APTD-0937
A GUIDE
FOR REDUCING
AIR POLLUTION
THROUGH URBAN PLANNING
U.S. ENVIRONMENTAL PROTECTION AGENCY
Office of Air and Water Programs
Office of Air Quality Planning and Standards
Research Triangle Park, North Carolina 27711
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APTD-0937
A GUIDE
FOR REDUCING
AIR POLLUTION
THROUGH
URBAN PLANNING
by
Alan M. Voorhees & Associates, Inc.
Westgate Research Park
McLean, Virginia 22101
and
Ryckman, Edgerley, Tomlinson & Associates
12161 Lackland Road
St. Louis, Missouri 63141
Contract No. CPA 70-100
EPA Project Officer: John L. Robson
Prepared for
ENVIRONMENTAL PROTECTION AGENCY
Office of Air and Water Programs
Office of Air Quality Planning and Standards
Research Triangle Park, N. C. 27711
October 1973
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The APTD (Air Pollution Technical Data) series of reports is issued by the
Office of Air Quality Planning and Standards, Office of Air and Water Programs,
Environmental Protection Agency, to report technical data of interest to a
limited number of readers. Copies of APTD reports are available free of
charge to Federal employees, current Contractors and grantees, and non-profit
organizations - as supplies permit - from the Air Pollution Technical Information
Center, Environmental Protection Agency, Research Triangle Park, North Carolina
27711, or may be obtained, for a nominal cost, from the National Technical
Information Service, 5285 Port Royal Road, Springfield, Virginia 22151.
This report was furnished to the Environmental Protection Agency by Alan M.
Voorhees and Associates, Inc., McLean, Virginia, and Ryckman, Edgerley,
Tomlinson and Associates, St. Louis, Missouri, in fulfillment of Contract No.
CPA 70-100. The contents of this report are reproduced herein as received
from Alan M. Voorhees and Associates and Ryckman, Edgerley, Tomlinson and
Associates. The opinions, findings, and conclusions expressed are those of
the author and not necessarily those of the Environmental Protection Agency.
Mention of company or product names is not to be considered as an endorsement
by the Environmental Protection Agency.
Publication No. APTD-0937
11
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ACKNOWLEDGEMENTS
This report was prepared pursuant to contract No. CPA 70-100 by
Alan M. Voorhees & Associates, Inc., and Ryckman, Edgerley, Tomlinson &
Associates, Inc. t under the guidance of the staff of the Office of Air Programs,
Environmental Protection Agency. The text contained herein is substantially
that of the contractors.
The project team at Alan M. Voorhees & Associates, Inc. (AMV) and
Ryckman, Edgerley, Tomlinson & Associates, Inc. (RETA) consisted of:
AMV
Mr. Alan M. Voorhees
Project Director
Dr. Salvatore J. Bellomo
Project Manager & Coordinator
Mr. Robert L. Morris
Vice President
Mr. Stephen C. Nelson
Urban Planner
Mi*. Joseph Brevard
Urban Planner
Mr. Edward Mierzejewski
Transportation Engineer
Miss Sally D. Liff
Transportation Planner
RETA
Dr. Edward Edgerley, Jr.
Project Manager
Dr. Frederick Brunner
Environmental Engineer
Mr. Kenneth W. Axtell, Jr.
Environmental Engineer
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CONTENTS
Chapter Page
PREFACE ..................
SUMMARY AND CONCLUSIONS ........ ix
1 ROLE OF AND LEGISLATIVE MANDATE FOR
URBAN PLANNING .............. 1-1
A. The Role of Urban Planning in Air Pollution
Control ................. 1-1
B. The Legislative Mandate for Planning Action. 1-4
1. National Environmental Policy Act of
1969 ................. 1_4
2. 1970 Clean Air Act .......... 1-5
3. Regulations Promulgated Pursuant to
Clean Air Act ............ 1-6
4. 1970 Federal-Aid Highway Act ..... 1-7
5. Urban Mass Transportation Assistance
Act of 1970 .............. 1-7
2 REDUCING AIR POLLUTION THROUGH LAND
USE AND PUBLIC FACILITY PLANNING . ... 2-1
A. Regional Development Strategies ...... 2-1
1. Alternative Regional Forms ...... 2-3
2. Balanced Communities and Subregions . 2-9
3. Low Density Development ....... 2-12
4. Regional Open Space Patterns ..... 2-13
5. Implementation of Regional Development
Strategies .............. 2-16
B. Location and Design Strategies ....... 2-17
1. Location of Stationary Sources ..... 2-18
2. Relocation of Stationary Sources .... 2-26
3. Control of Land Use Around Sources . 2-28
4. Location of Sensitive Receptors .... 2-30
5. Location and Design Control of New
T°wns. ............... 2_30
6. Planned Unit Developments ...... 2-32
7. Small Open Spaces .......... 2-35
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CONTENTS (Continued)
Chapter Page
3 REDUCING AIR POLLUTION THROUGH
TRANSPORTATION PLANNING, DESIGN AND
OPERATIONS 3-1
A. Transportation System Planning Strategies . 3-2
1. Multi-Modal Planning 3-2
2. Improved Highway Location and Network
Configuration 3-7
3. Compatible Highway/Land Use
Relationships 3-12
B. Transportation Design and Operation
Techniques 3-15
1. Techniques for Improving Traffic Flow . 3-16
2. Techniques for Reducing Pollution
Concentration 3-19
3. Techniques for Reducing Auto Traffic
Flow 3-21
Appendix
A INTRODUCTION TO AIR POLLUTION A- 1
Types of Pollutants and Their Sources A- 1
Classification of Pollutants A-l
Units of Air Pollution Measurement .... A-2
Air Pollutants and Their Sources A-3
Variations in Air Pollution Concentrations . . . A-5
Variations According to Location A-5
Variations by Time Periods A-7
Meteorology A-8
Site Conditions Affecting Dispersion A-11
Urban Heat Island Effect A-12
Building Configuration Effects A-13
Roughness Effects A-15
Urban Air Pollution Models A-16
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CONTENTS (Continued)
Appendix Page
COOK COUNTY ZONING ORDINANCE . , . , . B-J.
Performance Standards -- Siroke and
Particwlate Matter , ...... ,..,.,. B-l
Performance Standards Toxic Matter, .... B-3
Performance Standards Toxic Matter
Ml District .,,.,.,., ..... , B-3
Performance Standards >- Noxious and Odorous
Matter , .......... , ...... , B-3
Perforpaance Standards -- Noxious and
Odorous Matter -- Ml District, ...... B-4
FUEL ALTERNATIVES AND STACK HEIGHT . . C-l
Fuel Alternatives . ,,,...,,.,,.., C-l
Stack Heights. ,..,.», ..... .... C-5
D GIXISSAtty ..... ,......,...,. D-l
E REFERENCES ................ E-l
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FIGURES
Figure Page
1. 1 Air Quality Considerations in the Planning Process .... 1-2
2. 1 Alternative Land Use Plans for Hartford 2-5
2.2 Correlation of Internal Trips With Population Size . .... 2-9
2.3 Plan for Sub-regional Development: Canberra, Australia. 2-11
2.4 Examples of Large Open Space Systems 2-14
2.5 Prototype Multi-Use Center 2-34
2. 6 Pollution Level Vs. Distance to Edge of Roadway ..... 2-35
3. 1 Description of Urban Forms and Transportation System
Simulation Study 3-4
3. 2 Effect of Improved Transit Service on Modal Split and Air
Pollution in a High Density Corridor ............ 3-6
3. 3 Relationship of Carbon Monoxide and Hydrocarbon
Emissions to Speed . 3-10
3.4 Effects of Staggered Work Hours, Hudson Terminal
Afternoon Passenger Volumes 3-20
A. 1 Hourly Carbon Monoxide Concentrations on Weekdays
in Detroit Area A-7
A. 2 Concentrations of Nitric Oxide, Nitrogen Dioxide, Hydro-
carbon, and Oxidant During a Smoggy Day in Cincinnati,
Ohio A-9
A. 3 Diurnal Variation of Ground Level Concentrations From
Elevated Urban Sources A-9
A. 4 Urban Circulation and Dispersion After Sunrise A-14
A. 5 Urban Circulation and Dispersion After Sunset . . . . . . . A-14
C. 1 Sulfur Oxide Emissions from Burning Different Fuels in
Residential Heating -- St. Louis C-4
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TABLES
Table Page
2.1 Urban Planning Strategies and Techniques for
Reducing Air Pollution 2-2
2.2 Summary Comparison of Pollutant Production. ... 2-7
2.3 Major Pollutant Sources 2-20
3. 1 Techniques for Improving Traffic Flow 3-17
3.2 Techniques for Reducing Pollution Concentration . . 3-19
3.3 Techniques for Reducing Auto Traffic 3-22
A. 1 Estimated Emissions of Air Pollutants by Weight,
Nationwide, 1969 A-4
A. 2 Sulfur Content of Fuels A-4
A. 3 Sources of Atmospheric Particulate Matter A-6
C. 1 Estimated Yearly Sulfur Oxide Emissions in Tons
for Chicago C-4
viii
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PREFACE
Urban planning Ls the process of guiding the growth and change of
cities. Planners study physical, environmental, social, economic, and
political ramifications of development proposals. In light of these studies,
they recommend policy to local, regional, and state legislators. Although
urban planning encompasses many different disciplines and kinds of
activities, this Guide emphasizes only two aspects: land use and transporta-
tion planning. Other urban planning activities not directly concerned with
the spatial arrangement of buildings, public facilities, streets, parks and
the like, such as economic and social planning, are not considered in depth.
This Guide is designed to help planners understand the relationship
of air quality to land use patterns and transportation systems. Specifically,
the Guide has two purposes: to indicate the air pollution effects of various
planning strategies, and to suggest how land use and transportation planning
can be used directly to control air pollution. The first purpose is directed
toward most planning work where air quality is one of several important
considerations, but not the overriding objective. The second purpose relates
to situations where air pollution control is the principal objective, and
land use and transportation controls are two of several means for achieving
the objective. Thus, state air quality control regions may include in their
air quality implementation plans some of the land use and transportation
controls recommended here.
Regardless of which purpose the planner has in mind, air quality
considerations may portend substantial changes in traditional urban planning
practices. For example, because Federal ambient air standards apply to
all public areas of all cities, the practice of segregating polluting industries
may have to end. The clustering of dirty industries might spare cleaner
land uses from industrial smoke, dust, fumes, and odors; but clustering
can overtax the ability of one neighborhood's atmosphere to dilute pollutants,
while underutilizing it in another neighborhood. Thus, some cities, in order
IX
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to expand their industrial base, may now find it necessary to disperse
land uses that pollute the air. Another-change in urban planning practices
may be to repeal regulations requiring the construction of off-street parking
facilities as new buildings go up in polluted areas. In fact, it may be
necessary to prohibit off-street parking in these areas to discourage the
use of automobiles.
Research activity in land use and transportation policies, as they
relate to air quality, is expanding. This Guide summarizes existing
knowledge. The Environmental Protection Agency (EPA) has funded research
in ways of evaluating the air quality implications of alternative land use
arrangements, and the use of air zoning and emission density zoning to
control air pollution. Other Federal agencies recently have become active
in this type of work. Thus, many of the recommendations in this Guide are
subject to change as more insight is gained into the role of urban planning
in air pollution control.
The Guide outlines the laws and regulations that require assessment
of the air pollution impact of land use and transportation patterns. It then
discusses the many urban planning strategies available to control air pollution.
The appendices provide basic information on air pollution.
Ronald A, Venezia
Chief, Office of Land Use Planning
Office of Air Programs
Environmental Protection Agency
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SUMMARY AND CONCLUSIONS
Urban planners, by nature of their responsibility for guiding urban
growth and change, have a significant role to play in reducing air pollution
and its effects. Urban planning agencies can and should support the develop-
ment of regional source control programs but their major contribution lies
in evaluating, proposing, and implementing measures which help disperse
pollutant concentration, reduce exposure of people to pollutants and improve
the efficiency of urban travel. To accomplish these aims, urban planners
and their agencies should consider the following activities within planning
programs:
1. Research should be conducted and supported in order to better
understand current ambient air quality and the pollution sources,
meteorology and other conditions which affect it;
2. Air pollution considerations should be incorporated and evaluated
in the process of developing land use and transportation plans;
3. Air pollution considerations should be incorporated in the per-
formance of plan implementation functions (i.e., zoning,
subdivision regulation, project review, capital improvement
programming, etc.)
4. Source control programs for both stationary sources and vehicles
should be supported and a close working relationship with air
pollution control agencies should be maintained; and,
5. Encouragement should be given for new local, state, and Federal
legislation which would allow urban planning programs and
source control programs to better meet air pollution abatement
goals (i.e., code enforcement improvements, vehicle inspection
programs, zoning improvements, open space funding, transit
programs, etc.)
To assist planners and planning agencies in carrying out these activities
this report evaluates eleven land use/public facility planning strategies and
five transportation strategies which are of potential value in the reduction
of air pollution impacts. Also described are the techniques which would
be required in the implementation of these sixteen strategies. Following
are the major conclusions drawn from the evaluation of these strategies
and techniques.
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There are no easy answers for the urban planner. Indeed many
actions that will be beneficial will also have ancillary harmful effects.
For example, increasing the average speed of traffic will reduce the
concentration of hydrocarbons and carbon monoxide, but probably increase
the concentration of oxides of nitrogen. Increased travel speed also tends
to lengthen trips; thus resulting in increased use of automobiles. Decreasing
the density of land development reduces concentrations of air pollution but
increases dependence on the automobile as a transportation mode. Optimal
location of industries according to air pollution considerations may result
in severe tax and employment repercussions. Such trade-offs require
close study in light of each urban area's unique conditions and priorities.
At this point, much of what can be described regarding basic relation-
ships and strategies is at a crude stage of development. It is regrettable
that precise approaches cannot be prescribed and that results cannot be
guaranteed. Furthermore, it is frustrating to realize that the most far-
reaching strategies often require implementation tools which local govern-
ments and planning agencies do not have within their grasp. However,
future application of the described strategies in a way which can be quanti-
tatively evaluated plus a major research program (as anticipated by the
Office of Air Programs) should yield new and better tested guidelines
within a few years.
Based upon available research and case evaluations, the following
appear to be the most important relationships for consideration in an
urban planning program:
1. Planned relationships among industrial, commercial and resi-
dential land use can reduce concentrations of aerial wastes.
2. More effective use of large open spaces and green belts can
disperse pollutant concentrations and the number of people
exposed to unacceptable air pollution levels.
3. Significant reduction in hydrocarbons and carbon dioxide can be
gained through effective highway planning.
4. Improved public transportation can reduce vehicular travel and
vehicular emissions in varying amounts, depending upon the
areas involved.
xil
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5. Designing transportation facilities to be compatible with adjoining
land uses can have a significant impact on the number of people
exposed to undesirable levels of air pollution.
6. Control of arterial and freeway operations to ensure smoother
traffic flow can be significant both for short range and long
range reduction of automotive pollutants.
7. The selective creation of traffic-free zones, if supported by
sound traffic-planning, can substantially reduce certain pollu-
tants within congested activity areas.
In the short term (the next five years) the urban planner can expect
to achieve the greatest payoffs from: traffic flow improvements such as
those funded through the TOPICS Program; improvement of highway/land
use relationships; tighter control over location of stationary air pollution
sources and the land uses around such sources; and, creation of traffic-
free zones within congested activity areas.
Long term payoffs from urban and transportation planning strategies
can be much greater than short term. Within the next 30 years it is
expected that the urban population in the United States will increase by
75-80 million. Provision for this enormous increase, together with
necessary replacement of obsolete development, will provide a substantial
opportunity to plan and build in a rational manner to minimize the impacts
of air pollution. Careful consideration of regional land development
strategies, transportation plans and new plan implementation techniques,
as well as increased receptivity to the regulation of private vehicles, will
be a necessity if this opportunity is to be seized.
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CHAPTER 1
ROLE OF AND LEGISLATIVE MANDATE FOR
URBAN PLANNING
A. THE ROLE OF URBAN PLANNING IN AIR POLLUTION CONTROL
Air pollution is increasing because the population and economy are
expanding. Control technology is improving, but not fast enough to keep
pollution in check. To close the gap, Congress decreed in 1970 that land
use and transportation controls be added to the arsenal of weapons against
air pollution. Imposition of these controls requires both land use and
transportation planning, which are collected here under the label of urban
planning.
Urban planners work with many factors that affect air quality. They
plan the spatial distribution of industries, power plants, and other related
land uses commonly called''point sources" in air pollution control
work. Planners lay out transportation routes or, in air pollution terminology,
"line sources. " They work with zoning laws controlling the density of
residential neighborhoods, which are called "area sources" because of the
way residential furnaces and incinerators are distributed. Planners
influence the design, siting, and landscaping of buildings and the reservation
of open-space -- all of which affect the dispersion of air pollutants by
modifying the urban microclimate.
The treatment of the air pollution problem through urban planning is
a complex process, as illustrated in Figure 1.1 The entire process outlined
in the diagram is not covered in..this report. Rather, it and the companion
Guide for Reducing Automotive Air Pollution focus on the box labeled
"Feedback for Plan Modification. " The remaining elements of the diagram
serve here to illustrate how the Guides fit into the full context of urban
planning. It is hoped that the resulting program will serve as a model for
similar work in other areas of planning for environmental protection so
1-1
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ASSUMPTIONS, CONSTRAINTS, PROJECTIONS
URBAN PLAN
OTHER PLAN
ELEMENTS
TRANSPORTATION
PLAN
LAND USE
PLAN
EMISSIONS
t. AREA
2. POINT
3. LINE
I
BACKGROUND
AIR
POLLUTION
DIFFUSION
PHYSICAL,
CHEMICAL,
BIOLOGICAL
CONSTRAINTS
FEEDBACK FOR
PLAN
MODIFICATION
I
AIR
QUALITY
IDENTIFICATION
OF TROUBLE-
SOME
EMISSION
SOURCES
IS
AIR QUALI
TISFACTORY?
