United States
Environmental Protection
Agency
Air and Radiation
EPA420-P-99-028
September 1999
&EPA
Granting Air Quality Credit
for Land Use Measures:
Policy Options
> Printed on Recycled Paper
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Report No. SR99-09-01
Granting Air Quality Credit for Land Use Measures:
Policy Options
prepared for:
U.S. Environmental Protection Agency
Contract No. 68-C7-0051, Work Assignment No. 1-04
Septembers, 1999
prepared by:
Jack Faucett Associates
2855 Mitchell Drive, Suite 103
Walnut Creek, CA 94598
and
Sierra Research, Inc.
1801 J Street
Sacramento, CA 95814
(916)444-6666
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DISCLAIMER
Although the information described in this report has been funded wholly or in part by the
United States Environmental Protection Agency under Contract No. 68-C7-0051, it has
not been subjected to the Agency's peer and administrative review and is being released
for information purposes only. It therefore may not necessarily reflect the views of the
Agency and no official endorsement should be inferred.
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Granting Air Quality Credit for Land Use Measures:
Policy Options
Table of Contents
Executive Summary i
Land Use Measures i
Regional Land Use Forecasting ii
Modifying the Baseline Quantification Procedures iii
The SIP Option iii
The Conformity Option iv
Chapter 1 - Introduction 1
1.1 Purpose 1
1.2 Methodology 1
1.3 Report Organization 2
Chapter 2 - Policy Options 4
2.1 General SIP Requirements 4
2.2 The SIP Baseline 5
2.3 Economic Incentive Program 7
2.4 Voluntary Measures 9
2.5 Maintenance Planning 11
2.6 Transportation Conformity 11
2.7 Policy Options Not Chosen for Further Evaluation 14
Chapter 3 - Land Use Measures 16
3.1 General Land Use and Transportation Issues 16
3.2 Implementing Mechanisms 17
3.3 Land Use Measure Categories 22
3.4 Impact of Land Use Policies and Programs on Urban Form 24
3.5 Measuring the Impact of Urban Form Change on Travel and Emissions .. 28
3.6 Summary 32
Chapter 4 - Conclusions 34
4.1 The Baseline Option 34
4.2 The SIP Option 36
4.3 The Conformity Option 37
4.4 Summary 38
References 40
Appendix A - Interviewees
Appendix B - Sustainable Land Use Internet Web Sites
Appendix C - Related Work Efforts
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Executive Summary
Sustainable land use refers to a variety of policies and programs that aim to provide
attractive and safe places to live and work, minimize the use of natural resources, and
allow for alternatives to automobile travel. A number of studies have shown that
sustainable land use activities can reduce vehicle miles traveled and mobile source
emissions. This work supports EPA efforts to reduce mobile source air pollution by
providing tools to recognize and, where appropriate, credit these types of sustainable land
use and transportation practices.
This work builds on Work Assignment 0-09 (WA09), in which the consultant team
conducted surveys to determine whether air agencies are currently taking credit in their
state implementation plans (SIPs) for control measures that involve land use. The study
found that one air agency is taking credit for a land use measure, and several more
identify land use measures in air quality plans but do not quantify any emission
reductions. This report provides a detailed analysis of the policy options for recognizing
and granting credit for sustainable land use activities in light of some specific control
measures.
There are three general options for recognizing and providing credit for sustainable land
use activities in the air quality planning process: (1) modify procedures for quantifying
emissions in the SIP baseline so that the benefits of sustainable land use are better
reflected; (2) adopt sustainable land use activities as a SIP control measure; and (3) show
emissions reductions from sustainable land use activities to support a transportation
conformity determination.
Land Use Measures
In evaluating specific land use measures, it is important to distinguish between the urban
form desired as an outcome and the implementing policies and programs that bring about
a change in urban form. Implementing mechanisms can range from those at the state and
regional level (like state growth control policies, open space protection programs, and
development incentives) to local policies (like zoning ordinances, design review
guidelines, and local development incentives). Land use measures are typically defined
by the urban form they intend to achieve. For this report, land use measures have been
grouped into five categories:
• Transit-Oriented Development,
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Infill Development,
Jobs/Housing Balance,
Mixed-Use Development, and
Neotraditional Design Development.
These measures lead to two basic types of urban form change: one is a redistribution of
population and employment growth among analysis zones; the other is a change in micro-
scale urban design or land use mixing (intra-zonal changes). Land use measures designed
to produce transit-oriented development, infill development, or jobs/housing balance will
typically result in the first type of urban form change (growth redistribution). Mixed-use
development and neotraditional design measures will be more likely to produce the
second type of change (micro-scale changes). Many sustainable land use activities will
produce both types of changes. However, the distinction is important because it is much
easier to monitor and assess the travel impacts of growth redistribution than micro-scale
urban form changes.
Note that throughout this document, the term "land use measure" refers broadly to
strategies for achieving an emission reduction through land use. This term is not
necessarily consistent with the definition of a SIP control measure. The specific legal
issues with respect to enforcement that apply to SIP control measures may not apply to
land use measures as described in this document. The distinction between these terms
will be defined in subsequent policy documents.
Regional Land Use Forecasting
In assessing the options for recognizing sustainable land use, it is important to keep in
mind that the process for developing the SIP baseline and making the conformity
determination already accounts for some of the effects of land use policies and programs.
Mobile source emissions estimates are based on a regional land use forecast developed by
the Metropolitan Planning Organization (MPO) or Council of Governments (COG) as
part of the regional transportation planning process. This forecast consists of allocating a
regional population and employment growth total among zones based on existing factors
that can shape development. To the extent that land use policies and programs occurring
outside of the air quality planning process impact the allocation of population and
employment growth, they will be reflected in this regional land use forecast and therefore
in the mobile source emissions estimate.
Land use measures can be used for explicit credit only to the extent that they are not
reflected in the emissions baseline. One way this might happen is if the standard
analytical methodologies used to evaluate land use, travel, and emissions do not reflect
the full impact of a land use measure. This is often the case for measures that result in
micro-scale land use changes. Alternative methodologies would be needed to allow
quantification of the impact of these changes in order to take credit for them. The other
possibility is that the regional land use forecast does not include a measure because it is
not likely to occur without some future government action. This would be the case for
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land use measures initiated by an air agency expressly for air quality purposes. Local
governments would commit to sustainable land use activities as part of the regional air
quality planning process. The research conducted in WA09 and this project suggests that
this scenario is currently unlikely. However, it may become a more attractive option in
regions that have trouble controlling mobile source emissions.
Modifying the Baseline Quantification Procedures
One option for recognizing sustainable land use is to modify the baseline quantification
procedures to better account for urban form changes. Regional travel demand models can
be improved by the addition of pedestrian environmental factors, accessibility variables,
or mode choice modules that include non-motorized travel. While these changes can
improve the ability of models to reflect land use, the limitations of zone size will always
prevent a full accounting of micro-scale urban form changes.
Incorporating in the baseline the impact of land use policies and programs that are not
included in the regional land use forecast would be a significant departure from current
practice and probably not advisable. Since policies and programs included in the baseline
are not subject to the control measure enforceability and documentation requirements,
this option could lead to credit for a land use measure that does not get implemented.
While in the long run this would cause problems for showing conformity or ROP
requirements, credit for activities that are not included in the regional land use forecast
should be done using explicit control measures.
The SIP Option
Land use measures not reflected in the baseline could be used to show emission
reductions as a SIP control measure. EPA has issued guidance for several types of
control measure categories. The guidance for Economic Incentive Programs (EIP) and
for Voluntary Mobile Source Emission Reduction Programs (VMEP) can both apply to
land use measures. As most land use measures rely on local government implementation
rather than direct state control, the VMEP option may be more appropriate for many
regions. However, the emissions reduction allowed under VMEP is limited to 3 percent
of the inventory for each criteria pollutant.
Adding a land use measure under either the EIP or VMEP option will require the air
agency to estimate compliance and programmatic uncertainty. Compliance uncertainty
represents the degree to which governments adopt implementing mechanisms in support
of sustainable land use. Programmatic uncertainty represents the degree to which urban
form, travel, and emissions change as a result of the implementing mechanisms. Due to
the nature of the development process, the level of programmatic uncertainty will
typically be very high. Land development is strongly influenced by fluctuations in market
demand. And most land use policies do not guarantee that any changes will occur, since
local officials can choose to ignore the policies.
