127.13 Noise: Difference between revisions

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MoDOT's entire noise abatement policy has ben restructured to comply with new federal requirements
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|[[#NOISE ABATEMENT CRITERIA|Noise Abatement Criteria]]
|align="center" colspan="2"|'''Additional Information'''
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|[http://www.fhwa.dot.gov/hep/23cfr772.htm 23 CFR 772]
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|[http://edocket.access.gpo.gov/2010/pdf/2010-15848.pdf Procedures for Abatement of Highway Traffic Noise and Construction Noise]
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|[http://www.fhwa.dot.gov/environment/noise/regulations_and_guidance/analysis_and_abatement_guidance/ FHWA Analysis and Abatement Guidance]
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This article contains the MoDOT noise policy on highway traffic noise and construction noise and describes MoDOT's implementation of the requirements of the Federal Highway Administration (FHWA) Noise Standard at [http://www.fhwa.dot.gov/hep/23cfr772.htm 23 Code of Federal Regulations (CFR) Part 772].  This policy was developed by MoDOT and approved by FHWA.
[[image:127.13.jpg|left|150px]]
The primary sources of highway traffic noise are the tire-pavement interface, engine noise and exhaust noise.  In very general terms, the lower threshold of highway noise impact is roughly the point at which interference with normal human speech is appreciable.


==127.13.1 Introduction==
The 1972 Federal-aid Highway Act required FHWA to develop a noise standard for new Federal-aid highway projects. FHWA Noise Standards give highway agencies flexibility in conforming to national requirements.


===127.13.1.1 Overview===
This article presents MoDOT’s policy on how highway traffic noise impacts are defined, how noise abatement is evaluated and how noise abatement decisions are made. Noise abatement measures that are found to be feasible and reasonable must be constructed for such projects. Feasible and reasonable noise abatement measures are eligible for Federal-aid participation at the same ratio or percentage as other eligible project costs.  


The Federal Aid Highway Act of 1970 mandates that federal agencies consider the impact of their activities on nearby land uses.  The act applies to all federal projects including those with [[127.14 National Environmental Policy Act (NEPA) Classification and Documents|National Environmental Policy Act (NEPA)]] classifications as Categorical Exclusions ([[127.26 Environmental Classification|CEs]]).  The act requires FHWA and MoDOT to evaluate every project and determine whether it could have a negative impact on nearby residences or other noise-sensitive receptors.
==127.13.1 Purpose==


Sound (noise) occurs when an ear senses pressure variations or vibrations in the air.  Noise is unwanted sound.  A person’s brain relates a subjective element to a sound, and an individual reaction is formed.  Studies indicate that the most pervasive sources of noise in our environment today are those associated with transportation.  Highway traffic noise tends to be a dominant noise source in both the urban and rural environment.
MoDOT’s program to implement 23 CFR 772 is defined herein.  Where FHWA has given MoDOT flexibility in implementing the standard, this policy describes MoDOT’s approach to implementation.  Per FHWA, changes go into effect on July 13, 2011.  The old policy will apply to projects that have reached the practicable alternatives stage or beyond by this date.  This article will apply to projects not developed to that stage.


Public concern about noise led to federal legislation in 1970 that authorized the use of federal-aid highway funds for measures to abate and control highway traffic noise.  MoDOT has a federally approved [[127.13 Noise#127.13.4 Traffic Noise Policy| traffic noise policy]] to define and conform to the requirements of Title 23, Article 772, Code of Federal Regulations (23 CFR 772), and the noise-related requirements of the 1969 NEPA.  The guidelines in the MoDOT Noise Policy are used to determine the need, feasibility, and reasonableness of noise abatement measures and provide the basis for statewide uniformity in traffic noise analysis.
==127.13.2 Noise Standards==


===127.13.1.2 Laws and Regulations===
This article outlines MoDOT’s program to implement the FHWA Noise Standards found at 23 CFR 772. They include traffic noise prediction requirements, noise analyses, noise abatement criteria and requirements for informing local officials.


* The National Environmental Policy Act (NEPA) of 1969—provides broad authority and responsibility for evaluating and mitigating adverse environmental effects, including highway traffic noise, and directs the federal government to use all practical means and measures to promote the general welfare and foster a healthy environment.
==127.13.3 Definitions==
* 23 USC 109(h), Federal-Aid Highway Act of 1970—mandated that FHWA develop noise standards for mitigating highway traffic noise.
* 23 CFR 772, Procedures for Abatement of Highway Traffic Noise and Construction Noise—the FHWA regulations for mitigation of highway traffic noise in the planning and design of federally aided highways require conducting a noise analysis.


===127.13.1.3 Process===
'''Abatement,''' Measures used to mitigate or reduce traffic noise impacts.  


The FHWA regulations require MoDOT to a) identify traffic noise impacts and examine potential mitigation measures; b) incorporate reasonable and feasible noise mitigation measures into its highway projects; and c) coordinate with local officials to provide helpful information on compatible land use planning and control during the planning and design of a highway project.  The regulation makes a distinction between projects for which noise abatement is considered as a feature in a new or expanded highway and those for which noise abatement is considered as a retrofit feature on an existing highway.  The former are defined as Type I projects, the latter as Type II.  The district must establish the need for a noise analysis by determining whether a proposed project is a Type I or a Type II project in regard to noise abatement.
'''Activity Category A,''' Lands on which serenity and quiet are of extraordinary significance and serve an important public need and where the preservation of those qualities is essential if the area is to continue to serve its intended purpose.


{|border="1
'''Activity Category B,''' Exterior areas of single-family and multi-family domiciles.
|-
| style="background:#008000" align="center" colspan="2"|'''Project Definition'''
|-
|style="background:#008000; width:200px" align="center"| '''Type I project'''
|style="background:#cccccc"| A proposed federal or federal-aid highway project for the construction of a highway on new location or the physical alteration of an existing highway that significantly changes either the horizontal or vertical alignment or increases the number of through-traffic lanes.  The consideration of noise abatement as part of the highway construction project is mandatory if federal-aid funds are to be used and if a traffic noise impact is expected to occur.
|- 
|style="background:#008000" align="center"|'''Type II project'''
|style="background:#cccccc"|A proposed federal or federal-aid highway project for noise abatement as a retrofit feature on an existing highway.  MoDOT does not generally construct these types of projects.
|}


'''Activity Category C,''' Exterior areas of non-residential land uses including active sport areas, amphitheaters, auditoriums, campgrounds, cemeteries, day care centers, hospitals, libraries, medical facilities, parks, picnic areas, places of worship, playgrounds, public meeting rooms, public or nonprofit institutional structures, radio studios, recording studios, schools and television studios.


If the project is determined to be Type I, an appropriate traffic noise analysis is required.  Staff from [http://wwwi/design/units/enviromental.htm Design’s Environmental section] is available to determine the correct procedures for conducting a noise analysis. The traffic noise analysis, performed by a consultant, includes the following for each alternative under detailed study:
'''Activity Category D,''' Interior areas of the following land uses:  Auditoriums, day care centers, hospitals, libraries, medical facilities, places of worship, public meeting rooms, public or nonprofit institutional structures, radio studios, recording studios, schools and television studios.
* identify existing activities, developed lands, and undeveloped lands for which development is planned, designed, and programmed that may be affected by traffic noise from the highway
* determine existing noise levels
* predict future traffic noise levels for highest noise level in design year by the Traffic Noise Model (TNM), nomograph, or FHWA-approved method
* determine any traffic noise impacts
* evaluate any alternative noise abatement measures for reducing or eliminating the traffic noise impacts.


After determining the results of the traffic noise analysis:
'''Activity Category E,''' Exterior areas of developed lands that are less sensitive to highway traffic noise.  These land uses include: Hotels, motels, offices, restaurants/bars, and other developed lands, properties or activities not included in A-D or F.


:* If no noise impacts are identified, document the findings and conclude the analysis. 
'''Activity Category F,''' Land uses that are not sensitive to highway traffic noise.  These land uses include: Agriculture, airports, bus yards, emergency services, industrial, logging, maintenance facilities, manufacturing, mining, rail yards, retail facilities, shipyards, utilities (water resources, water treatment, electrical) and warehousing.
:* If noise impacts are identified, consider noise abatement measures.   
:* If abatement measures are not considered [[127.13 Noise#127.13.4.6 Reasonableness and Feasibility of Abatment| reasonable and feasible]], conclude the study. 
:* If abatement is reasonable and feasible, document the results of the analysis, including the likelihood of abatement measures and identification of impacts for which no apparent solution is available.


Districts will hold informational meetings and public hearings will be conducted for potential property owners who may be affected by traffic noise impacts.
'''Activity Category G,''' Undeveloped lands.


==127.13.2 Project Development Milestones==
'''Approach,''' Noise levels representing the worst traffic hour, L<sub>(h)</sub>, which are 1 decibel (dBA) below the levels in the [[#127.13.13 Part 772 Noise Abatement Criteria Table|Noise Abatement Criteria Table]].