INCORPORATION
OF DECISION
IN PLANNING
PROCESS
Figure 1.1 Air Quality Considerations in the Planning Process
1-2
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that the tools for considering the aspects of such problems as water pollution
and solid waste, for example, will be developed and used in the urban
planning process.
The need for this Guide is based on the fact that urban planning
decisions are often made without proper consideration of their air pollution
consequences. For example, the choice of a highway system instead of a
rapid transit system will affect an urban area's air quality. Most urban
and transportation planning activities of the past have considered air pollution
effects only indirectly if at all, and then only in a non-quantitative manner.
Three reasons explain the lack of consideration given to air pollution
by planners and public decision-makers. First, they lack precise knowledge
of the effect which the arrangement, design, and operation of urban elements
have upon air pollution. Second, there are no established procedures for
incorporating air pollution considerations into plan-making and plan-
administration activities. Third, very few communities have the legal tools
necessary to enforce land use policies of the breadth and depth required by
the air pollution problem.
The urban planner must not define his role too narrowly. Where he
lacks legal authority he can work to control air pollution through effective
public relations and an aggressive program. Planners can go beyond land
use and transportation control strategies and fo.ous public attention on the
quality of a region's source control program.
The Miami Valley Regional Planning Commission (MVRPC) in Dayton,
Ohio is a case in point. The MVRPC staff cooperated with the County Health
Department in discussions regarding the legal and organizational aspects of
a regional air quality program. It gave moral and financial support to a
local citizens' clean air group in generating a cadre of well-informed
individuals able to forcefully testify and lobby for strict standards. Further-
more, the MVRPC strongly recommended strict standards to the Health
Board. The Commission is now monitoring the effectiveness of the local
control program, and supporting legislation to expand and improve it.
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This Guide has been prepared to describe current air pollution
relationships and planning strategies, however, it must be noted that the
state of research and theory in this area is still quite meager.
B. THE LEGISLATIVE MANDATE FOR PLANNING ACTION
Recent Federal laws and regulations involve urban planners in air
pollution control work.
1. National Environmental Policy Act of 1969
This act establishes a broad national policy directed toward improving
the relationship between man and his environment, and creates the Council
on Environmental Quality (CEQ). Section 102(2)(C) of the act is designed
to ensure that the environmental effects of all major proposed federal
legislation, plans, and programs are properly considered. For any proposed
action significantly affecting the environment, a detailed statement must be
submitted analyzing the following points:
"(i) the erivir&nmental impact of the proposed action,
(ii) any adverse environmental effects which cannot be
avoided should the proposal be implemented,
(iii) alternatives to the proposed action,
(iv) the relationship between local short-term uses
of man's environment and the maintenance of
long-term productivity, and
(v) any Irreversible and irretrievable commitments of
resources which would be Involved in the proposed
action should it be implemented. "
2
The Office of Management and Budget has established a framework
for communicating environmental information among Federal, state, and
local agencies. This framework, originally intended to implement
requirements for coordination set forth in other Federal legislation, was
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amended February 9, 1971 to include the coordination of environmental
impact analyses. In this framework, selected state, regional, and local
planning agencies are designated as "clearinghouses" to be notified by
any state or local agency intending to submit an application for Federal
financial assistance. The clearinghouse, in turn, notifies all potentially
interested persons and groups within its jurisdiction of the planned project.
The state or local agency requesting Federal aid then obtains comments
from these persons and groups on the environmental impact of its project,
and these comments are included in the request to the Federal agency. If,
after reviewing the comments, the Federal agency determines there will be
a significant impact on the environment, it must submit an impact statement
to the CEQ. The impact statement, reflecting all the comments received
through the clearinghouse process, becomes part of the public record.
For additional information on the implementation of Section 102(2)(C)
of the act consult the "102 Monitor, " published monthly by the CEQ.
2. 1970 Clean Air Act
This act calls for the establishment of primary (relating to health)
and secondary (relating to welfare) ambient air quality standards by the
Administrator of the Environmental Protection Agency (EPA). The
Administrator is also required to set standards of performance for new
stationary sources of pollution and for motor vehicles. The act requires
states to prepare plans by January 30, 1972 for achieving and maintaining
the air quality standards within three years. The act authorizes the
Administrator to act if the states do not, and gives him powers of enforce-
ment.
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3. Regulations Promulgated Pttrsuant to Clean Air Act
The EPA set out requirements by which the states should prepare,
adopt, and submit implementation plans for air quality standards achieve-
o
ment. The requirements describe a "control strategy" by which a com-
bination of measures are designated to achieve the aggregate reduction of
emissions necessary to achieve and maintain a national standard. The
measures might include:
a. Emission limitations.
b. Federal or state emission charges or taxes, or other
economic incentives or disincentives.
c. Closing or relocation of residential, commercial, or
industrial facilities.
d. Changes in schedules or methods of operating commercial
or industrial facilities or transportation systems. These
would include any short-term changes made in accordance
with standby plans.
e. Periodic inspection and testing of motor vehicle emission
control systems.
f. Emission control measures applicable to in-use motor
vehicles, including mandatory maintenance, installation
of control devices, and conversion to gaseous fuels.
g. Measures to reduce motor vehicle traffic, such as
commuter taxes, fuel rationing, parking restrictions
and staggered working hours.
h. Expanded use of mass transportation through measures
such as increased frequency, convenience, or capacity,
or by providing special bus lanes on streets and highways.
i. Any other land use or transportation control measures.
j. Any other variation of, or alternative to, the above
measures..
The EPA established national ambient air quality standards for sulfur
oxides (SO ), particulate matter, carbon monoxide (CO), photochemical
4
oxidants, hydrocarbons (HC), and nitrogen oxides (NOx). "Ambient air
means that portion of the atmosphere, external to buildings, to which the
1-6
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general public has access. It does not matter what the wind patterns are,
how many people live, work, shop in any particular area, how long they
remain there, or whether there are plants, buildings, or other land uses
especially susceptible to air pollution damage in the area; the standards
apply equally to all areas open to the general public.
4. 1970 Federal-Aid Highway Act
This act requires the Secretary of the Department of Transportation
(DOT) to promulgate guidelines by October 1972 designed to ensure that new
highways will be consistent with a state's air quality implementation plan.
These guidelines will enable planners to predict and to minimize the effects
of a proposed roadway on air quality. Highways should be designed, located,
and operated so as not to hinder the achievement of air quality standards.
Detailed information on the Act is available from the state representative
of the Federal Highway Administration.
5. Urban Mass Transportation Assistance Act of 1970
This act amends the Urban Mass Transportation Act of 1964, placing
o
grant and loan applications under the "A-95" review process. In addition,
it requires that the applicant afford adequate opportunity for public hearings
for all parties interested in the economic, social, and environmental impact,
and must hold hearings unless no one with significant economic, social, and
environmental interest has requested such hearings. If hearings are held,
the Secretary of DOT is required to ascertain that they were adequate and
that all harmful environmental impacts have been minimized. Detailed
information on the act is available from the Administrator, Urban Mass
Transportation Administration, Washington, D. C., 20590.
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CHAPTER 2
REDUCING AIR POLLUTION THROUGH
LAND USE AND PUBLIC FACILITY PLANNING
Land use and public facility planning can be used to reduce air
pollution. The methods range from large to small scale, from long-range
to short-range, and from theoretical to applied.
Strategies are broad policies that define a course of action. Techniques
are the legal, organizational, functional, and financial tools and processes
through which strategies are implemented. Table 2.1 is an overview of the
strategies and techniques that are discussed in this chapter.
Large scale, long-range, theoretical methods are discussed first,
under the heading "Regional Development Strategies. " These are goal-
oriented, and treat air pollution as one criterion for reshaping the land use
pattern of an entire region. Small scale, short-range, applied methods
are discussed last, under the heading "Location and Design Strategies. "
These are geared to solving immediate problems without departing substantially
from current land development trends. The evaluation of primary and
secondary techniques is based on the consultants' experience and judgment.
A. REGIONAL DEVELOPMENT STRATEGIES
On the regional and metropolitan scale, urban planners have responsi-
bility for preparing long range plans (20 to 50 years) for producing a more
rational and more humanly satisfying environment. The achievement of
this objective requires the sensitive consideration of alternative arrange-
ments of the region's physical structure, including: the shape, density and
organization of settlement areas; the orientation and composition of subareas;
the pattern and type of transportation system; and, the shape and location
of major open space. Four possible land use approaches, which have
implications for the reduction of air pollution and its effects, are discussed
below; regional transportation aspects are discussed in Chapter 3.
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LEGEND
PRIMARY
TECHNIQUES
SECONDARY
TECHNIQUES
TECHNIQUES
STRATEGIES
Kv
Comprehensive &
Project Planning
Localized Zoning
(Location & Density)
Regional Zoning
(Location & Density)
Performance Zoning
Non-Conforming
Use Laws
Zoning Regulations
for Site Use
Air Zoning ft
Smokeless Zones
Subdivision
Regulations
Land Dedication
Regulations
Planned Unit
Development Regulations
Building & Housing
Codes
Urban Renewal
Land Acquisition
Programs
Open Space Tax
Incentives
Location & Re-
location Incentives
Speculative Public
Investment
Tax Equalization or
Gov't Consolidation
A-95 Review
Direct Urban Design
A. REGIONAL
DEVELOPMENT
Alternative Regional
Forms
~
Balanced Communities and
Subregions
N
Low Density Development
ri
Regional Open Space *
Patterns
*
.;.;
:
B. LOCATION & DESIGN
Location of Stationary Sources
-:
Relocation of Stationary Sources
Control of Land Use Around
Sources
<>
Location of
Sensitive Receptors
*
Location & Design Control
of New Towns
in
Planned Unit Developments
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1. Alternative Regional Forms
There exist numerous strategies for urban form and growth which
entail specific land use arrangements. These strategies may have
particular importance for air pollution control. In selecting from a variety
of urban growth concepts, therefore, the planner should be conscious of
their relative significance for air pollution control, particularly with regard
to potentials for improving air pollution dispersion efficiency and reducing
automobile travel (and thus auto emissions).
The following discussion of studies conducted in Hartford, Chicago,
Seattle, and Prince George1 s-Montgomery Counties, Maryland, demonstrates
the relationship between land development patterns and air pollution.
Hartford Studies A comprehensive analysis of the relationship
between air pollution and land use was undertaken for Hartford, Connecticut,
by Yocom and others. This study showed clearly that the distribution of
air pollution concentrations was related to the arrangement of land develop-
ment. Emission inventory maps were developed, based on the predicted
geographical distribution of land development and population, as well as on
assumptions about control technology. The land use development pattern
for the year 2000, approved by the Capital Region Planning Agency, was
used as a basis for estimating future air quality.
An alternate plan for the Capital Region would terminate all further
development in the Connecticut Valley, and concentrate all future develop-
ment along two highways to the northwest and the southeast. This arrange-
ment would produce a developed area elongated in a direction perpendicular
to the prevailing winds in the region. This scheme would produce by the
year 2000 an air quality pattern with the total area of unacceptable air quality
somewhat less than the approved plan but with the area of questionable air
quality somewhat larger.
2-3
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Another study for the Hartford region has looked into the interrela-
e
tionships between land use and trip length. The study considered five
alternative land use plans, illustrated in Figure 2.1, for the year 2000.
These land use plans represent the development pattern required by
present zoning regulations and four alternative arrangements of land
use that might be selected as desirable goals for the region's growth.
In each case, the population and number of jobs are the same but
the distribution and intensity vary. The black dots in the figure represent
regional or subregional centers, and the gray areas stand for intense urban
development, primarily industry or high-density residence. The remaining
white areas are considered low-density development and open space.
The significance of Figure 2,1 is the average trip lengths which result
from the different land use plans. The difference between the trip lengths,
and hence in automotive air pollution, produced by the Balanced Community
and the Single Center Concepts could be as high as 22 percent. Land use
plans can have significant effect on trip lengths, and consequently on auto-
mobile-produced air pollution.
Chicago Study - In Chicago, the air pollution implications of three
alternative metropolitan plans were analyzed on the basis of emission
estimates for two pollutants: oxides of nitrogen emissions and suspended
7
particulate emissions from certain industry groups. The alternative plans
investigated consisted of a Finger Plan (high-density corridors), a Multi-
Towns Plan, and a Satellite Cities Plan. For these two pollutants, it was
found that the Finger Plan and Satellite Cities Plan were equivalent with
respect to particulates, and both were about 30 percent lower than the
Multi-Town Plan; the Finger Plan, however, produced fewer oxides of
nitrogen than the other two plans.
On the basis of these tests, It was concluded that the Finger Plan was
the best alternative for air quality. Although this plan had fairly high
residential and industrial concentrations, it also provided dilution potential
2-4
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BALANCED
LINEAR
SATELLITE
SINGLE CENTER
LEGEND
CZI
REGIONAL OR
SUBREGIONAL CENTERS
INTENSE URBAN
DEVELOPMENT
LOW DENSITY DEVELOPMENT
AND OPEN SPACE
PRESENT ZONING
Figure 2.1 Alternative Land Use Plans for Hartford6
2-5
-------
for pollutants. This was true because the development corridors were
elongated and bordered on either side by large green areas. Thus, the
presence of green areas adjacent to pollutant sources is an important
land use factor in pollution reduction. In both cases, the land use option
providing the greatest opportunity for pollutant dispersion over green
areas resulted in lower apparent pollutant concentration.
Seattle Study In Seattle, Washington, two alternative transportation
networks, based on two different land use systems, were evaluated for their
o
effect on air pollution. The two plans were: Plan A, continuation of the
existing trends in land development; and Plan B, development patterned
into a "Cities and Corridors" concept. Total emissions associated with
Plan A were about 12 percent higher than those associated with Plan B.
The analysis concluded, however, that the land use configuration preferable
for air pollution reduction cannot be determined until total area emissions
and, more importantly, total ambient pollutant concentrations are estimated
and compared.
Maryland (Montgomery-Prince George's Counties) Study The effect
of alternative land use plans, transportation networks, and operational
characteristics in reducing air pollution were also evaluated for Montgomery
g
and Prince George's Counties in Maryland. In order to quantify the effect
of alternative land use plans and highway networks on air pollution, a
measure of the amount of air pollutants generated by automobile travel
associated with each land use plan was required. Relationships were
developed between vehicle miles of travel, emissions of pollutants, and
speed. On the basis of curves relating emissions to auto speeds, air
pollution produced by the alternative plans was calculated based on congested
and average operating speeds. Table 2. 2 shows a comparison of the pollutant
production for the alternative plans. In comparing the alternatives an index
2-6
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Table 2. 2. SUMMARY COMPARISON OF POLLUTANT PRODUCTION'
(Pounds/Day)
to
i
-a
Montgomery County
Hydrocarbons
Carbon Monoxide
Total Production/
Vehicle Miles
Alternative 2
General Plan
Alternative 5
Concept Plan C
Alternative 6
General Plan
Capacity
Post-
1975
Pre-
1968
Post-
1975
Pre-
1968
Post-
1975
Pre-
1968
Post-
1975
Existing System
Pre-
1968
56,300 4,570 149,500 12,870 147,700 12,180 232,950 19,520
663,260 95,460 1,874,290 275,100 1,794,390 262,6003,048,110 454,700
0.145 0.0218
0.158 0.0242
0.145 0.022
0. 188 0. 0286
Prince George's County
Hydrocarbons
Carbon Monoxide
Total Production/
Vehicle Miles
70,650 5,820 198,600 16,500 200,200 16,440 238,320 19,700
856,440127,150 2,491,880 365,1002,435,540 354,8202,994,720 439,060
0.154 0.0235
0.157 0.0238 0.146 0.0220 0.160 0.0242
-------
of the weighted average of pollutants produced per vehicle mile was
calculated. This index was used to choose the plan that contributed the
least air pollution as a result of less overall congestion in the network
and the arrangement of the transportation system and urban development.
Conclusions As indicated by research that has been done to date,
improved regional development patterns should reduce auto emissions and
the number of persons exposed to pollutants from both vehicles and stationary
sources. However, as was concluded in the Seattle study, the determination
of preferable land use patterns cannot be made until total area emissions and,
more importantly, total ambient pollutant concentrations are estimated and
compared. Two basic conclusions can be drawn regarding the effect of
regional development concepts:
a. Models for simulating the air pollution impacts of
alternative development forms need to be made more
comprehensive in their capacity to accommodate corridor
variables (i.e., trip length, travel speed, population
density, ambient air conditions, stationary source
emissions, etc.) None of the studies reviewed for this
project, for instance, evaluated development plans from
the standpoint of both auto and stationary emissions.
b. Even when such multi-variable models are developed,
it will be difficult to make generalizations about optimal
development forms. Localized investigations will be
required due to significant variations in regional ambient
air quality levels, the location of major stationary sources,
the clima to logical conditions, and the travel behavior of
residents.
With regard to trip lengths, it remains for the planner to consider
the effect of various land use concepts upon trip length in a given metro-
politan area. Minimum travel distance should be incorporated into the
land use plan selection criteria. It must be understood, however, that
shortening trip lengths is not a universal panacea for improving air quality.
As pointed out in subsequent sections, it is important to give equal attention
to increasing traffic speed and population density reductions, both of which
can be incongruous with the minimum travel distance criterion.
2-8
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2. Balanced Communities and Subregions
By taking a small area approach to regional and metropolitan develop-
ment it is possible to increase opportunity, accessibility, and convenience.