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Since most nonattainment SIPs address only a five- to seven-year horizon, they offer little
opportunity to recognize the longer-term benefits of land use. However, areas developing
longer-term Maintenance plans may want to consider inclusion of land use measures to
help ensure that clean air goals will continue to be met, especially those that are expecting
considerable growth. For land use measures initiated expressly for air quality purposes, it
may be difficult to use the SIP process as an incentive for local government participation
in measure implementation, unless air quality problems are constraining local growth or
transportation funding. While local governments in some regions are heavily involved in
efforts to reduce pollutants like fugitive dust, in other regions there is little burden placed
on local governments to reduce mobile source emissions. Thus, in these regions there
may be little opportunity to reduce the burden for those that commit to sustainable land
use activities.
Taking credit for land use measures in the SIP process raises the prospect of double-
counting benefits already reflected in the baseline. Air agencies typically have a poor
understanding of the land use and travel demand forecasts that form the baseline. To
ensure that land use measure benefits are surplus, air agencies will need to better
document the land use and travel forecasts that make up the baseline. Additional EPA
guidance may be needed regarding the form of this documentation. However, it should
be recognized that the more requirements are placed on documenting land use activities,
the less likely may be the adoption of land use measures.
To adopt, as a control measure, land use policies and programs that are not included in
the regional land use forecast, the state would typically need assurances from local
governments that the actions would be implemented as expected. The form that this
assurance should take is not clear under the existing guidance.
The Conformity Option
Land use measures that are not reflected in the baseline could also be used to show an
emissions reduction in the transportation plan conformity determination. The MPO
estimates the emissions that will result from the implementation of a long-range
transportation plan, and these emissions must be within the mobile source emissions
budget established in the SIP.* Estimates of emissions can be reduced by factoring in the
impact of control measures, thus providing "credit" for the measures.
* It is important to note that mobile source emission budgets are not always fixed at a
specific level. Some communities project emission budgets for years beyond the
attainment dates established in the Clean Air Act. The purpose of establishing budgets in
the "out years" is to allow transportation emission budgets to increase in proportion to
reductions occurring in other source categories (i.e., and stay within the emission cap
needed to demonstrate attainment.) This eliminates the problem of finding offsets for
growth in years beyond the specified attainment date and enhances their ability to
demonstrate conformity with the budgets established in the SIP. In this document, the
SIP option generally refers only to planning through the attainment year.
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This option has several advantages over the SIP process. Most importantly, conformity
addresses a longer time period than most SIPs, and thus better matches the time needed to
realize the benefits of land use measures. Also, because it is linked to future
transportation funding, the conformity determination may offer an opportunity to provide
incentives to local governments to adopt land use measures.
The Conformity Rule specifies that emission reductions from projects like TCMs that are
not "regionally significant" may be estimated with reasonable professional practice, rather
than incorporating them into the regional travel demand model. The Rule defines the
type of implementation commitment needed to include a control measure in a conformity
analysis. Measures that require regulatory action (i.e., zoning or other growth control
mechanisms) generally must be already adopted by the local government, or must be
included in the SIP, or the SIP must contain a letter of commitment from the
implementing authority.
There are several issues that EPA may wish to address with respect to land use measures
in conformity analyses. While the requirements for including control measures in the SIP
and conformity determination are essentially the same, at least several air agencies
perceive that there is less accountability for measures adopted to show conformity than in
the SIP. There is also a potential to double-count control measure benefits that are
already reflected in the baseline. Currently, it would be difficult for a reviewer to detect
this double-counting because there is little requirement for documenting the baseline land
use forecast and the policy assumptions that underlie it. As with SIP measures, additional
EPA guidance may be needed regarding documentation of the baseline land use
assumptions.
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1. Introduction
1.1 Purpose
Across the country, communities are re-thinking the land use policies that have shaped
urban form over the last half-century. In many regions, these land use policies have
contributed unnecessarily to traffic congestion, air pollution, and the loss of agricultural
land and open space, while leaving older, inner-city neighborhoods economically
depressed. Local, regional and state governments are now realizing that sustainable land
use is vital to preserving quality of life. This means building in ways that provide
attractive and safe places to live and work, minimize the use of natural resources, and
allow for alternatives to automobile travel. This work supports EPA efforts to reduce
mobile source air pollution by providing tools to recognize and, where appropriate, credit
these types of sustainable land use and transportation practices.
This work builds on Work Assignment 0-09 (WA09), in which the consultant team
conducted surveys to determine whether air agencies are currently taking credit in their
state implementation plans (SIPs) for control measures that involve land use. The study
found that one air agency is taking credit for a land use measure, and several more
identify land use measures in air quality plans but do not quantify any emission
reductions. WA09 also discussed some of the barriers that prevent the recognition of the
air quality benefits of sustainable land use measures in the air quality planning process.
This report provides a detailed analysis of the policy options for recognizing and granting
credit for sustainable land use activities with respect to some specific control measures.
Note that throughout this document, the term "land use measure" refers broadly to
strategies for achieving an emission reduction through land use. This term is not
necessarily consistent with the definition of a SIP control measure. The specific legal
issues with respect to enforcement that apply to SIP control measures may not apply to
land use measures as described in this document. The distinction between these terms
will be defined in subsequent policy documents.
1.2 Methodology
Information for this project was collected primarily through interviews and document
review. As part of the evaluation of policy options, interviews were conducted with EPA
staff, including Geoff Anderson, Jim Carpenter, Mark Coryell, John Hall and Mark
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Wolcott. Other interviews were conducted with staff at selected local, regional and state
agencies. These persons are listed in Appendix A.
EPA policy and guidance documents were reviewed as part of this work effort and are
listed in the References section. Also listed are a number of documents that were used to
evaluate specific land use measures and technical methods. A publication by the
California Air Resources Board entitled Transportation-Related Land Use Strategies to
Minimize Motor Vehicle Emissions: An Indirect Source Research Study was particularly
helpful. A number of Internet web sites were also reviewed to gather information about
sustainable land use policies and programs. These web sites are listed in Appendix B.
The work also included a review of several recent and ongoing federal work efforts that
complement this project. A description of these projects is included in Appendix C.
1.3 Report Organization
The remainder of this report is organized into three chapters, as described below.
Chapter 2 describes the policy options in detail. Three general options are considered.
Under the first option, the benefits of sustainable land use measures would be
incorporated into the baseline of the SIP or conformity process. The procedures for
developing this baseline are reviewed. Under the second option, land use policies or
programs would be adopted as a SIP control measure. EPA guidance with respect to
several categories of control measures is reviewed, including the Economic Incentive
Program (EIP) and the Voluntary Mobile Source Emission Reduction Program (VMEP).
Under the third option, land use policies or programs would be used to reduce mobile
source emissions to support a transportation conformity determination. This process and
its applicable rules are reviewed.
Chapter 3 describes specific land use measures and evaluates their potential to be used for
emission reduction credit. The chapter begins with a brief overview of the land use,
transportation, and air quality planning process and the responsibilities of different public
agencies in that process. Implementing mechanisms are then reviewed. These are the
policies and programs that are used to bring about a change in urban form, and they have
been grouped into seven broad categories. Chapter 3 then describes the following basic
categories of land use measures, defined by the type of urban form they attempt to
achieve:
• Transit-Oriented Development,
• Infill Development,
• Jobs/Housing Balance,
• Mixed-Use Development, and
• Neotraditional Design Development.
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The last part of Chapter 3 evaluates the potential for these land use measures to be used
for air quality credit. Here the focus is on quantifying the impact of policies and
programs on urban form, and quantifying the impact of urban form change on travel and
emissions.
Chapter 4 provides conclusions by tying together the issues raised in Chapters 2 and 3.
The potential for recognizing sustainable land use activities under each of the three
general policy options is evaluated in terms of the specific land use measure categories
and implementing mechanisms. The chapter identifies some issues that may be relevant
for EPA.
