PB-229 726
GUIDELINES FOR REVIEW OF ENVIRONMENTAL inPACT
STATEMENTS, VOLUME i, HIGHWAY PROJECTS
ENVIRONMENTAL PROTECTION AGENCY
SEPTEMBER 1973
DISTRIBUTED BY:
Kfiri
National Technical Information Service
U. S. DEPARTMENT OF COMMERCE
-------
GUIDELINES FOR REVIEW OF
ENVIRONMENTAL IMPACT STATEMENTS
Volume 1
HIGHWAY PROJECTS
U.S. ENVIRONMENTAL PROTECTION AGENCY
OFFICE OF FEDERAL ACTIVITIES
September 1973
-------
BIBLIOGRAPHIC DATA
SHEET
1. Kcport No.
S.NJccipicnt's Accession No.
4. 1 n lc and Subtitle
Guidelines for Review of Environmental Impact
Statements, Volume: Highway Projects
3. Kcport Pate Sept .
Date of issue
6.
7. Auiluir(s)
Mi 11 jam n
8. Performing Or^ani/.at ion Kc pi.
N"' N/A
9. Performing Organisation Namu anil
Environmental Protection Agency, A-104
Office of Federal Activities
401 M St. S.W., Rm., 537 WT
10. I'rujcct/Task/W'ork Unit Nc
N/A
Ma gh-inrr-r-on. n C
11. C!ontract '(inim No.
N/A
12. Sponsoring Organi/.ation Name.and Address
Environmental Protection Agency, A-104
Office of Federal Activities
401 M St. S.W., Rm., 537 WT
13. 'I'yP1' ol IU-port tt Period
(.t>vered
Final
14.
15. Supplementary Notes
16. Abstracts
This volume presents detailed guidance for the assessment of
the primary air, water, noise, and solid waste management impacts
from highway projects at the route location stage of highway
development.
17. Key Words and Document Analysis. 17o. Descriptors
Environmental Impact Statement
Highways
Air Pollution
Noise Pollution
Water Pollution
17b. Ulentifiers/Open-l'!nded Terms
17c. C'.OSATI Field/Group
18.
Availability Statement
Release unlimited
IV.
j>0.
Security Class
Report )
UNCI.ASSI1-
Securit y ( .lass
Cage
UNCI.ASSII
(This
n-n
(This
ii-: n
2i *" .v»i> .,
&*,
' *-'
22. I'rice
f <$/.*c
N I't S- 10 I N tl V . 3-72 I
THIS FORM MAY UK lU-PROOUCI-n
I
U S C O M M - D C '. «J t» S 2 tJ y J
-------
PREFACE
This volume presents detailed guidance for the assessment of the
primary impacts from highway projects at the route location stage of
highway development.
In its current form, this volume is ntended to serve as a supple-
ment to Environmental Protection Agertjy Order 1640.1 and existing
assessment techniques related to secondary impacts and transportation
system alternatives. In toto, these documents provide the detailed
framework for the Environmental Protection Agency review of
Federal-aid highway-project environmental impact statements.
As additional or refined review techniques and assessment proce-
dures become available, this document will be reissued or revised as
necessary. Note, however, that only the numbered copies are on the
distribution list for revised materials.
Comments and suggestions regarding this document should be
directed to the attention of Director, Office of Federal Activities
Environmental Protection Agency, Washington, D.C. 20460.
Preceding page blank
-------
CONTENTS
Page
Preface iii
List of Illustrations vii
I. Introduction 1
II. Review of Highway-Project Environmental Impact Statements 5
III. Project Description 9
:V. Probable Impact of the Proposed Project 11
IV.A. Air Impact Review 12
IV.A.l. Highway-Related Air Pollutants 12
IV.A.2. Review of Air Impact Analysis 14
IV. A.3. Assessment of Air Impact 21
IV.B. Water Impact Review 29
IV.B.I. Highway-Related Water Impacts 29
IV.B.2. Review of Water Impact Analysis 30
IV.B.3. Assessment of Water Impact 31
IV.C. Noise Impact Review 35
IV.C.l. Highway-Related Noise Criteria and Standards 35
IV.C.2. Review of Noise Impact Analysis 36
IV.C.3. Assessment of Noise Impact 38
IV.D. Solid Waste Management Impact Review 40
IV.D.I. Highway-Related Solid Waste Management Impacts 40
IV.D.2. Review of Solid Waste Management Impact Analysis .... 40
IV.D.3. Assessment of Solid Waste Impact 41
V. Relationship Between Local Short Term Uses of Study Area and the
Maintenance and Enhancement of Long Term Productivity 43
VI. Irreversible and Irretrievable Commitments of Resources Involved in
the Proposed Project 45
VII. Probable Adverse Impacts that Cannot Be Avoided 47
VIII. Alternatives to Proposed Action 49
References 51
Preceding page blank
-------
CONTENTS-(Continued)
Page-
Appendix A. Air Quality Control Regions That Included Transportation
Controls as Part of Their SIP 55
Appendix B. Air Impact Forecast Procedure for Carbon Monoxide 57
Appendix C. General Concepts of Traffic Flow and Speed Characteristics 61
VI
-------
LIST OF ILLUSTRATIONS
Table Page
1 Highway-related national ambient air quality standards 13
2 Traffic parameters for emission estimates 17
3 Level of analyses adequate for estimating the air quality impacts from
highway projects . : 23
Figure
1 EIS review process 7
2 Air analysis review sequence 15
3 Examples of emission growth trends 26
4 Example CO concentration patterns for a given highway segment 26
5 Noise analysis data and methodology 37
B-l CO quantification as a function of impact 59
C-l General concept of relationship of levels of service to operating speed
and volume/capacity ratio 62
C-2 Example variation of hourly traffic 64
C-3 Example hourly variations of traffic for average weekday 65
C-4 Example hourly variations of daily traffic 66
C-5 Example daily changes in traffic 67
C-6 Examples of monthly traffic volume variations 68
C-7 Relation of hourly volumes and annual average daily traffic 6l)
C-8 Example traffic volume variation between lanes (six-lane facility) 70
C-9 Total motor-vehicle travel and forecast for a selected state 70
C-10 Example diurnal variation in volume and speed 73
C-l 1 Typical relationship between volume per lane and operating speed in one
direction of travel under ideal uninterrupted flow conditions on freeways
and expressways 74
C-l 2 Relationship between v/c ratio and operating speed, in one direction of travel.
on freeways and expressways, under uninterrupted flow conditions 75
vn
-------
I. INTRODUCTION
Section 102(2 )(C) of the National Environmental Policy Act of 1970 stipulates that
Prior to making any detailed statement, the responsible Federal official shall consult with and obtain
the comments of any Federal agency which has jurisdiction by law or special expertise with respect
to any environmental impact involved. Copies of such statement and the comments and views of the
appropriate Federal, State,;and local agencies, which arc authorized to develop and enforce environ-
mental standards, shall be made available to the President, the Council on Environmental Quality and
to the public as provided by section 552 of title 5. United States Code, and shall accompany the
proposal through the existing agency review processes;...
In view of the legal jurisdiction of and special expertise within EPA, this section obligates
Federal agencies to obtain comments from EPA wherever an action related to air or water
quality, noise abatement, solid waste disposal, generally applicable environmental radiation
criteria and standards, or other provisions of the authority of EPA are involved. In addition,
section 309 of the Clean Air Act Amendments of 1970 gives EPA the explicit legal mandate
to comment in writing on the environmental impact of any matter relating to EiPA's duties
and responsibilities.* Section 309 provides
(a) The Administrator (of EPAj shall review and comment in writing on the environmental impact
of any matter relating to duties and responsibilities granted pursuant to this Act or other provisions
of the authority of the Administrator, contained in any (1) legislation proposed by any Federal
department or agency. (2) newly authorized Federal projects for construction and any major Federal
agency action (other than a project for construction) to which Section I02(2)(C) of Public Law 91-190
applies, and (3) proposed regulations published by any department or agency of Ihe Federal Govern-
ment. Such written comment shall he made public at the conclusion of any such review.
(b) In the event the Administrator determines that any such legislation, action, or regulation is unsatis-
factory from the standpoint of public health or welfare or environmental quality, he shall publish his
determination'and the matter shall be referred to the Council on Environmental Quality.
To implement this responsibility, EPA Order 1640.1 has established detailed policies.
responsibilities, and administrative procedures for the Agency's review of Federal actions
impacting the environment. This order provides that, where an environmental impact
statement (EIS) has been sent to EPA for comment, EPA's comments on the EIS shall also
constitute its comments for purposes of section 309.
Because 1640.1 does not include procedures for the technical review of EIS's, the
Office of Federal Activities, in conjunction with program and regional offices, is in the
*A listing of relevant legislation, Executive orders, and Office of Management and Budget circulars and
bulletins may be found in "Basic Documents Concerning Federal Programs to Control Environmental
Pollution from Federal Government Activities."1
-------
process of preparing detailed review guidelines for several major project categories. The
guidelines presented here are the initial volume.
The review of highway-project EIS's is complicated by the fact that the highway ElS's
are issued at a rather late period within the total highway-planning process. While this pro-
cedure does provide for a detailed impact assessment of the particular project, it does not
lend itself to an adequate assessment of the transportation system design that spawned the
project.
I
i
The highway-planning process generally involves the following four planning stages:
Transportation planning involves the development of all facilities used for the move-
ment of persons or goods and, specifically, leads to the specification of the highway
portion of the overall plan.
Systems planning* starts with transportation data defining the highway system with-
in the corridor and develops "system factors," such as corridor termini, forecast
demand on the facility, projected land use in the corridor, desired level of service,
and desired interchange system.
Route location then applies detailed local area considerations to select the prelimi-
nary location, basic type of roadway, number of lanes, and basic interchange design.
This selection process usually involves a large number of technical, social, and
economic effects.
Final design results in the completion of the process by producing the precise
roadway and interchange characteristics.
Under procedures for the implementation of the National Environmental Policy Act.
FHWA marks the "route location" as the point at which an EIS is to be prepared and cir-
culated for comment.* Typically, such project-level EIS's have not addressed the larger
questions of alternative transportation modes, alternative corridor locations, or Che syner-
gistic effect of the proposed roadway when combined with future projects. It is apparent
that these considerations are fundamental to the effort of minimizing the total tansportation-
related impact on a given region. The review of a project-level EIS should include a compre-
hensive assessment of all of the foregoing planning stages.
To accomplish this objective, however, two things must occur. First, project-level EIS's
will have to be direct products of transportation and systems plans that have been assessed
by EPA. The EIS review could then focus exclusively on the environmental impact at the
location/design stage. Second, EPA reviewers must have adequate guidance for conducting
environmental reviews at the transportation-planning level. Review guidance specific to the
*In some Federal Highway Administration (FHWA) publications systems planning is defined to include
transportation planning. j
tin cases where the subsequent final design planning dictates "... a new or changed environmental effect of
significance," FHWA requires an additional or supplemental impact statement ". .. to be processed in the
same manner as a new environmental statement."2
-------
transportation- and systems-planning stages are being developed and should be available
within the next year.
In recognition of the need for environmental assessments throughout the highway-
planning process, section 109(h) of the Federal-Aid Highway Act of 1970 requires that
"possible adverse economic, social, and environmental effects relating to any proposed
project on any Federal-aid system have been fully considered .. . ." Pursuant to this require-
ment, the FHWA has issued process guidelines3 requiring an action plan from each State high-
way agency. Each plan must define the State's planning process for Federal-aid highway
projects, and set forth how the proposed projects will be derived from the transportation-
arid systems-planning stages. In addition, the specific involvement of EPA at each planning
stage will be defined.
Because it will be some time before the action plans are implemented fully, EPA can
expect to continue to receive impact statements without the transportation-level considera-
tions before described. The reviewer should continue to insure that the project-level ElS's
have considered appropriate transportation-planning alternatives.
The highway-related impact areas for which EPA has special expertise include air
quality, water quality, noise levels, and solid waste management. The review must assess the
impact in these areas as they occur, directly through the construction and operation of the
project and indirectly through increased activity induced by the project. Unfortunately, the
quantification and assessment techniques necessary for an adequate review of the induced or
"secondary" effects are not well understood. Several studies are currently in progress4-5
that should provide at least the basic methodology for assessment of the secondary impacts.
Within the foregoing context, then, the review procedures in these guidelines arc specific
to assessment of the primary air-, water-, noise-, and solid-waste-management-related impacts
from highway projects at the route-location stage of development. Until the transportation-
planning and secondary impact studies are completed, the reviewer must continue to utilize
his own resources for reviews in these areas. The final project assessment should reflect botli
primary and secondary impact considerations.
In any case, it is imperative that EPA provide meaningful and constructive comments on
all draft EIS's received for review. If the reviewer feels that a statement is inadequate or
lacking in proper scope, an explanation of the inadequacies should be given. Such explana-
tions should include detailed commentary that outlines both the information required and
the reasons why this information is needed to do a comprehensive environmental analysis.
-------
II. REVIEW OF HIGHWAY-PROJECT ENVIRONMENTAL IMPACT
STATEMENTS
While the purpose of the review is to assess the environmental impact of the proposed
project, it is also obviously necessary to assess the completeness (i.e., adequacy) of the mate-
rial presented in the environmental impact statement (EIS). It is emphasized, however, that
the main objective of the EPA review is to assess the impacts related to air, water, noise, and
solid waste management, and not to critique the way in which the EIS is organized or written.
In determining the adequacy of the EIS, the reviewer must consider both the material
presented in the EIS and the material presented in reference documents. According to the
Council on Environmental Quality (CEQ) guidelines for preparation of impact statements,6
"Highly technical and specialized analyses and data should be avoided in the body of the
draft impact statement. Such materials should be attached as appendices or footnoted wth
adequate bibliographic references." In what follows, then, the term "EIS" is used in the
generic sense of "EIS and referenced technical documents,"provided that, first, the EIS
contains adequate summaries of the methodologies and results of the various technical
analyses, and, second, the detailed reports describing these methodologies and results arc
available.
The reviewer should note, however, that the foregoing does not preclude the require-
ment that the EIS itself contain sufficient "information, summary technical data, and maps
and diagrams, where relevant, adequate to permit an assessment of potential environmental
impact by commenting agencies and the public."6
EPA Order 1640.1 provides for assignment of separate ratings for the environmental
impact of the project (designated by LO, ER, or EU), and for the adequacy of the EIS
(designated by 1,2, or 3). The procedure for assigning a rating is as follows:
1. If sufficient information is available in the EIS to make a complete review of the
environmental impact
a. assign an EIS adequacy rating of 1
b. assess the environmental impact
c. assign the appropriate environmental-impact rating (LO, ER, or EU)
2. If some information is available, but it is insufficient to review all impacts asso-
ciated with the project
a. assign an EIS adequacy rating of 2
b. assess the impact presented in the EIS
c. if possible, identify and estimate the magnitude of the impacts not presented
d. based on b and c, assign an environmental rating to the project, and request
necessary additional information and/or analyses
Preceding page blank
-------
3. If insufficient information is available for even a partial review of the project
impacts, an HIS adequacy rating of 3 should be given. In this case, no assessment
or environmental impact rating should be made: instead, ;i completely revised
EIS should be requested.