The net result of creating subregions, each having a balanced supply of
employment facilities, retail and service centers, and housing types and
r*
prices, can be a significant reduction in peak-hour auto travel. One study
concluded that travel could be minimized through creation of defined
subareas. The key factors in this type of development are:
a. Populations should range in the order of 100, 000 to
200, 000. (The effect on internal trip lengths on
communities of 100, 000 to 200, 000 may be observed
from the curve shown in Figure 2. 2. )
100
80
h- 40
I
20
YASS (Itolawd Community)
QUEANBEYAN0
TUGGERANONG
WODEN
25 50 75 100 125
TOWN SIZE, 1000 people
ISO
175
Figure 2.2 Correlation of Internal Trips With Population Size1 °
2-9
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b. Subregions should be as distinct and isolated from
one another as the natural topography and existing
development pattern will permit.
c. Street and highway systems should be laid out to
focus on the subregional center(s).
d. High density residential development should be
located within 10 minutes travel time of high density
commercial and employment areas.
e. Housing must provide a wide range of types that will
attract a diversity of social and economic groups.
The reduction of trip lengths and the increased potential for non-auto
trips (transit and walking) caused by implementing this balanced subregional
concept (see Figure 2.3 for an illustration of how such subregions could be
planned and designed), results in a reduction of auto pollution emissions
comparable to the reduction of auto travel. Furthermore, this type of
development pattern is also highly compatible with other planning objectives
(i. e., wider housing opportunities, reduced sprawl, more economical public
service delivery, revitalization of central business district, etc.).
The subregionalization concept could be applied in a number of ways:
a. Guiding the establishment and design of new towns
which are currently being considered, planned, or
developed in a number of metropolitan areas.
b. Providing a framework for new suburban development.
c. Restructuring and renewal of built-up sections of
metropolitan regions, including "new towns-intown. "
2-10
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LEGEND
MAJOR ROADS
PUBLIC TRANSPORT ROUTE
0 TOWN CENTRES
Q REGIONAL CENTRES
O OTHER CENTRES
Figure 2.3 Plan for Sub-Regional Development: Canberra, Australia1 2
2-11
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3. Low Density Development
The potential impact which population density variations have upon
automobile pollution concentrations has been demonstrated by Rydell and
13
Collins in a simulation study, Application of the Rydell-Collins density
equation over the range of population densities (gross residential density)
occurring in the simulated city revealed that automobile pollutant concentra-
tions decreased as density decreased. Thus, it could be concluded from
this study that land use policies which are designed to achieve lower overall
population densities will* all other things being equal, improve ambient air
quality.
Obviously, this raises a number of difficult questions about the effect
of residential density* As pointed out previously, lower densities stimulate
trips of consistently greater length, thereby causing an Increase in overall
travel of 10 to 20 percent. The RydeU-ColUns study would seem to conclude
that the dispersion of people and automobiles over a larger area creates a
condition of lower pollutant concentration which compensates for the added
pollution due to increased vehicular miles of travel.
In fact, however, this pioneering study has only proven the need for
additional research* Such research would feave to be more sensitive to;
a. Trip length factors as well as trip generation rates.
b. Lost potential for transit travel caused by the lower
densities,
c. The fact that in most cases the trip generation rates for
low density development are higher tban for medium and
higher density development.
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For the time being, density changes on a broad scale appear to be
somewhat neutral in effect. On a smaller scale, however, density
reduction can have a significant effect. For example, reducing density
of development around major stationary sources of aerial wastes, such
as industries or power plants, will, depending upon climatological and
topographic conditions, tend to reduce the number of people affected by
emissions from such sources.
4. Regional Open Space Patterns
The use of open space or buffer zones to separate aerial waste sources
from residences has long been a technique employed by planners. In
addition, open spaces can be used to shape the community into the desired
growth pattern; more recently, it has become known that open space can
provide better dispersion of air pollutants. Some research has been done
on this subject and much more is underway and needed, but there are some
known techniques which are relevant.
Effective dispersion of air pollutants does occur over open space and
is increased if the land is planted. By absorbing moisture and then cooling
by evaporation,greenery creates a cooler, more humid surface which keeps
14
dust and other pollutants on the surface.
The location and size of open spaces are important. Wind direction,
type of pollutants, etc. are all relevant. Generally the width must be much
wider than the narrow buffer strips common today.
A variety of open space systems some of them empirically derived,
has been proposed on the basis of potential diluting, absorbing, and settling
effects of buffer space. Hilberseimer has suggested that when winds blow
from a single direction, there should be rows of built-up areas separated
by green zones, with the industries on the leeward side of the development
(see Figure 2.4). The green zones should be broad enough to reduce air
pollution to acceptable levels before the winds reach each succeeding
2-13
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CLEVELAND EMERALD NECKLACE
YELLOW SPRINGS GREENBELT
iSff Wm
iM4 tks|
A--,5.r .:;--> ;-j :.."-.':'.
WEDGES CONCEPT
HILBERSEIMER'S ALTERNATIVE
ROWS OF OPEN SPACE
Figure 2.4 Examples of Large Open Space Systems
2-14
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residential strip. When the wind direction varies over a range of less
than 180 degrees, Hilberseimer has concluded that diamond-shaped arrays
of industrial and residential locations are best; and over a range of more
than 180 degrees, triangular arrays are best.
In certain geographical areas, however, the green bands strategy
may be very difficult to implement. For example, because of the dispersed
wind pattern and source locations in the Chicago area, it would serve little
purpose to plan land use according to wind direction. Generally speaking,
the area's wind patterns pose a threat to people in all directions from major
sources. In such a case, buffer zones would have to completely surround
these sources. The 5, 000 acre greenbelt being preserved around Yellow
Springs, Ohio, as well as circumferential park systems (the Emerald
Necklace) around Cleveland, Ohio, are examples of this pattern of buffering
(see Figure 2. 4).
Perhaps more effective is the creation of open wedges or corridors
radiating from penetrating toward the center of the metropolitan area (see
Figure 2.4). In this system almost all development is only minutes away
from open areas. Such proximity to open space helps in the diffusion of
aerial wastes. This was well supported in the Chicago tests on alternative
development forms in which the Finger Plan (i.e., a concept based upon
corridors of development and wedges of open space) proved to generate the
least air pollution impacts in spite of the proximity of several of the fingers
to high concentrations of stationary pollution sources.
While the research is still inadequate, it does appear that the use of
regional open space systems to help disperse pollutants can be of significant
value. Furthermore, when its dispersion potential is added to all the other
benefits of open space preservation, the case for implementation of land
preservation programs becomes quite convincing.
2-15
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5. Implementation of Regional Development Strategies
To accomplish the restructuring of metropolitan areas according to
the strategies described above would call for every tool planners
have in their kit, plus some that have yet to be developed. Regional zoning
would be a most effective tool but only a few areas such as the Jacksonville,
Indianapolis, and Nashville consolidated governments are currently able to
exercise such power. In absence of such centralized public land control in
most areas, a high degree of voluntary coordination, review, and referral
must suffice. Furthermore, implementation will call for a very carefully
executed program of reclassifying vacant land to buildable zoning districts.
If intensification of land use, redevelopment of built-up sections, and pre-
servation of open space are to occur, land must be made a scarce resource
so that developers, builders, employers, and politicians will be deterred
from current "spread city" development patterns. Some alternative tcols
which might convince development interests to follow new development
strategies include:
a. Massive open space preservation programs which tend to
define and channel development opportunities (techniques
could include fee simple or easement acquisition, new
tougher conservation zones, and tax deferrals).
b. Restrictive public sewer and water extension policies in
concert with tight regulation of on-site sewer and water
systems.
c. Tax incentives for developments which follow the "plan."
d. Entry of local and state governments in the business of
development and redevelopment. {New York's Urban
Development Corporation is one of the best examples of
"public interest" developers.)
e. Control of new town locations and designs through metro-
politan and state clearing houses in their exercise of A-95
review powers.
f. Decentralization of low and moderate income housing from
congested.^ it ies to all sections of the metropolis so that
employttuijnt facilities can be closer to the total range of
2-16
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needed occupational skills. (A-95 review power over all
federally assisted housing, presently limited to single-
family housing developments of more than 50 units and
multi-family developments of more than 100 units, would
be the tool for promoting such housing goals. )
g. Selection of urban renewal projects which would encourage
concentration of jobs and people in close proximity.
However, judging from the difficulty many renewal programs
have had in attracting developers, additional incentives
may be required.
h. Selective placement of public facilities* and services so
that they serve as positive "development shapers. " In
other words, through capital improvement programs, model
cities programs, A-95 review of federally assisted facilities,
and the planning and programming of improvements of
highway and utility systems, development can be stimulated,
shaped, intensified or modified. This kind of public
entreprenuership departs from the standard "supply
follows demand" philosophy, but it is being done more
and more frequently by local governments. Furthermore,
denial of public service and facility improvements can
maintain clarity and definition of the subregional cluster
boundaries.
B. LOCATION AND DESIGN STRATEGIES
While modifications of regional and metropolitan form can apparently
provide pollution-reduction payoffs for relatively large numbers of metro-
politan dwellers, the facts remain that those payoffs are long-range and
that we currently lack some of the more important land use tools required
to implement them. Through selective application of location and design
strategies, however, it is possible to generate some shorter range effects
which fall essentially within the current range of planning powers. The
following discussion describes and evaluates some of these strategies.
2-17
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1. Location of Stationary Sources
In formulating comprehensive plans, the planner should attempt to
locate large industries and industrial areas so as to minimize their effects
on residential and commercial air quality. Hazardous air quality conditions
which exist today can often be traced to poorly located industry. For
example, many industrial areas historically developed in river valleys in
Ifi
order to benefit from cheap transportation. Depending on the surrounding
topography, such valleys are often the worst locations for sources of harmful
emissions.
The impact of pollution from industrial land uses can be reduced not
only by source control technology, but also by careful location planning of
such areas with respect to the local dispersion characteristics and with
respect to residential development location and densities. Because it is
always desirable to ensure that aerial wastes are discharged away from
residential areas, the planner must make increasingly comprehensive
studies of local meteorology, climatology, and topography in order to
improve spatial arrangements of industrial, commercial, and residential
areas. In fact, these considerations should become fundamental deter-
minants of industrial location dec is ion-making along with such criteria as
amount of existing vacant land, land cost, accessibility, demand for existing
industrial activity, and compatibility with adjacent land uses.
In general, the ideal site for industrial sources of aerial waste is com-
paratively level terrain in a region where the average wind velocity is ten
miles per hour or more, and where deep temperature inversions rarely
17
occur. However, because dispersion characteristics vary among regions,
the planner is urged to investigate the relevant conditions of specific areas
and to assess land uses accordingly. Following are two examples, illustrating
the significance of local dispersion characteristics in land use planning.
2-18
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When rebuilding Volgograd (formerly Stalingrad) after World War II,
its planners recognized that the wind almost always blows from the same
direction. They designed the city in major land use strips perpendicular
to the wind. The wind does not pass over the industrial area until it has
passed all of the other uses.
Placing the industrial area on the leeward side of the city is not
14
always the solution, however. In Linz, Austria, located in a mountain
valley, industrial sources were sited on the eastern side of the city to take
advantage of the prevailing westerly winds. On occasions when the more
mild easterly wind is in effect the pollution is banked against the mountains
and the residential area is often blanketed by smoke.
The problem at Linz was caused by the effect of low velocity winds on
air pollution concentrations. While high velocity winds disperse air borne
pollutants, low velocity winds may prevent dispersion. Wind frequencies
and speed must be considered in the planning process prior to locating
industrial areas to keep emissions away from residents.
Zoning -- The implementation of such plans for new industrial locations
is normally carried out through zoning regulations, which generally have
between one and five categories of industrial land. The list of major
stationary pollution sources shown in Table 2.3 should prove helpful to the
planner in determining permitted uses within different zoning districts. The
consideration of air pollution and other obnoxious effects abttributable to
industry has taken place for a number of years. However, the regulatory
process has been only partially effective because:
a. Community leaders are increasingly anxious to strengthen
the tax base with industrial development and often will amend
zoning regulations to allow industries to locate wherever
they desire.
b. Zoning power is decentralized to many local jurisdictions
within a region, and inter-community air pollution effects are
often not considered.
2-19
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Table 2. 3. MAJOR POLLUTANT SOURCES
Chemical Process Industries
Mineral Products Industries
Adipic acid
Ammonia
Ammonium nitrate
Carbon black
Q
Charcoal
Chlorine
Si
Detergent and soap
Explosives (TNT and Nitrocellulose)1"
Hydrofluoric acid
Nitric acid
Q
Paint and varnish manufacturing
Phosphoric acid
Phthalic anhydride
Plastics manufacturing
Printing ink manufacturing
Sodium carbonate8
Sulfuric acid
Synthetic fibers
Synthetic rubber
Terephthalic acid
Asphalt roofing
Asphaltic concrete batching
Bricks and related clay refractories1
Calcium carbide
Castable refractories
Cement
Ceramic and clay processes
Clay and fly ash sintering
Coal cleaning
Concrete batching
Fiberglass manufacturing
Frit manufacturing
Glass manufacturing
Gypsum manufacturing
Lime manufacturing
Mineral wool manufacturing
Paperboard manufacturing
Perlite manufacturing
Phosphate rock preparation
Rock, gravel, and sand quarrying
and processing
Food and Agricultural Industries
Alfalfa dehydrating*
Ammonium nitrate
Coffee roasting*
Cotton ginning*
Feed and grain
Fermentation processes
Fertilizers
Fish meal processing
Meat smoke houses
a
Starch manufacturing
Sugar cane processing
Petroleum Ilefining and Petrochemical
Operations8
Wood Processing
Metallurgical Industries
Primary metals industries:
Aluminum ore reduction
Copper Smelters
Ferroalloy production
Iron and steel mills
Lead smelters
g
Metallurgical coke manufacturing
Zinca
Secondary metals industries:
Aluminum operations
Brass and bronze smelting
Ferroalloys
Gray iron foundries
Lead smelting
Magnesium smelting
Steel foundires
Zinc processes
Petroleum storage (storage tanks and
bulk terminals)
Miscellaneous
Fossil fuel steam electric powerplants
Municipal or equivalent incinerators
Open burning dumps
Major sources of sulfur oxides and/or paniculate matter.
2-20
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c. Almost every city (particularly large central cities)
has its share of improperly located heavy industry which
was built prior to the adoption of zoning. Non-conforming
use provisions have not had the enforcement procedures
necessary to relocate those industries which are in con-
flict with surrounding uses.
In spite of these drawbacks to use of the zoning power, it remains the
best tool available and has been used with increasing effectiveness in
locating suburban industrial areas. Zoning regulations, in order to promote
further reduction of air pollution concentration, must be reexamined in light
of the effect that metropolitan meteorological and topographic characteristics
have upon pollutant dispersal.
Performance Zoning -- Consideration ought to be given to the performance
zoning approach. Performance standards are a method, usually limited to
industrial classifications, under which zoning districts are established not
by a detailed catalog of specific permitted uses, but by scientific measure-
ment of the external nuisance impact of the operation. Any use may be
located in any industrial district if it can comply with measurable standards
for noise, glare, odor, vibration, fire safety, smoke and toxic matter.
The excerpt from the Cook County, Illinois, zoning ordinance (Appendix B)
illustrates the type of emission standards which can be applied.
The use of performance standards has much in its favor, but it does have
some drawbacks which have not yet been overcome:
a. Performance zoning requires extra enforcement personnel
with high technical ability. (One suggested solution is to
shift the measurement and enforcement costs to the industry.)
b. Some industries are reportedly unwilling to locate in areas
where they cannot determine compliance with the standards
until after their plants are built.
c. If, after the plant is built, it is concluded that the emission
standards cannot be met, local governments are going to be
quite reluctant to tell that industry to relocate.
2-21
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d. The emission standards are usually limited to particulates
and toxic matter when , in fact, carbon monoxide, sulfur
oxides, oxides of nitrogen, and hydrocarbons may be
equally harmful to the health of surrounding households.
e. Since meteorological conditions are not taken into
account in setting standards, the actual air pollution
impact may vary from plant to plant.
Another important factor is the relationship between performance
standards, which are usually administered by planners, and emission codes,
which are usually administered by health departments or air pollution
authorities. Obviously, a conflict of standards is undesirable. Because
source control is so important, it is suggested that planners encourage the
proper local authorities to adopt comprehensive emission codes and enforce-
ment programs. If this happens, then the zoning performance standards
relating to stationary source emissions should be made compatible or deleted
from the ordinance.
For example, under the 1967 Clean Air Act passed by the State of
Washington, performance standards are superseded by the rules and
standards promulgated by county, multi-county, or regional air pollution
control authorities unless the zoning performance standards are more
stringent. Furthermore, agreements should be drawn up to describe the
mutually supportive roles to be performed by each agency. The most logical
approach would be for the health department or air pollution authority to
concentrate on obtaining compliance from existing industries while the
planning agency concentrates on trying to avoid new problems.
If there is no county or regional air pollution authority or if emission
regulations have not been developed, it is suggested that the planning agency
amend the zoning regulations to include measurable air emission standards
governing the performance of source operation. Such standards should
cover all major types of pollutants (i. e., gaseous as well as particulate
emission) and should be backed by a well staffed enforcement program.
However, if the jurisdiction's inspection office is understaffed or is not
able to obtain the expertise required to develop and enforce such standards,
2-22
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it is probably wiser not to venture into this area. As Rutgers law professor
Norman Williams observed, "it is a bit fantastic to make a big deal about
working out more elaborate planning controls, involving much more complex
administration, and then to turn it over to administrative machinery which
1 R
can't keep track of a copy of the current zoning map. " In such a case,
the greatest contribution to be made by the planning agency is to build air
pollution considerations into the location of industrial areas on the zoning
district map and to encourage development of a county or regional air
pollution monitoring and enforcement program.
Air Zoning -- Another variation of the zoning power would be to
establish restricted areas within which pollution producing industries would
not be permitted. Such restricted areas would be based upon evaluation of
current ambient air quality, topography, land use, population density, and
the atmospheric dispersion characteristics. In Britain, "smokeless zones"
have been legislated in order to eventually eliminate aerial wastes within
designated areas. In practice this strategy has suffered from highly subjective
judgments and difficulties in enforcement. Furthermore, like performance
zoning standards, only particulate emissions are regulated. However, it
would seem possible to modify the approach so as to broaden the range of
pollutants and to provide more objective measures and enforcement programs.