===127.13.2.1 Initial Screening Stage===
'''Barrier,''' A solid wall or combination of an earthen berm and wall to provide traffic noise reduction for impacted receptors.  


At the initial project screening stage, if maps and right of way/easement information are available, district personnel in consultation with staff from [http://wwwi/design/units/enviromental.htm Design’s Environmental section] will determine whether a noise analysis is required.  Details of this process are described in [[#127.13.1.3 Process|EPG 127.13.1.3 Process]].
'''Benefitted Receptor,''' A receptor that receives at least a 7 dBA reduction in noise level after the addition of noise abatement measure(s).  


===127.13.2.2  Location/Conceptual Plan Stage===
'''Berm,''' Earthen structure constructed to provide a traffic noise reduction for impacted receptors. Noise berms and noise barriers may be combined to provide noise abatement.  


At the location/conceptual plan stage, if traffic noise has not yet been evaluated and estimated, new right of way and easement acreages are available, district personnel consults with staff from [http://wwwi/design/units/enviromental.htm Design’s Environmental section] to determine whether a noise analysis is required (detailed in [[#127.13.1.3 Process|EPG 127.13.1.3 Process]]) for the project.
'''[[127.14 National Environmental Policy Act (NEPA) Classification and Documents#127.14.3.1 Categorical Exclusion|Categorical Exclusions (CE)]],''' The [[127.14 National Environmental Policy Act (NEPA) Classification and Documents|National Environmental Policy Act (NEPA)]] classification for projects with minimal environmental impacts.


For projects that require an Environmental Assessment ([[127.26 Environmental Classification|EA]]) or an Environmental Impact Statement ([[127.26 Environmental Classification|EIS]]), the environmental compliance manager and the district will coordinate on when to begin this process.  The district may be required to engage an outside consultant to conduct the noise analysis.
'''CFR,''' Code of Federal Regulations.  


===127.13.2.3 Other Stages===
'''Common Noise Environment,''' A group of receptors within the same Activity Category in [[#Table 127.13.13 Part 772 Noise Abatement Criteria|Noise Abatement Criteria Table]] that are exposed to similar noise sources and levels, traffic volumes, traffic mix and speed and topographic features.  Generally, common noise environments occur between two secondary noise sources, such as interchanges, intersections or crossroads and within the same or very similar developments.


If traffic noise has not yet been evaluated at preliminary plans, right of way plans, final design or letting states, a noise analysis report (detailed in [[#127.13.1.3 Process|EPG 127.13.1.3 Process]]) will be prepared for the project.  At any planning stage in the design of the project when it is determined that noise mitigation is warranted, the mitigation design will commenced.
'''Date of Public Knowledge,''' -- The date of approval of the Categorical Exclusion (CE), the [[127.14 National Environmental Policy Act (NEPA) Classification and Documents#127.14.3.2 Environmental Assessment|Finding of No Significant Impact (FONSI)]], or the Record of Decision (ROD), as defined in CFR part 771.


==127.13.3  Construction Noise==
'''dBA,''' A weighted decibel, unit corrected to best measure/express the relative loudness of sounds in air as perceived by the human ear.


The public often views highway construction noise as a short term, necessary price for growth and improvement.  Highway construction noise should generally be addressed in a qualitative, rather than quantitative, manner commensurate with the scope of the highway project.  Construction noise levels may be predicted, if warranted by public comment.  If potential construction noise impacts are identified, a common sense approach should be utilized to incorporate appropriate abatement measures into the highway project.
'''Design Year,''' The future year used to estimate the probable traffic volume for which a highway project is designed, typically 20 years into the future.  


==127.13.4 Traffic Noise Policy==
'''[[127.26 Environmental Classification|Environmental Analysis (EA)]],''' The [[127.14 National Environmental Policy Act (NEPA) Classification and Documents|NEPA]] classification given to projects where the significance of impacts are not clear and are intermediate between the complexity of Environmental Impact Statements and the simplicity of CEs.


'''Highway Traffic Noise Analysis and Abatement Guidelines'''
'''[[127.26 Environmental Classification|Environmental Impact Statement (EIS)]],''' The most detailed of NEPA classifications.  EISs are usually applied to the largest scale highway projects where significant impacts are expected.


This noise policy conforms to the requirements of [http://ecfr.gpoaccess.gov/cgi/t/text/text-idx?c=ecfr&sid=fefa3acbb129b6d3776622d29ead8a3b&tpl=/ecfrbrowse/Title23/23cfr772_main_02.tpl Title 23, Article 772, Code of Federal Regulations (23 CFR 772)], and the noise-related requirements of the National Environmental Policy Act (NEPA) of 1969. The guidelines delineated here will determine the need, feasibility and reasonableness of noise abatement measures and provide the basis for statewide uniformity in analysis of traffic noise.
'''Existing Noise Level,''' The noise resulting from natural, manmade sources and human activity considered to be usually present in a particular area.  


===127.13.4.1 Definitions===
'''Feasibility,''' Consideration of engineering factors and other constraints as they related to construction of noise abatement.


Following are definitions for terms used in these guidelines:
'''[[127.14 National Environmental Policy Act (NEPA) Classification and Documents#127.14.3.2 Environmental Assessment|Finding of No Significant Impact (FONSI)]],''' Acceptance document signifying the completion of a final EA by the federal agency.


'''Abatement''':  measures used to mitigate or reduce traffic noise impacts.
'''Impacted Receiver/Receptor,''' Any receiver that has an Leq at the loudest traffic noise hour approaching (within 1 dB) or exceeding the [[#Table 127.13.13 Part 772 Noise Abatement Criteria|Noise Abatement Criteria Table]] for the corresponding land use category, or exceeding existing noise levels by 15 dBA.  


'''Approach, as used in 23 CFR 772.5(g)''':  noise levels [L(h)] which are 1 decibel (dBA) below the levels shown in the [[#NOISE ABATEMENT CRITERIA|Noise Abatement Criteria (NAC)]].
'''Insertion Loss,''' The difference between an evaluated receptor’s L<sub>eq</sub>s with and without the barrier (barrier level minus no barrier level).


'''Barrier''': a solid wall or combination earthen berm and wall to provide traffic noise reduction for impacted receptors.
'''L<sub>eq</sub>,''' The equivalent steady-state sound level at a given time. Very simplistically this is sound exposure level.  


'''Berm''':  earthen berm constructed to provide a traffic noise reduction for impacted receptors.  Noise berms and noise barriers may be combined to provide noise abatement.
'''L<sub>eq(h)</sub>,''' The hourly value of L<sub>eq</sub>.  


'''CFR''': Code of Federal Regulations.
'''Multifamily Dwelling,''' A residential structure containing two or more residences. Each residence in a multifamily dwelling shall be counted as one receptor when determining impacted and benefited receptors.


'''DBA''': A-weighted decibel, unit used to measure noise that best corresponds to the frequency response of the human ear.
'''NAC,''' The Noise Abatement Criteria as shown in the [[#127.13.13 Part 772 Noise Abatement Criteria Table|Noise Abatement Criteria Table]]. These are absolute noise levels for each activity category at or above which a noise impact is indicated.


'''Design Year''': the future year used to estimate the probable traffic volume for which a highway project is designed, typically 20 years into the future.
'''Receiver/Receptor,''' A discrete or representative location of a noise sensitive area(s), for any of the land uses listed in the [[#127.13.13 Part 772 Noise Abatement Criteria Table|Noise Abatement Criteria Table]].  


'''Existing Noise Level''':  the noise resulting from the natural and mechanical sources and human activity considered to be usually present in a particular area.
'''[[127.14 National Environmental Policy Act (NEPA) Classification and Documents#127.14.3.3 Environmental Impact Statement|Records of Decision (ROD)]],''' Documentation that signifies acceptance of a final EIS by the federal agency.


'''Impacted Receiver/Receptor''': Any receiver that has a loudest hour Leq approaching (within 1 dB) or exceeding the [[#NOISE ABATEMENT CRITERIA|Noise Abatement Criteria]] for the corresponding land use category, or exceeding existing noise levels by 15 dB.
'''Representative Receptor,'''  A point or receptor that best represents the acoustic environment of a group of receptors.


'''Insertion Loss''':  the difference in Leq with and without the barrier (barrier level minus no barrier level).  The insertion loss goal for each impacted sensitive receptor is 5 dBA or more.
'''Substantially exceed the existing noise levels,''' Increases of 15 dBA above the existing noise level are considered to be substantial by MoDOT.  


'''Leq''':  the equivalent steady-state sound level; that is, the steady-state sound level for a stated period of time that contains the same acoustic energy as the time-varying sound level during the same time period.
'''Traffic Noise Impacts,''' Impacts that occur when the predicted traffic noise levels approach or exceed the NAC or when the predicted traffic noise levels substantially exceed the existing noise levels.  