To insure that all significant primary impacts have been considered and that the assess-
ments of the various types of impacts can be combined into a single assessment of the project,
a systematic review procedure is necessary. Since the CEO guidelines have defined.major"""
analysis categories to be included in EIS's, the review procedures are structured along the
same lines.
Figure 1 illustrates the review sequence followed in these guidelines. The detailed review
procedures for each category are given in the sections indicated. Since these guidelines are for
the review of EIS's, the sequence in which the six CEO categories are considered has been
changed. The basic idea is to determine the unavoidable adverse impacts for the proposed
project and for the alternatives to the proposed project. Then, a project assessment can be
made in terms of the following: First, are the adverse impacts of the proposed project with-
in acceptable limits? Second, can the impact be minimi/.cd by an alternative? Each review
category fits within this framework as follows:
Project description. Review the basic description of the proposed action, placing in cc.i-
text the purpose of the project, the project's relationship to the surrounding area, and the
project's relationship to other programs that might be affected.
Probable impact of the proposed project. Assess the project impacts and/or EIS ade-
quacy with respect to the impacts related to air, water, noise, and solid waste management.
Relationship between local short-term uses of study area ami the long-term productivity
of the proposed project. Identify and assess those impacts which might have cumulative or
long-term effects on the environment. Nonpollutant impacts, if applicable, should be
considered here and in the next category.
Irreversible and irretrievable commitments of resources to the proposed project. Identify
and assess those impacts which might irreversibly curtail natural resource utilization or the
diversity and range of beneficial uses of the'cnvironmcnt.
Probable adverse impacts that cannot be avoided. Summarize the assessment of those
adverse impacts which cannot be avoided. After all alternatives have been considered, make
final assessment of proposed project and relate to 1640.1 rating scheme.
Alternatives to proposed action. Repeat the review sequence, assessing the impacts
from those alternative actions that might avoid some or all of the adverse impacts identified
with the proposed project.
This review sequence should (including the 1640.1 rating scheme) be used by
the air, water, noise, and solid waste management technical reviewers, as well as by the EIS
coordinator. This procedure will aid the EIS coordinator in his task of combining the various
assessments into a total project assessment-rating response.
-------
SECTION III
PROJECT
DESCRIPTION
PROBABLE
IMPACT
SHORT-TERM
USES VS.
LONG-TERM
PRODUCTIVITY
IRREVERSIBLE
AND
IRRETRIEVABLE
RESOURCE
COMMITMENTS
SECTION IV
SECTION V
SECTION VI
SECTION VII
UNAVOIDABLE
ADVERSE
IMPACTS
SECTION VIII
ALTERNATIVES
REVIEW NEXT
ALTERNATIVE
EIS
ADEQUACY
RATING
(1.2.3)
ALL ALTERNATIVES
REVIEWED
PROJECT
RATING
(LO.ER.EU)
Figure 1.EIS review process.
-------
III. PROJECT DESCRIPTION
According to the Council on Environmental Quality guidelines, "the amount of detail
provided ... [in the description of the proposed action] should be commensurate with
the extent and expected impact of the action, and with the amount of information required
at the particular level of decision making.. . ." To insure that the review is consistent with
this philosophy, the specific data-and-analysis requirements are combined with the impact
assessment procedures given in the sections that follow.
Because the "particular level of decision making" relative to highway-project environ-
mental impact statements (EIS's) is the location stage of development, the amount of infor-
mation available at the location stage is oi interest. To indicate the data that should be
available for incorporation into the EIS, the following route location planning description
is reproduced from the Highway Research Board's document. "Data Requirements for
Metropolitan Transportation Planning."7 *
The initial inputs to the route location planning process are systems planning considerations
and mainline design-hour volume (DHV) traffic factors developed from both system annual average
daily traffic (AADT) forecasts and traffic count and inventory records. When related to design
criteria, these determine the functional type of facility to be built-gene rally, whether or not access
control is required. This may be a policy decision, however, and not necessarily a decision obtained
directly from analysis of the input data.
Next, the number of through lanes is determined, generally following American Association of State
Highway Officials (AASHO) methodology. This involves selection of a K factor (deciding whether
to satisfy traffic demand at the 30th, 50th, or some other specified "highest" hour); selection of a D
factor, or proportion of traffic in each direction; and selection of a T factor, or proportion of heavy
commercial vehicles. An additional input required for this decision is the set of design warrants that
relate the number of lanes to volume and character of demand for each type of facility at each level
of service.
Several alternate route locations are then determined. Additional sets of daia for this task are
measures of physical, social, economic, and environmental influences in (he corridor. Much criticized
in recent years because physical and economic considerations have been the prime determinants of
final locations, this task now gives social and environmental factors a considerable amount of
importance.
The final major decision involves choosing basic interchange decisions for each location. This
requires additional input of local and cross traffic data in the corridor, and the use of interchange
design techniques that relate interchange and ramp capacities to the volume and character of the
traffic making the several turning movements.
*Othcr basic references for design criteria include the "Jiighway Capacity Manual"8 and the American Asso-
ciation of State Highway Officials "policy" publications.'-10
Preceding page blank
-------
In general, then, rather comprehensive descriptions of the project and its associated
traffic projections are available for inclusion in highway project ElS's. The level of review
presented in these guidelines assumes that these data are available.
Before proceeding with the review of the specific pollutant impacts, the reviewer
should place the project in context with respect to the purpose of the project, the urea
through which the project will pass, and the relationship between the proposed project and
other projects. This effort should aid the reviewer in defining the general level of review
that will be required. To gain insight into a project, the reviewer may need to develop
information from outside sources. Usually,.investigation of the history of the project devel-
opment (previous attempts and why they were not successful, legislative background, etc.)
and discussions with local groups who may have personal knowledge of the project charac-
teristics can provide useful additional information and understanding of the project.
10
-------
IV. PROBABLE IMPACT OF THE PROPOSED PROJECT
Determination of the probable impact of the proposed project is the central effort of
the review process. The results obtained here are key inputs to the final assessment of the
project.
In what follows, the review-assessment procedures for impacts related to air (sec. IV.A),
water (sec. IV.B), noise (sec. IV.C), and solid waste management (sec. IV.D) are described in
detail. In general the review procedures are given in terms of
Description of the impacts expected
Review of the analyses needed to forecast the pollutant impacts
Assessment of the impact
Where applicable (and possible), impact forecast procedures are included for use by the
reviewer. These forecast procedures are of primary importance when reviewing an inade-
quate environmental impact statement (EIS). For such cases, an estimate of the project
impact should be made and used as the basis for the project rating and to substantiate
requests for additional analyses.
II
-------
IV.A. AIR IMPACT REVIEW
Pursuant to Section 110 of the Clean Air Act and 40 CFR Part 51, State implementa-
tion plans (SIP's) are required to provide for the implementation, maintenance, and enforce-
ment of the national ambient air quality standards within each air quality control region. To
achieve the standards for carbon monoxide and photochemical oxidants, detailed transporta-
tion control plans were required in 18 of these plans (see app. A).
Within this framework, the reviewer must determine whether the project is consistent
with the applicable SIP (or SIP's if an interstate project) or, in the absence of transportation-
related controls, whether the project-induced emission pattern changes will interfere with
attainment or maintenance of the national ambient air quality standards.
In either case, review of the air quality impact of a highway project will involve com-
parisons between the air quality projections assuming no project, air quality projections
assuming the completed project, and the air quality standards. The impact assessment then
is based on the significance of the differences between these air quality levels. Depending
on the complexity of the project/project-area combination, these assessments may be re-
quired at both the microscalc and mesoscale levels. In general, the microscale area is limited
to that area near the roadway which is affected directly by the roadway. The mesoscale
area, utilized for analyses in metropolitan areas, covers the larger area that could be affected
by the project, either directly by pollutants emitted from the roadway or indirectly through
the project's influence on overall traffic patterns.
IV.A.1. Highway-Related Air Pollutants
Table 1 lists those highway-related air pollutants for which national ambient air quality
standards are in effect (40 CFR Part 50).
Of the pollutants listed, the photochemical oxidants are unique in that they are not
emitted directly by sources. Instead, photochemical oxidants (and other products) are
formed through the interaction of certain hydrocarbons and oxides of nitrogen in the pres-
ence of ultraviolet light. It also should be noted that the criteria for hydrocarbons rest
almost entirely on their role as precursors of the compounds formed in the atmospheric
photochemical system and not on the direct effect of hydrocarbons themselves.
Further, it should be noted that, in practice, NOX (including both NO and NO,) is often
used as a measure of the total NO2 concentration produced by automobiles. This usage
results from the fact that, although a relatively small amount of NO2 is emitted from auto-
mobiles, the NO emitted subsequently is oxidized in the atmosphere to form NO,.
Since these "reactive" pollutants develop some time after they are emitted, the assess-
ment of their impacts generally is limited to the mesoscale analysis.
An obvious limitation on the type of air pollution analysis possible is the availability
of methodologies to complete the analysis. Because accurate quantification techniques are
12
-------
Table 1.-Highway-related national ambient air quality standards
Particulate matter
Carbon monoxide
Photochemical oxidants
Hydrocarbons
Nitrogen dioxide
Primary standard:
75 pig/m3 annual geometric mean.
2GOpg/m3 maximum 24-hour concentration not to be
exceeded more than once a year.
Secondary standard:
60 pig/m3 annual geometric mean.
150 jig/m3 as a maximum 24-hour concentration not
to be exceeded more than once a year.
10 mg/m3 (9 ppm) as a maximum, 8-hour concentration
not to be exceeded more than once a year.
40 mg/m3 (35 ppm) as a maximum 1-hour concentration
not to be exceeded more than once a year.
160/jg/m3 (0.08 ppm) as a maximum 1-hour concentra-
tion not to be exceeded more than once a year.
160 pg/m3 (0.24 ppm) as a maximum 3-hour concentra-
tion (6-9 a.m.) not to be exceeded more than once a
year.
100 j/g/m3 (0.05 ppm) annual arithmetic mean.
not yet fully developed, the types of analyses that can be performed are limited. The limita-
tions involve both the scale on which the pollutants are considered and the analysis techniques
that can be used.
Of the pollutants listed in table I, only CO and participates, which are relatively inert,
have been modeled with consistent accuracy. To model the chemically reactive pollutants,
HC, NOX , and photochemical oxidants, schemes involving complex chemical reaction formu-
lations combined with diffusion models (to simulate the atmospheric processes) must be used.
Although several of these models are in the advanced state of development, none have been
verified adequately for general use. Until such models become available the impact from
these pollutants must be determined from simplified techniques such as the rollback method
suggested for use in the SIP's (app. I to 36 F.R. 22412).
In view of these limitations, a state-of-the-art air pollution analysis would include
« A microscale analysis for the CO (related to the 1-hour and 8-hour standards) and
participate (related to the 24-hour primary standard) impacts
A mesoscale analysis of the CO (8-hour), HC, and NOt impacts.
13
-------
IV.A.2. Review of Air Impact Analysis
The review of the air analysis consists of
Reviewing the validity and applicability of the analysis method (a reasonable first
step, since the analysis method dictates the extent of the data base required)
Reviewing the analysis data and assumptions with respect to their validity and
representativeness of the most adverse (i.e., "worst") conditions
Estimating the impact for potential adverse situations not covered in the EIS
The reviewer should use these impact estimates to support requests for additional information
in the final EIS.
Figure 2 illustrate* the review sequence. Each of the boxed items is described in this
section. The circled items are described in the impact assessment section (IV.A.3).
The reviewer should note that the following data descriptions relate to the detailed
review of the air impact analysis, not necessarily to the EIS contents. The EIS contents
should be considered adequate if the basic data and analysis procedures arc at least summa-
rized, provided the detailed procedures are available in referenced documents (see sec. 11).
Analysis Methods.-The analysis method is defined as the computational scheme that
operates on emission and emission-dispersion information to produce air pollutant concen-
tration estimates. Although there are a variety of air quality estimation techniques avail-
able, n.12,13 they can bc categorized, in general, as atmospheric diffusion models, empirical
models, or comparison techniques. In any case, the validity of method depends on its
ability to represent accurately the transport and diffusion effects on the dispersion of the
pollutant emissions.
Diffusion models. Of the three categories, diffusion models have been the most widely
used and are considered superior for estimating CO pollutant concentrations* for a variety
of conditions (provided that they arc calibrated properly). These models arc based on solv-
ing a diffusion equation that describes the How of emitted pollutants through the atmos-
phere. There are currently two types of operational line source diffusion models: the
Gaussion models, which arc based on an analytic solution to the diffusion equation, and
the grid models, which require numerical solutions of the diffusion equation.
Recent extensions have been made to the Gaussian formulation14-15-16 that allow its
application to a variety of highway situations. The work done by Beaton et al.,16 of the
California Division of Highways, is of particular interest for microscale applications. Under
the auspices of the Federal Highway Administration (FHWA), Beaton's group has developed
*At present there arc no available diffusion models for the reactive pollutants NO^, HC, and photochemical
oxidants.
14
-------
ANALYSIS
TECHNIQUE
INADEQUATE
»
1
ADEQUATE
1
1
EMISSION
FACTORS
CONTINUE REVIEW
OF DATA FOR USE
IN EPA ANALYSIS
INADEQUATE
\
1
ADEQUATE
}-
.
HIGHWAY DATA
TRAFFIC
CONFIGURATION
INADEQU
UTILIZE
EPA FACTOR
METHODOLOGY
ATE
\
1
ADEQUATE
I
1
METEOROLOGICAL
AND
TOPOGRAPHIC
DATA
IF POSSIBLE
ASSUME DATA
FOR
QUANTIFICATION
INADEQUATE
\
I
ADEQUATE
I
1
'
BACKGROUND
CONCENTRATIONS
1
. ADEQ
/ Al
( IMP/
I QUAf
V PICA"
ADEO
ASSUME ADVERSE
CONDITIONS FOR
QUANTIFICATION
INADEQUATE
\
UATE
R \
\CT \INADEQUAT
ASSUME ADVERSE
CONDITIONS FOR
QUANTIFICATION
E/ QUANTIFY \
JTI- 1 ' 1 IMPACT I
rioN / V y
UATE |[
/ A
/ IMP
_ I ASSES
R
ACT
SMENT
" \ AND
\ RATING ,
Figure 2.Air analysis review sequence.
15
-------
a specific methodology for the air quality analysis of highway projects. In addition to the
development of a Gaussian model formulation,16 the group's analysis methodology includes
techniques for development of data that define the meteorology.17 emission factors,18
traffic information,19 and ambienc air quality sampling.20 The documents cited have been
distributed widely by FHWA, and the reviewer may expect to see these analysis techniques
used in future IZIS's. In general the techniques described in these documents, if modified
for non-California applications, will produce result? within the state-of-the-art error range.
For applications at the mesoscalc level, the Gaussian models usually are converted to
"area source" models, which allow consideration of a number of roadway segments with
each calculation (e.g., APRAC-1 A).21 Such models are generally computer dependent,
since a large number of calculations are involved.
Grid models applicable to highway air-pollution analyses have been reported in the
literature by Danard22 and Skalarew et al.23 Although these models are at an earlier stage
of development than the Gaussian models, they do have the potential for a more accurate
representation of the parameters influencing the dispersion process.