The primary value of this approach is that such zones could be imposed
at the regional level as an overlay district, without having to take all zoning
powers away from the localities. This makes it much more practical to
implement than regional or metropolitan zoning. It would, in most cases,
require new state legislation to create both the authority and the organizational
machinery to establish, evaluate, and enforce such air quality zones. In
effect, this would result in the setting of subregional ambient air standards
for critical sections of a region, except that, in this case, the standards
would be attached to the authority to exercise the "police power" as it
relates to land use.
2-23
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Even if not carried through to legislative action, the designation of
such air quality zones in regional and community comprehensive plans
would be of service to public officials. The zones would provide a valuable
input to the consideration of zoning amendments and the location of new
public facilities.
Power Plants and A irports
Power generation plants and airports also have critical
impact upon air quality. Locational decisions regarding these
two land uses are required infrequently, but when they are it is
important that the planner become fully involved in the con-
sideration of alternative sites.
Power plants are usually the largest single source of
sulfur oxides; airports, particularly the new regional jetports,
are generators of particulates, carbon monoxide, oxides of
nitrogen, and hydrocarbons (concentrations of the latter are
being reduced through modification of jet engines).
The location of electrical power plants, which generally
consume extraordinary amounts of coal, can be best controlled
by making them a "special permit use" or "special exception"
rather than by considering them a "use by right" within
specific zoning districts. The "special use" approach allows
more flexibility in defining the best location and also provides
the planning agency with greater control over the location
and site planning of such a major land use. Future power
plants apparently will be shifting to nuclear fuel but there
are still problems of public safety with regard to operation
and disposal of nuclear wastes. (See Appendix C)
As with industry, locations should be determined on
the basis of good atmospheric and topographic diffusion
characteristics and should be downwind from urban develop-
ment. Buffers are usually of little value due to the wide area
2-24
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affected by power plant emissions. Strict control of new
locations, plus public regulation of existing source operations
(i. e., fuel conversions, emergency production curtailment,
and emission codes) should produce the greatest improvement.
Airports and jetports are expanding rapidly and new
locations are being considered in several .metropolitan areas.
A recent study concludes 1I. . . it is difficult to escape the
conclusion that the expansion of airports to capacities near
(100 million) passengers/year will result in a noticeable
air pollution problem for large distances downwind from
19
the airport. " The control which an urban planner has
over public airport location lies more in his planning role
than in his administration of zoning regulations. Since the
airport is usually a public use, it is generally permitted in
any district. Although certain zoning regulations consider
airports as "special permit uses, " there is often a provision
which allows the legislative body to exercise such locational
decisions without review by, and recommendation from, the
planning or zoning board. Thus, the most important con-
tribution of the planner is in the evaluation of the air pollution
aspects of various alternative locations and for expansions
during the early stages of airport improvement studies.
Solid Waste Disposal
With regard to solid waste disposal, the first step is to
outlaw open burning. Most states have already done this,
but the implementation of these laws can be speeded up
through the provision of alternative disposal systems
(i.e., landfills and incinerators). Landfills., if well operated
and managed offer only small problems in aerial waste
generation (dustfall and blowing debris). New Incinerators,
however, can be major sources and require the planner's
2-25
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attention in considering rezonings and in preparing solid
waste disposal plans. The best solution is: (1) advance
planning of future sites on the basis of minimizing
environmental impact; and, (2) promoting public acquisition
of such sites in advance of urbanization so they will be
available when needed. Air pollution emissions from
incinerators can be reduced somewhat through the use
of buffer zones. But again, it must be emphasized that
any planning strategy or technique must be accompanied
by controls at the source.
2. Relocation of Stationary Sources
Although the principles of industrial location have changed significantly
since the early 1900's, there are still large numbers of manufacturing plants
located too close to medium and high density residential areas and within
low lying basins which do not easily diffuse aerial wastes. Many of these
plants also produce blighting influences due to their traffic generation,
noise, safety hazards, structural deterioration, and water pollution. Most
were constructed prior to the local government's adoption of zoning regulations.
Within most metropolitan areas, these industrial plants expose between
20 and 50 percent of the current population to emissions of particulates,
carbon monoxide, sulfur oxides, and hydrocarbons. To complicate matters
further, most of the affected persons are in low and moderate income
categories and can least afford the cost of relocation, of medical bills for
treating respiratory ailments, or the loss of a few days work.
Ideally, the solution would be to. relocate these industrial operations to
areas where their pollutants would be more adequately dispersed and where
there would be few nearby receptors. When this option is approached practi-
cally, however, many legal, financial, social, and physical issues arise.
How will the neighborhood residents travel to the plant's new location? Can
the city afford the tax revenue losses if the plant is relocated in another
jurisdiction? Will the industry close down if this additional economic burden
2-26
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is placed on its shoulders ? Can the plant, through enforcement of
emission standards, be made to reduce emissions to standard levels thus
avoiding the need for a move? Does government have a clear legal right
to force relocation? All these questions must be answered for each
community's unique situation before relocation programs can be
formulated and implemented.
Assuming for the moment that the answers to all these questions are
positive, how does one go about the task of implementing a relocation
program for major stationary air pollution sources? Some combination
of the following techniques would be required for relocating major stationary
sources:
a. Non-conforming use provisions have been contained in
zoning ordinances for years for the purpose of restricting
the expansion and the extended existence of land or
structural uses which are deemed incompatibly located.
Occasionally such provisions have incorporated
amortization schedules in order to set time limits for the
cessation of non-conforming uses. This is a "venturesome
area with few guide-posts. "^ Some state courts have
expressed opposition to amortization techniques; where
they have been tried, "unpopularn uses such as bill-
boards, gas stations and auto wrecking yards have
received most of the attention. Non-conform ing use
provisions, singularly, do not appear to offer great
potential for relocation of sources.
b. Urban renewal projects and planning which precedes
them (Community Renewal Programs and Neighborhood
Development Programs) could be used to remove in-
compatible sources within blighted areas. Although most
urban renewal programs have chosen to concentrate on
clearance of housing and marginal commercial structures,
some communities have used either spot clearance or
comprehensive redevelopment programs to eliminate
small polluting industries which are barriers to the
redevelopment potential of the site.
c. F^nancjal relocation incentives appear to be a necessary
ingredient in any program for the removal of waste
producing industries, either in combination with the zoning
and renewal techniques or by themselves. Many inner-city
2-27
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industries do not have the capital to absorb relocation
costs and, if incentives are not provided, they may be
forced to go out of business. Incentives could take the
form of direct relocation allowances or tax credits.
d. Tax equalization or governmental consolidation would
be the most important Incentive to industrial relocation.
Most communities are quite reluctant to force an industry
to move for fear that the industry will relocate outside
the political jurisdiction, thus causing a loss in property
and income tax revenue. It is doubtful then that any
substantial relocation could occur until local taxation
systems are made less competitive and more responsive
to region-wide considerations.
In summary, although it would appear that a substantial portion of our
population would be affected by relocating major industrial air pollution
sources, the issue is far too interwoven with social, political, and
economic factors to show any near"term promise of contributing to air
quality improvement.
3 Control of Land Use Around Sources
if it is not possible to locate or relocate stationary sources so that
their emissions are diverted from population concentrations (and this is often
the case either because of dispersed wind patterns or traditional develop-
ment patterns), certain actions can be taken to improve the situation through
better control of development around the sources.
The following actions could be taken by the urban planner on the basis
of his knowledge of ambient air conditions and dispersal characteristics of
the areas around such sources.
a. "Exclusive use" districting to prohibit housing and
commercial development within industrial zones.
b. Planning and zoning for low density development and
limitedj)uilding heights within the affected areas.
c. Providing buffers around sources in the form of open
land (the best filtering effects come from a combination
of rows of trees, shrubbery and lawn).
2-28
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d. Within industrial areas, providing for a gradation of
pollution and employment outward from the middle.
Industries with the worst pollution could be located in
the center; "cleaner" industries could be located on the
outside.
e. Within developed areas where conflicts exist:
1. Preventing increases in population through zoning
amendments; and
2. Conducting redevelopment and spot clearance
programs in order to remove dwelling units which
are blighted by, among other things, the presence
of air pollution.
Concerning the value of buffers, around sources, it is important to
recognize the variability of their impact. Their value increases in direct
proportion to the amount of source control of pollution that is effected.
For instance, a study was conducted in Chicago which estimated diffusion
effects on two gray iron foundries. Diffusion effects from foliage and
structures were ignored. Uncontrolled and 75 percent controls were
calculated for both plants; 95 percent controls were also calculated for the
larger unit. (The smaller unit was rated at 10 tons per hour, while the
larger foundry was rated at 25 tons.)
"At low or high wind speeds a buffer zone around an
uncontrolled foundry would have to be unrealistically large
to satisfactorily reduce downwind ground concentrations
of particulate matter. With 75 percent controls for the
smaller (unit) a buffer 2, 130 feet deep would bring con-
centrations outside the zone below 100 micrograms per
cubic meter. With an 82 foot stack, the plant would have
to be centered on a site totalling some 400 acres. With
95 percent control of the larger unit, concentrations at
any point downwind would not go above the 100 microgram
mark. "7
Through control of peripheral development around sources in a
manner which more sensitively incorporates air pollution considerations,
a large part of the effect of aerial wastes can be reduced for a large number
of people. Furthermore, the techniques described here, for the most part,
are within the range of feasibility.
2-29
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4._ Location of Sensitive Receptors
In planning the land use patterns near emission sources, it is
important to pay special attention to areas to be used by sensitive receptors:
the young, elderly, and sick. Although no specific distance standards are
available, ciie following land uses should be kept remote from emission
sources:
a. Elementary and secondary schools.
b. Intensely used recreational facilities, especially outdoor
play areas.
c. Orphanages and children's homes.
d. Elderly .housing facilities, senior citizen centers, and
nursing homes.
e. Hospitals, clinics, medical centers, and rehabilitation
centers.
The techniques for properly locating these land uses include zoning
regulation, the A-95 review of federally assisted projects (health facilities
and housing projects fall under this review), and close coordination with
school administrators and recreation officials regarding advance planning
of their site acquisitions. Where facilities within areas of poor air quality
are impossible to avoid, either because the} are there now or because
such facilities have to be in close proximity to the neighborhood residents,
improvements can perhaps be made to the site, the buildings, or the
facility's operation (i.e., installing central air-conditioning, scheduling
outdoor activities at non-peak hours, providing landscaped buffers, etc. ).
5. Location and Design Control of New Towns
The Urban Growth and New Community Development Act of 1H70 is now
encouraging a great deal of new town development activity. At last count,
''public and private developers from 23 states and territories have demon-
..21
strated substantial interest in building new communities ....
-------
Several new town projects are already under construction and indications
are that the trend is just beginning to pick up momentum. The National
Committee on Urban Growth recommends the creation of 100 new com-
munities with 100, 000 persons each and ten new cities of at least one
million persons each. This would account for about 20 percent of this
country's urban growth between now and the year 2000, but the financing
22
required to make this happen is still a major obstacle. However, even
looking at the new town potential with a more conservative eye, it would
seem possible that between 5 and 10 percent of metropolitan
growth could be attracted to new towns built either as satellite communities
or as new towns in-town.
New town location ani design will be important factors in improving the
quality of urban life; more specifically, they will offer the urban planner
the opportunity to more effectively deal with the air pollution problem.
First, the location of new towns offers an opportunity to more carefully
place an entire community with regard to optimal diffusion characteristics.
As was pointed out in the discussion of open space strategies, the separation
of communities or subregions by large amounts of green space (as would be
the case in many new towns) is an effective strategy. Furthermore, a new
town can be situated with better regard for wind direction and speeds.
Second, through careful consideration of the new town's internal design
it is possible to reduce the effect of locally generated airborne wastes.
This can be accomplished through better location of stationary sources,
the use of internal open space, the design of traffic/land-use relationships,
and the reduction of trip lengths and auto reliance.
Even if new towns are not successful in diverting large numbers of
households away from the more conventionally developed suburbs and
central cities, they have a large contribution to make in the area of experi-
mentation and demonstration. New techniques of reducing air pollution and
its impacts can more easily be tested in new developments and, if sueeossiuL
2-31
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then applied to the cities. For example, in France, a new city, Vaudreuil, is
being planned for the lower Seine region outside Paris. The city will pro-
vide housing and employment for up to 150, 000 residents. The design will
utilize new technology to eliminate as much noise and air pollution as possible.
Among the concepts under consideration are routing of traffic through under-
ground passages and tunnels, carrying smoke from factories in underground
conduits, burning gases off at the source, and processing refuse to supply
part of the city's central heating. The U. S. Department of Housing and Urban
Development, together with other U. S. agencies, will make technical contri-
butions to the French effort. The results of such innovative demonstrations
will have great significance for our existing cities.
Urban planners can exert influence on the location and design of new
towns through land use controls (zoning, subdivision regulations, special new
community zoning districts, etc.), the encouragement or discouragement of
such developments through the location and type of governmental capital
facility investments, and the review of new community applications for
Federal financial assistance (guarantees, loans and grants). Professionals
and lay boards at all levels of planning (state, regional, county and local)
can play a role in encouraging and guiding new town developments.
6. Planned Unit Developments
For many of the same reasons related above, except on a smaller scale,
urban planners should encourage more innovative approaches to land develop-
ment. In most cases planners are already providing such encouragement and
are revising land regulations to allow more flexibility for development concepts
such as planned unit development, cluster subdivisions, and density zoning.
Such development forms will increase convenience and thus reduce trip length.
Equally important, however, is the fact that such concepts permit the
preservation of buffers and open spaces between emission sources
(principally roads) and residences.
2-32
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Most planned unit developments created thus far tend to be predominantly
residential. However, the same concepts of design flexibility and mixing of
land use types apply to the development of multi-use centers. A multi-use
center (MUC) may be described as a concentration of living, working and
shopping land uses that are physically integrated by internal pedestrian
23
systems. The air pollution abatement contribution which an MUC can make
lies in the significant reduction in trip lengths and the reduced need for auto-
motive travel between the contained activities.
The Twin Cities Area Metropolitan Development Guide calls for 20
"diversified centers, " essentially the same as MUC's, as part of the 1985
Constellation Cities Plan. Figure 2. 5 represents such a diversified center,
The unified architectural complex would house commercial facilities, offices,
high-rise apartments, public facilities such as a hospital, and perhaps a college
with easy pedestrian access. A metropolitan transit line would feed directly
into the center, which would also be connected to the nearby freeway by its own
interchange. An industrial park (upper left) would be located nearby to share
in many of the public facilities and services, such as mass transit, required
by the diversified center. Parking closest to the center's facilities is accom-
24
modated in structures; more distant parking is accommodated on surface lots.
Although Figure 2. 5 portrays an MUC for a suburban area, the concept
can be, and has been, applied within central cities (e.g. , downtown Montreal,,
Baltimore's Charles Center, and Philadelphia's Penn Center) and new towns
(e.g. , the Vallingby Town Center and Reston's Lake Anne Village Center).
The development of suburban regional shopping centers, however, appears to
be the greatest opportunity for creation of multi-use centers. Many shopping
centers stimulate an intense development pattern around them but, because
the surrounding land has not been planned and controlled comprehensively,
they generally fail to generate the advantages of an integrated MUC. Such
centers should be complementary to existing central business districts in
large urban areas where there is a need to accommodate growth. The
techniques through which new, more convenient land use forms can be
created include:
2-33
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-^SZ-^K.^Jmr< fl
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r^>y ' ry . It-Jt=5
* COMMERCIAL. RESIDENTIAL
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COMPLEX
JFMMil
-> < t .-*-r- ,^-^^-T | f*M' . ^ -
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-------
a. Broadened planned unit development regulations which make
all large commercial, industrial, and residential develop-
ments subject to site plan review and conditional approval
agreements.
b. Urban renewal planning and project implementation,
c. Detailed planning studies, designed to pinpoint the best
locations for multi-use centers, that define alternative
ways of stimulating their development.
7. Small Open Spaces
The impact of open space upon air pollutants is ill defined and some-
what non-quantifiable at this time. General consensus is that open spaces
and buffers must be quite large in order to perform an adequate diffusion
function. However, Figure 2. 6 indicates that small buffer corridors along
roadways could have a dissipating effect on automotive carbon monoxide
POLLUTION LEVEL AT ROADWAY
100 K-*
T>
3?
O
UJ
8
8
80
60
40
20
AMBIENT POLLUTION LEVEL
60
40 60 80 100 120 140
DISTANCE TO EDGE OF ROADWAY, feet
160 180
Figure 2.6 Pollution Level Vs. Distance to Edge of Roadway25
2-35
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emissions. If developments were kept away from the roadway edge a
reduction could be obtained in carbon monoxide concentrations. The
placement of plant materials within that buffer could further increase the
dispersal of pollutants and the protection of nearby residences. Although
research has not been done in this area, the fact that trees and other forms
of vegetation create some air turbulence and produce more humidity which
can trap particulates appears to justify the creation of small open spaces.
The urban planner can contribute to the creation and preservation
of these small open spaces by:
a. Developing regulations for requiring developers to provide
land for parks or cash in lieu of the land.
b. Encouraging and guiding planned unit development.
c. Providing subdivision site plan reviews.
d. Expanding the right-of-way standards for thoroughfares.
e. Requiring larger setbacks.
f. Instituting beautification and roadside landscaping
programs.
g. Developing tree preservation regulations.
2-36
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CHAPTER 3
REDUCING AIR POLLUTION THROUGH
TRANSPORTATION PLANNING, DESIGN AND OPERATIONS
In dealing with air pollution at both the regional and local levels, it
is important to recognize the significance of transportation facilities in
urban planning. Pollutant concentrations caused by vehicular traffic, or
"line sources, " accumulate along high-volume freeways and arterials and
are widely recognized as severe health hazards.