'''Leq(h)''':  the hourly value of Leq.
'''Type I Project,'''
:1. The construction of a highway on new location; or,


'''NAC''':  Noise Abatement Criteria.
:2. The physical alteration of an existing highway where there is either:  
<div id="NOISE ABATEMENT CRITERIA"></div>
{|align="center" style="text-align:center"
|'''NOISE ABATEMENT CRITERIA'''
|-
|Hourly A-weighted Sound Level  decibels (dBA)
|}


{| border="1"
::a.  Substantial Horizontal Alteration.  A project that halves the distance between the traffic noise source and the closest receptor between the existing condition to the future build condition; or,  
!style="background:#FFD700"|Activity Category!!style="background:#FFD700"|Leq(h)!!style="background:#FFD700"|Description of Activity Category
|-style="background:#cccccc
|align="center"|A||align="center"|57(exterior)|||Lands on which serenity and quiet are of extraordinary significance
and serve an important public need and where the preservation of
these qualities is essential if the area is to continue to serve its
intended purpose.
|-style="background:#cccccc
|align="center"|B||align="center"|67 (exterior)|||Picnic areas, recreation areas, playgrounds, active sports areas, parks,
residences, motels, hotels, schools, churches, libraries, and hospitals.
|-style="background:#cccccc
|align="center"|C||align="center"|72 (exterior)|||Developed lands, properties, or activities not included in Categories
A and B above.
|-style="background:#cccccc
|align="center"|D||align="center"|n/a|||Undeveloped lands.
|-style="background:#cccccc
|align="center"|E||align="center"|52 (interior)|||Residences, motels, hotels, public meeting rooms, schools, churches,
libraries, hospitals, and auditoriums.
|}


'''Receiver/Receptor''':  specific location of outdoor activity on any property that is considered to contain noise-sensitive land use.
::b.  Substantial Vertical Alteration. A project that removes shielding (vegetation does not constitute shielding as it typically does not provide substantial noise reduction), as it thereby exposes the line-of-sight between the receptor and the traffic noise source (maintenance and resurfacing projects are not Type I projects). This is done by either altering the vertical alignment of the highway or by altering the topography between the highway traffic noise source and the receptor; or,


'''Substantially exceed the existing noise levels, as cited in [http://ecfr.gpoaccess.gov/cgi/t/text/text-idx?c=ecfr&sid=fefa3acbb129b6d3776622d29ead8a3b&tpl=/ecfrbrowse/Title23/23cfr772_main_02.tpl 23 CFR 772.5(g)]''': increases of 15 dBA or more above the existing noise level.
:3. The addition of a through-traffic lane(s). This includes the addition of a through-traffic lane that functions as an High Occupancy Vehicle (HOV) lane, High Occupancy Toll (HOT) lane, bus lane, or truck climbing lane; or,


'''Traffic Noise Impacts''':  impacts that occur when the predicted traffic noise levels approach or exceed the NAC or when the predicted traffic noise levels substantially exceed the existing noise levels.
:4. The addition of an auxiliary lane, except for when the auxiliary lane is a turn lane; or,


'''Type I Project''':  a proposed federal or federal-aid highway project for the construction of a highway on a new location, or for physical alteration of an existing highway that significantly changes either the horizontal or vertical alignment or increases the number of through-traffic lanes.
:5. The addition or relocation of interchange lanes or ramps added to a quadrant to complete an existing partial interchange; or,


'''Type II Project''':  a proposed federal or federal-aid highway project for noise abatement on an existing highway.
:6. Restriping existing pavement for the purpose of adding a through-traffic lane or an auxiliary lane; or,


===127.13.4.2 Selection of Locations for Analysis===
:7. The addition of a new or substantial alteration of a weigh station, rest stop, ride-share lot or toll plaza.


Traffic noise analysis will be conducted for developed lands and undeveloped lands, for development that is planned, designed and programmed.  Development will be deemed to be planned, designed and programmed if a building permit for a noise-sensitive land use (including but not limited to, a residence, school, church, hospital, or library) has been approved by the local agency with jurisdiction at the time of the noise analysis.
:8.  If any portion of a project evaluated under NEPA is determined to be Type I per 23 CFR 772.5, then the entire project area as defined in the environmental document is a Type I project.


MoDOT will furnish the results of all highway traffic noise analyses to local government officials within whose jurisdiction a proposed highway project is located.  Specifically, environmental documents and design noise reports will contain noise and other pertinent design information.  Local officials should coordinate and distribute this information to the local area affected.  Following this procedure will encourage planners, developers, and affected communities to practice noise compatible development.
'''Type II Project,''' A proposed Federal or Federal-aid highway noise abatement retrofit project on an existing highway.  Type II projects result from situations that predate highway noise regulation or adjacent developments that occur after highway construction.


===127.13.4.3 Date of Public Knowledge and Noise Abatement===
'''Type III Project,''' A proposed Federal or Federal-aid project that does not meet the criteria for Type I or Type II is designated as a Type III project. Type III projects do not require noise analysis. Examples of Type III projects are rehabilitations, bridge replacements, shoulder additions, and turning lanes.


MoDOT is required to identify when the public is officially notified of the adoption of the location for a proposed highway project. This date establishes the "date of public knowledge" and determines the date after which Federal/State governments are no longer responsible for providing noise abatement for new development that occurs adjacent to the proposed highway project.
==127.13.4 Applicability==


The date of public knowledge will be the date that a project's environmental analysis and documentation is approved, i.e., the date of approval of [[127.14 National Environmental Policy Act (NEPA) Classification and Documents#127.14.3.1 Categorical Exclusion|Categorical Exclusions (CE)]], [[127.14 National Environmental Policy Act (NEPA) Classification and Documents#127.14.3.2 Environmental Assessment|Findings of No Significant Impact (FONSI)]] or [[127.14 National Environmental Policy Act (NEPA) Classification and Documents#127.14.3.3 Environmental Impact Statement|Records of Decision (ROD)]].  After this date, MoDOT is still responsible for analyzing changes in traffic noise impacts, when appropriate, but MoDOT is no longer responsible for providing noise abatement for new development that occurs adjacent to the proposed highway project.  Provision of such noise abatement becomes the responsibility of local communities and private developers.
This article applies to all Type I Federal highway projects in Missouri; that is, any project that receives Federal-aid funds or is otherwise subject to FHWA approval. They include Federal projects that are administered by Local Public Agencies (LPAs) as well as the highway agency.


===127.13.4.4 Identification of Traffic Noise Impacts===
If there are any questions about whether a project is subject to this policy or the FHWA Noise Standard, contact MoDOT’s Environmental Section. Because of the long lead time to complete a traffic noise study, emphasis should be placed on determining the need for a noise study early in project scoping.  


'''TYPE I PROJECTS'''
MoDOT does not participate in a Type II noise program.


A noise analysis will be conducted for all MoDOT Type I highway transportation projects where potentially impacted receivers are present. Analysis, whether by nomograph, STAMINA 2.0, or other FHWA-approved traffic noise model, should be done even if potential abatement may not be feasible or reasonable.
==127.13.5 Traffic Noise Prediction==


Analysis of traffic noise impacts is conducted in accordance with [http://ecfr.gpoaccess.gov/cgi/t/text/text-idx?c=ecfr&sid=fefa3acbb129b6d3776622d29ead8a3b&tpl=/ecfrbrowse/Title23/23cfr772_main_02.tpl 23 CFR Part 772.9].  The level of detail and effort required for the traffic noise analysis on each alternative of a proposed project should be commensurate with the type of project and the associated impacts and/or issues.
The FHWA Traffic Noise Model, TNM 2.5, or the most recent version of TNM, will be used to predict traffic noise. Other models found acceptable to FHWA and pursuant to 23 CFR 772.9 may be proposed and will be evaluated on a case by case basis.  Traffic noise predictions will be performed for all reasonable build alternatives under consideration in [[127.14 National Environmental Policy Act (NEPA) Classification and Documents|NEPA]]  documents for Type I projects.


23 CFR Part 772.9 reads, in part:
Average pavement type will be used in all models, unless MoDOT obtains FHWA approval to use different pavement type(s).


"Analysis of traffic noise impacts and abatement measures.
The worst traffic noise hour will be used in noise predictions.  This period is usually preceding or after the peak traffic period.  Due to congestion and the resulting slowing of traffic, noise levels usually decrease and large, noisy, trucks often avoid the peak traffic period.