In addition to the federally sponsored models, there are at least a dozen commercial
models in use. The reviewer must determine that an acceptable model has been used for
the EIS analysis. If this determination presents a problem, personnel at the Division of
Meteorology. Office of Research and Development, Research Triangle Park, North Carolina.
should be consulted.
A discussion of procedures for quantification of the microscale CO impact is given in
appendix B.
Empirical models. The objective of these models is to infer, from measured data, the
parametric dependencies that relate the pollutant concentrations to the emission and trans-
port characteristics. This method, properly carried out, can produce valid estimates for
specific situations. It is generally the case, however, that an insufficient range of traffic
conditions and meteorological parameters are obtained to make such models truly repre-
sentative, and if they are used their results should be checked carefully (see app. B).
Comparison technique. The comparison technique simply assumes that similar projects
will have similar air quality impacts. This technique is the least reliable of the three. If it
is used the reviewer must determine that a true parallel has been made between the compari-
son project and the proposed project. Significant similar conditions that must be related are
Meteorological conditions: If both projects are in the same general area, the assump-
tion of similar meteorological condition is usually valid (provided that the areas arc
similar hi topography).
Topography: Significant differences could cause local stagnation conditions to be
overlooked.
16
-------
a specific methodology for the air quality analysis of highway projects. In addition to the
development of a Gaussian model formulation,16 the group's analysis methodology includes
techniques for development of data that define the meteorology.17 emission factors,1S
traffic information,19 and ambient air quality sampling.20 The documents cited have been
distributed widely by FHWA, and the reviewer may expect to see these analysis techniques
used in future lilS's. In general the techniques described in these documents, if modified
for non-California applications, will produce results within the state-of-the-art error range.
For applications at the mesoscale level, the Gaussian models usually are converted to
"area source" models, which allow consideration of a number of roadway segments with
each calculation (e.g., APRAC-1 A).21 Such models are generally computer dependent.
since a large number of calculations are involved.
Grid models applicable to highway air-pollution analyses have been reported in the
literature by Danard22 and Skalarew et al.23 Although these models are at an earlier stage
of development than tlie Gaussian models, they do have the potential for a more accurate
representation of the parameters influencing the dispersion process.
In addition \u the federally sponsored models, there are at least a do/en commercial
models in use. The reviewer must determine that an acceptable model has been used lor
the EIS analysis. If this determination presents a problem, personnel at the Division of
Meteorology, Office of Research and Development, Research Triangle Park, North Carolina.
should be consulted.
A discussion of procedures for quantification of the microscale CO impact is given in
appendix B.
Empirical models. The objective of these models is to infer, from measured data, the
parametric dependencies that relate the pollutant concentrations to the emission and trans-
port characteristics. This method, properly carried out, can produce valid estimates for
specific situations. It is generally the case, however, that an insufficient range of traffic
conditions and meteorological parameters are obtained to make such models truly repre-
sentative, and if they are used their results should be checked carefully (see app. B).
!
Comparison technique. The comparison technique simply assumes that similar projects
will have similar air quality impacts. This technique is the least reliable of the three. If it
is used the reviewer must determine that a true parallel has been made between the compari-
son project and the proposed project. Significant similar conditions that must be related are
Meteorological conditions: If both projects are in the same general area, the assump-
tion of similar meteorological condition is usually valid (provided that the areas are
similar in topography).
Topography: Significant differences could cause local stagnation conditions to be
overlooked.
16
-------
Traffic flo-v and mix: Usually some factor will be applied to scale these parameters.
The reviewer shouu! question the validity of the scaling method if major traffic
differences are projected.
Highway configuration: Different configurations between the projects (e.g., cut
versus elevated) could cause pronounced differences at specific locations.
In the remaining analysis-review discussions it is assumed implicitly that a diffusion
model will be used (at least for the microscale analysis). This assumption is made for several
reasons. First, as discussed earlier, diffusion models are the most accurate of the techniques
and should be used as the analysis method for most projects. Second, diffusion models
require the most comprehensive set of input data. If a simpler acceptable technique is used
its input data will be, in general, a subset of the data described.
Emission Factors.-The method for determining total motor vehicle emissions consists
of multiplying the appropriate emission factors (representing on-the-road emission rates) by
the vehicle-miles traveled. Table 2 summarizes the traffic parameters required for both the
emission factor and emission rate determinations.
The EPA report, "An Interim Report on Motor Vehicle Emission Estimates,"24 contains
the methodology for determining CO, HC, and NOX emission factors for light- and heavy-duty
Table 2.Traffic parameters for emission estimates
Analysis
level
Microscale
Mesoscale
i
Traffic parameters
Peak-hour volume
Average speed for
peak-hour travel
Emission factor data:
Region
Vehicle type
Age distribution
Annual travel
Average trip length
Average trip speed
Emission factor data:
Vehicle type
Age distribution
Annual travel
Source of estimated emissions
With project
Project traffic
Surface traffic (excluding
project)
Major point sources
Surface traffic (including
project)
Major point sources
No project
Surface traffic
Major point sources
Surface traffic
Major point sources
17
-------
gasoline-powered motor vehicles. Since this report is considered to represent the state of the
art for emission factor determination, the review of emission rates used in the LilS analysis
should be based on the FPA procedures. If an analysis uses emission (actors other than the
EPA report, the reviewer must determine their validity. In making this determination, it is
advisable that the reviewer seek assistance from the National Air Data Branch. Office of Air
Quality planning and Standards.
Traffic Data.- Review of the basic traffic data (traffic volume and speed estimates) is
probably the most difficult of the data reviews. These data, which result from a myriad of
sampling and projection techniques, are related directly both to the justification of the
project and to the pollution impact of the project. Without a sufficiently comprehensive
set of traffic data, quantification of the air impact is difficult, if not impossible.*
For many projects the fundamental traffic volume data are estimates of annual average
daily traffic (AADT), based on counts (made at intervals throughout the year) on the high-
way under consideration or on similar highways. In such cases empirical methods are used
to adjust the AADT data to design hour volumes. Since these techniques also produce, or
may be used to produce, peak-hour volumes for the design of individual roadways (which
also influence the speed estimates), it is important that the methodology used and its
limitations be described fully in the !:1S.
The average trip speed utilized in the emission factor determination represents the time
period of interest (e.g., time period of standard). For a microscale diffusion model analysis.
the vehicle speed must reflect the average operating speed, over the time period of interest.
for the particular lane under consideration (or lanes if the total roadway is considered as a
single line source).
In general, the reviewer should determine that the traffic volume and speed estimates
Are compatible with estimates presented in existing plans (land use, transportation.
SIP, etc.)
Are documented with respect to methodology used to determine them
Include appropriate recognition of the various types of "generated" traffic that
might occur
Are compatible with the-level of service of the proposed roadway
Highway Configuration.-The highway configuration includes the alinement interchange
locations, type and location of section changes, and highway dimensions. These parameters
influence the air quality impact-by defining the highway's proximity to receptors and by
influencing the pollutant dispersion characteristics.
*Seo appendix C for a general discussion of traffic data characteristics.
18
-------
Alinement. For modeling purposes, tl\e alincnicnt ot" the roadway is defined by the
location of the right-of-way lines. Its preeise loeation is used in relating the roadway to
reeeptors, local topographic problem areas, and relative wind directions.
Interchange locations. Since interchanges are points of traffic exchange between the
project and other roadways, these locations should be examined in detail with respect to the
receptors affected, traffic changes predicted between the with-project and no-project situa-
tions, and meteorological perturbations due to interchange configuration. II there arc
receptors at these locations, the CO contribution from both the project and the interchange
roadway should be modeled.
Section identification. The most common types of highway sections are at grade.
depressed, fill, and elevated. These section types can be handled fairly well by '.-xisting
models. For tunnels, cantilevered covering, intermittently covered sections, etc., diffusion
model techniques are not well defined. In general, these section types tend to confine the
pollutants, especially for the worst meteorological conditions of low wind speeds and low-
level inversions. Flcvatcd sections have much the same pollutant distribution characteristics
as elevated point sources; that is, the maximum ground-level concentrations will occur at
some distance from the source. Barring unique meteorological conditions, the elevated
section is the only type that can produce a maximum concentration point beyond the
highway right-of-way line.
Highway dimensions. For modeling purposes, specific dimensions of the roadway are
required to define precisely the "downwind distance." These data include:
Number and width of lanes: For multilane roadways with narrow riglm-ul'-\vay.
each lane probably should be treated as a separate source.
Width of separator: For divided roadways, each flow direction usually will be
treated as a separate source (as a result of the different traffic flow characteristics).
If the separator is sufficiently wide, the upwind lanes may be treated as a single
line source.
Distance from roadway edge to right-of-way line: The reviewer should note
wehther this distance is sufficient to accommodate an additional lane. If so. the
possibility of future lane additions should be considered.
Meteorology.-The meteorological parameters of prime importance to modeling efforts
are the wind speed, wind direction, atmospheric stability, and inversion (or mixing) height.
For the microscale analysis the critical values for each of these parameters, over each season.
must be estimated along the length of the project. In addition, these parameters should be
determined for the time periods corresponding to the peak traffic volumes. These data, when
modified for local highway configuration and topographic influence, must represent the
"worst" set of meteorological parameters applicable to the various segments of the project.
These worst cases are then combined with the traffic data along each segment to define ll.e
adverse cases for analysis.
-------
For diffusion model applications the meteorological data take the form of mixing
height and stability wind rose data. The mixing height is assumed to mean that a stable-
layer exists above this height. If the pollutant plume disperses sufficiently (as it prepresses
downwind) to be affected by the lid, the Gaussian distribution assumption must be
modified."
In general, only low inversion heights (less than 200 meters) will influence the micro-
scale pollutant analysis procedure. For example, a typical highway-related plume would
interact with a 200-meter inversion at about 400 meters from the source, which is well
beyond the maximum concentration point in the microscale analysis.
A wind rose gives the frequency of occurrence for each wind direction (usually to 1 ft
points) and wind-speed class (nine classes in Standard Weather Bureau use) for the period
under consideration. A stability wind rose gives the same type of information for each
stability class. The most critical daily periods for the construction of stability wind roses
are usually the morning (0700 to 0()00) and evening (1600 to 1800) rush hours. Depending
on the specific situation, other periods may need to be examined.
t
Various Federal, State, and local organi/.ations routinely collect and process meteoro-
logical data. The most notable of these is the National Climatic Center in Asheville. North
Carolina. This center will prepare, on request, a summary of all pertinent data available for
a given geographical area. In most cases, however, these data must be supplemented by
meteorological surveys along the project route. The extent, duration, and data reduction
techniques of such surveys should be reviewed with respect to their supportive role in the
air quality analysis;.that is.,
Have sufficient data been collected to define the worst conditions along the highway
route?
Has the survey covered time periods sufficient to determine.the critical diurnal
season?
Are the data collection and reduction techniques adequate?
Topography. -Local topography can influence both the wind direction and the atmos-
pheric dispersion characu. istics. Unless the meteorological parameters have been obtained
at each site application, these data should be adjusted to reflect at least the major topographic
influences, including
General wind How around buildings, hills, and mountains
Channeling effects of winds in canyons and valleys
Areas of drainage winds
Areas where surface inversions may exist due to cool-air drainage
20
-------
Areas of limited dispersion due to valley walls
Wind flow alterations around different types of highway sections (cut, fill, viaduct,
etc.)
Proper adjustment of the meteorological parameters to account for topographic effects
can be extremely tricky and should be done by a meteorologist familiar with diffusion model
applications.
Background Concentration.-Since it is the total pollutant concentration values that
must be compared to the standards, the pollutant contributions from the nonproject sources
must be included in the analysis. In general, the background concentration is defined us the
pollutant concentration level that, when added to the contribution from the project itself
and specific local contributions from other major sources, will give the total pollutant
concentration level.
For the most part, the background pollutant contribution comes from the mesoseale
sources, and can be obtained: through utilization of mesoscale diffusion models (for CO), by
(he "rollback" technique (for all pollutants), or by using preproject ambient air quality levels
(corrected for mi'.jor growth areas). The rollback technique, which has been used by most
States in their SIP's, is described in "Requirements for Preparation, Adoption, and SuhrnitUii
of Implementation Plans."25 In any case, the background projections should be checked
against i>ny applicable SIP projections.
Unless an extensive air quality monitoring network is in existence (as demonstrated in
the SIP), specific monitoring activities usually must be implemented along the project route.
These data are required to establish the existing ambient air quality levels. In addition, by
using the relationship between the existing traffic information and a comprehensive set of
existing air quality levels, the rollback technique (or modeling, if done) will provide more
accurate estimates of the pollutant concentrations expected from the projected traffic levels.
This is especially true for major projects or in areas with complex topographic characteristics.
In general, additional air quality surveys must be taken if local meteorological and source
characteristics, topography, or degree of urbanization at specific points along the project
differ significantly from conditions where the existing air quality monitoring stations are
located. Sensitive points that may require additional monitoring can be identified by existing
pollutant levels, a high or potentially high degree of urbanization within the design life of the
roadway, topography or meteorology conducive to pollutant trapping, those sections of road-
way prone to congestion within the design life of the road, or the proximity now or in the
future of sensitive receptors.
IV.A.3. Assessment of Air Impact
In conjunction with the air quality assessment, the reviewer must determine that the
analysis includes identification and quantification of all significant impact areas. Because the
impact from a highway is a function of both the type of highway and the area through which
21
-------
it passes, an initial estimate of the level of analysis required should be made. As a guide.
table 3 defines three levels of analyses that can provide adequate estimates of the primary
air quality impacts from a variety of highway-type project-area combinations. Project areas
are broadly categorized as rural, urban, and metropolitan. The specific points of transition'
between these categories will depend on the project under consideration and must be deter-
mined by the reviewer.
The review and assessment procedures for each of the review levels are described in suc-
ceeding paragraphs. Since these procedures apply to projects ranging from new freeway
construction in urban areas to highway modification in isolated areas, they are necessarily
generalized. It is important that the reviewer recognize the generalizations in these proce-
dures and that he be prepared to make adjustments to accommodate any exceptional
circumstances of a given project.
Review Level 1: Construction Impact.-Direct assessment of the air quality impact
from construction activities is difficult, owing to the lack of appropriate emission factors.
As a result, this review is based on insuring that "reasonable" precautions have been planned
to minimize the impact. Of the possible air pollutants, only participates in the form of
fugitive dust are generally a problem.* Reasonable precautions that can be used to minimi/.e
the fugitive dust impact include
Spatial and temporal distribution of cut-and-fill operations to minimize emission
concentrations
Liquid dampening of excavation areas to reduce level of emissions (note that adverse
water impacts must be avoided, see sec. IV.B).
Construction curtailment during times of limited dispersion conditions
In order to determine if proper emphasis has been placed on the construction impact
abatement methods, the reviewer should estimate the "potential" impact at selected sensitive
receptors. This potential can be quantified in terms of the percent of the generated pollut-
ants that would reach the receptor under the most adverse meteorological conditions (durinu
construction periods). This estimate combined with an estimate of the magnitude of the
project emissions should serve as an impact indicator. For example, a situation in which a
residential area would receive a significant portion of the emissions generated during a major
cut operation would warrant special abatement considerations.
