To help ensure that comparative analyses of project alternatives include consideration for minimizing or avoiding traffic noise impacts, comprehensive planning and coordination should be accomplished as early as possible in the project development process. This could reduce or eliminate the need for costly abatement later in the design process. This section focuses primarily on environmental noise procedures for highways. The level of noise (defined as unwanted sound) near state highways depends on six things:

Ø Traffic volume

Ø Speed of the traffic

Ø Percentage of trucks in the flow of traffic

Ø Distance to the highway

Ø Intervening topography and structures

Ø Atmospheric conditions

The Federal Highway Administration (FHWA) has established Noise Abatement Criteria guidelines (absolute noise impact) for several categories of land use activities; which include the following Leq noise levels:

Category A Leq = 57 dBA Lands on which “serenity and quiet are of extraordinary

significance and serve an important public need……”.

Category B Leq = 67 dBA Picnic areas, recreation areas, parks, residences, motels,

schools, churches, libraries, and hospitals.

Category C Leq = 72 dBA Developed lands, properties or activities not included in

Category A or B (i.e., most commercial and industrial

Activities).

Category D Leq = -- Undeveloped lands.

Category E Leq = 52 dBA Interior of residences, libraries, etc.

In determining and abating traffic noise impacts, primary consideration is to be given to exterior areas. Abatement will usually be necessary only where frequent human use occurs and a lowered noise level would be of benefit.

Heavier traffic volumes, higher speeds, and a greater percentage of trucks generally increase traffic noise. ITD has several strategies for controlling highway noise:

· Preserve existing buffer zones. Work with local jurisdictions to retain lands adjacent to highways in open space uses, promote the use of berms, and preserve beneficial topographic features along with the use of trees, shrubs, and other vegetation to soften the landscape.

· Support local jurisdictions in establishing principal routes for buses and trucks.

· Review local land use plans and advise local agencies to help achieve compatible development along highways.

· Identify potential noise impacts and mitigation measures early in the planning and design stages of highway improvements.

· When applicable, purchase R/W for lane additions from the side least affected by noise and other environmental impacts rather than purchasing equal amounts of R/W from each side. This strategy not only reduces environmental impacts, it reduces the number of R/W negotiations with adjacent property owners and can improve noise levels for residences on the opposite side of the road.

1310.01 Summary of Requirements. A traffic noise analysis is required by law for Type I federally funded projects. Type I projects:

· Involve construction of a highway on new location,

· Substantially change the horizontal or vertical alignment of an existing highway,

· Increase the number of through traffic lanes on an existing highway.

FHWA policy memorandums have clarified that “increasing the number of through traffic lanes on an existing highway” includes:

· The addition of ramps or ramp lanes at interchange locations,

· The addition of an auxiliary lane between interchanges if the lane is at least 1.5 miles long or if the lane is made continuous through a series of successive interchanges, or

· The addition of a full lane to a highway.

In rare cases, a traffic noise analysis is also required for projects that are not Type I. This occurs when the project itself creates a noise impact, for instance when a sideslope or berm is flattened for design purposes and adjacent noise sensitive receptors are affected.

Section 1300.05 provides technical guidance for implementing the noise analysis process.

1310.02 Abbreviations and Acronyms. Abbreviations and acronyms used in this section are listed below. Others are found in the general list in the appendix.

· dBA ---- A-weighted decibels

· DHV--- Design Hour Volume (30^th highest traffic volume in a given year)

· FHWA – Federal Highway Administration

· ITD ----- Idaho Transportation Department

· Leq ----- Equivalent sound level

· LHTAC Local Highway Technical Assistance Council

· LOS --- Level-of-Service

· NAC ---- Noise Abatement Criteria

· TNM---- Traffic Noise Model

130.03 Glossary.

Abatement – An action taken to reduce the impact of highway traffic noise.

Abatement Measures – Measures that must be considered in a traffic noise impact report when a highway project will result in a noise impact. This includes the following six measures:

Traffic management,
Alteration of horizontal and vertical alignments,
Acquisition of real property to serve as a buffer zone,
Construction of noise barriers,
Acquisition of property rights for barrier construction purposes, and
Insulation of public use, nonprofit institutional structures.