:(a) The highway agency shall determine and analyze expected traffic noise impacts and alternative noise abatement measures to mitigate these impacts, giving weight to the benefits and cost of abatement, and to the overall social, economic and environmental effects.
==127.13.6 Analysis of Traffic Noise Impacts==


:(b) The traffic noise analysis shall include the following for each alternative under detailed study:
Although traffic noise measurements are sufficient in determining existing traffic noise levels, a combination of measurements and modeling can serve to validate the model for the existing condition as well.  The combination is preferred.  Further instructions may be found at [http://www.fhwa.dot.gov/environment/noise/measurement/ FHWA-PD-96-046 DOT-UNTSC-FHWA-96-5].


::(1) Identification of existing activities, developed lands, and undeveloped lands for which development is planned, designed and programmed, which may be affected by noise from the highway;
Noise readings must be taken at representative receptor locations for proposed highway projects on new alignment, where no highway exists.


::(2) Prediction of traffic noise levels;
Measurements should be taken during the worst noise hour.  This corresponds usually to the period preceding or just after the peak traffic volume, in heavily congested urban areas.  This is largely because of slow peak traffic speeds and large trucks avoiding congested periods.  Measurements should not be taken during rain events or in winds exceeding twelve miles per hours.  Measurements will conform to FHWA requirements, [http://www.fhwa.dot.gov/environment/noise/measurement/mhrn00.cfm\ FHWA-PD-96-046 DOT-UNTSC-FHWA-96-5].


::(3) Determination of existing noise levels;
ANSI Type 1 or 2 integrating sound level meters are required.  FHWA guidance will be used, [http://www.fhwa.dot.gov/environment/noise/measurement/ FHWA-PD-96-046 DOT-UNTSC-FHWA-96-5].


::(4) Determination of traffic noise impacts; and
MoDOT’s standard procedure for validating traffic noise models is a comparison of existing noise levels and predicted noise levels, for the existing traffic condition.  If the levels are within three decibels for selected receptors, the model is assumed to be valid.


::(5) Examination and evaluation of alternative noise abatement measures for reducing or eliminating the noise impacts."
Outdoor areas of frequent human use are considered primary locations when determining noise impact and will be used for taking noise readings.  Play areas, balconies, swimming pools and patios are examples of frequent human use areas.  Engineering judgment must be exercised in determining which, if multiple frequent human use areas are present, is potentially most affected by highway noise.


Existing noise levels will be determined using FHWA's current noise measurement procedures, as described in "Sound Procedures for Measuring Highway Noise, Final Report."
For NEPA documents on Type I projects, noise analysis is required for all reasonable build alternatives.  Lesser evaluations may be appropriate for examination of broad corridors, such as Tier 1 Environmental Impact Statements, provided there is early FHWA and participating agency agreement.


Future noise levels will be predicted using FHWA's current highway traffic noise prediction model (e.g., "FHWA Highway Traffic Noise Prediction Model FHWA-RD-77-108").
If any segment or component of an alternative meets the definition of a Type I project, then the entire alternative is considered to be Type I and is subject to the noise analysis requirements early in the project planning process.


A traffic noise impact is deemed to occur whenever the predicted traffic noise levels approach or exceed FHWA's NAC or whenever predicted traffic noise levels substantially exceed existing noise levels.  "Approach" shall mean sound levels of one dBA less than the NAC, while "substantially exceed" shall mean an increase of at least 15 dBA from existing sound levels.
Noise analysis must include each Activity Category present in the study area.  See [[#Table 127.13.13 Part 772 Noise Abatement Criteria|Noise Abatement Criteria Table]] for additional details on each Activity Category.


===127.13.4.5 Consideration of Traffic Noise Abatment===
'''Activity Category A''' Justifications for designating land as Category A will be submitted through the Missouri FHWA Division Office and FHWA Headquarters, as this is the protocol outlined by FHWA, per 23 CFR 772.11. Impacts are either a substantial increase, 15 dBA or approaching the NAC, 56 dBA.


Generally, [[#NOISE ABATEMENT CRITERIA|traffic noise abatement]] will be considered whenever traffic noise impacts are identified.  However, MoDOT will not normally provide abatement for Activity Category C or in areas of mixed land use that are dominated by or changing to Activity Category C.
'''Activity Category B''' Each potentially affected receptor will be analyzed for traffic noise impact, which would be a substantial increase, 15 dBA or greater, or approaching the NAC, 66 dBA.


Traffic noise abatement measures will be implemented on a highway project if found to be reasonable and feasible.  A discussion of the reasonableness and feasibility of abatement is presented in the next section.  The traffic noise analysis document will contain a discussion of the reasonableness and feasibility of abatement and the types of abatement measures considered, whether or not any abatement measures are implemented.
'''Activity Categories C''' Each potentially affected property will be analyzed for traffic noise impact, which would be a substantial increase, 15 dBA or greater, or approaching the NAC, 66 dBA.  Receptors will be counted as feet of frontage, which will be the average of the residential frontages in the project area (e.g. one receptor equals 100 ft. of frontage).
   
'''Activity Category D''' This Category should only be used after exhausting all outdoor analysis options.  Each potentially affected property will be analyzed for traffic noise impacts, which would be a substantial increase, 15 dBA or greater, or approaching the NAC, 51 dBA.  Receptors will be counted as feet of frontage, which will be the average of the residential frontages in the project area (e.g. one receptor equals 100 ft. of frontage).  FHWA publication FHWA-DP-45-1R, Sound Procedures for Measuring Highway Noise: Final Report provides procedures to measure building noise reductions.


When noise impacts are shown to exist on a project, a number of possible noise abatement measures will be considered, including, but not limited to:
'''Activity Category E''' Each potentially affected property will be analyzed for traffic noise impact, which would be a substantial increase, 15 dBA or greater, or approaching the NAC, 71 dBA.  Receptors will be counted as feet of frontage, which will be the average of the residential frontages in the project area (e.g. one receptor equals 100 ft. of frontage).


:1. Traffic management measures: modified speed limits, traffic control devices, time-use restrictions for certain vehicles, and prohibition of certain vehicle types.
'''Activity Category F''' No action required.


:2. Changes in horizontal or vertical alignment to break the line of sight between receiver and source.
'''Activity Category G''' Representative data will be generated as needed to provide information to other governmental entities.
Approaching NAC is defined by MoDOT as being 1 dBA less than the NAC for Activity Categories A-E.


:3. Noise barriers or berms: a noise barrier or berm must provide a noise reduction of 5 decibels or more for first-row receivers.
A substantial increase over the existing noise level is an increase of at least 15 dBA. This level of increase is difficult to achieve.  Generally, this sort of impact would only be expected for larger highways on new alignment or new highways.


===127.13.4.6 Reasonableness and Feasibility of Abatement===
As previously noted, MoDOT does not participate in a Type II noise abatement program. If a local government commits to complete a noise abatement project on a MoDOT roadway, they may petition the Missouri Transportation and Highway Commission to fund 25 percent of the cost.  Proposed projects must meet all MoDOT noise impact and abatement criteria. No federal funds are available for use in these situations.


There are two main elements in the consideration of noise abatement: reasonableness and feasibility.  The criteria and procedures used to determine reasonableness and feasibility should be objective enough to be quantifiable, but flexible enough to allow MoDOT to make meaningful judgments on a case-by-case basis for unusual or special circumstances. The following discussion covers feasibility and reasonableness of noise abatement.
Impacted receptors will usually be identified by ID numbers given during noise analysis.  These ID numbers will correspond to a physical address.


'''FEASIBILITY'''
==127.13.7 Analysis of Noise Abatement Measures==


Feasibility deals with the engineering considerations of noise abatement, for example, topography, access, drainage, safety, maintenance, and if other noise sources are present.  Feasibility is the ability to provide abatement in a given location with consideration to the physical and acoustical limitations of the site.  MoDOT requires at least a 5 dBA insertion loss for first-row receivers for noise abatement to be considered feasible.
When traffic noise impacts are identified, noise abatement shall be considered and evaluated for feasibility and reasonableness.


'''REASONABLENESS'''
Noise barriers are most often used as noise abatement.  However, all potential noise abatement measures may be considered and used if they are both feasible and reasonable.


The reasonableness evaluation of proposed noise abatement mitigation measures is more subjective than evaluation of feasibility.  Reasonableness implies use of common sense and good judgment and is based on a number of factors.  These factors include, but are not limited to:
At this time, MoDOT is not a part of a FHWA-approved Quiet Pavement Pilot Program.  Therefore, use of quieter pavements is not an acceptable Federal-aid noise abatement measure for Federal projects.  Use of vegetation or landscaping is not an acceptable Federal-aid noise abatement measure.  For vegetative noise attenuation to be appreciable a minimum of a 100-ft. buffer is required and only dense evergreen vegetation is effective.  Use of absorptive materials will be considered, if circumstances warrant its use.