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2. Policy Options
The Clean Air Act Amendments (CAAA) of 1990 require states with areas that do not
meet National Ambient Air Quality Standards (NAAQS) to submit to EPA a State
Implementation Plan (SIP) that documents how the area(s) will achieve NAAQS within
the required time frame. States consider a wide array of control measures in the
development of SIPs. A land use measure would be a policy or program that changes the
urban form in a way that leads to fewer vehicle emissions.
Control measures have been classified by EPA based on source category and operational
mechanism. Transportation Control Measures (TCMs) refer to measures designed to
reduce emissions from transportation sources through a reduction in vehicle use or
changes in traffic conditions. Section 108(f) of the CAAA lists 16 examples of TCMs,
including several that could rely on land use or urban design changes. Economic
Incentive Programs (EIPs) are control measures that rely on market-based incentives to
reduce emissions and increase compliance flexibility. Voluntary Mobile Source Emission
Reduction Programs (VMEPs) refer to measures that rely on the voluntary actions of
individuals or businesses to reduce emissions. Each of these classes of measures could
include certain types of sustainable land use policies and programs.
2.1 General SIP Requirements
Under the CAAA, all SIP measures must be consistent with SIP attainment and Rate of
Progress (ROP) requirements. They must result in emission reductions that are
quantifiable, enforceable, and permanent. Quantifiable means that the emission reduction
can be measured reliably and replicably. Enforceable means that the actions required to
achieve emission reductions are independently verifiable, program violations are defined,
those liable can be identified, and penalties can be applied where applicable. Permanent
means that the emission reduction occurs throughout the life of the measure, and for as
long as it is relied upon in the SIP. While these principles apply to all SIP measures, EPA
has provided guidance that clarifies how the principles can be interpreted for some of the
specific classes of measures.
The required date for reaching attainment depends on the pollutant and the severity of air
pollution levels. For carbon monoxide, those areas remaining out of attainment (i.e.,
those "bumped up" to serious) must demonstrate attainment by December 31, 2000. For
the one-hour ozone standard, the attainment dates range, depending on their
nonattainment classification, between 1999 and 2010. For the eight-hour ozone standard,
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the draft planning guidance indicates that attainment dates will range between 2005 and
2010. For PM10, those areas remaining out of attainment (again, those bumped-up to
"serious") must demonstrate attainment between 2001 and 2006 (the latter for those areas
that comply with the "most stringent measure" requirements). Under the revised PM10
standard, the draft planning guidance indicates that attainment dates will range between
2006 and 2010. For PM2 5, draft planning guidance indicates that the attainment dates
will also range between 2006 and 2010.
These attainment dates are particularly significant for land use measures. Unlike some
other types of control measures, those involving land use often require a decade or more
before having any significant impact on mobile source emissions. For example, one land
use strategy is to use urban growth boundaries and other forms of open space protection
to increase pressure for infill development. Under this strategy, however, significant
infill can only be expected to occur if the region is growing and if new greenfield sites are
effectively unavailable for development. Changing the urban form using this strategy
would not be likely to have a significant impact on regional travel within the SIP
timeframe in all but the most extreme nonattainment areas.
Since the decision-making authority for land use rests almost exclusively with local
governments, it is important to consider how the policy options can create incentives for
local governments to participate in sustainable land use activities. If a state wants to
create an incentive through the SIP process for local governments to adopt land use
measures, the state could pass on the reduced emission control burden to the local
governments in some way. This could happen in the form of reducing the burden of other
control measures that require local implementation. As discussed later, granting credit
through the conformity analyses may provide better opportunities for offering incentives
to local governments through transportation funding decisions.
2.2 The SIP Baseline
Some land use policies and programs are implicitly factored into all SIPs through the
development of the baseline. To develop the SIP baseline, the state produces an
emissions inventory that reflects current and expected emission levels from each source,
for each criteria pollutant. In developing the mobile source emission inventory, the state
typically relies on the forecasts of future vehicle activity that are made by the regional
MPO. These travel demand forecasts make certain assumptions about the future
distribution of population and employment that are based, in part, on existing land use
policies and programs. While EPA has provided considerable guidance on procedures to
be followed in developing the travel forecasts (e.g. Section 187 VMT Forecasting and
Tracking Guidance, etc.), little guidance has been provided on how to consider issues
related to land use.
2.2.1 The Regional Land Use Forecast
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In most regions, the MPO or COG adopts an "official" land use forecast that then serves
as the basis for all of its transportation forecasts. The processes for developing this
forecast vary - some regions rely heavily on land use models while others use more of a
negotiating process with local governments. All regional land use forecasts reflect, to
some extent, the policies and programs that influence land use in the region. The MPO or
COG considers all the local, regional and state policies that can affect the land use
forecast together with past trends and the realities of the real estate market.
The only policies and programs that could explicitly be used for air quality credit as
control measures are those that are somehow not reflected in the baseline. There are two
reasons why this might occur. One possibility is that the analytical methodologies used to
evaluate land use, travel, and emissions do not reflect the full impact of a land use
measure - a measure that is already in place or an expected future measure. In this case,
alternative methodologies would be needed to allow quantification of the impact of the
land use measure. The other possibility is that a policy or program is not expected to
occur without some future government action (adoption, implementation, enforcement,
etc.), and therefore was not included in the baseline. In this case, the government agency
would have to commit to performing the action that will bring about the land use change,
and that commitment would be identified as a control measure.
Actions being initiated outside of the air quality planning process
The limited ability of existing analysis methodologies to quantify sustainable land use
activities can obscure the benefits of those programs that are occurring as part of the
regional planning process. Sustainable land use policies and programs are being
considered in almost every metropolitan area in the country for such reasons as to reduce
traffic congestion, promote economic vitality, preserve recreational open space and
agricultural lands, protect threatened species, and use infrastructure funds more
efficiently. While many communities recognize the potential air quality benefits of these
activities, air quality is not the driving factor in their implementation. The regional land
use forecasting process generally includes these policies to the extent that they are having
an impact on population and employment growth. It may still be possible to take explicit
credit for these policies if the emissions baseline does not reflect their full impact. As
discussed further in Chapter 3, the technical methodologies used to forecast travel and
emissions often do not detect changes in urban design and land use mixing that can
reduce vehicle travel. In addition, land use forecasting techniques differ widely between
regions, and some areas may not fully capture the effects (both positive and negative) of
local land use policies.
Actions initiated by the air agency
Because of the nature of the regional land use forecasting process, sustainable land use
activities that are occurring as part of a larger planning agenda will be included in the
regional land use forecast to the extent that they change population and employment
growth. One example of an activity that clearly would not be included in the regional
land use forecast would be one initiated expressly for air quality purposes. Based on the
interviews conducted as part of WA09 and this project, we feel this possibility is unlikely.
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However, it is possible that an air agency could initiate sustainable land use activities that
would otherwise not occur, and these measures might therefore not be reflected in the
baseline.
2.2.2 Modifying the Baseline Quantification Process
One way to recognize sustainable land use activities would be to modify the procedures
for developing the baseline to better account for land use measures. By improving land
use and travel demand models, it may be possible to better reflect in the baseline emission
reductions that result from land use measures that are in place. Some of these
improvements are discussed in Chapter 3. Of course, modifying these tools could also
improve the quantification of explicit land use measures in the SIP or as part of a
conformity determination. However, the current modeling tools will always be somewhat
limited in their ability to show the impact of land use on travel.
Baseline emissions could also be reduced by incorporating the impact of land use policies
and programs that are not included in the regional land use forecast (i.e., new policies and
programs). This would be a significant departure from current practice and not advisable.
That is because explicit revisions to land use policies would constitute a control measure.
If states are to take emission reduction credit for these revisions, the measures must be
fully enforceable and tracked as any other control measure commitments established
under a SIP.
2.3 Economic Incentive Program
Economic Incentive Programs (EIPs) are strategies that encourage emissions reductions
through market-based incentives. EPA has issued guidance for these measures in the
form of the 1994 EIP Rule, and is currently in the process of comprehensively updating
this guidance for discretionary EIPs.*
2.3.1 Description
There are four general types of EIPs:
• Emission Trading Programs,
• Financial Mechanism EIPs,
• Clean Air Investment Funds, and
• Public Information EIPs.