Unless the reviewer can pinpoint a major impact, this review is not critical to the overall
air quality rating of the project. The reviewer should, however, note those areas which may
be a problem and, if possible, suggest appropriate abatement action that could be taken.
Review Level 2: Microscale CO Concentrations.-The CO review, including both I- and
8-hour averages, should be carried out for all new major highways, regardless of population
Impacts from open burning of spoil are discussed in section IV.D.
-------
Table 3.Level of analyses adequate for estimating the air quality impacts from highway projects
1
Project area j
1 i
Rural with no population
Type of project in microscale area
1 ' r
J
Microscaie '. M-jsoscjie
area j area
Highway modification None
that rloes not in-
crease capacity
..
Nt".v minor highway Nont
or modification that
increases capacity
fxfsv/ rr.ajor highway Level 2.
maximum
CO
L
None
None
None.
r
Rural with increasing
population in microscale
area
! i
i
Urban ; Metropolitan
:
i
Microscaie ' Mesoscalc Microscale Mesoscaic t M>ctosea'e j Mesoscale
area : area
i
Ncno
L.evsi 2.
maximum
CO
Leve= 2.
rP^x irT>:jm
CO
None
None
None
urea area : are.-. area
'
Leve' 1. ' None ! Level ! None
c;>(\structio" . conif.;-.:'.:or.
iinoaci ! ;mr>a'. :
t
Leve;s 1 and 2. ' None LuvsU i :>:; 2, ; fMono
construction , conifi-jTio" !
irnoact anc: inipac' and i
' 1
maximurr ; niaxirnijrn :
CC : ~" '
i
_
Lr.-.'iis ! arid 2. N;me i Le-. !; 2iv.' 2. i Levet T.
CO:'5t1'u!J'.io:" ' CO; - ~\'O~ '. maxiinun^
impact an" . impad ana CO (8 nr.-.
mayimuni '', maxi~urr. HC (3 hri.
cc : 'cc- ; MC\
1
! : (annual.1
- !
-------
density, and for new minor highways or highway modifications increasing capacity in areas
already developed or for which development appears likely. The analysis of major highways
in unpopulated areas (as shown in table 3) is needed owing to their unpredictable induce-
ment of population growth. The air impact data in these areas can be an essential planning
input for future development.
The objective of this review is to determine that the air quality impact, in the micro-
scale area, has been identified and quantified properly for the entire project. A minimum
analysis that will produce these results consists of
Estimates of the magnitude and location of the maximum CO concentration values
along the length of the project
In those areas in which either of the CO standards is exceeded, the spatial location
of where the CO standards are first exceeded
CO concentration levels at sensitive receptors (schools, playgrounds, etc.) located
near the project
In general, it is convenient to assess the impact by considering the highway project in
terms of a series of contiguous "segments," along each of which a different set of conditions
prevails (that is, the meteorological conditions, traffic parameters, highway configuration.
and background concentrations). As a result, the maximum concentration contours should
be a series of straight lines (with local modifications for major extraneous sources). The
length of each segment for which common conditions may be assumed will vary depending
on the detail of the data base. For example, if the project topography is uniform, the same
meteorological conditions might be applied for a considerable length of the project. Obviously
it must be left to the reviewer's discretion, based on his understanding of the factors in-
volved, to determine the extent to which conditions may be assumed to be constant. It is
emphasized that the intent is to insure that the complete project has been analy/.ed. That is
to say that either each segment of the highway has been analyzed with respect to its specific
CO impact or, by a comparative analysis of data bases, the concentration of a given segment
has been shown to be less than the calculated concentration of a comparison segment. Again.
it is left to the reviewer to judge the applicability and accuracy of this approach.
In performing the CO concentration review, the following guidelines should be observed:
I. Area of interest extends from the project right-of-way line into the microscale area.
This limitation results from the special complications involved in applying line source models
to determine onroad concentrations. In the general situation this restriction is not critical to
the microscale impact assessment. With the exception of locations involving elevated highway
sections or unusual topographic situations, the maximum CO concentration value in the
"area of interest" will occur at the right-of-way line.
2. The CO concentration values along each segment should be based on the most adverse
(i.e., resulting in the highest concentration values) set of meteorological and traffic conditions.
In general the highest concentrations will result from using the most adverse meteorological
24
-------
conditions that could be expected to occur during the peak traffic hours and the associated
peak traffic data. The combination of these conditions is referred to as the "worst-worst"
conditions. Since the meteorological conditions involve a number of parameters (wind speed
and direction, atmospheric stability, mixing height, etc.), the selection of the most adverse
combination requires careful review.
3. The background CO concentration should be included in the total CO concentration
values presented. The background concentration, as used here, is the concentration resulting
from (a) major sources near the project, and (b) all other contributing sources in the mi.;ro-
scale and mesoscale areas. Although the background levels are difficult to obtain, estimates
of their magnitude must be made; without these data the project impact cannot be related
directly to the air quality standards.
4. CO concentrations should be estimated for that time period within the project life-
time for which maximum emissions are expected. The project lifetime is considered to be
the time period from the estimated time of completion (ETC) of the project through I.-TC
+ 20 years. Depending on the impact found for this critical period, concentration values for
other time periods within the 20-year span may be required (thus estimates of the vehicle
emission growth characteristics must be made). Vehicle emissions are the product of
emission factors and vehicle population. Since the emission factors are decreasing with time
(owing to increasing percentages of controlled vehicles) and vehicle population is increasing
with time, the net change in emissions can either increase or decrease, depending on which
parameter dominates. Figure 3 illustrates several emission growth possibilities, \lthough
both the project emissions and the background emissions (reflecting the mesoscale traffic)
may exhibit the same emission growth trends, their peaks may occur at different times:
thus, the critical time period defined here should reflect the maximum of the total emissions.
5. CO concentrations for the no-project alternative should be determined. I or the
situations involving improvements to an existing roadway, the procedure i-, guie ally straight-
forward since the comparison points (right-of-way line, sensitive receptors, etc.) are existing
for both situations. For new projects, comparison points must be selected. For this purpose
it is most convenient to select those existing sensitive receptors, closest to the project right-
of-way, which will remain undisturbed after the project is completed.
To determine if the impact has been quantified properly, or to estimate concentration
values at potentially critical areas that were not included in the FIS. the revicXver can use the
techniques described in appendix B.
Based on the results presented in the E1S or as estimated by the reviewer, one i.| ilk-
following situations will occur:
CO standards not exceeded. If the worst-worst case for the critical time period produces
CO concentrations below the standards for all of the highway '.'segments." the project is
satisfactory from an air quality standpoint (provided that review levels i .nul 3 are also
satisfactory). Exceptions to this assessment may be made if the proposed project accounts
for a significant long-term increase in CO concentration levels over the no-project alternative.
Figure 4 illustrates such a situation for a given highway segment. Note that the level of
25
-------
EXAMPLE 2
GROWTH EFFECTS
EXCEED EMISSION
FACTOR REDUCTIONS
to
01
O
u
EXAMPLE 3
EXAMPLE 1
EMISSION FACTOR REDUCTIONS ,
EXCEED GROWTH EFFECTS
ETC
ETC t 20
TIME
Figure 3.Examples of emission growth trends.
STANDARD
<
a:
o
I
8
WITH PROJECT
WITHOUT PROJECT
4-
ETC ETC + 20
Figure 4.Example CO concentration patterns for a given highway segment.
26
-------
degradation is dependent on the shape and location of the no-project line. The overall
microscale CO assessment would be based then on the number of questionable segments and
the severity of their CO degradation.
CO standards exceeded. This case allows for the possibility that either the 1-hour or
8-hour CO standard may be exceeded lor a tew segments and/or over a limited time period.
The primary concern is whether the project enhances the attainment and maintenance of the
CO standards. For this second case, comparisons between the with- and without-project CO
levels over time are required and should be the basis of the impact assessment.
Review Level 3: Mesoscale Analysis.--ln essence this analysis is a Projcct-SIP consist-
ency review, which is intended to reconcile the traffic generation and redistribution charac-
teristics of highway projects with specific (if any) vehicle use reduction or traffic pattern
control measures contained in the SIP. Of particular interest are those SIP's which include
detailed transportation control plans (see app. A). These control plans (as specified in 40
CFR Part 5.1 and further described in 38 F.R. 1464. Jan. 12. l')73) consist of
« Identification of specific transportation control measures to be implemented (reduc-
ing vehicle use. changing traffic How patterns, decreasing emissions from individual
motor vehicles, etc.)
A demonstration of the adequacy of these measures for attainment and maintenance
of the national ambient air quality standards
A detailed timetable for obtaining necessary legal authority and taking all other
steps necessary to implement the various measures
The reviewer must determine if the proposed project is compatible with.these plans.
The mesoscale air quality review is concerned with the 8-hour CO. 3-hour (6-<) a.m.)
HC, and annual average NO; standards (the 1-hour CO review is described under "Review
Level 2"). The analysis of these pollutant levels should be consistent with applicable SIP
emission inventory and analysis techniques (i.e.. diffusion modeling or rollback). The SIP
pollutant estimates should be used as a base line from which the project-induced changes
can be determined.
If the F.IS does not contain a mesoscale analysis, the reviewer can make an order-of-
magnitucle impact assessment by utilizing a pollutant burden analysis that consists of the
following elements:
I. From the SIP air quality projections, determine the time history of the CO. HC. and
NOr pollutant concentrations. Note that the analysis (mesoscale) area should be restricted
to that area which could be influenced by the project. This restriction should be made to
prevent inclusion of an area so large that the changes in total emissions will not reflect the
project influence-.
27
-------
2. Compare the relative emission totals of the with-project and no-project situations
over ETC + 20 years.* If possible, the pollutant trend and critical year between ETC and
ETC + 20 years should be determined.
3. If the with-project emissions are always less, the project is satisfactory.
4. If the with-project emissions significantly exceed the no-project emissions during a
time period in which the pollutant concentrations are critical (i.e., close to or exceeding
standards), the project is unsatisfactory and a detailed analysis should be requested.
5. If the with-project emissions exceed the no-project emissions during noncritical
periods, the project approval will depend on the total degradation involved. A detailed
analysis should be requested;.
*If the SIP data are for less than a 20-year period, the projection should be extrapolated.
28
-------
IV.B. WATER IMPACT REVIEW
In reviewing the water quality aspects of highway-project EIS's, particular emphasis
should be placed on the project's ability to conform to the Federal Water Pollution Control
Act Amendments of 1972. In particular, sections 208(b), 303(c), and 304(e) relate to water
quality impacts associated with the construction and operation of highway projects. The
reviewer also should be familiar with the following sections of the act, which provide for
non-EIS-related assessment activities within EPA:
Section 105(b)-Demonstration grants
Section 105(d)-PraclicaI application of was management techniques to point and
nonpoint sources
Section 305(b)-State annual report to EPA section on non-point-source control
Section 311 (b, c, f, j)-Oil and hazardous materials control
Section 404 (b, c)-Dischargc of dredged or fill material into navigable waters
In addition, the reviewer should be cognizant of EPA policies presented in the Admin-
istration's decision statement No. 4, "EPA Policy to Protect the Nation's Wetlands,"
February 21, 1973.
The reviewer also should utilize related agency outputs and programs to insure a com-
prehensive EIS review. Particular attention should be focused at coordinating the EPA
positions taken on projects requiring Corps of Engineers' permits (either at the public notice
review stage or at the EIS review stage).
IV.B.1. Highway-Related Water Impacts
The water problems associated with a particular highway project will involve one or
some combination of the following:
I
1
Turbidity of watercourses due to erosion
Watershed modification
Highway runoff contamination
Sanitary wastes from temporary and permanent waste disposal facilities
Contamination of surface and ground water supplies and recharge areas by polluted
fill material
The reviewer must determine that these issues have been developed adequately in the
EIS. Although some of these water problem areas may be less significant than others, the
reviewer should identify and assess all problem areas and, if possible, suggest alternative
abatement procedures.
29
-------
IV.B.2. Review of Water Impact Analysis
Before the assessment of the water impact, the reviewer must be able to ascertain the
relationship between the project and its surrounding area as well as the sensitivity of the
surrounding area. The essential elements in this review consist of identifying
\
l
The type of area traversed by the project
The project drainage system
The receiving water system
In each case the reviewer must be able to relate the descriptions to the five water problem
areas identified in section IV.B.I. '
Project Area Description.The project area must be identified fully and described in
such manner that the potential impact areas are identified completely (e.g., areas requiring
continuous fills, rerouting of streams, ground water interception').
The description should include any applicable land use or transportation plans (ongoing
or in preparation). Such plans not only provide additional descriptions of the project area,
but also provide a framework within which the project must exist. If such formal plans do
not exist it must be determined whether any local, State, or Federal projects will influence or
be influenced by the project under consideration.
In any case, the level of detail for the area description should be consistent with the
nature of the area. For instance, if segments of the project cross sensitive areas, such as
estuaries, marshes,'or wooded swamps, detailed descriptions of these areas must be included.
Drainage Pattern Description.-The EIS must describe the natural drainage system, the
temporary construction drainage system, and the postconstruction drainage system.* The
statement also should detail the permanent changes and describe how the temporary drainage
system will provide a minimum impact transition from the natural system to the postcon-
struction system. The project drainage area generally will involve1 larid areas outside the
project right-of-way that must be considered for potential runoff The extent of disruption
and pollution of this runoff should be assessed by the State highway authority, and a plan for
control should be set forth. As a minimum, this plan must include a contingency plan for
dealing with unanticipated water quality deterioration that can be activated by the onsite
construction manager. If appropriate, the reviewer should suggest that the plan be enlarged
to describe and schedule sediment control actions.
There also should be a general discussion of changes in drainage patterns caused by
initial or concurrent demolition of older highways in the project area. Often the contin-
gency and final plans fdVenvironmental protection ori highway'projects are not written to
*Scc "Guidelines for Hydrology, Vol. II"26 for a discussion and bibliography on highway drainage
facilities.
30
-------
cover demolition and preconstruction clearing (or, if written, the plans are ignored in the
haste to clear and begin new construction). These considerations are especially important
when the project lies within the flood plain of a watercourse.
Receiving Waters Description.-The EIS must provide complete information on the
affected water system, including data on quantity and quality, as it relates to the five highway
water problem areas. A listing of important bodies of water and critical stream reaches where
water quality is already low should be included. The applicable Federal-State water quality
standards, especially with regard to turbidity, should also be referenced and summarized in
the statement. The statement should explain how compliance with applicable standards will
be insured.
There are several planning and information dissemination provisions in the Federal Water
Pollution Control Act (sees. 303(e), 304(e), and 208(b)) that may be used to provide detailed
information on the receiving water system. Although the State planning documents filed
under section 303(e) requirements are not due until July 1974, useful preliminary information
should be available immediately.
Non-point-source pollution, particularly that pollution resulting from construction activ-
ity, is mentioned specifically in sections 208(b) and 304(e) of the act. Since non-point-source
control is predominantly a State- and local-government problem, the reviewer should look
for discussions in the draft statement that recognize this responsibility. All appropriate local
controls, such as pollution control ordinances, subdivision ordinances, and zoning ordinances.
should be discussed and must be complied with. If local legal controls for prevention of non-
point-source pollution do not exist, the statement should describe the procedures that will
be utilized to restrict poor npnpoint practices by private contractors.