:(a) Noise wall (or "sound wall") must provide noise reduction of at least 5 dBA for all primary receptors. Primary receptors are those that are closest to the highway.
==127.13.8 Feasibility==


:(b) Noise wall (or "sound wall") must provide attenuation for more than one receptor.
Feasibility is the ability to provide abatement in a given location considering the acoustic and engineering limitations of the site.  Acoustic feasibility refers to noise abatement measure(s) ability to achieve the minimum noise reduction at impacted receptors.  MoDOT requires at least a 5 dBA insertion loss for a minimum of 67 percent of first-row, impacted receivers for noise abatement to be considered feasible.  Engineering feasibility refers primarily to physical constraints and other constuctability constraints, such as topography, access, drainage, safety, maintenance, and presence of other noise sources.  In general, if these factors are too extreme or cannot be accommodated in providing the minimum noise reduction, noise abatement will be deemed unfeasible.  For reasons of safety (primarily wind load and clear space concerns), a noise wall's height is limited to 20 feet.  This criterion alone cannot be used to consider noise abatement unreasonable.


:(c) Noise wall (or "sound wall") must be 18' (5.5m) or less in height above the surrounding ground.
==127.13.9 Reasonableness==


:(d) Noise wall (or "sound wall") must not interfere with normal access to the property.
Each of the three required reasonableness factors must be met.


:(e) Noise wall (or "sound wall") must not pose a traffic safety hazard.
'''Mandatory Reasonableness Factors:'''


:(f) Noise wall (or "sound wall") must not exceed a cost of $30,000 per benefited receptor. A benefited receptor is defined as a receptor that receives a noise reduction of 5 dBA or more.
:1.  Viewpoints of owners and residents of the benefitted receptors will be obtained. These will usually be obtained through mailings or a public forum.  The viewpoints of non-owner residents will be evaluated as a portion of an aggregate of 25 percent of the total. The viewpoints of owners will be evaluated as a portion of an aggregate of 75 percent of the total.  For noise abatement to be considered reasonable, over 50 percent of the aggregate response must be in favorable.


:(g) The majority of the affected residents (primary and benefited receptors) must concur that a noise wall (or "sound wall") is desired.
:2.  Noise abatement measures shall not exceed an all-inclusive cost of $36,000 per benefitted receptor (e.g. materials, right-of-way, mobilization, installation, traffic control, and relocates).  Coordination with and approval of FHWA is needed prior to incorporating any unanticipated costs.  This cost shall be recalculated at an interval not to exceed every 5 years.


'''Cost per residence''':
:3.  Noise abatement measures must provide a benefit of a minimum of 7 dBA for 67 percent of first-row receptors.


MoDOT has established that noise abatement will be considered reasonable if the cost to provide the abatement is $30,000 or less per receptor.  All receptors that will benefit from noise abatement will be included in the cost index.  Benefited receptors are all residences, including those that are not first-row residences, but which receive a 5 dBA reduction in noise or greater due to the implementation of traffic noise abatement.
For reasons of safety (primarily wind load and clear space concerns), noise walls are limited to a height of 20 feet.  This criterion alone cannot be used to consider noise abatement unreasonable.


Residences include all dwelling units, such as homes, apartments and mobile homes.  Each first-floor apartment in an apartment complex will be counted as a separate dwelling unit.
For noise abatement measure reporting (23 CFR 772.13(f)), MoDOT shall maintain an inventory of all constructed noise abatement measures. The inventory shall include the following parameters: type of abatement; cost (overall cost, unit cost per sq. ft.); average height; length; area; location (State, county, city, route); year of construction; average insertion loss/noise reduction as reported by the model in the noise analysis; NAC category(s) protected; material(s) used (precast concrete, berm, block, cast in place concrete, brick, metal, wood, fiberglass, combination, plastic (transparent, opaque, other); features (absorptive, reflective, surface texture); foundation (ground mounted, on structure); project type (Type I, Type II); and optional project types such as state, county, tollway/turnpike, or other unknown funding sources.  This information shall be collected triennially by the design division.


'''Timing of development''':
[[127.14 National Environmental Policy Act (NEPA) Classification and Documents|NEPA]]  Decision:  Prior to a CE approval or issuance of a FONSI or ROD for a Type I project, the highway agency must identify:


This is an important factor in determining the reasonableness of noise abatement.  MoDOT will give greater consideration to:
:1.  The noise abatement measures that are feasible, reasonable, and likely to be incorporated into the project; and


:(1) residential areas along highways on a new location,
:2.  Noise impacts for which no abatement appears to be feasible and reasonable;
:(2) residential areas that were constructed before an existing highway, and
:(3) residential areas that have been in place along an existing highway for an extended period of time.


MoDOT will give less consideration to residential areas that have developed along an existing highway without proper consideration of traffic noise impacts by the local community or developer.
:3.  The NEPA documentation for Type I projects shall identify the locations where noise impacts will occur, where noise abatement is feasible and reasonable, and the locations that have no feasible and reasonable abatement.  The statement of likelihood will include the preliminary locations of feasible and reasonable abatement and a statement that the final recommendation will be made after the final design and public involvement processes are complete.  For example:  Noise walls are very likely between stations 41+00 and 42+00 and should average 12 feet.  The noise walls will attenuate noise on the south side of the highway.  The noise walls appear to be both reasonable and feasible. Final recommendations will be made after final design and the public involvement are complete.  


'''Views of impacted residents or organizations''':
Third party funding cannot be used to make up the difference in cost between the reasonable cost allowance and the actual cost. Third party funding can only be used to pay for additional features such as landscaping, aesthetic treatments, etc. for noise barriers that meet cost-effectiveness criteria.


This mainly applies to projects in which a noise barrier or berm is being considered for noise abatement.  Views of impacted residents will be a major factor in consideration of noise abatement.  MoDOT will make every reasonable effort to solicit the views and opinions of impacted residents before making a final determination on the reasonableness and feasibility of noise abatement.
MoDOT allows cost averaging for noise abatement on Type I projects, among benefited receptors within common noise environments if no single component of the common noise environments exceeds two times the highway agency's cost reasonableness criteria and collectively all common noise environments being averaged do not exceed the highway agency's cost reasonableness criteria.  A subdivision is an example of a common noise environment.


When considering the construction of noise abatement measures, MoDOT will consider any potential negative effects on the natural environment, as well as potential positive effects of noise reduction during highway construction.
==127.13.10 Federal Participation in Type I and Type II Projects==


===127.13.4.7 Public Involvement===
Federal funds may be used for noise abatement measures when:


During the project development stage for a proposed highway project, informational meetings, both formal and informal, will be conducted to solicit comments, opinions and concerns from local officials and the public.  A list of potentially affected areas and reasonable and feasible noise abatement measures will be developed and addressed in environmental documents prepared for the project.  Likely noise abatement measures will be presented and discussed at the [[:Category:129 Public Involvement#129.7 Design Public Hearings|Design Public Hearing]].  Following public comment, a Final Noise Report will be prepared if needed. Abatement design measures deemed reasonable, feasible and cost-effective will be incorporated into the document.
:1.  Traffic noise impacts have been identified; and


===127.13.4.8 Coordination with Local Officials===
:2.  Abatement measures have been determined to be feasible and reasonable pursuant to 23 CFR 772.13(d).


Highway traffic noise should be reduced through a program of shared responsibility. Local governments should use their authority to regulate land development in such a way that noise-sensitive land uses are either prohibited from being located adjacent to a highway, or that developments are planned, designed, and constructed so as to minimize noise impacts.
==127.13.11 Information for Local Government Officials==


It is MoDOT policy to furnish the results of highway traffic noise analyses to local government officials.  Local coordination will specifically be accomplished through the distribution of highway project environmental documents and noise study reports. MoDOT encourages local communities and developers to practice noise-compatible development.
To minimize future traffic noise impacts on currently undeveloped lands for Type I projects, MoDOT shall inform local officials within whose jurisdiction the highway project is located of:


===127.13.4.9 Extenuating Circumstances===
:1. Noise compatible planning concepts;


There may be extenuating circumstances where unique or unusual conditions (such as extremely noise sensitive areas, Section 4(f) resources, etc.) warrant special consideration of highway traffic noise impacts and/or implementation of noise abatement measures. Extenuating circumstances will be considered on an individual case-by-case basis.
:2. The best estimation of the distance to future design year noise levels that approach the exterior noise abatement criteria in [[#Table 127.13.13 Part 772 Noise Abatement Criteria|Noise Abatement Criteria Table]];


===127.13.4.10 Type II Projects===
:3. Non-eligibility for Federal-aid participation for a Type II project as described in 23 CFR 772.15(b), for developments in areas shown to be noise impacted.


Noise abatement will be considered along existing highways if all of the following criteria are met:
==127.13.12 Construction Noise==


:(a) The noise abatement will only be considered on an existing highway that was built or expanded after the adjacent development that is to be protected had occurred or for adjacent land use that was in existence prior to May 14, 1976.
For all Type I and II projects, MoDOT will as required in 23 CFR 772.19:


:(b) The noise abatement must meet all of the criteria of the [[127.13 Noise#127.13.4.4 Identification of Traffic Noise Impacts|Type I Noise Abatement Policy]].
:1.  Identify land uses or activities that may be affected by noise from construction of the project.  The identification is to be performed during the project development studies.