* Economic Incentive Program Rules, US Environmental Protection Agency, 40 CFR
Part 51, 1994.
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Emission trading programs create transferable emission reductions that authorize sources
to emit a unit of emissions. Emission trading programs are typically used for stationary
sources, though it might be possible to develop a trading program that applied to mobile
sources through land use. For example, if a particular development project could show a
reduction in mobile source emissions through land use, that reduction could be traded to
allow some other source to emit more. While this sort of trading would not reduce
overall emissions levels, it would add flexibility to a reduction strategy. However, most
development projects would not create an emission reduction large enough to be used as a
tradable credit.
Financial Mechanism EIPs include fees, taxes, or subsidies targeted at promoting
pollution-reducing activities or products. This type of EIP also includes time-saving
mechanisms. Most land use measures that rely on economic incentives would likely be of
this type. For example, programs that attempt to influence the behavior of developers
through taxes or subsidies would fall under this category. A Financial Mechanism EIP
could also attempt to influence developers by saving time and effort through a
streamlined permitting process.
Clean Air Investment Funds are state-run mechanisms to provide a way to lower costs for
sources facing high control costs and invest in technology innovation to improve long
term air quality. This type of EIP would not typically apply to land use.
Public Information EIPs include product certifications or public information campaigns
that attempt to influence public behavior in a way that reduces emission-producing
activities. Some land use measures might be included in the Public Information category.
For example, some regions have considered an outreach program that would use
analytical models to show developers how infill projects can save them costs.
Like all SIP measures, EIPs must be consistent with SIP attainment and Rate of Progress
requirements, and the emission reductions from EIPs must be quantifiable, enforceable,
and permanent. In addition, EIPs emission reductions must be surplus, meaning that the
reductions are not relied upon in the SIP as part of another control strategy. Like other
SIP measures, EIPs would be enforced by the state or the state's designate. The enforcing
agency would be responsible for ensuring that the EIP is creating the expected behavioral
response. However, unlike traditional command and control measures, the state may not
have direct control over the emissions source under an EIP. Rather, the state would have
direct control over the incentive being offered.
The quantification of emission reductions under an EIP must reflect the uncertainties
inherent in the program. EPA guidance specifically identifies two types of uncertainty:
• Compliance uncertainty, which is the extent to which the responsible party will
fully implement the VMEP program; and
• Programmatic uncertainty, which is the extent to which voluntary responses
actually occur and/or the inherent uncertainties of program design.
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Land use measures would have multiple levels of uncertainty. Consider, for example, a
regional growth management strategy adopted by the MPO that relies on voluntary
implementation by local governments. Compliance uncertainty could refer to the extent
to which local governments modify their policies in support of the regional strategy.
Programmatic uncertainty could refer to the extent to which new development adheres to
the local government policies, and the extent to which new development patterns
influence travel and emissions. Since the factors that affect development can vary so
widely, these levels of uncertainty probably need to be estimated on a case-by-case basis.
2.3.2 Application to Land Use Measures
Typically, an EIP land use measure would offer some type of monetary reward to builders
of sustainable development. This could be in many forms, including tax breaks, grants,
or a fee structure. These monetary rewards could be offered by local, regional, state or
federal government agencies, or perhaps even by non-governmental agencies. An EIP
land use measure could also work by offering non-monetary incentives, such as density
bonuses, relief from impact mitigation, or a streamlined permitting process for
sustainable development.
Most non-monetary incentives, and some monetary incentives, would be incorporated
into local government land use policy, and thus would be implemented at the local level.
This raises some questions as to how EIP land use measures would be enforced. For
monetary incentives over which the state has direct control, a land use measure would be
fairly similar to other EIP measures, and could be developed using existing guidance.
The state would be responsible for ensuring that the incentive is offered as planned, and
would need to monitor its effect on behavior to ensure that the measure was having its
expected impact.
For incentive programs operated by regional or local governments, adopting the measure
as a SIP EIP might require additional guidance. Since the state would not be directly
implementing the incentive program, it would have to receive some sort of enforceable
commitment from the local or regional agency. If state law required that the local
governments offer the incentive, this would probably be sufficient assurance. If not, the
state would need assurances that the local or regional agency would adopt the program (if
it was not yet in place) and would implement the program as expected. The form that
these assurances would take is not made clear in existing guidance. One possibility
would be some form of a Memorandum of Understanding (MOU) between the state and
local/regional agency.
2.4 Voluntary Measures
Another type of SIP measure is known as the Voluntary Mobile Source Emission
Reduction Program (VMEPs). VMEPs rely on the voluntary actions of individuals or
businesses to achieve emission reductions. EPA released guidance on incorporating
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VMEPs into SIPs in 1997.* The guidance offers more flexibility for the adoption of
voluntary measures, recognizing that the standard SIP requirements can be overly
burdensome for voluntary measures that typically offer only small emission reductions.
However, since states have only limited experience in measuring the effectiveness of
voluntary programs, EPA has limited the emission reduction allowed under VMEP to 3%
of the inventory for each criteria pollutant.
2.4.1 Description
Like other SIP measures, voluntary measures must be consistent with SIP attainment and
Rate of Progress requirements, and the emission reductions must be quantifiable,
enforceable, permanent, and surplus. Voluntary measures differ from other SIP measures
in that EPA does not require direct state authority over the program. This may make the
VMEP program particularly attractive as an option for land use measures. A VMEP
program can be implemented by a local or regional government, or by a private entity,
without the kind of state authority required of EIPs or other SIP measures. The state is,
however, required to monitor, assess, and report on the implementation of the VMEP, and
must make up any shortfall in emission reductions. As with EIP measures, the
quantification of emission reduction under a voluntary measure must reflect both
compliance uncertainty and programmatic uncertainty.
2.4.2 Application to Land Use Measures
Most types of land use measures fit the criteria to be adopted as a VMEP. Many
sustainable land use programs will not be directly operated by the state, for example.
Nearly all land use measures rely on "voluntary" action in the sense that they cannot
directly force action by private developers nor by the travelers who are affected by land
use. In addition, the VMEP guidance specifically accounts for the fact that states have
only limited experience in quantifying the emission reductions under these programs.
This type of guidance will be needed for many land use measures, where the uncertainties
in quantifying the impact of land use on emissions may make it difficult to adopt them as
EIPs or TCMs.
As with EIPs, the state would need some type of assurance that local governments would
implement a land use measure that was not yet in place. It is not clear from the guidance
what form this assurance should take.
States might not want to adopt a land use measure as a VMEP because of the 3% limit.
This limit applies to the combined reduction from all voluntary measures. So, for
example, a state that was taking credit for mobile source emission reductions under an
* Guidance on Incorporating Voluntary Mobile Source Emission Reduction Programs
in State Implementation Plans (SIPs), Memorandum from Richard D. Wilson, October
24, 1997.
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Ozone Action Day program and an employer-based trip reduction program might not
have much room left under the 3% cap. In this case, the state might want to adopt the
land use measure as an EIP or TCM. Doing so would require that the state have more
authority over the program operation and more certain methods for quantifying emission
reductions.
2.5 Maintenance Planning
Under the CAAA, the state prepares a maintenance plan for areas that achieve attainment
of NAAQS. The maintenance plan must show that air quality standards can be
maintained for ten years after redesignation from nonattainment to attainment. Eight
years after redesignation, a subsequent maintenance plan must be submitted that
demonstrates how NAAQS will be maintained for an additional ten-year period.
Maintenance plans must account for future increases in emissions, and therefore may
require the adoption of new control measures. The maintenance plan must also identify
contingency measures that will take effect should the region experience future violations
ofNAAQS.
Because the maintenance plan addresses a longer time frame than most control strategy
SIPs, it may provide an opportunity to take air quality credit for land use measures. Some
sustainable land use strategies may not produce travel and emission benefits for ten years
or more. So some regions may have policies and programs that do not result in
quantifiable benefits within the SIP attainment horizon, but do produce quantifiable
benefits beyond that during the maintenance period.