IV.B.3. Assessment of Water Impact
Assessment of the five highway-related impact areas involves relating the identified
impacts to specific criteria governing acceptable levels of degradation. While a quantitative
method for arriving at a Final assessment (i.e., rating) is not proposed here, it is recommended
that the reviewer assess the proposed highway project by analyzing the five water impact
areas with respect to: probable violations of applicable Federal, State, and local watci -related
standards; inconsistencies with Federal, State, or local regulations and plans; and any signifi-
cant degradation of water quality or water-related activities.
Sediment.--Turbidity and silting of adjacent streams and reservoirs are caused, for the
most part, by the erosion of the raw soils exposed during construction and maintenance opera-
tions. The primary impact of these effects generally will involve one or more of the following:
Increased operating costs or shortened life of affected reservoirs and channels
!
Damage or elimination of fish and other aquatic life
Possible damage to buildings, roads, and bridge foundations
31
-------
Soil erosion abatement or compensatory measures are described in publications avail-
able from EPA,27-28 the Department of Transportation (DOT),29-30 and the Soil Conservation
Service.31 Also, State highway departments often have publications containing sediment
control programs and criteria. The reviewer should be familiar with all of these publications.
The EPA publications, "Control of Erosion and Sediment Deposition from Construction of
Highways and Land Development"27 and "Guidelines for Erosion and Sediment Control
Planning and Implementation,"28 should be used as primary reference documents when
reviewing a statement for its treatment of the sediment control subject.
In particular, the reviewer should insure that all appropriate abatement measures have
been utilized to minimize erosion of exposed areas. Common abatement measures include
Construction scheduling such that the total exposed area is minimized over time
Timely application of seed, mulch, fertilizer, lime, sod or other vegetative cover
Use of diversion or intercepting ditches, riprap, concrete lining, retention basins, etc.
Combining borrow and fill areas (depending on construction scheduling) and/or
diking these areas to prevent silting of adjacent watercourses
In any case, borrow and fill areas should be located to minimize damage to wildlife and
marine ecosystems.
In the future, sections 208(b) and 303(e) of the Federal Water Pollution Control Act
will provide additional material defining the requirements for sediment control. Section
208(b) areawide plans will include procedures and methods to control sources of pollution
related to construction activity. These plans mainly will cover metropolitan areas.
The State planning process, under section 303(e), requires States to provide evaluation
of the non-point-source impact on water quality.* As these plans become operational
(in July 1973), regional reviewers can use the guidance available in 40 CFR 131.21 1 (July 9,
1973).
Watershed Modification.-Serious water quality problems can be caused by the impinge-
ment of the road system and its constructi'on on estuarine areas, marshes, wooded swamps.
and streams. The reviewer should pay particular attention to the impacts from drainage
systems, borrow and fill operations, and sedimentation basins and lagoons. The borrow and
fill operations should be consistent with the sediment control requirements described
previously.
Frequent and proper drainage should be provided by use of bridges and pile support
over valuable marsh areas, and of sufficient culverts in other fill areas so that drainage or
tidal flushing is not impeded. Improperly drained areas can trap water, thus increasing
unnatural evaporation. Such areas, if sufficiently large, also can become anaerobic and
*See EPA interim regulations. "State Continuing Planning Process," 38 F.R. 8034. Mar. 27. 1973.
32
-------
threaten public health. In marshlands, improperly drained highways also can reduce tidal
"flushing. This condition may interrupt extremely delicate and important ecological proc-
esses within the marsh. Further, drainage of marshlands can increase total runoff causing
higher flood flows in the streams. This effect results from lowering the water table, which
increases soil evaporation and changes the type of vegetation and elimination of the marsh-
land as a natural flood control reservoir.
I
In general, a route with a ditch system that intercepts, diverts, and conveys the least
amount of water will have the minimum water quality problems. A route that follows high
ground or ridges generally will intercept the least amount of water. Road ditches generally
speed up runoff from a drainage area by conveying water quickly to stream beds.
It is important that the flow of waters in estuarine areas be maintained similar to their
natural flows. Disturbance of natural flows can affect ecological determinants, such as sedi-
mentation patterns, mixing of fresh and salt waters, nutrient flows, shellfish beds, fish and
wildlife, and local vegetative patterns. A decrease in water level caused by diminished flows
can alter nearby vegetation significantly. Migration patterns of indigenous species (such as
anadromous fish) should be determined in order to ascertain whether the highway may act
as a migration barrier.
On flood plains, the highway fill and bridge openings should be designed to carry the
peak flood flow, and should result in minimum impingement upon the flood plain.32
Runoff-Borne Pollutants.-Oil, fuel, tar, pesticides, fertilizer, deicing salts (especially
in northern areas33), animal and human wastes, and the products of combustion are found in
highway runoff. If not properly controlled, these pollutants can affect water quality, wild-
life, and roadside vegetation. As with the sediment problem, runoff is a non-point-source
pollution problem and, as such, is primarily a local responsibility. The impact statement
should demonstrate this understanding.
Pollution of th^ water system by oil and hazardous-materials spills also can be signifi-
cant, and should be reviewed and assessed b,y consulting the National Contingency Plan.
The reviewer should be familiar with the provisions of this plan and, more important, any
appropriate State or local plans for spill prevention and control. Current regulations for spill
prevention and control are found in 40 CFR 109. The regional coordinators for oil and
hazardous materials should be consulted for the latest guidance under section 311 of the
Federal Water Pollution Control Act. If possible, these coordinators should participate
directly in the review.
Proposed actions to be taken in the event that spills along highways occur either during
construction or after construction should also be considered. A minimum list of items to
consider includes
Probability of spills occurring
Means of reporting and detecting spills
Designation of responsible organization for control and cleanup in the project area
33
-------
Sanitary Wastes.-Highway construction and operation also impacts the water environ-
ment via the accumulation and disposal of sanitary wastes. Waste disposal is accomplished
through portable toilets during construction and permanent rest areas after construction.
While these installations are few in number, they are not insignificant and do come under
the point-source discharge limitation and permitting provisions of the new act. In assessing
the statement for its completeness, the reviewer must determine that these two methods of
waste handling are employed and that raw or inadequately treated discharges are not reaching
the water system.
During construction activities work crews must be provided with portable toilets
meeting all State health department requirements and any applicable Federal guidelines.
Permanent waste collection and treatment facilities are generally of two types, rest
stops and multiple service areas. In either case treatment facilities are usually septic tanks
(with drain field) or extended-aeration activated-sludge units. In the event that local munici-
pal facilities are used, the reviewer should determine that future use will not overburden
these facilities.
Septic tank systems should be designed and installed in accordance with the "Manual
of Septic Tank Practice."34 Package treatment plants should be discussed from the stand-
point of at least maintaining the applicable Federal-State water quality standards. Extended
aeration plants lend themselves well to this type of use owing to their minimal BOD and
solids residue. Any indication that another process is to be used should be considered care-
fully by the reviewer.
Sanitary waste impacts also can occur when highway projects are adjacent to current
interceptor sewer construction or in-place interceptors. If applicable, the EIS should discuss
possible construction accidents that could disturb previously laid or new pipe. Pipe damage
and alteration of pipe alinement and grade can result in exfiltration with resulting ground
water contamination. This.type of impact will occur most frequently in urban areas during
freeway and arterial road construction.
Water Supply Protection.-The "Public Health Service Drinking Water Standards"35
presents maximum concentrations for biological, physical, chemical, and radiological
contaminants in water supplies. While these standards are required for interstate water
carriers, they function as guidelines for all other public water supplies. Water quality
impacts from highway design and construction should be assessed with respect to these
standards or, if more stringent, to local standards.
As a general goal, water supply protection should be accomplished as much as possible
by minimizing the degradation rather than by increasing treatment of the contaminated
waters, especially in rural areas where water treatment costs are quite high. Usually the
extent of treatment in rural cities and towns involves chlorination and/or clear well
sedimentation.
The statement also should discuss the degree of Federal-State-local water supply agency
involvement in project planning. Since protection of local water supplies is a local responsi-
bility, the views of project planners and water supply experts should he set forth. Resolution
of opposing views also should be described.
34
-------
IV.C. NOISE IMPACT REVIEW
IV.C.1. Highway-Related Noise Criteria and Standards
The Noise Control Act of 1972 gives EPA specific authority (among other things) to
Identify major noise sources, publish noise criteria, and control technology
information
Establish and enforce noise emission standards for products distributed in commerce
Coordinate Federal research and activities in noise control
The establishment of standards or regulations restricting noise levels from specific types of
activities is left to the appropriate Federal agencies.
Pursuant to these goals the Office of Noise Abatement and Control (ON AC) has initiated
the following efforts that are directly applicable to highway-related noise:
Published "Interstate Motor Carrier Noise Emission Standards"36
Published "Public Health and Welfare Criteria for Noise"37
Initiated research on noise effects, results due to be published by October 27, 1973
Until the noise effects document becomes available, the recommended criteria specified in
these guidelines should be followed.
For the specific case of highway projects, section 136(b) of the Federal-Aid Highway
Act of 1970 (adding sec. I09(i) to title 23 U.S.C.) directs DOT to promulgate ambient
noise standards for highway projects. Pursuant to section I09(i), noise standards have been
developed and issued as an attachment to the directive on highway noise, "IVicy and Pro-
cedures Memorandum 90-2."38
These standards contain desi-jn noise levels for different exterior land uses and activities.
and for certain interior uses. EPA is on record, however, as objecting to the standards, as
promulgated. Specifically, there is concern that the use of L]0 values alone may not ade-
quately control certain situations. In addition, it is felt that the L|0 value of 70 dBA* ; too
lenient. For example, a steady level of 60-65 dBA during most of the day or night might
have a greater impact on residents than shorter periods of 70+ dBA; yet a project of the first
type would be entirely acceptable under FHWA PPM 90-2 standards.
"The sound level in decibels on the "\ scale" of a standard sound-level meter.
35
-------
IV.C.2. Review of Noise Impact Analysis
The noise standards require anticipated noise levels to be computed for noise-sensitive
areas on the basis of the most adverse conditions expected to occur on the highway in
question. This computation is represented as the design noise level during the worst hour of
the day during the design year. The analysis should consist of
An adequate model for relating traffic parameters to estimated noise levels
Appropriate traffic parameters representing the worst hour of the day during the
design year
Existing noise levels representing the no-project situation
The NCHRP No. 11739 method for predicting highway noise is the one used at present
by EPA. It is emphasized, however, that other acceptable methods may be used by F.IS
jreparers. For example, a new method has been prepared by the DOT Transportation
Systems Center (TSC).40 Although this method has not been tested as extensively as the
NCHRP No. 117 method, and no comparisons between the two methods have been made,
the TSC approach appears to be at least as good as that of NCHRP No. 117. In general, if
the reviewer questions the validity of the model used, ONAC should be consulted.
Figure 5 illustrates the noise analysis inputs and methodology. Except for the roadway
gradient and surface conditions, the highway data cover the same range of information re-
quired in the air analysis. The notable exception is that here the traffic data from nonpeak
diurnal periods are used, because automobile noise increases with the third power (approxi-
mately) of the vehicle speed and truck traffic generally is greater during the nonpeak periods.
In any case, the traffic data should be reviewed to insure that "worst-case" conditions are
used.* A complete set of data must be obtained for each of the areas in which an analysis
is required.
As a minimum, the noise analysis should include the L10 and LJO dBA levels, and
should include noise projections after application of chosen noise abatement schemes. Aside
from traffic control measures (speed reduction, truck traffic restrictions, etc.), the most
effective noise abatement methods involve utilization of buffer zones or the installation or
construction of noise abatement barriers or devices.
In conjunction with the predicted noise levels from the highway, the existing noise levels
adjacent to the highway must be measured. Sites should be selected both for their proximity
to the projected noise source and for their noise sensitivity. Lu,, LS() and L9()t levels should
be given in dBA units as well as the noise characteristics at the identified test sites. In general,
the L90 value can be considered as the background level, whereas the L,0 value is representa-
tive of the peak level.
*See appendix C for a general discussion of traffic data characteristics.
^The reviewer should note that NCHRP No. 1 17 cannot be used to predict L9() values, since it only provides
an Ljo and an adjustment to LJQ.
36
-------
1
ROAD EL
TRAFFIC PARAMETERS
VEHICLE VOLUME
VEHICLE MIX
AVERAGE SP
REFERENCE NOISE
LEVEL OF 100 FT
PREDICTED r
AT OBSERVE
1
JOISE LEVEL
R-l-50
'
PREDICTED NOISE LEVEL
AT OBSERVER L,0
i
CRITERIA
i
COMPLETE METHOD
EVALUATION
^
»
ROADWAY CHARACTERISTICS
PAVEMENT WIDTH
VERTICAL CONFIGURATION
FLOW CHARACTERISTICS
GRADIENT
SURFACE
1
*
1
1
1
b
PREDIC
OBSERVER CHARACTERISTICS
OBSERVER DISTANCE
ELEMENT SIZE
SHIELDING
OBSERVER RELATIVE HEIGH1
\ \
ADJUSTMENTS
\
TED NOISE -t
- L50 . "*
t
'
| | ^ DISTANCE
\
'
* >\ ELEV/DEPR
i
'
ft»- SHORT METHOD EVALUATION | ELEMENT
CRITERIA > CRITER
SHORT METHOD SHORT
T
ACCEPT
ENVIRO
NO FUR
ANALY!
ABLE NOiSE
NMENT
THER
315 REQ'D
JHORT METHOD ONLY
IA < 1
'-
\
Mt°° I RRAn.PMT 1
J SHIELDING
POSSIBLE f
REQUIRED
'ROBLEM
ANALYSIS
Figure 5.Noise analysis data and methodology. (From NCHRP No. 117.39)
Noise impact during the construction phase is both temporary and more dilTicult to
analyze; however, it should also be addressed in the EIS. Estimates ol' the maximum con-
struction-generated noise at the nearest noise-sensitive area should be stated. In addition.
the length of construction, facilities impacted, noise abatement and control measures, noise
levels of equipment and operational limits (e.g.. time of day. numbers used at one time)
should be stated in the EIS.
37
-------
Possible considerations for noise abatement during const!action activities include
Construction contract specification for use of the quktest equipment available
(decibel values should be specified for each type of equipment)
Construction contract specification containing guaranteed levels of maximum noise
emission into various zones (residential, commercial, and industrial)
Construction contract specification for curfews on hours of construction
Methods of enforcement for the above clauses
If the reviewer pinpoints apparently sensitive areas or roadway conditions that have not
been analyzed, he should first determine that a problem is likely to exist and. if so, then
request the appropriate detailed analysis. Proceeding this way. the reviewer places the burden
of proof on the EIS preparer, resulting in a better response in the final I;IS.
To determine whether there is a problem, the reviewer first must quantify ll;e noise
impact by using NCHRP No. 1 17 and available and assumed worst-case highway-related
data as necessary (as defined in NCHRP No. I 17 and app. O. In some cases, however, the
impact determined for one area can be related to a different area based on comparison of the
traffic data, topography, etc.. of the two areas. After quantifying the impact, the assessment
procedure given in section IV.C.3 should be followed.