‘Absolute’ Noise Impact – One of two criteria used to determine when a noise impact occurs. Under this criterion, a noise impact occurs when the predicted noise level approaches or exceeds the FHWA Noise Abatement Criteria (NAC).

Alpha Factor – Modeling term used to differentiate terrain reflective characteristics. For example, decibel levels decrease 3 dB per doubling of distance over asphalt or concrete (‘hard’ alpha), and 4.5 dB per doubling of distance over plowed ground or ground thickly covered with vegetation (‘soft’ alpha).

Approach – Means one (1) dBA below the FHWA “Absolute” noise impact criterion.

Barrier Cost Planning Estimate – Determined by multiplying the length times the height of a proposed noise wall by $20 sq. ft. regarding walls over a quarter mile long, or $25 sq. ft. for proposed walls less than a quarter mile long. (These costs are applicable until August 2005; updated cost information will be evaluated at that time, as described in Section 1300.05(8).)

Benefited Receptor – A receptor that is projected to receive a noise reduction of 5 decibels (dBA), or more, as a result of proposed noise mitigation measures. All benefited receptors should be included when counting receptors, regardless of whether or not they were identified as impacted. Each unit in a multifamily building should be counted as a receptor in determining impacts; each benefited unit should be counted as a receptor in determining benefits.

Cost/Benefited Receptor – The dollar amount used in determining cost reasonableness of noise abatement.

Cost Effectiveness – Determined by multiplying the total number of benefited receptors by $20,000 and subtracting the estimated cost of constructing an effective noise wall. A positive remainder means the barrier is cost effective. (The $20,000 per receptor amount has been established for use until August 2005; it will be re-evaluated and possibly updated at that time, as described in Section 1300.05(8).)

dBA – The most generally used measure of the magnitude of traffic noise. The decibel (dB) or one-tenth of a Bel is a measure on a logarithmic scale which indicates the ratio between two sound powers. A ratio of 2 in power corresponds to a difference of 3 dB between the two sounds. The ‘A’-weighting tends to de-emphasize lower-frequency sounds (e.g., below 1,000 Hertz) and higher frequency sounds (above 4 Kilohertz) in an effort to mimic human hearing.

Date of Public Knowledge – The date of approval of the environmental determination (CE, FONSI or ROD) for a highway project. After this date, federal and state governments are no longer responsible for providing noise abatement for new development adjacent to the highway project.

Design Hourly Volume (DHV) – The traffic volume determined by ITD to normally represent the worst hourly traffic noise impacts on a regular basis in a given year. The DHV is used for design purposes as well as to model ‘current’ and ‘design year’ noise levels. These traffic volume estimates must be obtained from ITD District via the ITD HQ Planning Division.

Design Year – The future year used to estimate the probable traffic volume for which a highway is designed, usually 10 to 20 years from the beginning of construction.

Effective Noise Wall – A noise wall that provides a minimum insertion loss of 10 dBA at 10 feet and 5 dBA at 100 feet behind the wall, as well as a minimum 5 dBA insertion loss within 10 feet of the receptor(s) of concern.

Insertion Loss – The net change in noise level at a receiver location due to the installation of a barrier. For purposes of this document, the term may be used interchangeably with “attenuation” or “noise reduction”.

Leq – The equivalent steady-state sound level, expressed in decibels, which in a stated period of time (e.g., design hour) contains the same acoustic energy as the time-varying sound level during the same period of time.

Level of Service – A qualitative measure describing operational conditions within a traffic stream; generally described in terms of such factors as highway type, speed and travel time, freedom to maneuver, traffic interruptions, comfort and convenience, safety, and traffic volume.

Noise Abatement Criteria (NAC) – Noise levels for various activities or land uses established by FHWA, that are used to determine when an ‘Absolute’ noise impact occurs. NAC are not to be used as a design goal for a noise abatement measure.

Planned, Designed and Programmed – Means that the building permit(s) for development of undeveloped land has been issued by the local jurisdiction at the time of the noise analysis, or that the implementation of an approved final plat is in progress (i.e., streets and utilities are in place or under construction).

Receiver – Alternative to the term ‘receptor’.