Of course, many maintenance regions will not be in need of additional mobile source
control measures, and will be unlikely to commit to them. However, areas where
expected regional growth could result in significant increases in VMT may want to
examine the impacts of land use measures to ensure maintenance of the standard.
Furthermore, if the benefits of a sustainable land use policy or program could be
quantified fairly easily, and the measure could reduce emissions in a less expensive
manner than alternatives, then the region may wish to adopt a new land use measure to
allow it to drop other control measures. Interest in sustainable land use polices may also
be stimulated if, in the later years of a maintenance plan, VMT growth outweighs vehicle
technology improvements.
The requirements for maintenance plan control measures are the same as for measures
submitted in a nonattainment SIP. Emission reductions must be quantifiable,
enforceable, and permanent. Land use measures submitted in a maintenance plan would
be subject to the same rules and guidance as described above for TCMs, EIPs, and
VMEPs.
2.6 Transportation Conformity
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The CAAA of 1990 requires that transportation plans and programs are consistent with
efforts to attain air quality standards. Nonattainment areas must demonstrate that their
transportation plans and programs are in conformity with the area's SIP, and areas that
cannot make this demonstration may be ineligible for federal transportation funds. EPA
has released rules for making conformity determinations, most recently in 1997.
2.6.1 Description
Federal law requires that metropolitan areas (those with a population over 200,000)
prepare a long-range transportation plan, and update this plan at least every five years.
Typically, these plans are prepared for a 20-year horizon. Metropolitan areas also prepare
a Transportation Improvement Program (TIP), typically a 3- to 5-year document that
identifies specific project funding. Both of these documents, as well as any significant
projects not identified in the plan or the TIP, are subject to the conformity determination.
Conformity of transportation plans must be determined at least every three years.
The requirement for making a conformity determination rests with the MPO, the Federal
Highway Administration (FHWA), and the Federal Transit Administration (FTA). This
is done in consultation with EPA, the air agency, the state department of transportation,
and other relevant agencies. The MPO must show that the emissions that will result from
the projects identified in the 20-year plan are within those allowed by the SIP mobile
source emission budget.* Incorporating the impact of control measures would be one way
to reduce the transportation plan emissions. In this way, it would be possible to "take
credit" for land use measures in the conformity process. As in the SIP process, it would
be possible to take credit for land use measures in the conformity process implicitly (by
enhancing models to better account for land use impacts) or explicitly (by identifying the
policy or program as a control measure and quantifying its impacts outside of the standard
network analysis).
2.6.2 Application to Land Use Measures
As with the SIP baseline, all conformity determinations inherently reflect some land use
policies and programs. EPA guidance requires that "land use, population, employment,
and other travel model assumptions must be documented and based on the best available
* It is important to note that mobile source emission budgets are not always fixed at a
specific level. Some communities project emission budgets for years beyond the
attainment dates established in the Clean Air Act. The purpose of establishing budgets in
the "out years" is to allow transportation emission budgets to increase in proportion to
reductions occurring in other source categories (i.e., and stay within the emission cap
needed to demonstrate attainment). This eliminates the problem of finding offsets for
growth in years beyond the specified attainment date and enhances their ability to
demonstrate conformity with the budgets established in the SIP. In this document, the
SIP option generally refers only to planning through the attainment year.
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information." This means that the transportation plan update must account for any
revisions to the regional land use forecast. Any sustainable land use measure could be
used for explicit conformity credit only to the extent that it is not included in the official
regional forecast, or is not measured because of modeling limitations.
The Transportation Conformity Rule, Section 122(a), provides some guidance on how
emission reduction measures should be included in the conformity analysis.* All
expected projects that are "regionally significant" must be included in the emissions
analysis. Nonattainment areas classified as serious for CO and areas classified as serious,
severe, or extreme for ozone are required to use network modeling (as specified in the
rule) to analyze emissions. Projects that are not regionally significant, including TCMs,
do not necessarily need to be analyzed using network modeling, but can be analyzed off-
model in accordance with "reasonable professional practice." Following this logic, the
benefits of land use measures could be quantified using similar procedures if they are
interpreted to be TCMs. Given the complexity of land use analysis, EPA should carefully
consider whether communities should be allowed to assess the impact of land use policies
outside of the travel demand modeling process.
The Conformity Rule includes some requirements on the type of authority needed for a
control measure in order to take credit for the measure in the conformity determination. It
states that emission reduction activities that require regulatory action for implementation
can only be included if:
1. the action is already adopted by the enforcing jurisdiction, or
2. the activity is included in the SIP, or
3. the SIP contains a written commitment to implement the activity from the
authorized agency, or
4. the action has been approved by EPA, or is required under the CAAA without
the need for state action.
Many land use measures, like zoning ordinances or subdivision regulations, do require
regulatory actions, and would be subject to the rules above. So a land use measure like
local zoning changes that was not yet adopted nor identified in the SIP could not be used
for conformity credit, according to the rule. Some other land use measures would not
require regulatory action, such as some incentive programs. The rule states that if these
are not included in the transportation plan or TIP, then the MPO must obtain written
implementation commitments from the appropriate entities in order to include them in the
conformity emissions analysis. Including the incentive program in the plan or TIP would
serve as assurance that the program would receive funding and would be implemented in
a timely manner.
* Transportation Conformity Rule Amendments: Flexibility and Streamlining; Final
Rule, US Environmental Protection Agency, 40 CFR Parts 51 and 93, August 15, 1997.
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2.6.3 Time frame
Transportation plans typically cover a period that extends beyond the attainment year
addressed by the SIP. To determine conformity in these years, the plan's emissions are
compared with the mobile source emission budget established in the SIP. For example, in
a severe ozone nonattainment area that adopts a 20-year transportation plan, the emissions
resulting from the plan in 2020 must be shown to be less than the SIP mobile source
budget for the attainment year of 2005 (or 2007), unless future year emission budgets
have been developed. In those communities that are projecting rapid growth, it may be
difficult to demonstrate conformity with the budget in later years of the plan (e.g., 10
years after the attainment year). Under this circumstance, sustainable land use policies
may prove to be an attractive control measure option.
The longer time frame is one of the primary benefits of using the conformity process for
land use credit. Many land use measures cannot be expected to produce significant
emission reductions within ten years, which effectively makes them irrelevant for
attainment-year SIP planning. However, land use is more likely to have an impact within
a 20-year horizon. Some metropolitan areas may be in need of additional control
measures at the 15-year or 20-year point. In many regions, technological improvements
to vehicles can more than compensate for expected increases in VMT over the next
decade or so. But the benefits of current technological improvements will reach a limit
over time, when fleet turnover has replaced most older technology vehicles. At that
point, the expected rise in VMT will require additional reductions in mobile source
emissions, and land use measures could serve this role.
2.6.4 Other Benefits of Using the Conformity Process
In addition to the longer time frame, there are several other issues that may make the
conformity process more attractive for land use credit than the SIP process. The
conformity requirements for interagency consultation bring together all relevant local,
regional, and state agencies in a frequent and regular forum. (While interagency
consultation often occurs in SIP process as well, it is not explicitly required.) Any
difficulty in showing conformity will focus the participants specifically on strategies to
reduce mobile source emissions. Since this process is being conducted in conjunction
with a new regional land use forecast and transportation plan, it provides a good
opportunity to consider the impact of land use. The conformity process may also provide
a better means to offer incentives for local government participation. The inability to
demonstrate conformity can mean an interruption in federal transportation funds, and this
can mean that transportation projects are delayed or canceled. To local governments that
fear losing a desired project, this may offer an incentive to adopt sustainable land use
policies and programs.
2.6.5 EPA's Role in Conformity Determinations
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There may be some question as to what EPA would need to do to better facilitate taking
credit for land use measures in the conformity process. EPA does not make conformity
determinations itself, and nothing currently prevents an MPO from including land use
measures in its conformity determination (aside from the requirements previously
discussed). However, EPA does play a role in the process, and EPA promulgates the
conformity rules. Additional guidance may be needed if EPA wishes to promote the use
of effective sustainable land use measures.