IV.C.3. Assessment of Noise Impact
The assessment of the noise impact is simply a judgmental comparison of the anticipated
noise levels during the worst hour of the day for the design year, the existing measured am-
bient noise levels, and the noise criteria for the areas affected.
To determine the applicable noise criteria, the reviewer should determine the existing
and anticipated noise-sensitive land uses near the proposed route, particularly those facilities
in which speech or sleep occurs (such as residences, motels, hotels, hospitals, and schools.
as well as recreational areas such us parks, campgrounds, and nature preserves). For under-
developed areas a review of the current /oning and any land use plans, including population
projections, should be made to anticipate future noise problem areas.
Within each of the noise-sensitive areas, the following criteria should be applied to the
noise levels presented.
Speech Communication.*-In residential areas or other areas where conversation out of
doors is anticipated, it is desirable to be able to converse at distances up to I 2 feet (4 meters).
*Pagcs 19-31 of NCHRP No. 117-*9 present similar nfnrmatinn and may he used as a guide l<> recommended
criteria for speech communication and for sleep interference (sec next paragraph).
38
-------
As indicated in "Effects of Noise on People" (p. 50, fig. 15),4' the level of noise ;it 1 2 feet
should not exceed 55 dBA. This standard would provide interior levels of approximately
45 dBA, assuming open windows for ventilation.
Sleep Interference.-For sleeping purposes a background level of 35 dBA is desirable.
Peak levels should not exceed the background level by more than 10 dBA. Thus, peak levels
should not exceed 45 dBA. With windows open for ventilation, this recommendation
suggests a peak outside level of 55 dBA to protect sleep.
L10 Criteria. -Based on fcPA's objection to the FHWA's PPM W-2 standard of !.., = 70
dBA. reviewers should treat L)0 = 70 dBA as a maximum virtue not to be exceeded, with a
desirable level less than Lm = 70 dBA. Discretion will have to be used in determining the
appropriate L)0 value, but the value should be dependent on existing and future land uses
and existing ambient noise level. A correction factor for day-night noise levels may be
desired, depending on local conditions.
Although a completed project may not create levels in excess of those recommended.
site-by-site consideration must be given to the increase from existing levels. "Community
Noise" (eh. 5)42 indicates that the degree of annoyance experienced from intrusive sounds
depends on the noise level increase above existing levels as well as on the existing levels.
Some consideration, therefore, must be given to the sites where levels will be increased
substantially even if they do not exceed recommended maximum level specifications.
Intermittent excesses (e.g., from truck traffic) should not exceed the range of ambient
levels by more than 10 dBA- It is noted that extraordinary events such as very close truck
passages or low aircraft flyovers may produce levels that exceed background levels by 25 to
35 dBA. Although people may become acclimati/.ed to such events, considerable annoyance
and physical distress are associated with extraordinary noise. Thus, the 10-dIJA excursion
allowed for infrequent events by the foregoing criterion is conservative. In general then.
excesses of less than 5 dBA above the ambient range are acceptable, whereas intermittent
peaks of 5 to 10 dBA are only marginally acceptable. Ten- to I 5-dBA excesses may signal
a potentially serious problem, and peaks greater than 15 dBA would probably initiate strong
individual or concerted public action.
Some consideration should be given to additional abatement measures or alternate
routing or compensation if the range increase is 5-10 dBA. If the increase is over 10 dBA.
the impact is considered serious and warrants close attention.
-------
IV.D. SOLID WASTE MANAGEMENT IMPACT REVIEW
IV.0.1. Highway-Related Solid Waste Management Impacts
The legal and technical requirements for comprehensive planning ami integrated solid
waste disposal operations are State-local responsibilities.* To date, however, formal regula-
tion of solid waste management practices, other than for puhlic health protection, is in a
rudimentary state. In view of these limitations, key elements in the liPA review of the
highway impact are
Determination whether applicable solid waste operations or plans are adversely
affected
In the absence of State or local criteria, determination that existing solid wasiu
operations have been identified and will not be affected adversely
Uighway-p;oject-related solid waste impacts can occur from construction operations,
disruption of community services (during construction and operation), and roadway opera-
tion. Although the impact during the construction period is the most visible, disruption of
the community service can produce important long-term problems and should be considered
in detail.
IV.D.2. Review of Solid Waste Management Impact Analysis
Construction Impact. -To evaluate the construction impact, the reviewer must be
able to
Identify the types and approximate quantities of disposable materials (spoil) that will
be generated
Determine the disposal methods proposed or available for each type of spoil
identified
In general, the proposed methods of disposal should be that subset of available methods
which minimizes the total impact (air and water pollution, overloading of existing facilities,
routing, etc.). If the spoil competes for available sanitary landfill sites, an estimate of the
impact on these sites must be explored. If there is significant impact (such as significant
decrease in site lifetime), solid waste disposal alternatives for the user communities also
should be described.
If borrow and fill areas are used they must be operated in such a way that the impact.
both during and after construction, is minimized. If "sensitive" areas are involved (marshes.
*Pursuant to this concept, the Solid Waste Disposal Act (1M. S')-272) aulluiri/.es l-ll'A to encourage the enact-
ment of improved and uniform Stale and local laws governing solid waste disposal.
40
-------
tidelands. etc.) the requirements of section IV.B must be met. Where possible, topsoil
removed during cut or grading operations should be salvaged (i.e., stockpiled) for reuse along
the roadway cuts and slopes (as specified in 1M 20-6-6730).
Spoil from clearing and grubbing operations generally is disposed of by landfilling, burn-
ing, or recycling. If the disposal method is burning, the attendant participate concentrations
should be determined and checked against the secondary 24-hour standard. If required, the
reviewer can check the concentration values (or make initial estimates) by using the method-
ology given in Turner's "Workbook."11 If modeling is used, the input data should reflect
the most probable 24-hour average meteorological conditions, and emission factors from
AP-4'243 or those determined in consultation with the Emission Factors Branch of the Office
of Air and Water Programs. Regardless of the air quality impact, the reviewer should evaluate
the merits of recycling as a method of disposal (chipping for mulch, composting, etc. I.
Disruption of Community Service.-The E1S must define the amount and nai'.irc of
disruption to existing solid waste management systems or plans in the project-affected area.
The discussion should include adequate solutions to any permanent, serious disruptions or
system alterations, as well as comments from State and local sanitation officials. If necessary,
the reviewer should obtain independent opinions from such officials.
i
In communities with established refuse collections or where refuse collection may even-
tually be established, community isolation-can add significantly to collection costs. Although
such cases are not common, the reviewer should insure that this possibility has been
considered.
Roadway Operations, -Solid waste production during operation of roadways consists.
for the most part, of litter accumulation along the roadway and at roadside rest points (sani-
tary waste impacts are described in sec. IV.B). As a minimum, the I:1S should identify the
mechanism for the collection and disposal of litter.
IV.D.3. Assessment of Solid Waste Impact
Although any significant solid waste impact should influence the project rating, an
environmental objection rating (ER and EU) usually is reserved for those projects which
Utilize improper methods for spoil disposal
Significantly disrupt or make no attempts to minimize the disruption of existing
solid waste disposal operations
Have not demonstrated compliance with applicable State and local solid waste
operations or plans
41
-------
V. RELATIONSHIP BETWEEN LOCAL SHORT TERM USES OF STUDY AREA
AND THE MAINTENANCE AND ENHANCEMENT OF LONG TERM
PRODUCTIVITY
For the most part, this analysis category (and the next, sec. VI) are applicable to non-
pollutant-related impacts. Although such impacts are not within EPA's areas of expertise,
the reviewer is not precluded from commenting in these areas. Comment should be made,
however, only if the reviewer has sufficient information and expertise to provide a compre-
hensive assessment of the probable impact.
From the Council on Environmental Quality guidelines,6 "This section should contain
a brief discussion of the extent to which the proposed action involves tradeoffs between the
short term environmental gains at the expense of long term losses, or vice'versa, and a dis-
cussion of the extent to which the proposed action forecloses future options." Assessment
of impacts within this category requires that the reviewer determine the extent of the limita-
tions (if any) placed on future benefits of the project area. For example, projects through
estuaries, marshes, etc., may foreclose future choice of use and may permanently impair the
natural activity of the area; or elimination of recreation and'parklands* can precipitate
drastic changes in the social and economic character of the project area. To the extent
possible, both primary and secondary impacts should be identified and assessed.
*Thesc areas may also be subject to the Historic Preservation Act44 and the Department ol'Transpurtation
Act,4(f).45
Preceding page blank
43
-------
VI. IRREVERSIBLE AND IRRETRIEVABLE COMMITMENTS OF
RESOURCES INVOLVED IN THE PROPOSED PROJECT
The intent here is to determine that the environmental impact statement has identified
properly "the extent to which the action irreversibly curtails the range of potential uses of
the environment."6 As in section V, this review considers a specific category of nonpollut-
ant impacts. Assessments in these areas, if well posed, can provide significant inputs to the
EPA review response.
Especially noteworthy are project situations that might result in changes in the eco-
system. For example, highways that cut through stream corridors, wetlands, or a natural
estuary can result in irretrievable damage to those sensitive bionics. Other impacts that m;iy
he irreversible, and hence should be identified, include changes in neighborhood character.
loss ci recreational areas, loss or alteration of historic sites, and expenditure of construction
materials and fuels.
45
Preceding page blank
-------
VII. PROBABLE ADVERSE IMPACTS THAT CANNOT BE AVOIDED
The probable adverse impacts that cannot be avoided will be the basis for the overall
assessment routing of the project.
For each alternative considered, the reviewer should: (a) summari/c the probable
adverse impacts, and (b) relate the adverse impacts to the proposed project and other alterna-
tives. After all alternatives have been considered the reviewer should be able to determine
whether the proposed project both minimizes the environmental impact over all other alterna-
tives and is within acceptable environmental impact limits.
Although these guidelines are mainly concerned with the primary pollutant impacts, to
the extent possible, the project assessment rating also should include consideration of
secondary pollutant impacts and primary and secondary nonpc'.lutunt impacts. The crux
of the review assessment is to insure that the EIS contains sufficient information to "explore
alternative action that will avoid or. minimize adverse impacts and to evaluate both the long-
and short-range implications of proposed actions to man, his physical and social surroundings
and to nature."6
Preceding page blank
47
-------
VIII. ALTERNATIVES TO PROPOSED ACTION
The primary purpose in considering alternatives is to attempt (o mitigate (or eliminate)
the unavoidable adverse impacts identified with the proposed project. Each alternative pre-
sented should be assessed as fully as possible, using the procedures given in sections IV through
VII. Alternatives may be thought of as project related (partial or complete alinement modifi-
cations, configuration changes, traffic control, etc.) or project replacement (mass transporta-
tion systems, corridor relocations, etc.). At the environmental impact statement (KilS) stage
of project development (i.e.. "location study" stage), the project replacement alternatives
will probably not be included in the EIS. Such alternatives should be suggested, however, if
the assessment of the proposed project indicates a significant impact, and if the reviewer is
aware that a viable project replacement alternative exists.
In addition to the no-project alternative, the reviewer should determine the applicability
of the following types of alternatives:46
No project, with improved traffic How on existing roadway system. The idea is to
eliminate the need for the project (or reduce its scope) by increasing the existing
traffic capacity. Several of the more effective techniques for increasing capacity are
widened intersections, reversible lanes, one-way streets, traffic responsive control.
and loading regulations. For downtown systems, application of the Traffic Opera-
tions Program to Increase Capacity and Safety (TOPICS)47 also should be considered.
Refinement to improve compatibility between the highway and the surrounding
land use. In effect, this refinement is simply "relocating" the right-of-way in such
manner that sensitive receptors (or areas) are avoided.
Realinement to improve highway location and network configuration. Here the dis-
tribution of the pollutant capacity at the mesoscale level within the region is used
as the criterion for integrating the highway into the existing roadway network.
The effort required for assessment of each alternative will be a function of the type of
alternative under consideration. For example, if an alternative alinement is considered for
a given highway segment, only the source-receptor relationship will change: the basic traffic
data will remain the same. In any case the alternative must be reviewed in sufficient detail to
identify all impact changes, whether they increase or decrease.
The reviewer should recogni/.e that the HIS consideration of alternatives will, in general.
be one of demonstrating why the alternative was unacceptable. In most cases socioeconomic
considerations will be a major factor. It is the reviewer's task to
Preceding page h/
-------
line that all viable alternatives have been considered
line that their environmental effects have been set forth adequately.
the alternatives from the standpoint of their environmental-impact-mitigalion
lilies over the proposed project
50
-------
REFERENCES
1. U.S. Environmental Protection Agency, Office of Federal Activities. "Basic Documents Concerning
Federal Programs to Control Environmental Pollution From Federal Government Activities." rev. cd..
Washington, EPA, Dec. 1972.
2. U.S. Department of Transportation, Federal Highway Administration, "PPM 90-1, Guidelines for
Implementing Section I02(2)(C) of the National Environmental Policy Act of 1969, Section Ko3(f)
of 49 U.S.C.. Section 4701'of 1653 U.S.C.. and Section 309 of the Clean Air Act of 1970." Aug. 1971.
3. U.S. Department of Transportation, Federal Highway Administration, "PPM 90-4. Process Guidelines
(Economic, Social, and Environmental Effects on Highway Projects)," Sept. 1972.
4. Council on Environmental Quality, "Proposal for Secondary Impacts of Federal Infrastructure Invest-
ments." EQC-317, Washington. CEQ, 1972.
5. U.S. Department of Transportation. "Guidelines for the Social and Environmental Assessment of
Transportation Alternatives, RFP-DOT-OS-30173," Washington. DOT. Mar. 1973.
6. Council on Environmental Quality, "Preparation of Environmental Impact Statements." 38 /'(
-------
14. Calder, K. L., "Air Pollution Concentrations From a Highway in an Oblique Wind," unpublished
manuscript, Research Triangle Park, N.C., Environmental Protection Agency, Division of
Meteorology, 1972.
15. Zimmerman, J.R., and Thompson, R. S., "An At-Grade Highway Pollution Dispersion Model," unpub-
lished manuscript, Research Triangle Park, N.C., Environmental Protection Agency, Division of
Meteorology, undated.
16. Beaton, J. L., Skog, J. B., Shirley, E. C., and Ranzieri, A. J., "Mathematical Approach to Estimating
Highway Impact'on Air Quality ."Sacramento, State of California, California Division of Highways,
Report No. CA-HWY-MR 657082S-4-72-12, May 1972.
17. Beaton, J. L., Skog, J. B., Shirley, E. C., and Ranzieri, A. J., "Meteorology and Its Influence on the
Dispersion of Pollutants From Highway Line Sources," Sacramento, State of California, California
Division of Highways, Report No. FHWA-RD-72-33, Apr. 1972.
18. Beaton, J. L., Skog, J. B., Shirley, E. C., and Ranzieri, A. J., "Motor Vehicle Emission Factors for
Estimates of Highway Impact on Air Quality," Sacramento, State of California, California Division
of Highways, Report No. FHWA-RD-72-34, Apr. 1972.