One of the major questions involves the allocation of resources to
achieve the goal of developing a rapid and convenient transportation system
which may be in conflict with the goal of preserving a clean air environment.
There are a number of feasible transportation alternatives, however, which
may have varying levels of environmental impact.
Both the role of the urban planner and the highway designer should be
concerned that the transportation plan, design, and operational alternatives
selected are sensitive to air quality criteria. Because transportation
facilities influence land uses, and vice versa, there is a high degree of
interrelationship in these functions.
Recent Federal legislation has underscored the urgency of integrating
transportation planning and pollution reduction programs. The Federal-
Aid Highway Act of 1970 specifically indicates that Federal air quality
standards be observed in the construction of highways. It states:
"The Secretary, after consultation with the Administrator
of the Environmental Protection Agency, shall develop and
promulgate guidelines to assure that highways constructed
pursuant to this title are consistent with any approved plan
for the implementation of any ambient air quality standard
for any air quality control region designated pursuant to the
clean air act as amended. "2
3-1
-------
This section of the Guide deals with the transportation planning
approach toward reducing air pollution. Suggested techniques are offered
to the planner who is attempting to incorporate air quality criteria into
the planning process.
A. TRANSPORTATION SYSTEM PLANNING STRATEGIES
Among the methods available to the planner are several which offer
a number of alternatives or combinations of alternatives, including
consideration of: decreasing highway travel by expanding transit use;
improving route location planning for new highways and the configuration
of existing roadway networks; developing compatible highway/land-use
relationships.
1. Multi-Modal Planning
One important way in which the planner can approach air pollution
reduction is by developing plans which may tend to decrease highway travel
through expanded transit usage. Strategies which call for wider use of
mass transit, including commuter rail, rapid transit, and buses should
be investigated and advocated where appropriate. Substitution of bus or
rapid rail transit for automobile travel can reduce hydrocarbon, carbon
monoxide, and nitrogen oxide concentrations.
The simulation described below was conducted to investigate the
metropolitan significance of mode choice and urban development for
pollution reduction.
Travel patterns were simulated by computer for a hypothetical 625
square-mile metropolitan area of two and one-half million people, under
varying assumptions about urban patterns, highway networks, and transit
3-2
-------
27
networks. Figure 3. 1 illustrates the varying assumptions used in the
analysis. Eight different urban patterns were investigated. The spatial
allocations of population and employment investigated included:
Sprawl
Moderate corridors
Heavy corridors
Corridors rotated
Extreme corridors rotated
Satellite cities
Centralized employment, sprawl population
» Centralized employment, radial population.
Four highway networks were examined:
A basic arterial grid
Freeways along major arterials
Major radial freeways with an outer beltway and inner
loop added
Additional radial freeways and an inner beltway added
for maximum coverage.
Three basic transit networks were examined:
A basic bus network with express bus service
Rapid rail along major radials with bus service
Relocated rapid rail service and an outer rapid rail loop.
A series of alternatives was then constructed consisting of a land
use-highway-transit arrangement; work travel patterns were simulated to
arrive at estimates of work trip length, average network speed, and
transit usage.
Analysis of the data indicated that the Satellite City Concept with the
maximum transit network and basic arterial highway system yields the
minimum length in miles. Transit usage is maximized by centralizing
employment and increasing urban densities in radial corridors.
3-3
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UMAN PATTERNS
Population
Population
Pottern B
Moderate Corridors
HIGHWAY NETWORKS
Alternate Psq
The Basic All-Arterial Geld
Alternate f"
Fre«*oyi Along Mo)o> Radiols
Employment Papula
Employme
,ploym»nl
Potter* D
Corridors Rotated
Pop,.lni,o
Employment
Employment Radial Population
Alternate 37
Mojof Radial Freeway* With Outer
Belt.oy And Inner Loop Added
Alternate 4
Additional Radial Freewoyi And Ar> Inner
Beltway Added For Maximum Coverage
TRANSIT NETWORKS
Alternate I
Basic Bui Network With E.pren Bui S.r»ice
Alternate 3
Relocates Rapid Roil Radial Service
And Addl An Outer RopirJ Ra.l Loop
Combines Rapid Rail Alono Major
Radials With Bus Service
LEGEND
0-3500
3500-5250 £
5250-122501
AND OVER
POPULATION
PER ZONE
^X
rj^^
0-1100
1100-2JOO
2200-6600
AND OVER
EMPLOYMENT
PER ZONE
ARTERIAL GRID
FREEWAYS
BASIC BUS LINES
EXPRESS BUS LINES
RAPID RAIL
Figure 3.1 Description of Urban Forms and Transportation System Simulation Study
,27
-------
These simulated changes in trip length, speed, and transit usage
indicate the substantial advantages of expanded transit operations in the
center city. Improved transit service and corridorization help increase
transit usage for work trips and reduce air pollution during the peak period.
Figure 3. 2 illustrates the effect of improved transit service on modal split
and air pollution reductions taking into account distance from the Central
Business District (CBD). Transit System 2 represents an improved level
of transit service over Transit System 1, thereby diverting riders from
automobiles and causing a reduction in automobile emissions.
The effect is to reduce air pollution from 18 percent in the CBD to
one percent in the periphery of the hypothetical city. At a distance of four
to five miles from the CBD there is a significant reduction in automobile
air pollution as a result of the improved transit service.
Other studies of modal split have indicated similar findings. In the
Twin Cities area, for example, the regional air pollution impact of transit
was negligible. 28 However, the positive effects (air pollution reductions)
hi the downtown area were considerable. Auto use during peak hours could
be reduced by about 13 percent by 1985 in and within about two miles of
the downtown area as a result of substantially improved express transit.
Automotive pollution in these critical areas could be expected to be reduced
by a similar amount.
Conclusions which have emerged from studies in the metropolitan
Chicago area indicate the influence which shifts to transit have upon air
pollution concentrations. The Skokie-Swift mass transit demonstration
project was opened in the Chicago area early in 1964 under the joint
sponsorship of HUD, the Chicago Transit Authority, and the village of
Skokie to provide improved CBD access for suburban residents.
As a result of this operation, auto trips declined by approximately 2000
trips per day, creating an estimated reduction in airborne hydrocarbons
of 13 percent.
3-5
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AIR POLLUTION REDUCTION
6 9
MILES FROM CBO
12
15
Figure 3.2 Effect of Improved Transit Service on Modal Split
and Air Pollution in a High Density Corridor27
3-6
-------
Transit improvements and associated policies which result in higher transit
ridership levels may result in reduction of pollutant concentration. However,
a policy of high density corridorization to support transit as described above
can conceivably be self-defeating with regard to reduction of pollution if
other urbanization effects contribute to air pollution levels. It should be
noted that transit, particularly rail rapid transit, is not a singular panacea
for transportation and air quality problems. All elements of the trans-
portation and urban plan must be jointly evaluated.
2. Improved Highway Location and Network Configuration
In considering alternative highway systems, the planner should consult
with the local air pollution control office. A planning framework should be
devised within which pollutant concentrations associated with various highway
alternatives can be predicted. Based upon such a framework, planners
could determine impacts with regard to location and capacity.
In conjunction with conventional travel forecasts, total emission
rates of various pollutants can be determined from individual automobile
emissions. However, methodologies are needed to translate such traffic
estimates into anticipated pollutant concentrations at various distances
from the highway and under varying meteorological and topographical
conditions. Dispersion modeling techniques need to be more effectively
implemented to provide this information. Armed with such data, the planner
can consider the impact on adjacent land uses in accordance with expected
pollutant behavior.
A suitable planning framework has been suggested by Schneiderman
31
et al. , in the form of proposed legislation. It would require the assembly
of data which comprehensively describes the pollution effects of a proposed
highway facility. The suggested framework is:
1. State highway departments shall obtain and consider
the following information in considering the air pollution
effects of the proposed location:
3-7
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1) Estimated future concentrations of each of the
following substances measured at intervals of
50 feet horizontally and vertically from the
center line of the proposed highway to a distance
of 2500 feet from the center line:
(a) carbon monoxide
(b) oxidants
(c) nitrogen oxides
(d) hydrocarbons
(e) asbestos
(f) lead
(g) particulate matter.
Such estimates shall be based on estimates of
traffic contained in FHWA Form PR-1, and
shall employ the method set forth for estimating
diffusion from line sources in D. Turnejr,
Workbook of Atmospheric Dispersion Estimates
(Public Health Service Pub. No. 999-AP-26 1967).
Such estimates shall be made for the various
climatic conditions prevailing in the area through-
out the year on a 24-hour, 8-hour and peak hour
basis.
2. Existing concentrations of pollutants for each 50 foot interval
shall be made for the proposed route of the highway. Such
measurements shall be made under the various climatic
conditions prevailing in the area throughout the year and
shall be made on a 24-hour, 8-hour and peak hour basis.
3. Existing average concentrations and estimated concentra-
tions after construction of the highway of each of the
pollutants listed in section (1) for the metropolitan area
as a whole and for each geographical subregion of the
metropolitan area through which the proposed highway
will pass.
4. Existing land use in each 50 foot interval for which
estimates and measurements are made under sub-
sections (1) and (2) and land use shown on any official
regional or metropolitan plan.
5. The most recent medical and scientific research of
the effects upon humans, animals, vegetation, and
property of the estimated concentrations of the sub-
stances at each 50 foot interval.
3-8
-------
This framework is discussed only to indicate a satisfactory level
of comprehensiveness for highway pollution data. Particular requirements
and standards utilized would have to be coordinated with local ambient
air quality standards. Using a similar procedure, an analysis of the
proposed Lower Manhattan Expressway undertaken by the New York City
Department of Air Resources revealed that excessively high carbon
monoxide conditions would have resulted.
Thus, the first step in highway pollution reduction for new facilities
would be the structuring of a planning process which estimates pollution
impact. The implementation of such a procedure may influence highway
air pollution impact in three ways:
a. Proposed facilities with high emission potential might be
diverted from sensitive areas.
b. Proposed facilities might be reconsidered in favor of a less
hazardous alternative.
c. Land adjacent to the proposed highway can be planned in
accordance with anticipated pollution levels.
Highway exhaust emission studies are unlikely to result in any
significant pollution impact reduction in the short run. However, over the
long term and in conjunction with sound land use planning, a substantial
percentage of new development may be expected to be relatively free from
excessively high automobile pollutant concentrations.
Decisions regarding the type of metropolitan transportation network
or the relative traffic loads on freeways versus arterials, or the merits of
constructing new roadway links versus improving existing ones are of
significance to the goal of air pollution reduction. However, establishing
guidelines for such network decisions is quite complex and will depend to
a large extent upon the particular area and its travel characteristics.
Among the goals to be considered are network configurations that:
a. Reduce trip length and total automobile travel,
b. Move traffic at faster and more consistent speeds.
c. Support the expanded use of transit.
d. Do not induce large amounts of new traffic to enter
congested areas.
3-9
-------
Generally, an increase in average network speed decreases carbon
monoxide and hydrocarbon emission rates per vehicle mile. Figure 3. 3
shows emissions per vehicle mile versus average network speed in miles
per hour for two major air pollutants, carbon monoxide (CO) and hydro-
carbons (HC). These relationships, combined with travel simulation
information, make it possible to identify the effect of different transport
networks on exhaust emissions for similar urban patterns.
200
5 150
E
i
o
I
O
100
50
10
CO
15 20 25
AVERAGE SPEED, mph
30
35
Figure 3.3 Relationship of Carbon Monoxide and Hydrocarbon
Emissions to Speed32
3-10
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Nitrogen oxide emissions increase with higher air/fuel ratios,
compression ratios, and engine temperatures. The relationship between
nitrogen oxide emissions and vehicular speed is not so well established.
27
It was found in the simulation study described at the beginning of this
chapter that highway network alternative 4 (see Figure 3.1), additional
radial freeways and an inner beltway for maximum coverage) provided the
best overall reduction in carbon monoxide and hydrocarbon emissions
essentially because of its increased average speed. It should be noted,
however, that the increase in speed is facilitated by the lower density of
the sprawl and heavy corridor configurations which were tested. Urban
planners should give close attention to this trade-off relationship between
trip length and average travel speed (i. e., trip length and travel speed
tend to be inversely proportional) since it will vary from city to city, depending
on various land uses and travel behavior.
A new high-speed highway will tend to induce new automobile traffic
to enter the city, possibly negating emission reductions due to higher
average speeds. (For a discussion of "induced" travel demand see
reference 33. ) Even though a new road may merely divert traffic from
other links, the resulting higher pollution concentrations may be serious.
The outputs of certain pollutants from a highway may be exceeded by the
total outputs from a number of arterials; but the highway, as a single line
source of concentrated pollutants, exceeds the emissions from any one of
31
the arterial streets.
However, it must also be recognized that streams of slow moving
vehicles may, under certain meteorological conditions, produce extremely
high pollutant concentrations in arterial street canyons. If adjacent regions
are heavily populated, the impact may be great enough to outweigh the
highway effects noted earlier. Such network configuration decisions are
complicated and vary among specialized situations, but it is essential that
the planner incorporate all these considerations in order to achieve the
maximum reduction in air pollution.
3-11
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3. Compatible Highway/Land Use Relationships
A general approach to the reduction of pollution impact is through
the regulation of joint corridor development and land uses adjacent to
rights-ol-way. If a highway has been determined to be absolutely necessary,
then it remains for the planner to ensure that receptors are sufficiently
removed from the area of high pollutant concentration.
In a study soon to be released, the General Electric Company
performed comprehensive air quality monitoring in area adjacent to high-
ways. The results of this study should substantially improve our knowledge
of the basic factors related to air quality and automobile emissions. Also
the District of Columbia Department of Highways is sponsoring a project
to investigate the concentrations of carbon monoxide adjacent to freeways.
Buffers between major roadways and resident locations are a most
effective technique for improving the compatibility of those roadways as
shown in Figure 2.6. Automotive carbon monoxide emissions dissipate by
about one percent for each of the first 50 feet of distance from the roadway
edge. Furthermore, carbon monoxide concentrations approach background
level at a distance of 160 feet.
One way to achieve this buffering is by utilizing legal provisions to
include extensive adjacent land during the process of advance right-of-way
acquisition. Depending upon comprehensive projections of pollutant behavior,
state highway departments can adopt land acquisition policies which provide
for buffer strips of variable width. However, the most effective buffer
strips are quite wide, and extensive acquisition of property for this purpose
may conceivably meet with legal opposition if conventional standards of
"public use" are observed. This would especially be true if right-of-way
acquisition involved massive relocation or displacement of property for
which there is a great deal of political sentiment.
3-12
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But new highway development within less developed areas is unlikely
to create such a conflict. Furthermore, there appears to be adequate
allowance in the law for acquiring buffer property, if the objectives of the
project contribute reasonably to public health, safety, or- welfare. Some
state courts consider such a public use test satisfied if formal commitments
are secured, assuring that such projects will not be resold or diverted
from public use for a stated period.
A number of state constitutions now allow the taking of land for
suitable building purposes on either side of a highway. Other1 states have
passed statutes allowing the acqusition of entire lots oven though only a
portion of the lot is needed for the highway,,
In the long term, therefore, it would be possible for the planner to
legally ensure adequate buffer space during the process of right-of-way
acquisition. This land could then be reserved for planted open space or
left vacant. An additional advantage of such a strategy is the uniformity
of administrative control over the land. Rather than being subject, to the
conflicting goals of perhaps several jurisdictions, an entire highway
corridor would be under the control of a state highway agency.
Through the administration of subdivision regulations, it is also
possible for local governments to increase their right-of-way standards for
public acquisition projects and land-owner dedications. The goal of pollution
impact reduction coincides with numerous other planning justifications for
increased right-of-way widths (the encouragement of frontage roads so that
access can be channelized, the reduction of highway traffic noise, and the
flexibility for future widening and traffic flow improvements),
Regulatory control of corridor land uses in developed areas is
another method of reducing pollutant impact. Devices such as municipal
setback requirements and corridor zoning can be utilized to achieve such
control. Objectives of using this kind of regulator;- approach would be
to impose selective limitations upon both commercial strip development
and proximity of inhabited structures to highways.
3-13
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Corridor zoning has been applied chiefly to protect the highway
environment by controlling abutting land use. But if applied with respect
to new highway development at the state or Federal level, it could become
a useful device for reducing pollution impact.
Zoning ordinances have been only moderately successful in
providing effective district controls for highway corridor land. One
remedy might be for Federal agencies to encourage uniform corridor
-development regulations through preparation and dissemination of model
regulations. A more promising Federal or state action would be to require
the existence of local controls which prescribe setback distances for various
land uses and highway classifications. Setbacks would be based upon
sensitivity of the particular land use to air pollutants, current and fore-
casted traffic volumes, and local dispersion characteristics. Certain
highly sensitive receptors such as hospitals, senior citizen housing projects
and schools would be prohibited from close locations. Making such regula-
tions a condition of qualification for Federal and state fund allocations would
possibly stimulate responsive local action.
As pointed out earlier, the presence of plant materials within buffer
strips can increase the dispersion of emission. More sensitive treatment
of existing woodlands as well as increased and improved post-construction
landscaping would be wise practices for highway departments. Urban and
transportation planners can work toward improved landscaping through local
zoning provisions which call for buffers, through the conduct of route studies
and through A-95 reviews of corridor location plans and design plans.
Another point which must be considered by the planner is the
regulation of joint development and multiple uses of highway rights-of-way.
Many planners feel that joint projects involving transportation rights-of-way
3-14
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offer great potential for integrating land use and transportation systems,
minimizing negative effects from freeways, opening up the limitations on
buildable space, and innovative urban designs. Joint-use projects may
include land within the right-of-way and may also be developed using the
airspace both above and below highways.
Although the joint development approach reduces many of the
environmental impacts caused by highways, it can also magnify air pollution
problems. Numerous studies have shown that locating inhabited structures
such as the George Washington Bridge apartments in close proximity to
highway facilities is likely to result in an unsatisfactory air quality
31
situation. Not only will excessive concentrations accumulate within
the buildings themselves, but the increased urban density results in more
intense traffic conditions and more exposure of people to the pollutants.