2.7 Policy Options Not Chosen for Further Evaluation
One policy option that was considered but not chosen for further evaluation is the
promotion of sustainable land use through the environmental review process. One
example of this option is the Clean Air Communities Program proposed by the South
Coast Air Quality Management District and described in the WA-09 report.* In
California, environmental review is performed under the state's California Environmental
Quality Act, or CEQA. The SCAQMD has produced a CEQA Handbook that contains
guidance for conducting air quality impact studies. As part of a review of this Handbook,
the SCAQMD had proposed a modification of the environmental review process that
would reward new development employing sustainable land use practices. This proposal
has since been dropped by SCAQMD, and inquiries revealed no similar efforts in other
areas of the country. While this policy option remains an attractive tool for the promotion
of sustainable land use, the issues associated with state and federal environmental review
are complex and beyond the scope of this work assignment.
###
* This program came out of the EPA's Clean Air Communities Initiative. See Clean
Air Communities, Clean Air Act Advisory Committee, US EPA, August 7, 1997.
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3. Land Use Measures
3.1 General Land Use and Transportation Issues
The transportation and air quality planning process involves some complex
interrelationships between different public agencies at the local, regional, state, and
federal government levels. It is useful to review the responsibilities and authority of these
agencies with respect to land use, transportation, and air quality.
Local governments have most of the power to control land use within their borders. They
issue permits for development, and control where and how development occurs. They
also have some responsibility for the local transportation infrastructure, including the
local street system and bicycle and pedestrian facilities. Local governments possess their
land use authority at the will of the state. In a few cases, states have placed some
restrictions on local government land use powers by requiring compliance with state
regulations or by granting land use powers to a regional agency.
The Council of Governments (COG) serves the local governments and the state by
preparing the land use forecasts used in transportation and air quality planning. COGs
use a variety of procedures to develop a land use forecast. Nearly all, however, begin
with a fixed amount of regional population and employment growth, often determined by
the state. The forecasting process involves allocating this growth total to the cities and
counties of the region, and then down to the level of transportation analysis zones, or
TAZs. Some metropolitan areas employ land use allocation models like DRAM/EMPAL
to perform their land use forecasts, with post-model adjustments. Others rely completely
on past trends, local plans, and negotiations between the MPO/COG and local
governments. In either case, local governments have some input in developing the
forecast. The forecasts thus reflect to some extent the policies and programs in place that
shape land use.
The Metropolitan Planning Organization (MPO) is responsible for regional transportation
planning and for distributing state and federal transportation funds. The MPO prepares
the long-range regional transportation plan and the short-term Transportation
Improvement Program, and is responsible for ensuring that these documents do not
violate air quality plans. Sometimes the MPO and the COG are the same agency. In
most cases, neither the MPO nor the COG has any real power to control land use
decisions.
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The air agency is designated by the state and is responsible for developing the air quality
plans for the metropolitan area and enforcing certain rules and regulations related to air
quality. The air agency itself has no power to control land use decisions, and relies on the
forecasts of the COG and MPO to develop air quality plans. However, in some cases the
MPO is also the local air quality agency charged with developing air quality plans. These
areas have a unique opportunity to develop transportation and air quality plans that have
coordinated goals and analytical consistency.
The phrase "land use" may be used in different ways by these agencies. To city planners,
land use refers to the type of activity conducted on a site - industrial, retail, low-density
residential, parks, etc. Land use is also sometimes used more broadly to encompass some
elements of urban design, such as building setback and height, pedestrian paths, and
landscaping. In travel demand forecasting, land use typically means simply demographic
and employment figures at the level of transportation analysis zone (TAZ). Typically,
TAZs are the size of one or several census tracts, which can be a half-mile to several
miles across. For residential areas, a standard land use forecast consists of the
population, number of households, and some characteristics of the households like auto
ownership, income, number of workers, etc., for each zone in the region. For non-
residential areas, land use is typically defined as retail and non-retail employment by
zone, student enrollment, and perhaps a measure of retail or office floor space. These
population and employment figures then become the basis for the trip generation, trip
distribution, and mode choice travel demand modeling steps.
3.2 Implementing Mechanisms
Before discussing land use measures, it is important to identify the specific policies and
programs that are used to achieve a desired urban form. Usually these will be policies
and programs adopted or operated by a government agency, though a non-government
agency could also offer a development incentive program. Implementing mechanisms
differ across levels of government and authority. For example, in order to facilitate
transit-oriented development (TOD), a local government could amend its general plan,
modify its zoning ordinance or design review guidelines, adopt an incentive program to
encourage development in focused areas, or make necessary capital improvements. In
reality, the local government would probably adopt several of these policies and others.
A state or regional body like an air agency or MPO/COG could also promote TOD,
though in a more indirect way. Its program might include providing educational materials
to developers on the benefits to them of building near transit, encouraging local
governments to amend their policies in support of TOD and providing model ordinances
for them, or facilitating cooperation between the transit agency (who might own land
around rail transit stations), local governments, and developers.
There are numerous implementing mechanisms for sustainable land use measures. For
this report, implementing mechanisms have been grouped into the following seven
categories:
• Regional/state growth controls;
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Regional/state/federal development incentives;
Regional/state/federal education and facilitation programs;
Local government growth controls;
Local government design controls;
Local government incentives; and
Private developer actions, without specific government policies or programs.
These categories attempt to distinguish between mechanisms that primarily affect where
building occurs (growth controls and some incentives) from those that primarily affect
how building occurs (design controls and some incentives).
3.2.1 Regional/State Growth Controls
Regional/state growth controls refer to non-local government programs to restrict the
location and intensity of new development. Often, these are programs or policies
primarily intended to protect open space (for agricultural use, recreational use, habitat
conservation, runoff prevention, etc.), not to reduce VMT. Some of the programs can
work directly by providing funding for the purchase of open space land. Other programs
prevent the use of state infrastructure funds in certain areas, or attempt to preserve the
agricultural use of lands. They can also work indirectly by forcing local government
actions, such as requiring local governments to designate growth areas or to accept new
housing. Nearly all examples of these programs are at the state level. One exception is
the Portland, Oregon area, where a regional government agency has been granted some
land use powers by the state.
Because most state growth controls are designed primarily to protect open space, they
generally have limited ability to achieve the urban form changes needed to reduce vehicle
emissions. For example, without proper controls, a state program to protect open space
within a metropolitan area could push new development farther out and increase regional
VMT. Programs such as Washington's Growth Management Act and Maryland's Smart
Growth Initiative require that local governments designate growth areas, and discourage
use of state infrastructure funding outside of these areas. While these programs may
result in more orderly development patterns, and discourage development that is
unwanted by local governments, they do not require local governments to build more
compact, mixed use, or transit-oriented development that could reduce vehicle use.
3.2.2 Regional/State/Federal Development Incentives
Regional/state/federal development incentive programs attempt to lure new development
to desired areas. They can work through monetary incentives, like grants, tax breaks or
fee reductions, or through non-monetary incentives like a transfer of development rights
(TDR). An example is the Transit Village Program in New Jersey, which provides
resources and technical assistance to local governments to promote development around
passenger rail stations. The aim of most of these programs is usually to protect open
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space or spur economic revitalization, not to reduce vehicle use. For example, New
Jersey also has a state TDR program to protect open space. Landowners in areas desired
for open space are given development rights in exchange for maintaining the low density
character of their land. These rights can be sold to developers and used to build at higher
densities in existing urban areas. While this program may work well to protect open
space, it could actually result in more development and higher emissions in the
nonattainment area than would otherwise occur.
3.2.3 Regional/State/Federal Education and Facilitation Programs
Education and facilitation programs attempt to encourage sustainable development
through publicity, education, technical assistance, intergovernmental cooperation, or
similar efforts. These are programs that do not offer significant development incentives
nor restrict growth through controls. They can be implemented at any level of
government, though most significant programs are at the regional, state, or federal level.
One example is the San Francisco Bay Area Air Quality Management District's measures
focused on TOD and pedestrian travel. These measures are intended to serve as a catalyst
for local governments to take actions in support of sustainable development. In
particular, the Air District, along with the region's MPO and COG, has committed to the
following:
• Encourage local governments to revise general plans and zoning ordinances to
encourage transit-oriented development and pedestrian improvements;
• Develop planning pilot projects;
• Provide technical assistance to local government agencies;
• Publicize noteworthy examples of clean air plans, policies and programs; and
• Encourage pedestrian improvements in capital improvement programs.