:(c) Existing highest sound levels must approach or exceed the [[#NOISE ABATEMENT CRITERIA|NAC]].
:2.  Determine the measures that are needed in the plans and specifications to minimize or eliminate adverse construction noise impacts to the community.  This determination shall include a weighing of the benefits achieved and the overall adverse social, economic and environmental effects and costs of the abatement measures.


:(d) The Type II noise abatement project must be eligible for federal funds and must be requested by a local government entity.  The majority of the affected residents (primary and benefited receptors) must concur that a noise wall is desired.
:3.  Incorporate the needed abatement measures in the plans and specifications.


:(e) Any required adjustment to the existing highway will be considered part of the cost of the noise abatement.
==127.13.13 Part 772 Noise Abatement Criteria Table==
 
{| border="1" class="wikitable" style="margin: 1em auto 1em auto"
:(f) The local government entity must provide 75% of the cost.  The Commission will provide the 25% matching funds.  If the cost of the abatement exceeds $30,000 per benefited receptor, the local government entity will pay 100% of the cost exceeding the $30,000 per benefited receptor.  A benefited receptor is defined as a receptor that receives a noise reductions of 5 dBA or more.
|+
 
! style="background:#BEBEBE" rowspan="2" |Activity Category!! style="background:#BEBEBE" colspan="2" width="250px"|Activity Criteria<sup>1</sup> !! style="background:#BEBEBE" rowspan="2"|Evaluation Location !! style="background:#BEBEBE" rowspan="2"|Activity Description
===127.13.4.11 Construction Noise===
|-
 
!style="background:#BEBEBE"|L<sub>eq(h)</sub>!! style="background:#BEBEBE"|L<sub>10(h)</sub> 
To reduce the impacts of construction noise, MoDOT has special provisions in the construction contract that requires that all contractors comply with all applicable local, state, and federal laws and regulations relating to noise levels permissible within and adjacent to the project construction site.  Construction equipment will be required to have mufflers constructed in accordance with the equipment manufacturer's specifications.  Further, MoDOT will monitor project construction noise and require noise abatement in cases where the criterion is exceeded.
|-
 
|align="center"|A||align="center"| 57||align="center"| 60||align="center"| Exterior||Lands on which serenity and quiet are of extraordinary significance and serve an important public need and where the preservation of those qualities is essential if the area is to continue to serve its intended purpose
===127.13.4.12 Noise Abatement Review Team===
|-
 
|align="center"|B<sup>2</sup>||align="center"|67||align="center"|70||align="center"| Exterior|| Residential
MoDOT will consider the style, architectural features and aesthetics of noise walls (or "sound wall") to ensure the following:
|-
|align="center"|C||align="center"| 67||align="center"|70||align="center"|Exterior||Active sport areas, amphitheaters, auditoriums, campgrounds, cemeteries, day care centers, hospitals, libraries, medical facilities, parks, picnic areas, places of worship, playgrounds, public meeting rooms, public or nonprofit institutional structures, radio studios, recording studios, recreation areas, Section 4(f) sites, schools, television studios, trails and trail crossings
|-
|align="center"|D||align="center"| 52||align="center"|55||align="center"|Interior||Auditoriums, day care centers, hospitals, libraries, medical facilities, places of worship, public meeting rooms, public or nonprofit institutional structures, radio studios, recording studios, schools, and television studios
|-
|align="center"|E<sup>2</sup>||align="center"|72||align="center"|75||align="center"|Exterior||Hotels, motels, offices, restaurants/bars, and other developed lands, properties or activities not included in A-D or F
|-
|align="center"|F||align="center"|-||align="center"| -||align="center"|-||Agriculture, airports, bus yards, emergency services, industrial, logging, maintenance facilities, manufacturing, mining, rail yards, retail facilities, shipyards, utilities (water resources, water treatment, electrical) and warehousing
|-
|align="center"|G||align="center"|-||align="center"|-||align="center"|-||Undeveloped lands that are not permitted for development
|-
|colspan="5"|<sup>'''1'''</sup> The L<sub>eq(h)</sub> and L<sub>10(h)</sub> Activity Criteria values are for impact determination only, and are not design standards for noise abatement measures.
|-
|colspan="5"|<sup>'''2'''</sup> Includes undeveloped lands permitted for development for this activity category.
|}


:(1) The walls will blend into and with the surrounding area.
:(2) The walls are visually pleasing to the residents of the area being served.
:(3) The walls are visually pleasing to the through traffic on the route and do not detract from the overall aesthetics of the highway.


For each project requiring walls for noise abatement, a design review team consisting of a representative from the Design, Maintenance and Traffic, and Construction and Materials divisions and a fourth member from a private architectural firm will review the designs and make recommendations for appropriate noise walls.  The final design will be made in consultation with the residents of the areas.


[[category:127 MoDOT and the Environment]]
[[category:127 MoDOT and the Environment]]

Revision as of 07:16, 31 March 2011

Additional Information
23 CFR 772
Procedures for Abatement of Highway Traffic Noise and Construction Noise
FHWA Analysis and Abatement Guidance

This article contains the MoDOT noise policy on highway traffic noise and construction noise and describes MoDOT's implementation of the requirements of the Federal Highway Administration (FHWA) Noise Standard at 23 Code of Federal Regulations (CFR) Part 772. This policy was developed by MoDOT and approved by FHWA.

The primary sources of highway traffic noise are the tire-pavement interface, engine noise and exhaust noise. In very general terms, the lower threshold of highway noise impact is roughly the point at which interference with normal human speech is appreciable.

The 1972 Federal-aid Highway Act required FHWA to develop a noise standard for new Federal-aid highway projects. FHWA Noise Standards give highway agencies flexibility in conforming to national requirements.

This article presents MoDOT’s policy on how highway traffic noise impacts are defined, how noise abatement is evaluated and how noise abatement decisions are made. Noise abatement measures that are found to be feasible and reasonable must be constructed for such projects. Feasible and reasonable noise abatement measures are eligible for Federal-aid participation at the same ratio or percentage as other eligible project costs.

127.13.1 Purpose

MoDOT’s program to implement 23 CFR 772 is defined herein. Where FHWA has given MoDOT flexibility in implementing the standard, this policy describes MoDOT’s approach to implementation. Per FHWA, changes go into effect on July 13, 2011. The old policy will apply to projects that have reached the practicable alternatives stage or beyond by this date. This article will apply to projects not developed to that stage.

127.13.2 Noise Standards

This article outlines MoDOT’s program to implement the FHWA Noise Standards found at 23 CFR 772. They include traffic noise prediction requirements, noise analyses, noise abatement criteria and requirements for informing local officials.

127.13.3 Definitions

Abatement, Measures used to mitigate or reduce traffic noise impacts.

Activity Category A, Lands on which serenity and quiet are of extraordinary significance and serve an important public need and where the preservation of those qualities is essential if the area is to continue to serve its intended purpose.

Activity Category B, Exterior areas of single-family and multi-family domiciles.

Activity Category C, Exterior areas of non-residential land uses including active sport areas, amphitheaters, auditoriums, campgrounds, cemeteries, day care centers, hospitals, libraries, medical facilities, parks, picnic areas, places of worship, playgrounds, public meeting rooms, public or nonprofit institutional structures, radio studios, recording studios, schools and television studios.

Activity Category D, Interior areas of the following land uses: Auditoriums, day care centers, hospitals, libraries, medical facilities, places of worship, public meeting rooms, public or nonprofit institutional structures, radio studios, recording studios, schools and television studios.

Activity Category E, Exterior areas of developed lands that are less sensitive to highway traffic noise. These land uses include: Hotels, motels, offices, restaurants/bars, and other developed lands, properties or activities not included in A-D or F.

Activity Category F, Land uses that are not sensitive to highway traffic noise. These land uses include: Agriculture, airports, bus yards, emergency services, industrial, logging, maintenance facilities, manufacturing, mining, rail yards, retail facilities, shipyards, utilities (water resources, water treatment, electrical) and warehousing.

Activity Category G, Undeveloped lands.

Approach, Noise levels representing the worst traffic hour, L(h), which are 1 decibel (dBA) below the levels in the Noise Abatement Criteria Table.

Barrier, A solid wall or combination of an earthen berm and wall to provide traffic noise reduction for impacted receptors.

Benefitted Receptor, A receptor that receives at least a 7 dBA reduction in noise level after the addition of noise abatement measure(s).

Berm, Earthen structure constructed to provide a traffic noise reduction for impacted receptors. Noise berms and noise barriers may be combined to provide noise abatement.

Categorical Exclusions (CE), The National Environmental Policy Act (NEPA) classification for projects with minimal environmental impacts.