In the process of designing or reviewing joint development projects, the
planner should pay particular attention to improving the dispersion of
pollutant concentrations.
B. TRANSPORTATION DESIGN AND OPERATION TECHNIQUES
In addition to benefits to be derived from general transportation
planning, many benefits can be derived from small scale facility design
improvements and operational changes. These measures encompass the
following means of reducing harmful exposure to air pollutants:
Smoothing the flow of traffic
Reducing concentrations of traffic, both geographically
and by time of day
Reducing the total amount of automobile travel.
3-15
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The Guide for Reducing Automotive Air Pollution, a companion document
oriented toward transportation and traffic specialists, discusses a number
of techniques. All have been previously used or at least proposed in the
context of improving the capacity and quality of the urban transportation
system. The following discussion of techniques at the design and operational
level is a summary of the above-referenced guide, and that reference should
be consulted for more detailed information.
1. Techniques for Improving Traffic Flow
Carbon monoxide and hydrocarbon emissions increase with con-
gested traffic and decrease with freely flowing traffic. If the objective is
to reduce carbon monoxide and hydrocarbons, any measure that would
smooth the flow of traffic by reducing rapid acceleration and deceleration of
vehicles would be beneficial. Some techniques for accomplishing this are
listed below. The reader should clearly understand, however, that easing
congestion may have ancillary effects that would tend to undermine the goal
of cleaner air. The relationship between increased travel speed and
27
increased trip length has been established. Furthermore, a reduction
in congestion may tend to induce more people to drive. If no steps are
taken to reduce auto travel, the net result of improved traffic flow might
be more, longer, and more dispersed trips with greater amounts of pollu-
tants spread over a wider area. Thus, it is strongly recommended that
other measures set forth below be used concomitantly with improved traffic
flow techniques to reduce the overall number and length of automobile trips
in urban areas.
Each technique listed in Table 3.1 for improving traffic flow is
rated according to its "probable effectiveness, " using a scale of 1 (least
effective) through 5 (most effective). While it is impossible to place a
precise measure of effectiveness on each technique, there is sufficient
knowledge to assign an approximate value. The effectiveness ratings are
3-16
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TABLE 3. 1
TECHNIQUES FOR IMPROVING TRAFFIC FLOW
Probable
Effectiveness
A. Freeways
1. Re verse-lane operations 3
2. Driver advisory displays 1
3. Ramp control 2
4. Interchange design 2
B. Arterials
1. A linemen! 1
2. Widening intersections 3
3. Parking restrictions 2
4. Signal progression 2
5. Reversible lanes 3
6. Reversible one-way streets 3
7. Helicopter reports 2
C. Downtown Distribution
1. Traffic responsive control 5
2. One-way street operations 3
3. Loading regulations 3
4. Pedestrian control 1
5. Traffic Operations Program to Increase
Capacity and Safety (TOPICS) 5
3-17
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based on traffic volume affected, pollution reduction, population exposure,
and any adverse pollution affect (e. g., more or longer trips likely to be
induced, or likely to cause traffic congestion). The techniques apply to the
following areas:
a. Freeways -- Freeways have been the subject of
numerous operational studies and experiments. As
a result, the techniques for improving traffic flow
on freeways are relatively well developed.
b. Arterials -- Arterials are the backbone of most urban
street systems. Quite often, however, these systems
are unsuited for modern traffic demands and have
received less attention during recent years.
c. Downtown Distribution -- The downtown transportation
system is probably the most complex component of the
urban road system. From a functional viewpoint, the
nature of the downtown street system is largely
circulatory -- designed to serve adjacent land uses --
with the level of service to through traffic being of
secondary concern. Traffic flow is interrupted
frequently by pedestrian movements, vehicle turning
conflicts, traffic signals, and a high number of stop-
start transit vehicles in the traffic stream. A major
portion of vehicle time is spent idling, accelerating, and
decelerating, the result being a relatively high level of
air pollutant emissions. Any operational techniques
that can improve the stop-start nature of downtown
traffic flow can significantly reduce air pollution levels.
Due to high daytime population densities in the downtown
area, reduction in air pollution levels can benefit a
relatively large percentage of the population.
Although the application of these traffic-flow improvement techniques lies
basically with traffic engineers, it is important that the planner be aware
of them. Furthermore, there are several techniques that the planner
could use directly in the administration of a planning program. For
instance:
a. Central business district planning efforts should use
these techniques for improving downtown traffic and
pedestrian movement.
3-18
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b. Zoning ordinances should regulate loading
operations.
c. Planners who have a role in preparing a TOPICS
(Traffic Operations Program to Increase Capacity
and Safety) program should be increasingly sensitive
to its pollution-reduction payoffs.
2. Techniques for Reducing Pollution Concentration
The utilization and design of highways can be effective in reducing
the air pollution concentrations in the ambient air. If peak-hour traffic
concentrations were reduced by distributing traffic over a larger area and
over a longer period of time, that air space available to disperse pollutants
would be greater. Also, good design can imporve the operational charac-
teristics of the transportation system and thus minimize the concentration
of air pollution to which people, plants and structures are exposed. Con-
centration reduction techniques and their probable effectiveness are listed
in Table 3. 2
TABLE 3. 2
TECHNIQUES FOR REDUCING POLLUTION CONCENTRATION
Probable
Effectiveness
A. Staggered Work Hours 3
B. Roadway Concentrations 2
C. Cross-sections 2
D. Elevated, At-grade, Depressed Roadways 2
3-19
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A possible means of reducing peak-hour demands is to spread travel
over a longer period of time by staggering work hours. Staggered work
hours were first used in the United States during World War II, when
approximately 60 cities used the idea to alleviate the critical problem of
mass transportation capacity shortages. All cases achieved some degree
of success; many cities reduced peak period travel demand by as much as
34
30 percent. A more recent experiment in lower Manhattan has shown a
changed pattern in peaking characteristics. Figure 3.4 indicates the effects
for the afternoon peak of staggered work hours at the Port of New York
Authority Hudson Terminal.
8,000
6.000
4.000
2,000
FEBRUARY 1970 - 23,691
OCTOBER 1970
23,786
1,000 PASSENGER
REDUCTION
4:30 4:45 5:00 5:15 5:30 5:45
Figure 3.4 Effects of Staggered Work Hours,
Hudson Terminal Afternoon Passenger Volumes34
3-20
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The decision to design a new highway as an elevated, at-grade or
depressed facility can have a major effect on its air pollution impact.
Arguments in favor of depressing highways in urban areas usually point
to reduced neighborhood disruption and noise. These arguments may be
valid, but depressing a highway affords little opportunity for local wind
currents to disperse the emissions. Thus, the motorists traveling on a
depressed highway, as well as persons in adjacent areas, may be exposed
to unusually high concentrations.
Elevated highways, on the other hand, promote rapid dispersal of
pollutants away from the motorist. By virtue of being elevated, they are
more exposed to wind currents which transport as well as disperse pollutants.
While this pollutant dispersal represents a positix^e factor for the motorist,
the highway design engineer and urban planner must pay close attention to
how it affects adjacent land uses. It may benefit the motorist to have all
the pollutants transported away from an elevated highway, but if they are
transported directly into an adjacent building the result may be a serious
detriment to the occupants. In this regard, local meteorologists should be
consulted to determine the micro-climate of the design corridor. Needless
to say, the aesthetic aspects and other environmental impacts of elevated
highways have to be considered.
Efforts to reduce air pollution by changing highway design may not
be aimed as much at reducing total emissions as at reducing concentrations
at various significant distances from the roadway. Emissions can be
reduced by the design of the highway itself, or by regulating the relationship
between the highway and the adjoining land use.
3. Techniques for Reducing Auto Traffic Flow
Any program that focuses exclusively on improving traffic flow to
reduce air pollution is likely to be self-defeating. Traffic flow improvement
efforts must be accompanied by techniques for the reduction of auto travel.
3-21
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Currently, the best short-range approaches to reducing auto travel are:
to improve public transportation services, to reduce the number and length
of trips and to regulate the use of automobiles.
Traffic reduction techniques and their effectiveness ratings are
given in Table 3. 3.
TABLE 3.3
TECHNIQUES FOR REDUCING AUTO TRAFFIC
Probable
Effectiveness
A.
B.
Transit Operations
1. Bus lanes on city streets
2. Bus lanes on freeways
3. One-way streets with two-way buses
4. Park-ride, kiss-ride
5. Service improvements and cost reductions
Regulation
1. Parking bans
2. Auto-free zones
3. Gasoline rationing
4. Idling restrictions
5. Four- day, forty- hour week
Pricing Policy
1. Parking policy
2. Road-user tax
3. Gasoline tax
4. Car pool incentives
1
1
1
3
2
4
4
5
2
2
2
5
5
2
D. Planned Unit Development
a. Transit Operations -- The modal choice decision is
influenced by the myriad characteristics of competing
modes. Of particular importance are relative travel
time, relative cost, and relative service levels.
3-22
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Because of the difficulty of providing effective bus
service in low density residential areas, one of the
most promising transit improvements is the provision
of park-ride and kiss-ride facilities in conjunction
with express bus or other transit services.
b. Regulation -- There are several governmental policies
that go beyond the normal pricing policy in that they
regulate traffic by writ. Although they may be difficult
to implement in the political framework of decision
making, there can be no doubt about their effectiveness
in reducing traffic congestion and air pollution. In
any event, they may be useful measures to bear in
mind for possible implementation during emergency
air episodes.
The most effective potential technique -- gasoline
rationing -- is unfortunately the least likely to be adopted
and the most difficult to implement. Basically, each
vehicle would be alloted a certain amount of gasoline per
unit of time. It would be up to the vehicle owner to
limit his trips to those which he could accomplish within
his gasoline allotment.
Banning vehicles completely in certain parts of a city
has been tried in many locales. Tokyo has banned cars
from 122 of its busiest streets on Sundays, the busiest
shopping day in Japan; air pollution levels were cut in
half. New York City took similar action, resulting in
as much as a 90-percent reduction in carbon monoxide
levels on some auto-less streets. However, such a ban
tends to raise traffic levels, congestion, and attendant
pollution levels in adjacent areas.
c. Pricing Policy -- One way to reduce emissions is to
impose operating penalties or disincentives, which would
place special charges on traffic using congested roads.
Implementation of these techniques is often difficult. These
techniques, together with the urban planning strategies described in
Chapter 2 offer some methods for the planner to include when considering
the impact of alternative plans on urban air quality.
3-23
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APPENDIX A
INTRODUCTION TO AIR POLLUTION
To effectively incorporate air pollution considerations into urban
planning, the planner must become familiar with air pollution terminology
and characteristics. The purpose of this appendix is to provide this
information.
TYPES OF POLLUTANTS AND THEIR SOURCES
Classification of Pollutants
Air pollutants are commonly classified as either gaseous or particulate.
Gaseous pollutants behave much like the air itself; they do not settle out.
Particulate pollutants may be either solid or liquid, and their performance
in the atmosphere varies according to chemical composition and size:
heavier particles settle close to the point of emission; and smaller, less-
dense particles travel great distances. Urban aerosols, formed by the
grinding or atomization of solids and liquids, are particulate matter ranging
in size from approximately 6 x 10"7 to 1 micron; they include mist, smoke,
dust, fumes, and spray.
Air pollutants also can be categorized as either primary or secondary.
A primary pollutant is emitted directly into the atmosphere and initially
retains its form as emitted. A secondary pollutant is formed in the
atmosphere from reactions that may be chemical, photochemical, or
biological.
A third way of classifying pollutants is by chemical composition --
either organic or inorganic. Many of the most common pollutants -- the
oxides of carbon, nitrogen, and sulfur -- are inorganic; organic pollutants
include hydrocarbons, aldehydes, and ketones.
A-l
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To classify an air pollutant properly, all three classifications should
be used: for example, carbon monoxide is a primary, inorganic, gaseous
pollutant.
Units of Air Pollution Measurement
Air pollutants can be quantified in several ways: on the basis of
emissions from sources, according to concentrations in the ambient air,
or according to rates of exposure.
The source strength of air pollutants can be quantified in units of
mass or weight per unit volume- for example, grams per cubic meter of
air or pounds per cubic foot. Emissions may also be stated in terms of
\veight per unit time, weight per unit weight of product, weight per BTU,
weight per unit area for area sources, or mass per unit distance for vehicles.
Concentrations of pollutants in the ambient air are normally reported
as mass or weight per unit volume of air, such as micrograms per cubic
meter. The unit parts per million (ppm), although used, is being discontinued.
Settleable particulate matter sometimes is expressed in terms of tons per
square mile per month or the currently recommended grams per square
meter per month; and suspended particulate it, measured in micrograms
per cubic meter or Coh's (Coefficient of Haze), a unit of measurement of
visibility interference.
Also of concern in the expression of concentrations of air pollutants
is the quantity and duration of exposure experienced by plants, animals, or
humans. Called the dosage or rate of exposure, units indicate both concentra-
tion and time involvement, with levels stated in terms of micrograms per
cubic meter either per hour, 8-hour period, day, or year. In many cases,
the average concentration over a given period of time is of concern; in
other cases, the maximum concentration is more important.
A-2
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When reviewing regulations or statements concerning concentrations
of air pollutants, it is important to understand the units used; that is,
whether they relate to the ambient air concentrations, to emissions, or to
exposure dosages.
A ir Pollutants and Their^Sources
Pollutants emitted to the air in greatest abundance are carbon
monoxide (CO), particulate matter, oxides of sulfur (SO }, oxides of
A
nitrogen (NO ), and hydrocarbons (HC). Emission inventories of these five
A.
pollutants are commonly divided into five source categories: transportation,
fuel combustion in stationary sources, industrial processes, solid waste
disposal, and miscellaneous. Nationwide emissions by category for 196P,
presented in Table A. 1, indicate that carbon monoxide is the major pollutant
by weight, and that transportation activities are the major carbon monoxide
contributor.35 A different study36 indicates that emissions of urban origin
from stationary combustion and transportation activities account for greater
than 75 percent of the total emissions in these five pollutant categories.
The motor vehicle (gasoline and diesel) is a major contributor to air
pollution. It contributes approximately 60 percent of the total carbon
monoxide from all sources, about 50 percent of the hydrocarbons, and
35 percent of the nitrogen oxides.
Oxides of sulfur are chiefly products of fossil fuel combustion.
About 80 percent of the sulfur in coal and nearly all that in liquid and gas
fuels appears in flue gases as sulfur dioxide (SO2>. Almost all fuels,
except wood, contain sulfur: however, they differ widely in their sulfur-
content. Bituminous coal has a high sulfur content; in some locales as
high as 6 percent. Most crude oil contains less than 1 percent. Gasoline
seldom contains more than 0. 25 percent. For the relative sulfur content
of various fuels, see Table A. 2. Natural gas is virtually free of sulfur.
A-3
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TABLE A. 1. ESTIMATED EMISSIONS OF AIR POLLUTANTS
BY WEIGHT,a NATIONWIDE, 196935
Source
Transportation
Fuel combustion in
stationary sources
Industrial processes
Solid waste disposal
Miscellaneous
Total
a
In millions of tons per year.
CO
111.5
1.8
12.0
7.9
18.2
151.4
Particulates
0.8
7.2
14.4
1.4
11.4
35.2
ar.
SULFUR CONTENT
SO
X
1. 1
24.4
7.5
0. 2
0.2
33.4
OF FUELS
HC
19.8
0.9
5.5
2.0
9.2
37.4
36
NO
X
11.2
10.0
0.2
0.4
2.0
23.8
Percent by Weight
Type of Fuel
Bituminous 0.3 - 6. 0
Anthracite 0. 6 - 1.0
Coke 1. o maximum
Wood Negligible
Crude Oil 0. 2 - 1.7
Fuel Oil 1.0 maximum
Diesel Oil 0. 5 maximum
Gasoline 0. 1 - 1.0
A-4
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Another common source of SO in the atmosphere is metallurgical
operations. Many ores, such as copper, lead, and zinc are primarily
sulfides. During the smelting of these ores, sulfur is oxidized and is
evolved as sulfur dioxide.
The more important sources of particulate matter are industrial
process operations, domestic heating plants, industrial power plants,
refuse incinerators, open fires, construction activities, diesel engines,
and automobiles (see Table A. 3). The amount of particulate matter
released from each of these sources varies considerably. The most
common emissions are carbon or soot particles, metallic oxides and salts,
oily and tarry droplets, acid droplets, silicates and other inorganic dusts,
and metallic fumes.
Ozone is the principal constituent of the atmospheric substances
called photochemical oxidants. They are secondary pollutants, formed by
the action of sunlight in a series of complex reactions between hydrocarbons
and oxides of nitrogen, which are both emitted primarily from transpor-
tation sources.
VARIATIONS IN AIR POLLUTION CONCENTRATIONS
Variations in air pollutant concentration at or near ground level are a
function of both meteorological parameters and emissions, both of which
vary in time and space. Both fluctuate from place to place according to
daily and annual patterns; the latter also exhibit weekly variations. Thus,
pollutant concentrations are a function of location, time of day, day of the
week, and season of the year.
Variations According to Location
Variations according to location are the natural produce of non-
uniform distribution of pollution sources (freeway versus center city
A-5
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TABLE A. 3. SOURCES OF ATMOSPHERIC
PARTICULATE MATTER
Combustion
Fuel burning
Incineration
Open fires
Burning dumps
Forest fires
Materials Handling
and Processing
Loading and unloading
(sand, gravel, ores,
coal, lime, bulk
chemicals)
Mixing and packaging
(fertilizers,
chemicals, feed)
Crushing and grinding
(ores, gravel,,
chemicals, cement)
Food processing
(milling, e.g., flour,
cornstarch; drying;
handling grain)
Earth
Moving
Construction
(roads, dams,
buildings,
site clearance)
Mining
(blasting,
sorting, refuse
disposal)
Agriculture
(land prepara-
tion, soil
tilling)
Miscellaneous
House cleaning
Sand blasting
Crop spraying
Poultry feeding
Rubber-tire
abrasion
Engine exhaust
traffic) and the random movements of air and weather patterns (rain and
fog). Figure A. 1 illustrates significant variations in pollutant concentration
(in this case, carbon monoxide) as recorded at three different sites in the
Detroit area.