Receptor – Residences, businesses and outdoor areas where highway traffic noise may affect frequent human activities. The closest corner of a residence (or business receptor) to highway centerline is to be used as the receptor location in modeling traffic noise impacts and attenuation projections. (Each direction of travel should be modeled as a separate roadway on divided roads). Sound level meter measurements should not be located closer than 10 feet from a building. Therefore, when taking field measurements at receptor sites involving buildings, the meter should be located at least 10 feet from the closest corner and at an equal distance to the highway. In the case of outdoor areas, the closest active recreational use facility (e.g., patio, campground site, swimming pool, tennis court, picnic shelter) to the highway is to be used as the receptor location in modeling traffic noise impacts and attenuation projections.

Relative Noise Impact – One of two criteria used to determine when a noise impact occurs. Under this criterion, a noise impact occurs when the project design year noise level exceeds the existing traffic noise level by 15 dBA or more; even if it does not approach or exceed the ‘Absolute’ noise abatement criteria.

Shielding factor – Any constructed or natural barrier located between the roadway and receptor which provides a reduction in roadway traffic noise at the receptor site.

Stamina 2.0/Optima – FHWA traffic noise model which is being phased out by the new TNM modeling software. When approved by ITD and FHWA, Stamina may still be used for a limited time only; final phase-out is expected approximately December 2004. The use of the same model is encouraged throughout the life of a project (i.e., planning, environmental analysis, preliminary and final design).

Substantial Increase – Alternative to the term ‘relative noise impact’.

Substantial Reduction – Noise level reduction of at least 5 dBA at impacted receptors.

Ten-point Transect – A line perpendicular to the highway upon which noise receptor locations are modeled at 50ft, 75ft, 100ft, 125ft, 150ft, 200ft, 250ft, 300ft, 400ft, and 800ft from centerline of an undivided highway or directional centerline in the case of a divided highway. This transect data will be provided to local officials in an effort to prevent future traffic noise impacts on currently undeveloped lands in conformance with 23 CFR 772.15. This transect data is also useful in determining the distance to model receptor locations on developed sites regarding noise impact analysis.

TNM – Transportation Noise Model, Federal Highway Administration’s computer program for highway traffic noise prediction and analysis. TNM replaces FHWA’s prior prediction model and the Stamina/Optima computer programs.

Trucks – Heavy trucks have 3-axles or more, medium trucks have 2-axles and 6-wheels.

Type I Project – A proposed highway construction at a new location or the physical alteration of an existing highway that significantly changes either the horizontal or vertical alignment or increases the number of traffic through lanes.

Type II or Retrofit Project – A stand alone federal-aid project (retrofit project) for noise abatement on an existing highway.

Section 1320.00 – Applicable Statutes and Regulations

1320.01 National Environmental Policy Act. The National Environmental Policy Act (NEPA), 42 USC 4231, requires that all actions sponsored, funded, permitted, or approved by federal agencies undergo planning to ensure that environmental considerations such as noise impacts are given due weight in project decision-making. Federal implementing regulations are at 23 CFR 771 (FHWA) and 40 CFR 1500-1508 (CEQ). For details see Section 310 through Section 312.

1320.02 Federal-Aid Highway Act of 1970 and Implementing Regulations. The Federal-Aid Highway Act of 1970 authorized the development of highway traffic noise standards. 23 USC 109 (i) directs the Secretary of Transportation to develop and implement traffic noise standards for highway projects. Noise impact criteria and abatement procedures implemented by FHWA are in 23 CFR 772 (Procedures for Abatement of Highway Traffic Noise and Construction Noise). This regulation requires preparing a noise study to determine what noise impacts, if any, will result from the proposed highway improvement and what measures will be taken to lessen these impacts. If noise impacts are expected, noise-reduction measures that are determined by ITD and FHWA to be reasonable and feasible must be incorporated into the highway improvement. Laws and regulations can be accessed at the web site below:

http://www.access.gpo.gov/nara/cfr/

Section 1330.00 – Policy Guidance (Reserved)

Section 1340.00 - MOU’s/MOA’s (Reserved)

Section 1350.00 – Technical Guidance

Guidance for conducting traffic noise studies and preparing documentation is provided in the documents described in this section. The purpose of this guidance is to determine if the proposed project will create noise impacts, and if so, the likelihood of providing abatement measures. In addition, to lessen the likelihood of future noise impacts, local officials are to be provided appropriate information for their land-use planning and implementation efforts.