Because the air agency and other regional agencies do not have any authority over land
use decisions, they can rely only on local government implementation.
Other regions have tried to encourage sustainable land use through non-binding long-
range plans or "visions." Again, since these regional agencies lack the authority to
control development, they must rely on voluntary participation by local governments. For
example, the Denver region's Metro Vision 2020 Plan calls for future development to
occur in a more compact fashion than current development trends. The Plan identifies a
flexible urban growth boundary, and relies on voluntary local government
implementation to enforce the boundary.
3.2.4 Local Government Growth Controls
Local government growth controls include city and county policies to restrict the location
and intensity of new development. These policies include zoning ordinances and general
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plans, and they often work in conjunction with local government design controls and
incentive programs.
Zoning regulates the type and intensity of new development. In most cities, all land is
covered by zoning regulations to some degree. Since zoning can work only by restricting
certain development, its impact depends on the market demand to build. On the urban
edge, zoning that requires very low densities can effectively preserve land as open space.
In infill areas, raising zoning densities can facilitate higher density development than
previously allowed. Zoning can also encourage (or prevent) land use mixing. In most
states, zoning works in conjunction with general plans and specific plans. The general
plan lays out the vision for development in the municipality, and the zoning ordinance
incorporates that vision into city code.
Zoning is one tool used to implement an urban growth boundary (UGB). A UGB is a line
drawn around an urban area, beyond which new urban development cannot occur. This is
accomplished by zoning the land beyond the UGB for very low density, adopting policies
that prevent the extension of city services to new development beyond the boundary, and
facilitating more development within the UGB. Zoning can also be used to encourage
mixed use development. Traditionally, zoning was used to segregate different land uses
thought to be incompatible, and this prevented office and retail facilities from locating
within walking distance of residential areas. If these restrictions are lifted, mixed use
development can occur in places where developers find it profitable to do so. One
variation on this is mixed-use overlay zoning - a second layer of zoning is added to an
area that is predominantly single-use. Overlay zoning could be used to allow, for
example, small commercial development in residential areas or housing development in
commercial areas. Similar policies can encourage second units in areas dominated by
single-family detached homes, which can effectively increase residential densities.
Zoning ordinances and general plans are probably the strongest tools that governments
have to affect land use. However, zoning is only as strong as the locally elected officials
want it to be. Low density zoning does not prevent building on urban fringe lands
because local officials can grant zoning variances. Higher density zoning near transit or
other infill sites will have no impact if local officials make the approval process too
difficult or too risky for developers, or if there is no market demand. Zoning works only
in the negative - it can shape urban form through restriction, but it does not create
demand. Therefore, zoning needs to be carefully structured to shape development in
sustainable patterns. For example, an urban growth boundary that does not include
enough land for new development and does not facilitate infill, will merely push growth
into other jurisdictions farther out.
3.2.5 Local Government Design Controls
Local governments can exercise control over site design through the design review
process. New projects come before the local government design review board, which can
require architectural or design changes in order to approve a project. The board may use
design review guidelines to standardize its decisions. Design review guidelines might
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require that in certain areas, a project must be mixed use, or can require features related to
bike and pedestrian facilities (paths, racks, showers, etc.), landscaping, building and
parking placement, etc.
Subdivision regulations offer another opportunity for local governments to affect design
on developing land. Subdivision regulations can require that a new subdivision include
sidewalks, bicycle paths, transit lines, bridges, easements for access to schools, etc. They
also can set street standards.
Like zoning ordinances, the effectiveness of design controls depends on local officials. In
many cities, design review guidelines are only advisory and may be ignored as planning
boards see fit. Getting developers to modify a project design depends greatly on local
market forces. In areas without high demand, the ability and will of local government
planners to exact design concessions from developers can be quite limited.
3.2.6 Local Government Incentives
Incentive programs offer monetary or non-monetary rewards to developers who build in
desired locations or who include certain design features in new projects. At the local
level, these programs can work in a variety of ways, such as offering grant money or tax
abatements, modifying an impact fee structure, allowing higher density development
through density bonuses or TDRs, or reducing the time to obtain necessary permits.
Local governments can require that new development pay an impact fee to cover
infrastructure improvements, or make improvements in-kind as an exaction. These fees
or exactions can be structured to encourage development that reduces vehicle use. For
example, development impact fees or parking requirements can be reduced for mixed-use
or transit-oriented development, or for developments that make improvements to the
pedestrian and bicycle infrastructure. Some local governments have attempted to extend
impact fees to require traffic and air quality mitigation measures from all new
development as part of an indirect source review (ISR) program. These types of
programs were first introduced in the 1970's but have been less common in recent years.
Under such a program, new development can be required to include specific design and
land use features in order to reduce the vehicle emissions associated with the site, or pay a
fee instead. Sacramento County is considering this type of program.
Density bonuses allow new development to be built at a higher density than would be
allowed under zoning regulations, in exchange for including certain desirable features in
the development. For example, an office project that includes child care or housing near
transit could be allowed to build a taller building. Incentives can also work by saving
time. For example, the local government permit process can be streamlined to encourage
sustainable development projects. In many cities, the permitting process for new
development is often easier for single-use, auto-oriented development than for mixed-use
projects. Local policies can be revised to make the approval of certain types of projects
easier, which can reduce the time and cost for developers building mixed-use projects.
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Local governments can provide tax incentives for infill development by establishing
enterprise zones. An enterprise zone is typically created for an economically depressed
part of the city as a way to create jobs and spur revitalization. Developers are offered
reduced taxes and fees for building in the zone. Or local governments can reduce the cost
of building in certain desired locations by making infrastructure improvements.
The ability of incentive programs to have a significant impact on new development
depends to a large degree on the nature of the existing development fees and risks.
Offering a reduction in a traffic impact fee or parking requirement that is already minimal
will have little impact on developer behavior. Development incentives will have to be
fairly large to have a significant impact on a developer's choice of building location, and
many local governments will not have the resources to offer these types of incentives over
a long period of time. It may also be difficult to determine how much impact an incentive
program is actually having, given that there are so many factors that affect the cost and
risk associated with development.
3.2.7 Private Developer Actions, without Specific Government Policies or Programs
Of course, sustainable development can occur without a specific government policy or
program. Every city can experience new development even if it does not modify its
development controls or adopt incentive programs. Once built, this development will be
reflected in any update of the regional land use forecast. However, the emissions baseline
may not fully reflect the beneficial impact of the project.
In most cases, a single development would have to be quite large to have a regional
emissions impact. There are several mixed-use, infill projects in the planning stages that
might meet this criterion, such as the Playa Vista development in Los Angeles, the
Stapleton development near Denver, and the Atlantic Steel development in Atlanta. All
of these projects are planned to incorporate features to reduce vehicle use, such as
housing, retail and office mixed use, pedestrian and bicycle connections, and high transit
access. Assessing the extent to which these projects are included in a baseline forecast
would have to be done on a case-by-case basis.
3.3 Land Use Measure Categories
Land use measures are typically thought of in terms of how they change urban form.
While some land use measures might be defined in terms of the implementing mechanism
itself, most will take credit for a change in urban form. Techniques for monitoring the
change in urban form and measuring its impact can vary. For purposes of this project,
land use measures have been grouped into the following five categories based on urban
form types:
• Transit-Oriented Development,
• Infill Development,
• Jobs/Housing Balance,
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Mixed-Use Development, and
Neotraditional Design Development.
Transit-oriented development (TOD) refers to moderate to high density development
along a regional transit system. Most TOD programs are focused around rail transit
stations, though the concept can be applied to a bus corridor or ferry terminals. Ideally,
TOD consists of housing and complementary retail, office, and public service
development, though some TOD programs have focused on only a single land use. TOD
can reduce mobile source emissions by increasing transit mode share.
Infill development refers to any type of new development that occurs within existing
built-up urban areas. Infill development occurs on a vacant or under-developed site, and
is the opposite of greenfield development, which occurs at the urban edge on land that has
never been developed. Brownfield development is a specific type of infill development
that occurs on sites with real or perceived environmental contamination due to a previous
use. Infill development can reduce vehicle emissions by increasing transit mode share,
increasing walk and bike mode shares, and reducing vehicle trip lengths.