The many meteorological observations accumulated over decades
permit a fairly reliable estimate of the air pollution potential in various
sections of the United States. Regions with a clean sweep of winds within
the major storm tracks are least likely to develop high pollution conditions;
regions dominated by stagnant air masses and light winds are most likely
to experience high pollution conditions.
A-6
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Variations by Time Periods
Space heating and solar radiation are the two major factors influencing
seasonal variations in air pollution levels. Secondary pollutants, such as
photochemical oxidants, generally are worst in the late summer or autumn
when optimal combinations of solar radiation, temperature, and atmospheric
stagnations coincide.
Weekly variations in carbon monoxide are a function of the different
transportation and activity patterns associated with weekdays, weekends,
o o
and holidays. A study revealed a distinct 20 percent decrease in the
average carbon monoxide concentrations during the weekend compared to
the higher weekday levels. In urban communities where there are many
weekend travelers, the reduction is considerably less.
In general, meteorological conditions at night encourage the accumu-
lation of pollutants; those in the day encourage their rapid dispersion
Diurnal variations in carbon monoxide concentrations are illustrated in
Figure A. 1. Figure A. 2 shows diurnal variation in concentrations of
hydrocarbons, nitrogen oxides, and oxidants. In these examples, carbon
monoxide, hydrocarbons, and nitrogen oxides exhibit two daily peaks.
40
Considerable work has been directed toward correlating these peaks
UJ
Q
X
O
o
00
X
<
O
LODGE-FORD FREEWAY INTERCHANGE
GRAND CIRCUS PARK
GM TECHNICAL PARK, WARREN
4 -
2 -'
M 2*
M
TIME OF DAY
Figure A.1 Hourly Carbon Monoxide Concentrations on Weekdays in Detroit Area38
A-7
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with traffic flow and meteorological factors. The studies have indicated
that concentrations of these three pollutants generally exhibit a higher
correlation with traffic volume than with meteorological conditions. Only
one peak has been observed for photochemical oxidants. It generally
occurs near midday, in spite of more atmospheric mixing at that time,
due to favorable reaction conditions of solar radiation and temperature.
A delay between the hydrocarbon and nitrogen oxide peaks and the oxidant
peak is normal because the oxidants are produced by chemical reactions
involving hydrocarbons and nitrogen oxides.
Figure A. 3 illustrates the daily variation in ground-level pollutant
concentrations that can be expected some distance downwind from a tall
stack on a clear day with light winds. In this example, the pollutant is
emitted from the stack at a constant rate; therefore, the changes shown
in ground-level concentration result entirely from meteorological
influences. The morning maximum is due to a stable atmosphere and
prevention of upward dispersion of the pollutant by an inversion layer, a
meteorological condition described in the following section. The rapid
decrease in concentration is due to the heating of a progressively deeper
layer of air above the ground and mixing of the pollutant throughout this
layer. After the period of maximum heating, increased stability near the
surface causes concentrations to increase in the late afternoon.
METEOROLOGY
Meteorological and topographical conditions in some areas favor the
accumulation of pollutants. Lighter particles and gases diffuse only as
rapidly as meteorological conditions permit. During this diffusion, the
nature of the pollutants may be changed by natural, physical, or chemical
processes, such as solar radiation, rain, fog, and interaction with the
normal constituents of the atmosphere. Typical examples are the
oxidation of nitric oxide to nitrogen dioxide and the photochemical action
that forms oxidants.
A-8
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I- 8-
z E
|S
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In a dry atmosphere, the adiabatic lapse rate (rate of temperature
decrease with increase in elevation) is 1 C per 1000 meters (5.4 F per
1, 000 feet). When the actual lapse rate is greater than this theoretical
rate, a parcel of air that begins to rise continues to do so, and the
atmospheric condition is called "unstable. " If, however, the actual lapse
rate is less than the adiabatic rate, the surface air remains near the
surface and the atmospheric condition is called "stable. "
An increase of temperature with altitude (an inversion) can occur at
any time, but is most common during the night and early morning. An
inversion acts as a lid; it separates layers of air and prevents polluted
air from rising. If an inversion is accompanied by low winds, a layer of
highly polluted air may build up over a broad area.
Three major forces -- wind, heating, and cooling -- cause shifts
from stable to unstable conditions and back again. Wind, in addition to
horizonatal motion, usually has vertical eddies and, since rapid vertical
air motions tend to be adiabatic, helps to establish an adiabatic lapse rate.
The sun, which heats the surface more than the air, increases the lapse
rate, and, thus, contributes to instability. Conversely, at night the ground
loses more heat by radiation than the air does, tending to make the surface
cooler than the air layers above; this cooling contributes to stability.
Usually there is a daily cycle from stability to instability and back again.
When the cycle is broken and the atmosphere remains stable for a prolonged
period, a serious accumulation of pollutants is possible.
High pollution potentials are generally favored by light winds and
clear skies which promote the formation of temperature inversions. A
buildup of high pollution concentrations in the central core of the cities
then occurs as the result of this inversion "lid" coupled with a near-surf ace
air movement toward the center city. This air flow is the result of the
heat island effect in which the asphalt and concrete city heats up and acts
like a chimney, drawing in cooler air from the surrounding areas.
A-10
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High pollution potential is defined as a stagnating anticyclonic
condition which, coupled with the continued operation of several sources,
is conducive to the occurrence of high concentrations of pollution. As
defined, the high pollution potential refers to developing meteorological
conditions only. The National Meteorological Center in Suitland, Maryland,
prepares daily 36-hour alerts. This information, called Air Stagnation
Advisories (ASA), is available through U. S. Weather Bureau Stations.
Being an objective system, the method has its shortcomings, the greatest
of which is the lack of individual appraisal and forecasting for each city,
based on its local meteorology and areal distribution of pollution sources.
The local air pollution control office can provide the necessary in-depth
knowledge of a specific urban community.
Within the space of a few miles, microclimatic conditions may con-
siderably influence the effects of pollution. A detailed survey of the
meteorological terrain is needed to assess variations in local conditions;
this is particularly advisable when planning future communities and
industrial areas. For example, it used to be a rule of thumb to locate
industrial areas downwind of a settlement with respect to the prevailing
wind direction. Unfortunately, in many instances the wind at times of
stagnation or near-stagnation conditions may be quite different from the
most frequent wind. In some cases, the slight draft under those conditions
may be entirely opposite to the prevailing wind, thereby causing a more
severe pollution condition than would have been anticipated.
SITE CONDITIONS AFFECTING DISPERSION
The city in a general sense may be considered a collection of micro-
climates. The pattern and profile of the air motion in the total atmosphere
over an urban area are modified, sometimes considerably, in each of these
microclimates by the spatial arrangement and character of buildings and
other .structures, by surrounding vegetation, and by roadway configurations.
A-ll
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Superimposed on this is the air movement resulting .from traffic flow. In
addition, the relative influence of each of these factors depends on the
magnitude of the background air movement and solar heating conditions.
Factors found to be dominant at higher wind speeds may decline in
significance at the lower wind speeds which present the greater potential
for severe pollution episodes.
Urban Heat Island Effect
The combined effects of topography and urbanization decidedly
influence the radiation, moisture, and temperature conditions of a city.
These, in turn, modify the wind flow patterns. In an urbanized region,
vegetation is replaced by a vast man-made environment, resulting in
changes in moisture conditions which, in turn, alter the heat distribution.
The air is heated by multiple sources including industries, automobiles,
space heating, and solar radiation.
It has been estimated that the automobile is an important artifical
heat source in the street canyons of a city. Very heavy traffic in parts of
o 41
London, for example, add an estimated 8 F to the air temperature. Bach
calculated that for the built-up area of Sheffield, England, the annual
artificial heat generation is about one-fifth of the direct solar radiation
received. The ratio is one-third for Berlin. Particulate matter, a by-
product of most artificial heat generation, may be 5 to 25 times greater
in the urban area than in the rural area.
Temperatures in the urban heat island have been found to be on the
o
order of 5-8 C greater at night than in the surrounding rural areas.
Sidewalks, roads, and concrete buildings have relatively high heat
capacities and conductivities. The daytime heat storage is greater than
for grass-covered fields or forests. The lack of evaporational cooling
from the dry building surfaces increases the stored solar energy. After
sunset, the stored daytime heat is released from buildings and pavements
A-12
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resulting in air temperatures and winds in the city higher than those
42
occurring in the surrounding country. Munn notes that the heat storage
ability of a city is believed to be the major factor of the heat island
formation. He adds that the city is a collection of microclimates, each
dependent upon the character of a built-up area within the entire city.
The heat island effect is found to be maximum in late summer and
early autumn when the skies are clear and winds are light. Figures A. 4
and A. 5 illustrate the morning and evening air culation and dispersion
models in a city and in the surrounding country under anticyclonic conditions.
Building Configuration Effects
The orientation of a building with respect to the winds produces
significant distortions in the local wind pattern. The significance of the
flow distortions becomes clear when vehicular emissions exist within an
area surrounded by buildings. Air currents can trap pollution, confining
it close to the buildings. Pollutants emitted from building roof vents may
also become trapped. Hence, roadway vehicular emissions and emissions
from rooftops can be conveyed into windows, doorways, and air intake
systems.
As background wind speeds decrease, the effect of the vertical
temperature profile (lapse rate) increases and becomes a major controlling
factor in the atmospheric dispersion of vehicular emissions in the urban
street canyon.
During periods of light winds and clear skies, air flow around
buildings is, to a great degree, the result of convective updrafts coupled
with winds flowing into the center of the urban heat island. The updrafts
remove pollutants from the area of the building more effectively than
strong horizontal winds if no inversion exists.
The upward dispersion of vehicular emissions is often restricted in
the early morning hours by the presence of a stable layer existing from the
A-13
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300 -
. 200 -
ui
Q
±100-1
CITY COUNTRY
Figure A.4 Urban Circulation and Dispersion After Sunrise41
o
1 100
Figure A.5 Urban Circulation and Dispersion After Sunset41
A-14
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ground to roof level. The pollutants are trapped in or below this layer.
This phenomenon is most pronounced in the walled street canyons of
urban centers.
Various building configurations and orientations alter the air flow
pattern considerably. Rows of tall buildings lining urban streets modify
the microclimate by changing the topography and general aerodynamic
boundaries. In these street canyons the dispersion of the pollutants is
determined by the turbulent wake of the traffic, by the differential heating
of building tops and streets, and by the general background air movement.
Wind speeds at street level may be only 40 percent of the wind speed above
the roofs of the buildings.
More open roadway planning with the buildings set back will alleviate
this canyon effect. While traffic volume along a roadway section has the
most direct relationship to emissions, the higher midafternoon wind speeds
are the most effective factor in reducing the urban street canyon air
pollution concentrations. This effect is gradually lost later in the afternoon
as the overall wind speeds start to decrease and traffic volume once again
peaks.
Roughness Effects
The background wind is also modified by the texture and height of
surrounding features: buildings, trees, grass, brush, and streets. For
example, as wind passes from an orchard to an open field, the wake effect
is similar in many ways to that behind a building. Within approximately
one-quarter mile, the original near-surface wind speed is re-established.
There is an updraft in the air movement as it encounters a rougher
surface, such as a row of trees.
Thus, a wide tree-covered green belt along both sides of a major
traffic artery provides more rapid dispersion of vehicular emissions. In
A-15
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an urban area, similar transitions can be arranged -- between roadway
and green belt, park and buildings, parking lots and streets, and low-
and high-rise buildings. The resulting turbulence can lead to more
dispersion and dilution.
URBAN AIR POLLUTION MODELS
Many mathematical models describing the diffusion process have
been developed to relate pollutant emissions to ambient pollutant levels.
These models vary from one equation of plume dispersion from a single
source to complex programs capable of considering all sources in a
major metropolitan area and providing the resulting ground-level con-
centrations at all locations in the area. The great number of calculations
in all but the most simple models requires the use of a computer.
A mathematical model, with appropriate input data and the proper
interpretation of results, can be a valuable tool for the planner. It can
be used to determine: (a) consequences of a new pollution source on
pollutant levels and patterns; (b) effects of alternative solutions in urban
planning on pollution levels; (c) evolving pollution patterns in an expanding
city; (d) effectiveness of various control strategies to reduce pollution
levels in an area; and (e) emergency curtailment measures to be taken
during episodes of high pollution levels.
A model should be selected to match the amount of data available,
types of sources being considered, and time span of importance (e. g.,
long-term pollutant average for planning purposes and one-hour maximum
for emergency episode prevention). The data required fall into three
categories: (1) source information, including location, emission rates,
and stack exit parameters; (2) meteorology, particularly wind speed, wind
direction, and mixing depth: and (3) measured pollutant levels to verify or
calibrate the model output.
A-16
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Some caution should be exercised in using modeling results. The
accuracy of output values is limited by the accuracy and adequacy of the
input data. Also, the models are derived by assuming normal dispersion
patterns and, therefore, are generally not capable of predicting pollutant
levels near localized obstructions or in the vicinity of highly irregular
topography.
A-17
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APPENDIX B
COOK COUNTY ZONING ORDINANCE
This excerpt from the Cook County, Illinois, Zoning Ordinance
illustrates the type of emission standards which can be applied in an
urban area.
PERFORMANCE STANDARDS -- SMOKE AND PARTICULATE MATTER
A. Any use established in a Manufacturing District or in a Motor
Freight Terminal District after the effective date of this comprehensive
amendment shall be so operated as to comply with the performance
standards governing smoke and particulate matter set forth hereinafter
for the district in which such use shall be located. No use lawfully established
on the effective date of this comprehensive amendment shall be so altered
or modified as to conflict with, or further conflict with, the performance
standards governing smoke and particulate matter established hereinafter
for the district in which such use is located. Any use lawfully established
on the effective date of this comprehensive amendment shall be permitted
to be altered, enlarged, expanded, or modified, provided that new sources
of smoke and/or particulate matter conform to the performance standards
established hereinafter for the district in which such use is located. The
total emission weight of particulate matter from all sources within the
boundaries of the lot shall not exceed the net amount permitted in the district
in which the use is located after such alteration, enlargement, or modification.
B. In addition to the performance standards specified hereinafter,
the emission of smoke or particulate matter in such manner or quantity as
to be detrimental to or endanger the public health, safety, comfort, or
welfare is hereby declared to be a public nuisance and shall henceforth be
unlawful.
B-l
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C. For the purpose of grading the density of smoke, the Ringelmann
Chart, published and used by the United States Bureau of Mines, shall be
employed. The emission of smoke or particulate matter of a density
greater than No, 2 on the Ringelmann Chart is prohibited at all times,
except as otherwise provided hereinafter.
ALLOWANCE FOR HEIGHT OF EMISSION3
Height of Emission
Above Grade (Feet) (Pounds^Per Hour Per Acre)
50 0.01
100 0.06
150 0.10
200 0.16
300 0.30
400 0.50
a Interpolate for intermediate values not shown in table.
Determination of the total net rate of emission of particulate matter
within the boundaries of any lot shall be made as follows:
1. Determine the maximum emission in pounds per hour
from each source of emission and divide this figure by
the number of acres of lot area thereby obtaining
the gross hourly rate of emission in pounds per acre.
2. From each gross hourly rate of emission derived
in (1) above, deduct the correction factor (interpolating
as required) for height of emission set forth in the table,
thereby obtaining the net rate of emission in pounds per
acre per hour from each source of emission.
3. Add together the individual net rates of emission derived
in (2) above, to obtain the total net rate of emission from
all sources of emission within the boundaries of the lot.
Such total shall not exceed one pound per acre of lot area
during any one hour.
B-2
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PERFORMANCE STANDARDS -- TOXIC MATTER
Any use established in a Manufacturing District or in a Motor
Freight-Terminal District after the effective date of this comprehensive
amendment shall be so operated as to comply with the performance
standards governing emission of toxic matter set forth hereinafter for
the district in which such use is located.
Performance Standards -- Toxic Matter --Ml District
In the Ml District, no activity or operation shall cause, at any time,
the discharge of toxic matter across lot lines in such concentrations as to
be detrimental to or endanger the public health, safety, comfort, or
welfare, or cause injury or damage to property or business.
PERFORMANCE STANDARDS -- NOXIOUS AND ODOROUS MATTER
A. Any use established in a Manufacturing District or in a Motor
Freight-Terminal District after the effective date of this comprehensive
amendment shall be so operated as to comply with the performance
standards governing noxious and odorous materials set forth hereinafter1
for the district in which such use shall be located. No use lawfully
established on the effective date of this comprehensive amendment shall
be so altered or modified as to conflict with, or further conflict with, the
performance standards governing noxious and odorous materials established
hereinafter for the district in which such use is located.
B. In addition to the performance standards specified hereinafter,
the emission of noxious and odorous matter in such manner or quantity as
to be detrimental to or endanger the public health, safety, comfort, or
welfare is hereby declared to be a public nuisance and shall henceforth
be unlawful.
B-3
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Performance Standards --Noxious and Odorous Matter -- Ml District
In the Ml Districts no activity or operation shall cause at any
time the discharge of matter across lot lines in such concentration as
to be noxious. The emission of matter in such quantities as to be readily
detectible as an odor at any point along lot lines is prohibited.
B-4
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APPENDIX C
FUEL ALTERNATIVES AND STACK HEIGHT
This Guide discusses land use and transportation planning as it may
be used to achieve better ambient air quality. There are many air
pollution controls that are not ordinarily considered as land use or trans-
portation planning. These include emission controls, changes in industrial
processes and raw materials, fuel switching, changes in industrial opera-
tion and maintenance procedures, and regulations governing stack height.