1350.01 Information for Local Officials .

· District/LHTAC environmental staff will provide the local jurisdiction with an estimation of future noise levels (for various distances from the highway improvement) for both developed and undeveloped lands or properties in the immediate vicinity of the project. (See Exhibit 1300-1)

· District/LHTAC staff will also provide information that may be useful to local communities to protect future land development from becoming incompatible with anticipated highway noise levels. Local officials responsible for issuing building permits or approving plat requests for future development adjacent to the project should be encouraged to include a statement on the permits/plats indicating that the developer will be responsible for either avoiding traffic noise impacts or providing any associated abatement.

· District/LHTAC staff will provide local officials with information regarding eligibility for Federal-aid participation for Type II projects as described in 23 CFR 772.13(b). ITD does not program Type II projects. (Refer to Section 1300.05(7) for further information on Type II projects).

· In addition, local officials are to be reminded that after the date of public knowledge, ITD & FHWA are not responsible for noise abatement in the project area.

· Notification shall be sent to local officials by the District (or LHTAC) no later than 10 days after approval of the CE, FONSI, or ROD by FHWA.

Exhibit 1300-1 and Exhibit 1300-2 display the recommended format and sample cover letter for the local officials information. This information will be sent by the District or LHTAC to the Mayor/City Manager or Chairman of the Board of County Commissioners with copies, as applicable, to:

· Chairman of the Planning Commission

· Director of the Planning and Zoning Dept.

· City/County Engineer

· Chief Building Inspector

· HQ Environmental Manager

1350.02 Traffic Noise Screen.

· A noise screen will be conducted by District environmental staff or LHTAC on all Type I projects, except projects involving new alignments. Projects involving new alignments will always require a traffic noise impact analysis.

· District/LHTAC environmental staff will use the FHWA TNMLOOK model to determine the predicted design year traffic noise level for applicable receptor sites adjacent to the highway project (i.e., the closest FHWA category B receptor to the roadway, as well as any category C receptor located closer than the closest Category B receptor; Category A receptors should be referred to ITD HQ for resolution). Model input should be based on design hour volumes (DHV) at posted speeds. TNMLOOK is based on a straight roadway and flat terrain; as conditions deviate from this, reliability decreases.

If-the closest Category B receptor to the roadway (including undeveloped lands where development is planned, designed, and programmed) does not exceed 60 dBA, no further noise analysis is necessary. The same principle would apply to Category C receptors, i.e., if the closest does not exceed 65 dBA, no further noise analysis is necessary. If the closest category B receptor to the roadway does not exceed 60 dBA and no traffic noise impacts are anticipated on undeveloped lands where development is planned, designed and programmed, then no further noise analysis is necessary, unless a category C receptor is predicted to approach or exceed 72 dBA in the design year. The noise model printouts showing these results should be attached to the Environmental Evaluation submittal package or EA and appropriately referenced in the document. For example the Environmental Evaluation 654 Form would have ‘No’ checked alongside ‘#1. Noise’ and a short statement referencing the noise printout in the Environmental Evaluation Summary Sheet or the EA Impact Section, such as: “As indicated on the attached Noise Screen Printouts, the predicted noise level at the closest residence to the roadway is __ dBA; since this level is noticeably below the FHWA Noise Abatement Criteria, the project will not result in a traffic noise impact”.

If predicted design year noise levels exceed 60 dBA, then continue with Section (3), below. Generally, Section (3) will require the services of a traffic noise consultant.

1350.03 Traffic Noise Impact Analysis. The outline below serves as a general guide for preparing a traffic noise analysis report. For those existing alignment Type I projects which have been screened out by the District, LHTAC, or HQ Environmental staff using the screening procedure in Section 1300.05(2), the resulting screening documentation is sufficient and a complete traffic noise analysis report is not necessary. The latest version of TNM is the preferred analysis method. For cases in which a traffic noise analysis is necessary based on the results of screening, the report will include:

· A brief description of the Project and Affected Environment

- A brief description of the project.