19. Beaton, J. L., Skog,. J. B., Shirley, E. C., and Ranzieri, A. J., "Traffic Information Requirements for
Estimates of Highway Impact on Air Quality," Sacramento, State of California, California Division of
Highways, Report No. FHWA-RD-72-35, Apr. 1972.
20. Beaton, J. L., Skog, J. B., Shirley, E. C., and Ranzieri, A. J., "Analysis of Ambient Air Quality for
Highway Environmental Projects," Sacramento, State of California, California Division of Highways,
Report No. FHWA.RD-72-38, Apr. 1972.
21. Stanford Research Institute, "User's Manual for the APRAC-1A Urban Diffusion Model Computer
Program," SRI, Menlo Park, Calif., Sept. 1972.
22. Danard, Maurice B., "Numerical Modeling of Carbon Monoxide Concentrations Near Highways," / A/>/)l.
Meteorol. 11(6), 947-957, 1972.
23. Sklarew, R. C., Fabrick, A. J., and Proger, J. E., "Atmospheric Simulation Modeling of Motor Vehicle
Emissions in the Vicinity of Roadways," presented at the 1972 Summer Computer Simulation
Conference, San Diiego, June 14-16,1972.
.24. Kirschner, D. S., and Armstrong, D. Pv "An Interim Report on Motor Vehicle Emission Estimation,"
Research Triangle Park, N.C., Environmental Protection Agency, Office of Air and Water Programs,
Aug. 1973.
25. "Requirements foi Preparation, Adoption, and Submittal of Implementation Plans." 36 Fed. Reg.
15486, Aug. 1971.
26. Task Force on Hydrology and Hydraulics, AASHO Operating Subcommittee on Roadway Design.
"Guidelines for Hydrology, Volume H-Highway Drainage Guidelines," Washington, AASHO (341
National Press Building), 1973.
27. U.S. Environmental Protection Agency, Water Programs Office, "Control of Erosion and Sediment
Deposition From Construction of Highways and Land Development," Washington, EPA, Sept. 1071.
52
-------
28. U.S. Enviionmental Protection Agency, Office of Research and Monitoring. "Guidelines for Erosion
and Sediment Control Planning and Implementation," Washington, EPA, Aug. 1972.
29. U.S. Department of Transportation. "Instructional Memorandum 20-3-70, Prevention, Control, and
Abatement of Water Pollution Resulting from Soil Erosion," Apr. 30, 1970.
30. U.S. Department of Transportation, "Instructional Memorandum 20-6-07, Prevention, Control, and
Abatement of Water Pollution Control by Federal Activities-Executive Order I 1288," Dec. 29, 1967.
31. U.S. Soil Conservation Service, "Agricultural Information Bulletin No. 347, Control Erosion on
Contract Sites," Washington, SCS, Dec. 1970.
32. Bureau of Public Roads. "Standard Specifications for Construction of Roads and Bridges on Federal
Highway Projects." rP-i>9, Washington, U.S. Department of Transportation, Federal Highway
Administration. BPR, 1969.
33. National Cooperative Highway Research Program, "Effects of Deicing Salts on Water Quality and
Biota, Literature Review and Recommended Research." Report 91, Highway Research Board.
Washington. 1970.
34. U.S. Public Health Service. "Manual of Septic-Tank Practice," rev. ed.. U.S.P.II.S. Pub. No. 526,
Washington, U.S. Government Printing Office, 1967.
35. U.S. Public Health Service. "U.S. Public Health Service Drinking Water Standards," U.S.P.II.S.
Pub. No. 956, Washington, U.S. Government Printing Office, 1962.
36. "Interstate Motor Carrier Noise Emission Standards," 40CFR Part 202. 38 l-\'d. Reg. 20102. July 27.
1973.
37. U.S. Environmental Protection Agency. "Public Health and Welfare Criteria for Noise" (diaft).
Washhgton, EPA, Office of Noise Abatement and Control, July 9. 1973.
3S. U.S. Department o!'Transportation, Federal Highway Administration, "PPM 90-2, Subject: Noise
Standards and Procedures." Feb. 1973.
39. Highway Research Board. "Highway Noise, A Design Guide for Highway Engineers," NCHRP 117,
Washington, HRB, 1971.
40. U.S. Department of Transportation, Transportation Systems Center, "Manual for Highway Noise
Prediction (Short Version)," Washington, DOT, Mar. 1972.
41. U.S. Environmental Protection Agency, "Effects of Noise on People." NTII) 300.7. Washington,
EPA, Dec. 31, 1971.
42. U.S. Environmental Protection Agency, "Community Noise," NT1D 300.3, Washington. EPA.
Dec. 31, 1971.
43. U.S. Environmental Protection Agency, "Compilation of Air Pollutant Emission Factors." Report
AP-42, 2d ed.. Research Triangle Park. N.C.. EPA, Office of Air Programs. Apr. 1973.
53
-------
44. Sec. 470(0. 16 U.S.C. (Sec. 106 of the Historic Preservation Act of 1966).
45. Department of Transportation Act, Section 4(0, "Maintenance and Enhancement of Natural
Beauty of Land Traversed by Transportation Lines." (Federal Aid to Highways Act of 1970.)
46. U.S. Environmental Protection Agency, Office of Air Programs, "A Guide for Reducing Air
Pollution Through Urban Planning," Washington, EPA, Dec. 1971.
47. U.S. Department of Transportation, Federal Highway Administration, "PPM 21-18, Urban Traffic
Operations Program to Increase Capacity and Safety," 23 U.S.C. 135, May 1972.
54
-------
APPENDIX A
AIR QUALITY CONTROL REGIONS THAT INCLUDED
TRANSPORTATION CONTROLS AS PART OF THEIR SIP
Stale Air Quality (.'onlnil Region
Alaska Northern Alaska Intrastatc
Ari/ona Phoenix-Tucson Intraslute
Calit'ornia San Francisco Bay Area Intrastale
Sacranu'iito Valley Intrastate
Metropolitan Los Angeles Intrastate
San Joaquin Valley Intrasiate
San Diego Intrastate
Colorado Metropolitan Denver Intrastate
District of Columbia I National Capital Interstate
Maryland I National C'apilal Interstate
Metropolitan Baltimore Interstate
Illinois Metropolitan Chicago Interstate
Massachusetts Metropolitan Boston Intrasiate
Minnesota Minneapolis-St. Paul Intrastate
New York I New Jersey-New York-Connecticut Interstate
New Jersey I New York-New Jersey-Connecticut Interstate
Metropolitan Philadelphia Interstate
Pennsylvania
Metropolitan Philadelphia Interstate
Southwest Pennsylvania Intrastate
Nevada Clark-Mohave Interstate
Ohio Metropolitan Dayton Intrasiate
Oregon Portland Interstate
Texas Metropolitan San Antonio Intrastate
Metropolitan Dallas-l-'orl Worth Intrastate
Austin-Waco Intrastate
\':\ Paso. Las Cruces. et al.
Corpus Christi-Victoria Intrasiate
Metropolitan llouston-dalvcston Intrastate
Utah Wasatch Front Intrastate
Washington Puget Sound Inlrastate
liastc.ru Washington-Northern Idaho Intersta
55
-------
APPENDIX B
AIR IMPACT FORECAST PROCEDURE FOR CARBON MONOXIDE
In conducting the review of the level 2 air analysis (1-hour and 8-hour CO), it may be
necessary to spot-check air quality concentration values presented in the environmental
impact statement (E1S), estimate concentration values for critical situations not covered by
the K1S, or estimate the general impact level of the project if no analysis is presented.
In each case the recommended modeling technique is the Hiway line source diffusion
model.15 This model is implemented at the Computer Center, Research Triangle Technical
CV- jr (RTTC). Durham, North Carolina (stored on the Unamap file), and is maintained by
the Meteorology Branch, Office of Research and Development. All regional offices are on-
line to the computer at RTTC and should be able to use this model.
Spot Check.-This situation assumes that a rather comprehensive air analysis has been
presented in the EIS, but that the reviewer questions the order of magnitude of the concen-
tration values presented. If an analysis technique other than diffusion modeling has been
used, spot checking is especially important, ll the spot checks do^compare favorably* and
the overall MIS analysis procedure shows no individual inadequacies, the EIS results should
he accepted.
Supplemental Estimate at Critical Areas.-11 a satisfactory analysis has been made but
the reviewer has identified critical situations that were not considered, he should estimate
the concentration levels at these points. It is advisable that the reviewer first spot check other
data points to verify the predictive consistency of his technique with the general analysis
given.
Maximum Impact Estiinate.-If an unsatisfactory air quality analysis has been presented.
or if any of the data leading to the air quality estimates are deemed inadequate, the reviewer
should estimate the concentration values at several points along the right-of-way. Following
is suggested procedure.
I. Approximate the maximum 1-hour CO impact at the closest right-of-way line by
using the Hiway diffusion model and an assumed set of worst-worst conditions. This estimate
is a tjiiick first step to get an indication of the impact, and thus is an indication of how much
effort should go into precise definition of missing data.
The reviewer should recogni/.e, however, that precise comparison of results between the F.IS technique and
the I:PA technique is not required.
57 Preceding page blank
-------
a. If peak- (worst-) hour data are missing, use figure C-7 to estimate peak volume
from the maximum annual average daily traffic (AADT) value (if AADT is missing
and a reasonable estimate cannot be made, rate the air portion of the EIS as
inadequate and terminate air quantification). Depending on the type of roadway,
a directional split may be required. This requirement is a function of the roadway
location and should be judged by the reviewer.
b. If average speed data are missing, estimate from figure C-l 1 or C-12 as possible.
c. Utilize EPA emission factors24 with national average assumptions as required.
d. If meteorological data are missing, assume: wind speed of 1 meter per second,
wind flow parallel to roadway, and "E" stability.
e. Estimate background concentration from State implementation plan.
f. Calculate the 1-hour CO concentration contribution from project, and add
background.
2. If the 1-hour CO value is less than 10 ppm, the project should not adversely affect
the area and no further analysis is necessary. If the 1-hour CO value is greater than 10 ppm,
a detailed analysis (utilizing "realistic" data) should be requested. For controversial projects,
the reviewer may wish to utilize available realistic data in the analysis before requesting
further analyses in the EIS.
Figure B-l illustrates an acceptable procedure for analyzing the realistic 1-hour and 8-
hour CO concentration levels. The procedure is shown in a form that could be recommended
to the EIS preparer. For use by the reviewer, the procedure would be modified by the
substitution of assumed data for measured data, where necessary.
58
-------
|10
-------
APPENDIX C
GENERAL CONCEPTS OF TRAFFIC FLOW AND SPEED CHARACTERISTICS
Before proceeding, the reader should note'the following definitions:
Average /inniuil ihiily traffic. The total yearly volume divided by the number of days in
the year, commonly abbreviated as AADT.
Averuge highway speed. The weighted average of the design speeds within a highway
section, when each subsection within the section is considered to have an individual
design speed.
Capacity. The maximum number of vehicles that has a reasonable expectation of passing
over a given section of a lane or a roadway in one direction (or in both directions for a
two-lane or a three-lane highway) during a given time period under prevailing roadway
and traffic conditions.
Design speetl. A speed selected for purposes of design and correlation of those features
of a highway, such as uirvature. superelevation, and sight distance, upon which the
safe operation of vehicles is dependent.
Level of service. This term, broadly interpreted, denotes any one of an infinite number
of differing combinations of operating conditions that may occur on a given lane or
roadway when it is accommodating various traffic volumes. The two parameters that
define the level of service are the operating speed and (he ratio of volume to capacity
(v/c)
-------
\EVEVLO>^^X
SERViCEA^VV
sLEVEL OF SERVICE C
LEVEL OF SERVICE E
0 VOLUME/CAPACITY RATIO
Figure C-1.-General concept of relationship of levels of service to
operating speed and volume capacity ratio. (Not to scale.)
Level of service C. Still in the zone of stable flow, but speeds and maneuverability are
more closely controlled by- the higher volumes. Most of the drivers are restricted in
their freedom to select their own speed, change lanes, or pass. A relatively satisfactory
operating speed is still obtained, with service volumes perhaps suitable for urban design
practice. (
Level of service I). Approaches unstable flow, with tolerable operating speeds being
maintained though considerably affected by changes in operating conditions. Fluctua-
tions in volume and temporary restrictions to How may cause substantial drops in
operating speeds. Drivers have little freedom to maneuver, and comfort and conven-
ience are low, but conditions can be tolerated for short periods of time.
Level of service E. Cannot be described by speed alone, but represents operations at
even lower operating speeds than in level D, with volumes at or near the capacity of
the highway. At capacity, speeds are typically, but not always, in the neighborhood of
30 mph. Flow is unstable, and there may be stoppages of momentary duration.
62
-------
Level of service F. Force flow operation at low speeds, where volumes arc below capac-
ity. These conditions usually result from queues of vehicles backing up from a restric-
tion downstream. The section under study will be serving as a storage area during parts
or all of the peak hour. Speeds are reduced substantially and stoppages may occur for
short or long periods of time because of the downstream congestion. In the extreme.
both speed and volume can drop to zero.
Operating speed. The highest overall speed at which a driver can travel on a given high-
way under favorable weather conditions and under prevailing traffic conditions without
at any time exceeding the safe speed as determined by the section-by-section design
speed.
Peak-hour traffic. The highest number of vehicles found to be passing over a section of
a lane or a roadway during 60 consecutive minutes.
Volume. The number of vehicles that pass over a given section of a lane or a roadway
during a time period of I hour or more. Volume can be expressed in terms of a lane
or a roadway during a time period of 1 hour or more. Volume can be expressed in terms
of daily traffic or annual traffic, as well as in hourly terms.
These terms will be used throughout this appendix without further definition. Of particular
importance is the concept of the "level of service." It is the design level of service that dic-
tates the highway configuration (number of lanes, number of interchanges, section changes.
etc.) and thus the free flow capacity of the roadway. If the design level of service is too low
(e.g., level C instead of level B) traffic congestion will result and the predicted average speeds
will not be maintained. This concept will be described in more detail.
When hourly traffic counts for a full year are available, it is possible to show the distri-
bution of hourly volumes by arranging these volumes in descending order of magnitude.
Figure C-2 shows such a curve in terms of total volume measured. By constructing curves
of this sort, which are representative of the project conditions (i.e.. similar area, highway
design, etc.), the design hourly volume (DHV) most suitable for the project may be deter-
mined. The suitability of the DHV value is usually a compromise between annual service
provided and cost. For example, consider figure C-2 as representative of the proposed
project conditions. Fifty percent of the year the volume is 235 vehicles per hour (vph) or
less; however, only 13 percent of the annual traffic flow occurs during these hours.
A DHV based upon a flow of 235 vph or less would cause 87 percent of the annual
traffic flow to operate under inadequate service conditions. On the other hand, if the maxi-
mum record hourly volume of 1,575 vph were utilized as the DHV. the highway would have
substantial excess capacity during all but 1 hour of the year, an "economically unfeasible
situation." Customary practice has been to use a DHV value between the 10th and 50th
highest hourly volume (frequently the 30th). It should be noted that, in the example of
figure C-2, the peak volume Is greater than twice the 30th-hour volume, which illustrates the
danger in using the DHV instead of the peak volume for air quality calculations.
63
-------
100 1.000
NUMBFR OF HOURS
> VOLUME SHOWN
Figure C-2.Example variation of hourly traffic.
