Summary of Noise Barriers Constructed by December 31, 2019

Updated June 2021

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 2019, especially the period from 2017 to 2019.

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 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. For any questions please contact us.

This narrative uses the time frame from 1963 to 2019 when discussing noise barrier trends; with a focus on the years 2017-2019, which is the most recent collection period.

The 1963-2019 data reflects the flexibility SHAs have in noise abatement decision-making:

49 SHAs have built at least one barrier.
36 SHAs have each built at least 10 miles of barriers.
13 SHAs have built at least 100 miles of barriers.
Three SHAs have built no barriers.

The data also shows that from 1963 through the end of 2019:

Just seven SHAs account for over half (51.9%) of total barrier length in linear feet.
Six SHAs account for about half (49.5%) of total barrier cost in 2019 dollars.

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 and Type II 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 1963, which had the earliest reported noise barrier. Noise barriers (walls and berms) have been the preferred form of abatement used by SHAs of the options available under 23 CFR 772 ¹. Noise barrier materials include concrete, block, wood, metal, earth berms, brick, fiberglass and plastics, composites, noise absorptive materials, 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 2019 dollars):

From 2017 to 2019 (the current reporting period):

States constructed 19,839,740 square feet of noise barriers (All types). This is 3,233,673 square feet less than the last reporting period from 2014-2016².
- 701,096 square feet of these were Type II barriers
The barriers totaled 240 linear miles in length.
- 9 of these miles were associated with Type II barriers.
- 17 of these miles were State or Toll funded barriers.
Total construction costs for these barriers were approximately $624 million.
- Construction costs for this period represent 7% of total expenditures since program inception in 1963.
- Of the $624 million, Type II barriers accounted for $24.2 million, or 4% of expenditures.
At least³ 91% of these barriers were constructed to protect land uses that include Activity Category B – outdoor residential land uses.
The average noise reduction was 7.43 dB(A).
Absorptive materials were used on at least⁴ 18% of the barriers built this period.

From 2014 to 2016 (the previous reporting period):

States constructed 24,053,374 square feet of barriers.
The barriers totaled 289 linear miles in length.
Total construction costs for these barriers were approximately $764 million.

From 1963 to 2019:

Forty-eight states and the Commonwealth of Puerto Rico constructed 269,441,621 square feet of barriers.
- This total includes the square footage for barriers which were later demolished, as well as the square footage for their replacements if they were constructed by December 31, 2019.
The barriers total 3,537 linear miles in length.
Total construction costs for these barriers were approximately $8.6 billion.
- The average unit cost for these barriers has been $38.50/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, the District of Columbia and Rhode Island have not constructed any noise barriers to date.

Average Unit Costs (combining all materials and barrier types:

From 2017-2019 it was $53.39 per square foot.
- For Type II barriers during this period, it was $32.35 per square foot.
From 2014-2016 it was $37.82 per square foot.
- For Type II barriers during this period, it was $31.83 per square foot.
For the past decade, from 2010 to 2019, it was $37.36 per square foot.
- For Type II barriers during this period, it was $34.94 per square foot.

Type II Barrier Construction (since 1963):

The first Type II barrier reported dates to 1973. It was a berm/wood combination barrier in Michigan that cost $269,546 in 2019 dollars.
Type II barriers account for approximately 15% of all square footage.
States have constructed 40,874,338 square feet of Type II barriers.
The barriers total 542 linear miles in length.
Total construction costs for these barriers were $1.45 billion.
The average unit cost for Type II barriers was $37.63/square foot.
These barriers have an average height of 14 feet.
Twenty-seven states have reported building at least one Type II noise barrier.

Materials Used (since 1963):

Barriers constructed with a single material make up 84% of all barriers –
- Concrete comprises 57% of these barriers.
- Block represents 17% of these barriers.
- Wood comprises 5% of these barriers.
- Metal, berm, and brick together account for another 4% of single material barriers.
- 'Other' materials comprise the final 1% of these barriers.
  - This category includes - Acrylic, Acrylite, Carsonite, Composite, undefined Concrete, Fiberglass, Glass, unspecified Other, Plastic Opaque, Plastic Other, Plastic Transparent, or PVC.
Barriers constructed with a combination of materials make up 12% of all barriers ⁵.
Absorptive materials were used on over 8% of all barriers.
At least 27% of barriers have a Reflective surface ⁶.

Items of Note:

During this reporting period some States had difficulty obtaining and reporting data. As such, the information for this reporting period is sometimes incomplete and may be updated during the next reporting period. Some states continue to report difficulty determining noise barrier costs with the increase in use of alternative project delivery approaches such as design-build where barrier costs are not itemized separately. In addition, some states updated their previous inventories with additional information, or cleaned up incorrectly repeated entries.

A new trend that is expected to continue is the demolition and reconstruction of older noise barriers. As the highway system continues to age and require new Type I projects, older barriers may have to be removed or relocated to accommodate new roadway geometries. Barriers totaling 767,903 square feet have been reported as 'demolished and replaced'.

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. Some years and periods contain more and better quality data than others, this can also affect the averages as presented. Typically, data completeness and quality has improved through time.

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 barriers they have averaged spending $180 million of highway program funds annually ⁷ for this form of noise abatement. The average annual spending for this reporting period (2017-2019) was $208 million per year. Since the first highway traffic noise barrier was constructed in 1963, seventy-one (71%) of all spending has been for Type I projects, and nineteen percent (16%) for Type II projects ⁸.

1 This report only includes noise barriers as a noise mitigation measure. Costs and types of insulation for NAC D have not been reported by any SHA. In addition, no SHA has utilized the acquisition of a buffer zone as a noise abatement measure. Costs and reductions for other avoidance measures, such as re-alignment, have not been documented.

2 Data collection for this reporting period began in early 2020. However, due to the COVID-19 global pandemic some States were unable to report their data or reported partial data for the 2017-2019 collection.

3 From 2017 to 2019, 1,190,898 square feet of barriers had no NAC reported. This is 5.9% of the total square footage for this reporting period.

4 From 2017 to 2019, 4,649,390 square feet (23.12%) of barriers did not have a surface treatment reported.

5 4% of barriers did not report a material.

6 0.5% (1,413,565 square feet) of barriers were reported as having 'Both' absorptive and reflective surfaces. 64% (172,336,554 square feet) of barriers reported no surface treatment.

7 This average is from 1972 to 2019. Costs for 1963-1971 are either a single barrier or none reported, these years are excluded from the average.

8 Barriers reported by SHAs may not have a Type assigned; or may be listed as using State (6%), Toll (1%), County, Other, Local, or a Combination (4%) of funds. These make up the remaining 13% of barrier expenditures since 1963.