- Identifying the local jurisdiction and their efforts/ordinances to promote compatibility between land development and highways regarding noise abatement.,

- Identification of noise sensitive areas and receptors with potential noise impacts.

- A description of the existing land use and if the land use is changing, and

- A Figure depicting the zoning in the project area.

· An Impact Analysis

- A table displaying existing and design year noise levels, which includes distance to centerline for receptor locations (build & no-build). Each direction of travel should be modeled as a separate roadway on divided roads. Document all noise levels on the table in whole numbers. A sample table is presented in Exhibit 1300-3. Formatting the table in this manner is recommended to facilitate application of the abatement checklists.

a. Because design year noise levels can only be determined by computer modeling, existing noise levels should also be determined by computer modeling to allow a direct comparison of noise levels obtained by the same methodology.

b. Field measurements are required to calibrate and validate the model. Representative sites, including the closest residence to the roadway, are to be selected for measurement. Each site selected shall include a minimum of three 10-minute traffic counts (cars, medium trucks & heavy trucks) concurrent with a sound level meter reading. 10 minute counts are easily converted to 60 minute counts for insertion into the FHWA model by simply multiplying the respective vehicle count by 6 (e.g., 123 cars becomes 738 cars, 7 medium trucks becomes 42 medium trucks, etc.). More than 3 counts or sampling periods greater than 10 minutes may be required to ensure statistically reliable data, as determined by the noise analyst’s judgment and based on the traffic volumes of the roadway under study (lower volume roadways require longer sampling periods, and time periods of an hour or even 24 hours could be required, depending on the traffic volume). Actual meter readings are to be compared with results from the FHWA model. Adjustments to variables within the model may be necessary to calibrate the model. To be validated, the model must be within 3 dBA of the applicable meter reading; unless it can be documented that noise from other sources has a noticeable effect on the field measurements.

c. In cases where highway traffic is not the dominant source of noise, the dominant source must be identified and noise levels produced by that source(s) displayed on the table and factored into the analysis.

d. Truck percentage ratio between medium and heavy trucks should be determined from observed traffic counts, if not otherwise available.

- Figure(s) identifying receptor locations & type, right-of-way lines, centerlines, property access, crossroads, and any shielding/barrier information which can markedly influence impact results or abatement considerations (e.g., receptors located on complex hilly terrain may require topographic contour lines and spot elevations, whereas this data can be ignored given relatively level terrain conditions); and

- Narrative identifying NAC criteria, receptors impacted & severity of impact [e.g., are impacts less than, equal to, or greater than the no-build scenario; are increases unnoticeable (< 3 dBA), slightly noticeable (3 to 5 dBA), noticeable (5 to 15 dBA), or substantial (>15 dBA).

-Analysis , modeling, and field measurements may result in decimal dBA values, however, these decimal values should be rounded (not truncated) to the nearest whole number for presentation in the tables and text of the analysis report.

· Abatement Considerations

- Non-barrier & Barrier Checklists (Exhibits 1300-4 & 1300-5, respectively) serve as a general guide and should be used to assess noise abatement measures. Both of these checklists first consider feasibility of noise abatement. When measures are deemed feasible, the checklists proceed to evaluations of reasonability of abatement. After completion of these checklists, the District will complete the Noise Abatement Decision document presented in Exhibit 1300-6 for each receptor or group of receptors.

a. Truck Restrictions may be evaluated as a traffic management measure to mitigate traffic noise in cases where such restrictions do not conflict with the intended use of the roadway or create unreasonable delay or hardship on the motoring public.

b. Speed restrictions may be evaluated as a traffic management measure to mitigate traffic noise where these restrictions do not conflict with the roadways designated use, they do not create unreasonable delay or hardship on the motoring public, and they do not create a safety or enforcement problem.

c. A depressed roadway can effectively mitigate much of the traffic noise to adjacent receptors. If a project needs additional fill material, a lower roadway grade may be a cost effective method to provide fill material while reducing traffic noise, or to provide berm material for noise barrier purposes.

d. The views of impacted residents are to be a major consideration in reaching a decision on noise barrier implementation (i.e., Barriers will not be built if most affected residents do not desire t