Planners may, on occasions, deal with all of these controls. Two are
discussed below.
FUEL ALTERNATIVES
Today's economy is profoundly dependent upon oil and gas. Petroleum
provides the fuels for practically all of the nation's transportation, and
oil and gas together satisfy over 90 percent of the national requirement
for heat, three-fourths of the energy used by commerce and industry,
and nearly a third of the fuel used for power generation.
Two fossil fuels, coal and oil, have been and remain widely used
fuels for space heating and industrial uses. The types of coals used in
early times, and even until recent years, were selected on the basis of
cost and BTU production rather than on their air pollution potential. High
sulfur content and low temperature of combustion often result in the
emission of vast amounts of sulfur compounds and particulates to the air
environment. In fact, coal fires produce smoke, sulfur dioxide , nitrogen
oxides, and particulates. The use of oil as a new source of fossil fuel
has greatly diminished particulate air pollution because of its nearly total
combustion.
C-l
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The third fossil fuel, natural gas, has now become a major source
of energy for power production and residential space heating and is
attractive because of its extremely low air pollution potential. Although
there is an abundance of natural gas now, it is likely to be the first energy
source to experience shortages. Based on current trends natural gas
consumption will continue to increase at the rate of 4 to 5 percent per year
in the immediate future, but after that, when it becomes less available for
large volume, long-term contracts, it will be used less and less by large
consumers where other fuels can serve as well.
Two non-combustive sources of energy are of particular interest.
These are nuclear and hydroelectric power plants. It is also conceivable
that solar energy will eventually be a major "clean" source, but major
technological development will be required.
Hydroelectric power is a limited source because of the practical
restriction in available sites for power generating plants. Hydroelectric
plants account for less than 5 percent of the energy produced in the United
States, considering both stationary and non-stationary sources. Although
the amount of energy from this source will increase substantially, it is
forecast to decline as a percentage of total national energy consumption.
It appears that there may be a tendency toward increasing use of
nuclear energy. One of the vital planning functions in the coming decade,
therefore, will be the location of power plants on a regional basis. The
plants should preferably be near the urban areas of power demand; however,
planners must contend with thermal pollution. Nuclear power plants
require approximately 50 percent more cooling capacity than do fossil fuel
plants of equivalent size. If cooling towers are installed, as proposed for
some nuclear power plants, air quality effects such as fog and humidity
should be considered. If cooling is accomplished by cold water from rivers,
lakes, or oceans, the quantities of water required would affect the site
selection of nuclear power plants.
02
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The ranking of fuels from the lowest to the highest cost per energy
unit begins with coal, and then proceeds to oil, natural gas, and finally to
nuclear energy. Because of the higher costs and other problems of
nuclear reactors, combustion of fossil fuels (coal, oil, and natural gas)
is certain to increase for a number of years. Coal and oil combustion,
however, create the worst air pollution; more than 50 percent of the sulfur
dioxide, 25 percent of the nitrogen oxides, and nearly 30 percent of the
particulates of the total tonnage of pollutants are produced by electric
power generation.
During times of air pollution emergency, proper planning can reduce
emissions either by fuel switching techniques or by production curtailment.
As an example of the impact of fuel changes, Figure C-l shows the re-
duction in pollution achieved through switching from high-sulfur fuel to
low-sulfur fuel in residential heating units. The changes from coal to
fuel oil and natural gas have a drastic impact on emission quantities.
Significant gains can be realized through such an approach, especially
in the reductions of pollutant emission due to space heating. In particular,
urban renewal programs and administration of housing codes offer oppor-
tunities for the planner to exercise some control over residential and
commercial heating system conversion. One study43 defined the four
basic factors that influence the change in the levels of sulfur oxides in
Chicago. These are: the control ordinance limiting the sulfur content of
fuel, the natural evolution of the city, changes in fuel use patterns, and
industrial relocation. The degree to which each of these factors affects
the individual components of the region, such as manufacturing, residential,
utility, and commercial areas is shown in Table C-l which presents data
and projections for total yearly sulfur oxide emissions for 1970, 1975, and
1980, based upon anticipated control of the sulfur content of fuels and on
changing patterns in the urban area.
C-3
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250
FUEL OIL
(0.4% SULFUR)
2,000 4,000 6,000 8,000
DWELLING UNITS PER SQUARE MILE
Figure C.I Sulfur Oxide Emissions from Burning Different
Fuels in Residential Heating-St. Louis
10,000
Table C.I. ESTIMATED YEARLY SULFUR OXIDE
EMISSIONS IN TONS FOR CHICAGO43
Heavy
Residential Utilft
Light
Industry Commercial Total
1970
1975
1980
.VJMb H A V* *«
56,
32,
35,
fe^rfV^AA *,»*k
300
17%
700
36%
900
40%
69,
32,
27,
400
21%
900
37%
300
30%
_ X.
169,800
50%
200
0%
0
0%
30,
17,
19,
900
9%
000
19%
800
22%
11,300
3%
6,800
8%
6,800
8%
337,700
100%
89,600
100%
89,800
100%
C-4
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It may be effective to institute a broad policy of economic incentives
through penalties and tax advantages to accelerate the conversion of
existing heating units to low sulfur fuels. Long-term low interest loans
and tax advantages could be applied to entice homeowners to replace old
heating units. In areas identified as seriously polluted, such a policy
could be implemented by requiring property owners to convert to low-
pollution units within a specified period.
Another approach to fuel conversion would be to legislate dwelling
unit density/fuel ratios for new and redeveloped areas. Depending upon
the ambient concentration of, for example, sulfur dioxide, the density of
development can be controlled by municipal subdivision regulations. Based
upon the maximum tolerable pollutant concentration, density limits can be
calculated for various fuels of differing sulfur content. Because natural
gas produces virtually no sulfur dioxide emissions and electricity
produces none, regulations would not restrict densities in areas where
these heat sources are used.
STACK HEIGHTS
In addition to site changes, there are other measures, associated with
source configuration, which can be taken to reduce the sphere of pollutant
impact. Because methods of isolating sources through land use regula-
tion must be coordinated with their emission characteristics, it is im-
portant that the planner consider some of the more significant design
aspects of stationary sources.
For example, there exist methods of determining the required mini-
mum height of a discharge stack that will prevent accumulation of pollutant
concentrations from exceeding permissible limits near the ground. Such
methods can be applied to assess the actual ground level pollution hazard
of specific industrial or power facilities, permitting a useful basis for
altering land use allocations.
C-5
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Taller stacks generally result in the reduction of contaminants near
ground level. To alleviate air pollution hazards, tall stacks that tend to
emit gaseous wastes to the atmosphere can be built. Increasing the stack
height can also modify the impact of a looping plume. A looping plume
may result when a turbulent eddy, caused by certain brisk winds, encloses
a puff of smoke and brings it rapidly down to ground level with little dilution
of pollution. The taller stack reduces the frequency of ground level effects
from looping plumes, but widens the area of possible impact.
For over 30 years, stack heights of 400 to 600 feet have been found to
be effective in reducing sulfur dioxide pollution from smelting operations
and other forms of air pollution. There must, however, be a practical
upper limit to the maximum power plant stack height and size because of
the diminishing returns and questions of cost, construction difficulty,
and aircraft hazards. What this size limit may be depends upon the
amount of pollution emitted, the frequency of the unfavorable meteoro-
logical conditions, and the definition of acceptable concentration levels.
Given these quantities, the planner can evaluate the potential effect of
devices such as buffer zones.
06
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APPENDIX D
GLOSSARY
Adiabatic
Aerosol
Air pollution
Ambient air quality
Anticyclone
Arterial
At-grade roadway
BTU
Coh
Convective updraft
Occuring without gain or loss of heat.
A dispersion of solid or liquid particles of
microscopic size in gaseous media.
Examples are smoke, fog, and mist.
The presence of unwanted material in the
air in sufficient amount and under such
circumstances as to interfere significantly
with comfort, health, or welfare of persons,
or with full use and enjoyment of property.
A physical and chemical measure of the
concentration of various chemicals in the
outside air. The quality is usually determined
over a specific time period (for example,
5 minutes, 1 hour, 1 day).
An area of relatively high atmospheric
pressure. In the northern hemisphere, the
wind blows spirally outward in a clockwise
direction.
A major through street, four lanes or more
with no (or only limited) access control.
Roadway which is at the same level with
adjacent land.
British thermal unit. A measure of heat,
specifically, 1 BTU is the amount of heat
required to raise the temperature of 1
pound of water 1°F at or near 39. 2°F.
Coefficient of haze. A unit of measurement
of visibility interference.
Vertical component of a circulatory air
movement caused by differences in density
within an air mass of non-uniform temperature.
D-l
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Corridor
Depressed roadway
Diffusion
Dispersion
Diurnal
Downtown distribution
system
Dust
Elevated roadway
Emissions
Episode
Freeway
An area extending radially from the central
business district generally served by a major
transportation route.
Roadway which is below adjacent land.
Mixing of pollutants with surrounding air by
means of random particle or molecular
motion. (Often used interchangeably with
dispersion. )
Transport of pollutants by atmospheric
currents. (Often used interchangeably with
diffusion. )
Daily, especially pertaining to actions or
events that are completed within 24 hours
and that recur every 24 hours.
The local streets in the downtown area that
serve adjacent buildings and facilities.
A term loosely applied to solid particles,
predominantly larger than colloidal,
capable of temporary suspension in air or
other gases.
Roadway which is above adjacent land.
The total substances discharged into the air
from a stack, vent, tail pipe, carburetor,
or other source.
The occurrence of stagnant air masses during
which air pollutants accumulate, so that the
population is exposed to an elevated concen-
tration of airborne contaminants.
A major limited access highway of 4 or more
lanes.
D-2
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Gas
Geostrophie wind
Inversion
Modal split
Mode
Model
Month
Peak traffic demand
Plume
Right-of-way
Smog
One of the three states of aggregation of
matter, having neither independent shape nor
volume, and tending to expand indefinitely.
Wind that exists in a region approximately 300
to 1000 meters above the surface of the
earth and is generally not influenced by
surface friction. Its speed constitutes a
balance of the forces from the pressure
gradient and rotation of the earth,
A layer of air in which temperature increases
with height.
The calculation of the proportion of total
person trips which will use available
transportation modes.
Method of transportation such as bus, auto,
walking, rapid transit, or taxi.
A mathematical set of equations intended to
simulate a real life situation.
For reporting analysis of ambient air on a
monthly basis, results are calculated to a
base of 30 consecutive 24-hour periods.
That traffic flow on an individual street or
in an entire area which is the greatest.
Usually, the peak traffic demand is considered
over a short period of time (15-60 minutes)
per day.
A column of smoke.
The land occupied by a roadway.
A combination of smoke and fog. Extensive
atmospheric contamination by aerosols
arising partly through natural processes
and partly from human activities. Often
used loosely for any air contamination.
D-3
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Smoke
Topography
Vapor
Weaving
Year
Small gas-borne particles that are produced
by incomplete combustion, consisting
predominantly of carbon and other combustible
material, and present in sufficient quantity
to be detectable independently in the presence
of other solids.
The configuration of a surface, including its
relief and the position of its natural and
man-made features.
The gaseous phase of matter that normally
exists in a liquid or solid state.
The crossing of traffic streams moving in
the same general direction, accomplished by
merging and diverging.
For reporting analysis of ambient air on a
yearly basis, results are calculated to a base
of 12 30-day periods.
D-4
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APPENDIX E
REFERENCES
1. U. S. Clean ALr Act (42 U.S. C. 1857 et seq. ) sec. 110 (a)(2). (This
is commonly called the 1970 Clean Air Act and includes the Clean
Air Act of 1963 and all amendments through December 31, 1970. )
2. U.S. Office of Management and Budget. Circular No. A-95. Revised
February 9 and July 26, 1971.
3. EPA. Requirements for Preparation, Adoption, and Submittal of
Implementation Plans. Federal Register, 36:158, August 14, 1971.
4. EPA. National Primary and Secondary Ambient Air Quality Standards,
Federal Register, 36:84, April 30, 1971.
5. Yocom, J. E. , D. A. Chisholm, and G. F. Collins. Air Pollution
Study of the Capital Region. Capital Region Planning Agency, Hartford,
Connecticut, December 1967.
6. Voorhees, A. M., C. F. Barnes, Jr., and F0 E. Coleman. Traffic
Patterns and Land Use Alternatives. Highway Research Board Meeting,
Washington, D. C., January 1962.
7. Northeastern Illinois Planning Commission. Managing the Air Resource
in Northeastern Illinois, Technical Report No. 6. August 1967 0
8. Kurtzweg, J. A. and D. W. Weig. Determining Air Pollution Emissions
from Transportation Systems. National Air Pollution Control
Administration. National Air Pollution Control Administration.
9. Voorhees, A. M. and Associates, Inc. A Transportation Study for
Montgomery and Prince George's Counties, Maryland. The Maryland
National Capital Park and Planning Commission, June 1970.
10. National Capital Development Commission. Canberra Land Use
Transportation Study: General Plan Concept, January 1967,
11. For example see: Alan M. Voorhees & Associates, Inc. Factors and
Trends in Trip Lengths. National Cooperative Highway Research
Program, Report 89, 1960.
12. National Capital Development Commission. Tomorrow's Canberra,
Australian National University Press, 1970,
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13, Rydell, C. P. and Collins, D. Air Pollution and Optimal Urban
Forms. National Center for Air Pollution Control. June 1967.
14. Rydell, C. P. and Schwarz, G. Air Pollution and Urban Form: A
Review of Current Literature, A IP Journal, March 1968.
15. Hilberseliner, L. The New City. Chicago: Paul Theobold, 1944.
16. Urban Land Institute. Land Use Control, Research Monograph
No. 17, 1970.
17. St. Louis Area Council of Governments. Report and Recommendation
of East-West Gateway Coordination Council as a Coordinated Air
Pollution Abatement Program for the St. Louis Metropolitan Area.
January 1967.
18. Williams,, Norman^ Development Controls and Planning Controls --
The View from 1964. Proceedings of the 1964 Annual Conference,
American Institute of Planners.
19. Fay, J. A. Air Pollution from Future Giant Jetports. Air Pollution
Control Association, June 1970.
20. Babcock, Richard F. Report on Contemporary Land Use Control
Methods and Techniques. Dayton Plan Board, 1966.
21. American City Corporation. Urban Life in New and Renewing
Communities, No. 6. July 1971.
22. Rockeffer, B. New Communities, A New Avenue for Social-Purpose
Investing. Address before New York Bond Club, April 1971.
23. Kwantes, P. W, General Transportation Aspects of Multi-Use
Centers. Unpublished paper, 1971.
24. The Joint Program (now the Twin Cities Metropolitan Council),
Twin Cities Area Metropolitan Development Guide, Report No. 5.
April 1968.
25-, Tippets, Abbet, McCarthy, and Stratton. Air Rights Potentials
in Major Highways -- Criteria for Joint Development, October 1969.
26. U.S. Congress. Federal-Aid Highway Act of 1970. Public Law
91-605, 91st Congress, H. R. 19504, Sec. 137, 1970.
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27. This hypothetical simulation was conducted by Alan M. Voorhees &
Associates, Inc. and Ryckman, Edgerley, Tomlinson & Associates
and was based upon research findings from: Bellomo, S. J.,, R. B.
Dial, and A. M. Voorhees. Factors, Trends and Guidelines Related
to Trip Length. National Cooperative Highway Research Program
Report 89, 1970.
28. Voorhees, Alan M. & Associates, Inc. Development of a Long Range
Transit Improvement Program for the Twin Cities Area. Twin Cities
Metropolitan Transit Commission, November 1969.
29. Woh-i, M. Users of Urban Transportation Services and Their Income
Circumstances.. Traffic Quarterly, January 1970.
30. Krambles, G. Putting New Spokes in Urban Transit. Conference
on New Approaches to Urban Transportation, Washington, D. C.,
November 1967.
31. Schneiderman, M, C. K. Conn, and G. Raulson. Air Pollution and
Urban Freeways: Making a Record on Hazards to Health and Property.
The Catholic University Law Review, Fall 1970.
32. EPA. Air Pollution Emission Factors. Preliminary Document,
AP-42, April 1971.
33. Wohl, M. and B. V. Martin. Traffic System Analysis for Engineers
and Planners. New York: McGraw-Hill, 1967.
34. Downtown-Lower Manhattan Association and the Port Authority of
New York. Staggered Work Hours in Lower Manhattan -- First
Anniversary Report. April 1971.
35. The Mitre Corp. Environmental Trends: Radiation, Air Pollution,
Oil Spills. MTR-6013. May 1971.
36 HEW U S Public Health Service. Nationwide Inventory of Air
Pollutant Emissions, 1968. NAPCA Publication AP-73, August 1970.
37 Crocker, B. B. and K. B. Schnelle. Introduction to Air Pollution
Control. American Institute of Chemical Engineers Today Series,
1969.
38 Colucci, J.M. andC. R. Begeman. Carbon Monoxide in Detroit,
New York, and Los Angeles Air. Environmental Science and
Technology. 3:1, p. 41-47, January 1969.
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39. Stern, Arthur C., ed. Air Pollution, Vol. 1, 2nd ed. Academic
Press, New York: 1968.
40. Brunner, F. A. and K. B. Schnelle, Jr. Air Pollution Patterns in
an Urban Street Canyon. Paper presented at ASCE National
Environmental Engineering Meeting, St. Louis, Missouri. October
1971.
41. Bach, W. An Urban Circulation Model. Arch. Met. Geoph. Biokl.,
Series B. 18:155-168, 1970.
42. Munn, R. E. Descriptive Micrometeorology. Academic Press.
New York: 1968.
43. Cohen, A. S. and A. P. Hurter, Urban Evaluation and Air Pollution.
Air Pollution Control Association, June 1970.
* 0. P. O. 1*73 ~- 747.yM ,
331. REGION NO. «
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