Section 1310.00 – Introduction
1310.01 Summary of
Requirements.
1310.02 Abbreviations and Acronyms.
Section 1320.00 – Applicable
Statutes and Regulations
1320.01 National Environmental Policy Act.
1320.02 Federal-Aid Highway Act of 1970 and
Implementing Regulations.
Section 1330.00 – Policy
Guidance (Reserved)
Section 1340.00 - MOU’s/MOA’s
(Reserved)
Section 1350.00 – Technical
Guidance
1350.01 Information for Local Officials .
1350.03 Traffic Noise Impact Analysis.
1350.05 Consultant Scopes of Work.
1350.06 ITD Traffic Noise Analysis and Abatement
Policy and Procedures.
1350.07 Type II Noise Evaluation Procedures for
Existing Highways..
1350.08 Noise Barrier Information Database and
Evaluation of Cost Effectiveness.
1350.09 FHWA Guidance and Reference Information.
Section 1360.00 – Permits and
Approvals
Section 1300.07 – Non-Road
project Requirements (Reserved)
EXHIBIT 1300-1 INFORMATION for
LOCAL OFFICIALS (Sample)
EXHIBIT 1300-2 Sample Cover
Letter re: Information to Local Officials.
EXHIBIT 1300-3 SAMPLE TABLE
DISPLAYING RECEPTOR INFORMATION.
EXHIBIT 1300-4 Idaho
Transportation Department (ITD).
EXHIBIT 1300-6 Idaho
Transportation Department (ITD) NOISE ABATEMENT DECISION CHECKLIST
EXHIIT 1300-7 CONSTRUCTION
NOISE.
EXHIBIT 1300-8 Highway Noise
Analyses.
Section
1310.00 – Introduction
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
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 (30th highest
traffic volume in a given year)
·
FHWA –
·
ITD ----- Idaho
Transportation Department
·
Leq ----- Equivalent
sound level
·
·
LOS --- Level-of-Service
·
NAC ---- Noise
Abatement Criteria
·
TNM---- Traffic
Noise Model
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:
‘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.
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
·
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 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.
- 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