CFR, Code of Federal Regulations.

Common Noise Environment, A group of receptors within the same Activity Category in Noise Abatement Criteria Table that are exposed to similar noise sources and levels, traffic volumes, traffic mix and speed and topographic features. Generally, common noise environments occur between two secondary noise sources, such as interchanges, intersections or crossroads and within the same or very similar developments.

Date of Public Knowledge, -- The date of approval of the Categorical Exclusion (CE), the Finding of No Significant Impact (FONSI), or the Record of Decision (ROD), as defined in CFR part 771.

dBA, A weighted decibel, unit corrected to best measure/express the relative loudness of sounds in air as perceived by the human ear.

Design Year, The future year used to estimate the probable traffic volume for which a highway project is designed, typically 20 years into the future.

Environmental Analysis (EA), The NEPA classification given to projects where the significance of impacts are not clear and are intermediate between the complexity of Environmental Impact Statements and the simplicity of CEs.

Environmental Impact Statement (EIS), The most detailed of NEPA classifications. EISs are usually applied to the largest scale highway projects where significant impacts are expected.

Existing Noise Level, The noise resulting from natural, manmade sources and human activity considered to be usually present in a particular area.

Feasibility, Consideration of engineering factors and other constraints as they related to construction of noise abatement.

Finding of No Significant Impact (FONSI), Acceptance document signifying the completion of a final EA by the federal agency.

Impacted Receiver/Receptor, Any receiver that has an Leq at the loudest traffic noise hour approaching (within 1 dB) or exceeding the Noise Abatement Criteria Table for the corresponding land use category, or exceeding existing noise levels by 15 dBA.

Insertion Loss, The difference between an evaluated receptor’s Leqs with and without the barrier (barrier level minus no barrier level).

Leq, The equivalent steady-state sound level at a given time. Very simplistically this is sound exposure level.

Leq(h), The hourly value of Leq.

Multifamily Dwelling, A residential structure containing two or more residences. Each residence in a multifamily dwelling shall be counted as one receptor when determining impacted and benefited receptors.

NAC, The Noise Abatement Criteria as shown in the Noise Abatement Criteria Table. These are absolute noise levels for each activity category at or above which a noise impact is indicated.

Receiver/Receptor, A discrete or representative location of a noise sensitive area(s), for any of the land uses listed in the Noise Abatement Criteria Table.

Records of Decision (ROD), Documentation that signifies acceptance of a final EIS by the federal agency.

Representative Receptor, A point or receptor that best represents the acoustic environment of a group of receptors.

Substantially exceed the existing noise levels, Increases of 15 dBA above the existing noise level are considered to be substantial by MoDOT.

Traffic Noise Impacts, Impacts that occur when the predicted traffic noise levels approach or exceed the NAC or when the predicted traffic noise levels substantially exceed the existing noise levels.

Type I Project,

1. The construction of a highway on new location; or,
2. The physical alteration of an existing highway where there is either:
a. Substantial Horizontal Alteration. A project that halves the distance between the traffic noise source and the closest receptor between the existing condition to the future build condition; or,
b. Substantial Vertical Alteration. A project that removes shielding (vegetation does not constitute shielding as it typically does not provide substantial noise reduction), as it thereby exposes the line-of-sight between the receptor and the traffic noise source (maintenance and resurfacing projects are not Type I projects). This is done by either altering the vertical alignment of the highway or by altering the topography between the highway traffic noise source and the receptor; or,
3. The addition of a through-traffic lane(s). This includes the addition of a through-traffic lane that functions as an High Occupancy Vehicle (HOV) lane, High Occupancy Toll (HOT) lane, bus lane, or truck climbing lane; or,
4. The addition of an auxiliary lane, except for when the auxiliary lane is a turn lane; or,
5. The addition or relocation of interchange lanes or ramps added to a quadrant to complete an existing partial interchange; or,
6. Restriping existing pavement for the purpose of adding a through-traffic lane or an auxiliary lane; or,
7. The addition of a new or substantial alteration of a weigh station, rest stop, ride-share lot or toll plaza.
8. If any portion of a project evaluated under NEPA is determined to be Type I per 23 CFR 772.5, then the entire project area as defined in the environmental document is a Type I project.

Type II Project, A proposed Federal or Federal-aid highway noise abatement retrofit project on an existing highway. Type II projects result from situations that predate highway noise regulation or adjacent developments that occur after highway construction.

Type III Project, A proposed Federal or Federal-aid project that does not meet the criteria for Type I or Type II is designated as a Type III project. Type III projects do not require noise analysis. Examples of Type III projects are rehabilitations, bridge replacements, shoulder additions, and turning lanes.

127.13.4 Applicability

This article applies to all Type I Federal highway projects in Missouri; that is, any project that receives Federal-aid funds or is otherwise subject to FHWA approval. They include Federal projects that are administered by Local Public Agencies (LPAs) as well as the highway agency.

If there are any questions about whether a project is subject to this policy or the FHWA Noise Standard, contact MoDOT’s Environmental Section. Because of the long lead time to complete a traffic noise study, emphasis should be placed on determining the need for a noise study early in project scoping.

MoDOT does not participate in a Type II noise program.

127.13.5 Traffic Noise Prediction

The FHWA Traffic Noise Model, TNM 2.5, or the most recent version of TNM, will be used to predict traffic noise. Other models found acceptable to FHWA and pursuant to 23 CFR 772.9 may be proposed and will be evaluated on a case by case basis. Traffic noise predictions will be performed for all reasonable build alternatives under consideration in NEPA documents for Type I projects.

Average pavement type will be used in all models, unless MoDOT obtains FHWA approval to use different pavement type(s).

The worst traffic noise hour will be used in noise predictions. This period is usually preceding or after the peak traffic period. Due to congestion and the resulting slowing of traffic, noise levels usually decrease and large, noisy, trucks often avoid the peak traffic period.

127.13.6 Analysis of Traffic Noise Impacts

Although traffic noise measurements are sufficient in determining existing traffic noise levels, a combination of measurements and modeling can serve to validate the model for the existing condition as well. The combination is preferred. Further instructions may be found at FHWA-PD-96-046 DOT-UNTSC-FHWA-96-5.

Noise readings must be taken at representative receptor locations for proposed highway projects on new alignment, where no highway exists.

Measurements should be taken during the worst noise hour. This corresponds usually to the period preceding or just after the peak traffic volume, in heavily congested urban areas. This is largely because of slow peak traffic speeds and large trucks avoiding congested periods. Measurements should not be taken during rain events or in winds exceeding twelve miles per hours. Measurements will conform to FHWA requirements, FHWA-PD-96-046 DOT-UNTSC-FHWA-96-5.

ANSI Type 1 or 2 integrating sound level meters are required. FHWA guidance will be used, FHWA-PD-96-046 DOT-UNTSC-FHWA-96-5.

MoDOT’s standard procedure for validating traffic noise models is a comparison of existing noise levels and predicted noise levels, for the existing traffic condition. If the levels are within three decibels for selected receptors, the model is assumed to be valid.

Outdoor areas of frequent human use are considered primary locations when determining noise impact and will be used for taking noise readings. Play areas, balconies, swimming pools and patios are examples of frequent human use areas. Engineering judgment must be exercised in determining which, if multiple frequent human use areas are present, is potentially most affected by highway noise.

For NEPA documents on Type I projects, noise analysis is required for all reasonable build alternatives. Lesser evaluations may be appropriate for examination of broad corridors, such as Tier 1 Environmental Impact Statements, provided there is early FHWA and participating agency agreement.

If any segment or component of an alternative meets the definition of a Type I project, then the entire alternative is considered to be Type I and is subject to the noise analysis requirements early in the project planning process.

Noise analysis must include each Activity Category present in the study area. See Noise Abatement Criteria Table for additional details on each Activity Category.

Activity Category A Justifications for designating land as Category A will be submitted through the Missouri FHWA Division Office and FHWA Headquarters, as this is the protocol outlined by FHWA, per 23 CFR 772.11. Impacts are either a substantial increase, 15 dBA or approaching the NAC, 56 dBA.

Activity Category B Each potentially affected receptor will be analyzed for traffic noise impact, which would be a substantial increase, 15 dBA or greater, or approaching the NAC, 66 dBA.

Activity Categories C Each potentially affected property will be analyzed for traffic noise impact, which would be a substantial increase, 15 dBA or greater, or approaching the NAC, 66 dBA. Receptors will be counted as feet of frontage, which will be the average of the residential frontages in the project area (e.g. one receptor equals 100 ft. of frontage).

Activity Category D This Category should only be used after exhausting all outdoor analysis options. Each potentially affected property will be analyzed for traffic noise impacts, which would be a substantial increase, 15 dBA or greater, or approaching the NAC, 51 dBA. Receptors will be counted as feet of frontage, which will be the average of the residential frontages in the project area (e.g. one receptor equals 100 ft. of frontage). FHWA publication FHWA-DP-45-1R, Sound Procedures for Measuring Highway Noise: Final Report provides procedures to measure building noise reductions.

