Limits Federal funding for the construction of noise barriers in the absence of a highway project (Type II projects), to those communities where land development or substantial construction predated the existence of any highway.
• Gives each SHA the flexibility to determine the feasibility and reasonableness of various noise abatement options for Type I projects and to set up a Type II program if they choose.

States balance the abatement's benefits against its costs before making decisions on their use.

Options available outside of FHWAs regulation include local zoning and planning strategies. State and Local governments can implement these methods of noise abatement, which are the most effective:

• Noise compatible planning by requiring that developers construct developments in ways that minimize noise impacts, and
• Land use control strategies, which regulate land development to prohibit noise-sensitive land uses adjacent to a highway.

This inventory reports on abatement strategies implemented by SHAs since the noise program began in 1963. Noise barriers (walls and berms) have been the preferred form of abatement used by SHAs of the options available under 23 CFR 772¹. Noise barrier materials include concrete, block, wood, metal, earth berms, brick, fiberglass and plastics, and combinations of all these materials.

Highway Traffic Noise Barrier Construction Trends:

The full dataset submitted by the SHAs is available for searching, viewing, and downloading on the following pages. FHWA summarized the information received from the SHAs into graphs and tables. The data reveals the following information and trends (all costs below are reported in 2013 dollars):

From 2011 to 2013 (the current reporting period):

• States constructed 647 noise barriers (Type I and Type II)
  • 70 of these were Type II barriers
• The barriers totaled 207 linear miles in length.
  • 16 of these miles were associated with Type II barriers.
• Total construction costs for these barriers were approximately $491 million.
  • Construction costs for this period represent 7% of total expenditures since program inception in 1963.
  • Of the $491 million, Type II barriers accounted for $39.44 million.
• At least² 87% of these barriers were constructed to protect Activity Category B outdoor residential land uses.
• The average noise reduction was 7.12 dB(A).
• Absorptive materials were used on at least³ 30% of the barriers built this period.
• South Dakota reported building two Type II noise barriers, the first in the State.

From 2008 to 2010 (the previous reporting period):

• States constructed 585 barriers (Type I and Type II).
• The barriers totaled 275 linear miles in length.
• Total construction costs for these barriers were approximately $671 million.

From 1963 to 2013 (the period of time since the noise program began):

• Forty-eight states and the Commonwealth of Puerto Rico constructed 5,839 barriers.
• The barriers total more than 2,992 linear miles in length.
• Total construction costs for these barriers were approximately $6.56 billion.
  • The average unit cost for these barriers has been $32.51/square foot.
• These barriers have an average height of 14 feet.
  • Average barrier height varies by state from a low of 7 feet to a high of 18 feet.
• Alabama, District of Columbia and Rhode Island have not constructed any noise barriers to date.

Average Unit Costs (combining all materials and barrier types):

• From 2011-2013 it was $33.81 per square foot.
  • For Type II barriers during this period, it was $31.69/square foot.
• From 2008-2010 it was $35.14 per square foot.
• From 2004 to 2013, it was $35.46 per square foot.
• From 1963 to 2013, they have varied by State from a low of $11/square foot in North Dakota, to a high of $75/square foot in Delaware.

Type II Barrier Construction (since 1963):

• The first Type II barrier reported dates to 1973. It is a berm in Michigan.
• Type II barriers account for approximately 14% of all noise barriers ever constructed.
• States have constructed 813 Type II barriers.
• The barriers total 519 linear miles in length.
• Total construction costs for these barriers were more than $1.33 billion.
• The average unit cost for Type II barriers was 36.40$/square foot.
• These barriers have an average height of 14 feet.
• Twenty-seven states have constructed at least one Type II noise barrier.

Materials Used (since 1963):

• Barriers constructed with a single material make up 86% of all barriers
  • Concrete comprises 60% of these barriers.
  • Block represents 22% of these barriers.
  • Wood comprises 8% of these barriers.
  • Metal, berm, and brick together account for another 9% of single material barriers.
  • 'Other' materials comprise the final 1% of these barriers. This category includes plastics and fiberglass.
• Barriers constructed with a combination of materials make up 9% of all barriers⁴.
• Absorptive materials were used on at least 7% of all barriers⁵.

Items of Note:

Some states have reported difficulty determining noise barrier costs with the increase in use of alternative project delivery approaches such as design-build. Several states have also reported use of geographic information systems to develop noise barrier inventories. Both of these trends continue during this reporting period.

In addition, for the 2011-2013 reporting period, states began to report the Activity Category, Average Expected Noise Reduction, Surface Texture, and Foundation for each barrier. Previous barrier inventories may not have this information available. Some states updated their previous inventories with this information. Availability of this data varies by Year and State.

It also is important to note that cost data in the listing are approximate due to varying state practices for estimating costs. The data represent best estimates of SHAs for barrier construction. There may be non-uniformity and/or anomalies in the data due to differences in individual SHA definitions of barrier information and the project features the SHA includes in the reported noise barrier costs. Additionally, California did not provide data from 1999 through 2004 and limited data for the 2005 through 2007 inventory update. This lack of information affects the quality of data for these years, since California's reported noise barriers comprise approximately 17% of total US noise barriers by area and 19% of total US noise barriers by length.

Finally, rounding errors may cause some totals to be slightly more or less than 100% in the trend values noted above. For the actual values, please see the following pages, which contain the SHAs datasets.

Summary:

Since 1963, forty-eight states and the Commonwealth of Puerto Rico have constructed highway traffic noise barriers while three (Alabama, District of Columbia and Rhode Island) have not. The most notable trend in highway traffic noise barrier construction is that since SHAs built the first noise they have averaged spending $156 million of highway program funds annually⁶ for this form of noise abatement. The average annual spending for this reporting period (2011-2013) was $164 million per year. Since the first highway traffic noise barrier was constructed in 1963, sixty-nine (69%) of all spending has been for Type I projects, and twenty percent (20%) for Type II projects⁷.

1 This is a noise barrier inventory per 23 CFR 772.13(f), as such costs and types of insulation for NAC D are not reported. In addition, no SHA has utilized the acquisition of property or land as a noise abatement measure.

2 Some barriers had no NAC reported. Others listed NAC B in addition to another.

3 209 barriers did not have a surface treatment reported.

4 5% of barriers did not report a material.

5 4228 barriers did not report a surface treatment.

6 There are no costs reported for 1963-1971, these years are excluded from the average.

7 Barriers reported by SHAs may not have a Type assigned, or may be listed as using State or Toll funds; these make up the remaining 11% of barrier expenditures since 1963.