U.S. Department of Transportation
Federal Highway Administration
Office of Natural and Human Environment
Publication Number - FHWA-HEP-12-044
The basis of the Federal-aid highway program is a strong federal-state partnership. At the core of that partnership is a philosophy of trust and flexibility, and a belief that the states are in the best position to make investment decisions and that states base these decisions on the needs and priorities of their citizens. The FHWA noise regulation (23 CFR 772) gives each state department of transportation (SDOT) flexibility to determine the feasibility and reasonableness of noise abatement by balancing of the benefits of noise abatement against the overall adverse social, economic, and environmental effects and costs of the noise abatement measures. The SDOT must base its determination on the interest of the overall public good, keeping in mind all the elements of the highway program (need, funding, environmental impacts, public involvement, etc.).
Reduction of highway traffic noise should occur through a program of shared responsibility with the most effective strategy being implementation of noise compatible planning and land use control strategies by state and local governments. Local governments can use their power to regulate land development to prohibit noise-sensitive land use development adjacent to a highway, or to require that developers plan, design, and construct development in ways that minimize noise impacts. The FHWA noise regulations limit Federal participation in the construction of noise barriers along existing highways to those projects proposed along lands where land development or substantial construction predated the existence of any highway.
The data reflects the flexibility in noise abatement decision-making. Some states have built many noise barriers while a few have built none. Through the end of 2010, 47 SDOTs and the Commonwealth of Puerto Rico have constructed over 2,748 linear miles of barriers at a cost of over $4.05 billion ($5.44 billion in 2010 dollars). Three states and the District of Columbia have not constructed noise barriers. Ten SDOTs account for approximately sixty-two percent (62%) of total barrier length and sixty-nine percent (69%) of total barrier cost.
This paper contains lists data supplied by SDOTs. Cost data in the listing are approximate due to varying state practices for estimating costs and because states did not report costs for 500,000 square feet of noise barriers. The data represent best estimates of SDOTs for barrier construction. There may be non-uniformity and/or anomalies in the data due to differences in individual SDOT definitions of barrier information and the project features the SDOT 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 16% of total US noise barriers by area.
Tables 1-9 provide data on barrier construction, height, materials, and unit costs (all cost information is in 2010 dollars). In summary, Tables 1-9 reveal the following:
Approximately 20% of total expenditures have occurred in the last five years; 42% in the last 10 years and 58% in the last 15 years in 2010 dollars. Total construction in the current inventory period (2008-2010) was approximately $554 million (2010 dollars) compared to the previous inventory period (2005-2007) noise barrier expenditures of approximately $747 million (2010 dollars).
For the current inventory period (2008-2010), the overall average unit cost, combining all materials, is $30.78 per square foot. The average unit cost, combining all materials, for the last 10 years is $30.56 per square foot.
Approximately 264 miles of barriers have been built with highway program monies other than Federal-aid.
Overall by length, approximately 78% of Federal-aid barriers have been Type I (a barrier built on a highway project for the construction of a highway on new location or the physical alteration of an existing highway which significantly changes either the horizontal or vertical alignment or increases the number of through-traffic lanes).
Forty-six states and the Commonwealth of Puerto Rico have constructed more than 1,938 linear miles of Type I barriers, at a total cost of approximately $3.5 billion.
Twenty-seven states have constructed at least one Type II noise barrier (a barrier built along an existing highway, i.e., a retrofit noise barrier), at a total cost of more than $1.19 billion.
Three states and the District of Columbia have not constructed any noise barriers to date: Alabama, Rhode Island, and South Dakota.
Noise barrier materials include concrete, block, wood, metal, earth berms, brick, and combinations of all these materials. Concrete and block, for single material barriers, represent the majority of total material usage with 53.31% 21.48% of all noise barriers respectively. Wood comprises 7.52% of all barriers, while metal, berm, and brick together account for 5.32% of the total. Barriers constructed with a combination of materials make up (10.98% of all barriers. Absorptive materials were used on 1.47% of all barriers. The remainder is of unidentified materials, or constructed with alternative materials such as recycled materials, plastics, composite polymers, etc.
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.
Forty-seven states and the Commonwealth of Puerto Rico have constructed highway traffic noise barriers; three States and the District of Columbia have not. The most notable trend in highway traffic noise barrier construction is that since SDOTs the built the first noise barriers in the early 1960’s they average spending more than $100 million of highway program funds annually for this form of noise abatement. Starting in 1995, SDOTs have averaged spending more than $196 million per year. Since the first highway traffic noise barrier was constructed, seventy-eight percent (78%) of all spending has been for Type I projects, and twenty-two percent (22%) for Type II projects.
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