10,000
For most existing highway systems, continuous volume counts are available at only a
limited number of locations. As a result, the construction and application of hourly traffic
volume curves must reflect special precautions to include the peak traffic situations that
could occur over the diurnal, weekly, and seasonal time cycles.
Figure C-3 shows, in terms of percent average daily traffic (ADT), a typical weekday
diurnal cycle for both urban and rural highways. In addition, it may be important to look
separately at the hourly traffic variation on weekends. Figure C-4 shows how these daily
variations can look. In this relationship, the weekday travel is dominated by commuter
traffic, while the Sunday traffic is no doubt recreational. Even though the three separate
peaks are equal in magnitude, temporal changes in meteorology may cause one peak to be
more important than the others..
Daily changes are shown in figure C-5. Here the characteristics of urban and rural
traffic are contrasted. The urban traffic stays at about the same level during the week.
increases.as the weekend traffic begins to leave town on Friday, and falls to a low on
Sunday. The rural traffic pattern is generally opposite.
64
-------
WISCONSIN RURAL
1961
12M 4AM SAM 12N 4PM
HOUR OF DAY
8PM
12M
Figure C-3.-Example hourly variations of traffic for average weekday.
Seasonal variations also may be considerable and. when combined with associated
meteorological regimes, may be very important. Figure C-6 shows variations which may
occur. The data for the State: of Washington show comparatively little seasonal variation
in urban traffic and high variation in rural traffic due to recreational travel. When the
Tucson urban area traffic is compared with Washington urban traffic, ihe effect of climate
can be seen easily.
To aid the traffic engineer in relating annual traffic volumes and peak hourly flows, the
"Highway Capacity Manual"*' contains an analysis of traffic data collected during 1961 and
1962 throughout the United States. Figure C-7 sum'mari/.es these results. In the absence
of peak-hour data, the reviewer can use these curves to estimate the peak-hour volume from
the AADT. There are two pitfalls in relating annual average daily traffic (AADT) to traffic
flows. First, sampling must be conducted to estimate the AADT and not highway capacity.
High constant traffic flows throughout the day indicate that the AADT is not actually being
measured. Second, if the highway is near capacity use, the peak use will be less than that
predicted by the 30th-hour method, since the 30ih-hour factor decreases with increased
highway use.
Since pollutant dispersion is enhanced by distance from the source, the lateral location
of slow-moving and congested traffic is important to the immediate downwind receptor.
65
-------
o
<
u.
O
Z
LU
O
-------
LLJ
P 14
u_
O
a?
o
cc.
i-
12
10
M
T W T
DAY OF WEEK
Figure C-5.-Example daily changes in traffic. (From the "Highway
Capacity Manual."8)
Figure C-8 illustrates the variation that can occur between lanes. This figure shows
average lane distributions in one direction found on selected six-lane freeways at various
volumes. Note that at the larger flow rates the fast lanes (2 anil 3) account for about 70
percent of the traffic volume.
Since the AADT projections are the key data inputs, it is important (hat all factors
influencing these projections are accounted for. The AASIIO Policy on Geometric Design.9
which, although somewhat out of date, is still used by most highway departments, defines
both the primary and secondary traffic growth parameters as follows:
Normal Traffic Growth. No.inal traffic growth is the increase in traffic volume due to pcner.:1'
increase in number and usage of motor vehicles.
From the past trend, the motor vehicle travel may he projected to the future year for which (he
design is to be made. This may be done by plotting a curve of total vehicle miles against years.
-------
130
O
2
z
<
LL.
o
o
LL
LL
<
CC
0
LU
I
I
z
o
WASHINGTON RURAL
WASHINGTON URBAN
1961
TUCSON
1958-60
(SOURCES: WASHINGTON STATE DEPT. OF
HIGHWAYS MD TUCSON, ARIZ., AREA
TRANS^ . T. STUDY)
!. I
F M A
0 N 0
MONTH OF YEAR
Figure C-6. -Examples of monthly traffic volume variations.
(From the "Highway Capacity Manual."8)
similar In rigurc |('-l'| and projecting the curve by judgnicr.i to Ilk1 year desired. lvni .iii :irea. a nioie
accurate analysis may he performed hy plotting separate curves Tor area popub.ium. numlvi -if u'lu-
cles per unit of population in the region, and average miles of travel per vehicle hased on local IMMI'IIIK'
consumption. The product of these three values taken from (he curves for the year chosen I'oi design
gives the total vehicle miles of travel for that year. The dashed line in l-'igme If l>| is., travel I'oKvasi
for a selected Slate evolved from such an analysis.
I'or any one facility, estimates lor the increase in normal traflic should lie hased on ticiuU and
estimates for the region. State or locality in which the highway is situated.
(ii'iiL-raicd Traffic. Generated traffic consists of motor vehicle trips (other than hy public i ransn )
that would not have been made if the new facility had not been provided. Generated traffic i:. made
up of dircc categories: new trips not previously made by any mode of travel: trips that previously
were made by public transit and trips that previously were made to a different dc .'lalion, Inn for
which the change is attributable to the attractiveness of the improved highway and not to change in
-------
20-
e 15 '
i 10-
z
H 5-
0
< 0-
U_ )(-
O "
UJ
S 20-
1-
5 15-
u
cr
a. 10 -
5 -
(A) RURAL HIGHWAYS
i
\^ ONE DIRECTION OF
^i**-*-^
^^fr" »-===
TWO DIRECTIONS OF
TRAVEL
==3
TRAVEL
(B) CITY STREETS
V^ ONE DIRECTION OF
TWO DIRECTIONS OF
i I i i i i
TRAVEL
i
TRAVEL
25
20
15 -
10 -
5 -
25
20 -
15
10 -
5 -
(A) RURAL
ONE DIRECTION OF TRAVEL
TWO DIRECTIONS OF TRAVEL
(B) URBAN
ONE DIRECTION OF TRAVEL
TWO DIRECTIONS OF TRAVEL
10 30 50 100
HOUR OF YEAR
200
10 30 50 100
HOUR OF YEAR
200
cr
D
O
I
z
t-
Q
<(
Li.
O
UJ
O
h~
z
UJ
O
UJ
MULTILANE;
HIGHWAYS
20 -.
15 -
10 -
5 -
(A) RURAL HIGHWAYS
v^^
^ ^^*--_
^^^^^^^^"^"'^^'^"^^^^^^^^
TWO DIRECTIONS OF TRAVEL
i i i i i i
cr
o
o
z
H
Q
5
20 -
15 -
10 -
5 -
(B) CITY STREETS
TWO DIRECTIONS OF TRAVEL
i i i i i i
u
UJ
O
Z
UJ
O
It
UJ
Q.
10 30 50 100 200
HOUR OF YEAR
TWO- LANE
HIGHWAYS
FREEWAYS
20 -
15 -
10 -
5 -
(A) RURAL
L
^SLCINE DIRECTION OF TRAVEL
^^^^^^^^^^^^^^^^
^^^^^^^""^"^"^^^^^"1^^^^!^^^^^^^*
-rv-> 'DIRECTIONS OF TRAVEL
ii.ii i
or
20 -
15 -
1
10 -
5 -
(B) URBAN
V ONE DIRECTION OF TRAVEL
:T>*-^* *
' ,
TWO DIRECTIONS OF TRAVEL
i i i I i I
10 30 30 100 20
HOUR OF YEAR
EXPRESSWAYS
Figure C-7.-Relation of hourly volumes and annual average daily traffic.
iTi the "Highway Capacity Manual."8)
69
-------
50
i
rr 40
EC
i-
_i
<
O
30
20
V
LANE 1
12345
RATE OF FLOW IN ONE DIRECTION (1.000 VPH)
Figure C-8.-E:
-------
a type of highway on which it is pleasant, relaxing and safe to drive as a controlled access highway.
generates more traffic than one with frequent interference, annoyance, and ha/ard. Arterial highway
improvements that lead to destinations with adequate parking facilities usually create many more new
trips than similar improvements where the parking situation is critical. Highway improvements in
areas where public transit or other modes of transportation arc inadequate generally produce more
generated traffic than those in areas where other transportation means are, or are made attractive.
As in the case of attracted traffic, the amount of generated traffic may depend upon the capacity
and the volume on existing roads that are relieved by the improved highway.
Little information is available on generated traffic. There are not many examples, and often
traffic is measured so that the increase called generated traffic includes other forms of traffic growth.
In establishing the traffic volume for the design of a highway, generated traffic should be in-
cluded as component even though it may be based upon judgment only. For most rural highways
generated traffic as herein defined is likely to run 5 percent or over but rarely as much as 25 percent.
Development Traffic. Development traffic is that due to improvement on adjacent land over
and above the development which would have taken place had not the new or improved highway been
constructed. In interstate analysis this has been referred to as the "L" factor or the percentage
increase over a statewide increase to allow for greater development along a highway than throughout
a State. This component of future traffic, unlike that of generated traffic, continues to develop for
many years after a new facility is constructed. Increased traffic due to normal development of adja-
cent land is included in normal traffic growth, but experience with mar.y improved highways indicates
that adjacent land is developed more rapidly than land elsewhere. The traffic resulting therefrom
should be accounted for in estimating future traffic volume.
When a rural highway is a freeway, as in Interstate analysis, there is likely to be development
traffic resulting from abnormal development along the freeway, near iimr.j'iangcs or along crossroads
having interchange with the freeway. A factor to allow for traffic above that resulting from land
development due to such abnormal land development may be appropriate.
In strictly rural areas that are well removed from cities and villages, this type of traffic growth
is apt to be less significant than in the near urban areas. In some instances, it can be neglected alto-
gether with the assumption that the normal traffic growth accounts for traffic due to all land develop-
ment. In urban and suburban areas, and in rural areas between a city and satellite communities, traffic
resulting from rapid development of adjacent land generally will be significant.
The method of obtaining development traffic may not be precise and the volumes obtained are
only approximate, but in many cases the volume from this cause is appreciable. The omission of this
item in estimating future traffic might explain why the volumes for a number of prominent improve-
ments in the past proved to be underestimated.
It cannot be overemphasized that underprediction of the project utili/ation leads to an
underprediction of its environmental impact. If the estimated AADT is low, the estimated
peak volume will be low and the average speed will be high, all of which would produce
underestimated pollutant concentration values. The reviews must insure that a comprehen-
sive analysis of the traffic projection data has been made.
For the mesoscale analysis, the vehicle speed that must be utilized with the emission
factors is the average trip speed representative of the time period of interest (8-hour CO.
3-hour HC. or annual average NO^).
71
-------
The average trip-speed (i.e., overall travel speed, or journey speed) is defined as the
distance covered, divided by the elapsed time. This speed reflects the amount of acceleration.
deceleration, and idle modes of engine operation, as well as cruise conditions for a given
roadway or system of roadways. Average trip speed on urban and suburban artcrials with
uncoordinated signals and a 25-mph speed limit normally will range between I 5 and 22 mph.l(1
Downtown streets may operate at the lower limit of stable How conditions with an overall
travel speed of about 10 mph.lf>
For the microscale analysis, the vehicle speed must reflect the average operating speed
of the particular lane (or lanes if the total roadway is considered a single source) under con-
sideration. Following is a description of the speed variation characteristics of individual
roadways.
As with traffic volumes, speed distributions and averages have significant diurnal v; ria-
tions. These variations are a result of many influences, the most notable of which are the
volume-capacity effects. Typically, speed reduction accompanies volume increases during
rush-hour conditions. Figure C-10 shows an example of such a relationship. In this case the
minimum speed occurred during the morning peak. During the afternoon peak, however, a
lesser volume increase did not result in a speed reduction; instead, it was accompanied by a
slight increase in average speed. This phenomenon is often due to differences in the driver
population. During the morning peak, traflic is principally a clean buildup of home-to-work
drivers; but in the afternoon the peak period may include the transition from the more
casual midday drivers to the work-to-home group.
For any given time of day. there is also a variation in average speed for eacii lane of
multilane freeways. In general, the slowest average speed occurs at the shoulder lane (lane I ).
Other factors influencing differential lane speeds are the number of entrances and exits.
Interestingly enough, lane 1 generally is influenced the least by the entrances and exits. As
the volume increases, however, these effects diminish and the lane speed differential becomes
less.
In general, the speed/How relationship for freeways are somewhat curved, reflecting
faster speeds at intermediate How rates than are found on other types of highways. Figure
C-l 1 illustrates the typical relationship between operating speed and volume, given u'eal
uninterrupted flow conditions, on freeways and expressways. Curves for less than idea'
average highway speeds are also shown. The curves in figure C-l I were developed from data
on file at the Bureau of Public Roads. They portray actual hourly volumes having a high
peak-hour factor (that is. constant high traffic demand throughout the hour). The shaded
area at the right represents highly v nstuble conditions. Such volumes are found occasionally
in one or two lanes (usually those n trest the median), but average hourly volumes of this
magnitude over all lanes are recorder too rarely to he considered as reasonably attainable.
The solid curves in the figure show the uninterrupted speed/flow relationships above
the point of critical density (about 2,000 cars per hour). If uninterrupted flow is not
maintained, an increase in (low causes the speed to decrease rapidly, with a marked simul-
taneous decrease in How rate (dashed line in fig. C-l 1 ). For example, at a rate of How
72
-------
8AM
10AM
NOON
TIME OF DAY
2F'M
4 CM
6f'M
Figure C- 10. -Example diurnal variation in volume and spued.
(From the "Highway Capacity Manual. ";i )
of 1.4()()vph per hi IK'. UK- operating speed might range I'ruin 45 inpli will, iicc-ll,>wmg condi-
lions lo only I 5 inpli under highly congested. stop-and-go condition.-..
It should he noted that since figure C'-l 1 must he modified lo relleel the unupic limiting
conditions ot an aclu;il roadwjy ilesign. it should be used only as a c/;cc/v on llie ideal
capacily-opeiatini: characterislics of a proposed roadway.
If the volume/capacity (v/ci ratio is substituted for the ahsoluie volume, llie data in
fiuure C'-l 1 can he applied to any highway, of any number of lanes, for which ihe v-apacity
can he determined, regardless of whether or not the associated conditions are ideal. I i^niv
C - 1 2 illustrates this fact, along with the basic limiting values of operating .speed and v i- ratio
(hat identify the several levels of service.
-------
8 12
AVERAGE LANE VOLUME (100 I'ASS.
Figure C 1 1.-Typical relationship between volume ptr lane iincl operatiiK)
speed in one direcvion of travel under ideal uninterrupted flow conditions o-i
freeways and expressways. (From the "Highway Capacity Manual."8)
74
-------
0.6 0.7 0.8 0.9
0.1
0.2
NO. OF
LANES
BASIC
INDEPENDENT
LEVEL
OF ~
SERVICE b
RANGES
8
V/C HA 1 IU
r C ! D +
« A r « n +1* r
._*J r U n !
-*+. E ^
PHF
1.00
0.91
0.83
0.77
1.00
0.91
0.83
0.77
1.00
0.91
0.83
0.77
Figure C-12. Relationship between v/c ratio and operating speed, in one direction
of travel, on freeways and expressways, under uninterrupted flow condilions.
(From the "Highway Capacity Manual."8)
75
------- |