Activity Category E Each potentially affected property will be analyzed for traffic noise impact, which would be a substantial increase, 15 dBA or greater, or approaching the NAC, 71 dBA. Receptors will be counted as feet of frontage, which will be the average of the residential frontages in the project area (e.g. one receptor equals 100 ft. of frontage).

Activity Category F No action required.

Activity Category G Representative data will be generated as needed to provide information to other governmental entities.

Approaching NAC is defined by MoDOT as being 1 dBA less than the NAC for Activity Categories A-E.

A substantial increase over the existing noise level is an increase of at least 15 dBA. This level of increase is difficult to achieve. Generally, this sort of impact would only be expected for larger highways on new alignment or new highways.

As previously noted, MoDOT does not participate in a Type II noise abatement program. If a local government commits to complete a noise abatement project on a MoDOT roadway, they may petition the Missouri Transportation and Highway Commission to fund 25 percent of the cost. Proposed projects must meet all MoDOT noise impact and abatement criteria. No federal funds are available for use in these situations.

Impacted receptors will usually be identified by ID numbers given during noise analysis. These ID numbers will correspond to a physical address.

127.13.7 Analysis of Noise Abatement Measures

When traffic noise impacts are identified, noise abatement shall be considered and evaluated for feasibility and reasonableness.

Noise barriers are most often used as noise abatement. However, all potential noise abatement measures may be considered and used if they are both feasible and reasonable.

At this time, MoDOT is not a part of a FHWA-approved Quiet Pavement Pilot Program. Therefore, use of quieter pavements is not an acceptable Federal-aid noise abatement measure for Federal projects. Use of vegetation or landscaping is not an acceptable Federal-aid noise abatement measure. For vegetative noise attenuation to be appreciable a minimum of a 100-ft. buffer is required and only dense evergreen vegetation is effective. Use of absorptive materials will be considered, if circumstances warrant its use.

127.13.8 Feasibility

Feasibility is the ability to provide abatement in a given location considering the acoustic and engineering limitations of the site. Acoustic feasibility refers to noise abatement measure(s) ability to achieve the minimum noise reduction at impacted receptors. MoDOT requires at least a 5 dBA insertion loss for a minimum of 67 percent of first-row, impacted receivers for noise abatement to be considered feasible. Engineering feasibility refers primarily to physical constraints and other constuctability constraints, such as topography, access, drainage, safety, maintenance, and presence of other noise sources. In general, if these factors are too extreme or cannot be accommodated in providing the minimum noise reduction, noise abatement will be deemed unfeasible. For reasons of safety (primarily wind load and clear space concerns), a noise wall's height is limited to 20 feet. This criterion alone cannot be used to consider noise abatement unreasonable.

127.13.9 Reasonableness

Each of the three required reasonableness factors must be met.

Mandatory Reasonableness Factors:

1. Viewpoints of owners and residents of the benefitted receptors will be obtained. These will usually be obtained through mailings or a public forum. The viewpoints of non-owner residents will be evaluated as a portion of an aggregate of 25 percent of the total. The viewpoints of owners will be evaluated as a portion of an aggregate of 75 percent of the total. For noise abatement to be considered reasonable, over 50 percent of the aggregate response must be in favorable.
2. Noise abatement measures shall not exceed an all-inclusive cost of $36,000 per benefitted receptor (e.g. materials, right-of-way, mobilization, installation, traffic control, and relocates). Coordination with and approval of FHWA is needed prior to incorporating any unanticipated costs. This cost shall be recalculated at an interval not to exceed every 5 years.
3. Noise abatement measures must provide a benefit of a minimum of 7 dBA for 67 percent of first-row receptors.

For reasons of safety (primarily wind load and clear space concerns), noise walls are limited to a height of 20 feet. This criterion alone cannot be used to consider noise abatement unreasonable.

For noise abatement measure reporting (23 CFR 772.13(f)), MoDOT shall maintain an inventory of all constructed noise abatement measures. The inventory shall include the following parameters: type of abatement; cost (overall cost, unit cost per sq. ft.); average height; length; area; location (State, county, city, route); year of construction; average insertion loss/noise reduction as reported by the model in the noise analysis; NAC category(s) protected; material(s) used (precast concrete, berm, block, cast in place concrete, brick, metal, wood, fiberglass, combination, plastic (transparent, opaque, other); features (absorptive, reflective, surface texture); foundation (ground mounted, on structure); project type (Type I, Type II); and optional project types such as state, county, tollway/turnpike, or other unknown funding sources. This information shall be collected triennially by the design division.

NEPA Decision: Prior to a CE approval or issuance of a FONSI or ROD for a Type I project, the highway agency must identify:

1. The noise abatement measures that are feasible, reasonable, and likely to be incorporated into the project; and
2. Noise impacts for which no abatement appears to be feasible and reasonable;
3. The NEPA documentation for Type I projects shall identify the locations where noise impacts will occur, where noise abatement is feasible and reasonable, and the locations that have no feasible and reasonable abatement. The statement of likelihood will include the preliminary locations of feasible and reasonable abatement and a statement that the final recommendation will be made after the final design and public involvement processes are complete. For example: Noise walls are very likely between stations 41+00 and 42+00 and should average 12 feet. The noise walls will attenuate noise on the south side of the highway. The noise walls appear to be both reasonable and feasible. Final recommendations will be made after final design and the public involvement are complete.

Third party funding cannot be used to make up the difference in cost between the reasonable cost allowance and the actual cost. Third party funding can only be used to pay for additional features such as landscaping, aesthetic treatments, etc. for noise barriers that meet cost-effectiveness criteria.

MoDOT allows cost averaging for noise abatement on Type I projects, among benefited receptors within common noise environments if no single component of the common noise environments exceeds two times the highway agency's cost reasonableness criteria and collectively all common noise environments being averaged do not exceed the highway agency's cost reasonableness criteria. A subdivision is an example of a common noise environment.

127.13.10 Federal Participation in Type I and Type II Projects

Federal funds may be used for noise abatement measures when:

1. Traffic noise impacts have been identified; and
2. Abatement measures have been determined to be feasible and reasonable pursuant to 23 CFR 772.13(d).

127.13.11 Information for Local Government Officials

To minimize future traffic noise impacts on currently undeveloped lands for Type I projects, MoDOT shall inform local officials within whose jurisdiction the highway project is located of:

1. Noise compatible planning concepts;
2. The best estimation of the distance to future design year noise levels that approach the exterior noise abatement criteria in Noise Abatement Criteria Table;
3. Non-eligibility for Federal-aid participation for a Type II project as described in 23 CFR 772.15(b), for developments in areas shown to be noise impacted.

127.13.12 Construction Noise

For all Type I and II projects, MoDOT will as required in 23 CFR 772.19:

1. Identify land uses or activities that may be affected by noise from construction of the project. The identification is to be performed during the project development studies.
2. Determine the measures that are needed in the plans and specifications to minimize or eliminate adverse construction noise impacts to the community. This determination shall include a weighing of the benefits achieved and the overall adverse social, economic and environmental effects and costs of the abatement measures.
3. Incorporate the needed abatement measures in the plans and specifications.

127.13.13 Part 772 Noise Abatement Criteria Table

Activity Category Activity Criteria1 Evaluation Location Activity Description
Leq(h) L10(h)
A 57 60 Exterior Lands on which serenity and quiet are of extraordinary significance and serve an important public need and where the preservation of those qualities is essential if the area is to continue to serve its intended purpose
B2 67 70 Exterior Residential
C 67 70 Exterior Active sport areas, amphitheaters, auditoriums, campgrounds, cemeteries, day care centers, hospitals, libraries, medical facilities, parks, picnic areas, places of worship, playgrounds, public meeting rooms, public or nonprofit institutional structures, radio studios, recording studios, recreation areas, Section 4(f) sites, schools, television studios, trails and trail crossings
D 52 55 Interior Auditoriums, day care centers, hospitals, libraries, medical facilities, places of worship, public meeting rooms, public or nonprofit institutional structures, radio studios, recording studios, schools, and television studios
E2 72 75 Exterior Hotels, motels, offices, restaurants/bars, and other developed lands, properties or activities not included in A-D or F
F - - - Agriculture, airports, bus yards, emergency services, industrial, logging, maintenance facilities, manufacturing, mining, rail yards, retail facilities, shipyards, utilities (water resources, water treatment, electrical) and warehousing
G - - - Undeveloped lands that are not permitted for development
1 The Leq(h) and L10(h) Activity Criteria values are for impact determination only, and are not design standards for noise abatement measures.
2 Includes undeveloped lands permitted for development for this activity category.
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