Jobs/Housing balance refers to reducing the disparity between the number of residences
and employment in a sub-region. In all metropolitan areas, some sub-regions have more
jobs than housing, while others have more housing than jobs. This disparity is thought to
contribute to longer commute trips. By achieving a more even balance of jobs and
housing within subregions, trip lengths and regional VMT may be reduced.
Mixed-use development typically refers to development that locates complementary land
uses such as housing, retail, office, services, and public facilities within walking distance
of each other. Mixed-use development can occur as part of a large new development
project, such as an entire housing subdivision. Or it can occur in built-out
neighborhoods, by adding neighborhood-scale retail and services in areas that are used
exclusively for housing or offices, for example, or by adding housing to commercial
areas. Mixed use development can reduce vehicle emissions by increasing walking and
bicycling mode share, and by reducing vehicle trip lengths.
Neotraditional neighborhood development refers to a set of land use and urban design
elements that are designed to replicate pedestrian-oriented neighborhoods built before
automobiles became the dominant travel mode. While this term is often applied loosely
to a wide variety of development, it usually includes some land use mixing that allows
walking from housing to retail and/or office development. Neotraditional development
also encompasses numerous design features that encourage walking. These include
design improvements to public spaces such as the addition of pedestrian-scale signs,
benches, landscaping and small parks, and infrastructure improvements like sidewalks,
bicycle facilities, narrow streets and greater street connectivity. Commercial
development is typically oriented to sidewalks, with office space ideally over ground
floor retail. Parking is minimized and located behind buildings away from the street
frontage. Neotraditional neighborhood development can be located on new greenfield
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sites or on infill sites. It can reduce vehicle emissions by increasing walking and
bicycling mode shares.
Obviously there is considerable overlap between these categories. A typical transit-
oriented development, for example, can occur on an infill site that features mixed land
uses and incorporates neotraditional design features. In fact, most of the land use
measures that could be considered for air quality credit will promote more than one of
these types of urban form. They are distinguished in this report because they may vary in
their implementation mechanisms, their ability to reduce emissions, and in the methods
needed to quantify their impact.
There are also a number of measures that are typically considered part of sustainable
development, but do not strictly involve land use. These include improved bicycle and
pedestrian facilities, traffic calming and street design, and parking strategies like cash-out
programs, parking pricing, and reduced parking standards. These strategies can all play a
role in reducing vehicle use and often work in conjunction with the land use measures
listed above. They are not considered further in this paper, however.
3.4 Impact of Land Use Policies and Programs on Urban Form
The effect of land use policies and programs on urban form, travel and emissions is
complex. Our understanding of these relationships is incomplete, and the technical
methods used to represent them have inherent uncertainties. While developing a specific
methodology for quantifying the impact of land use measures is beyond the scope of this
work effort, it is important to raise some of the quantification issues that affect the policy
options available for emissions credit. It is useful to represent these relationships as
follows:
Policies/Programs -» Changes in Urban Form -» Changes in Travel -> Changes in Emissions
The quantification effort will require estimating how the policies or programs will affect
urban form, how the urban form change will affect travel, and how the travel change will
affect emissions. We will focus here primarily on the first two relationships: the impact
of land use policies and programs on urban form, and the impact of urban form changes
on travel. Most of the issues with respect to the impact of travel on emissions are not
specific to land use and are well-documented elsewhere.
Evaluating the impact of policies and program on urban form requires a system to
measure the urban form and monitor its change. In general terms, there are two types of
urban form change: one is a redistribution of regional population or employment growth
between zones; the other is a change in urban design or small-scale land use mixing.
While in reality most land use measures could produce both types of urban form change,
it is useful to consider them separately.
3.4.1 Redistribution of growth between zones
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A shift in growth between analysis zones would be the likely impact of an effective
measure to promote infill, jobs/housing balance, or TOD. This type of urban form change
will be relatively easy to measure and monitor. The zonal population or employment
figures can simply be compared to those in the baseline.
Infill Development
To monitor the progress of a control measure designed to increase infill development, the
agency would need to define a set of zones as infill target areas. These would likely be
areas in the central city or inner-ring suburbs that have significant amounts of vacant or
underutilized land. To measure infill progress, the population or employment in these
target zones should increase more than in an uncontrolled baseline scenario, while growth
in non-infill zones should occur at a rate slower than in a baseline.
Jobs/Housing Balance
Measures designed to increase jobs/housing balance can be monitored using available
land use data, though more sophisticated metrics may be needed. At the simplest level,
sub-regions could be defined as sets of analysis zones and the ratio of population to
employment could be tracked over time. This would not account for the variances in
employment needs across education and skill levels, however. Some studies have
developed more sophisticated indices of employment accessibility that account for the
differences between high-skill, white collar jobs and lower-skilled blue collar and service
jobs.
Transit-Oriented Development
Comparing zonal growth figures would also work to some extent to monitor transit-
oriented development. Zones containing, or near, regional transit stations should
experience a population or employment increase above a baseline forecast, at the expense
of non-transit-oriented zones. The ability to accurately measure transit-oriented
development will depend on zone size, however. Most studies indicate that the
maximum distance travelers will walk to a transit station is a quarter- to half-mile. If the
objective of the TOD measure is to reduce vehicle starts, then population or employment
densities must increase within this distance from a transit station. Analysis zones that are
several miles across will not be able to discern clustering around a transit station from a
general increase in zone density.
3.4.2 Micro-Scale Urban Form Changes
Micro-scale changes in urban form, such as site- or neighborhood-level land use mixing
and urban design factors, will be more difficult to measure and monitor. These types of
changes would be the likely outcome of an effective mixed use or neotraditional design
measure.
Land Use Mixing
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Measuring land use mixing or urban design features may require some analysis tools that
are not currently available to most regional agencies. Land use mixing at the site or
neighborhood level cannot typically be measured using population and employment
figures unless very small zones are used. These types of changes will probably need to be
measured on a project-by-project basis. For example, if a control measure was intended
to increase the mixing of office facilities with retail and services (such as restaurants,
convenience stores, dry cleaning, day care, etc.), progress could be monitored by tracking
the portion of new office developments that incorporate these features. There will be no
way to compare this to a standard land use baseline forecast, so some assumptions will
have to be made regarding the amount of mixing of "uncontrolled" development patterns.
Another option would be to define mixed use target areas and then monitor the number of
retail, office, and service facilities using business registration data. The monitoring
agency would need to define the objectives of a mixed use strategy. For example, in
areas dominated by office use, a goal would be to increase the ratio of retail floor area to
office floor area.
Neotraditional Design
Changes in urban design may also require some alternative measurement techniques.
One simple option would be to track improvements to the pedestrian and bicycle
infrastructure that result from a control measure, such as the addition of pedestrian paths,
sidewalks, street crossings, bicycle lanes, bicycle racks, etc. Some studies have
developed other simple measurements of the pedestrian environment, such as blocks per
square mile or street widths, but this would not work well to measure change in
neighborhoods that are already built-out. There have been a number of recent efforts to
develop composite measurements of the pedestrian environment in order to test its
influence on travel behavior. In the Portland region, for example, every analysis zone
was assigned a Pedestrian Environmental Factor (PEF) from 4 to 12 by rating four
attributes: street connectivity, sidewalk continuity, ease of street crossing on principal
arterials, and topographic constraints to pedestrian mobility.* These rating systems are
somewhat arbitrary, however, and it might be difficult to use them to track changes in the
pedestrian environment due to a control measure.
3.4.3 Quantifying the Impact of Policies and Programs
There are no standard procedures for quantifying the impact of land use policies and
programs on urban form. If we consider only the sustainable land use activities that are
occurring as part of the larger regional planning process, then the existing procedures for
developing the regional land use forecast account to some extent for all local, regional,
and state land use policies. Typically, the COG will produce an initial land use forecast,
and then negotiate with local governments over the details. The COG must weigh the
desires of local governments with past trends and the realities of market forces. General
plans, zoning ordinances, development incentives, etc., do not guarantee that any change
LUTRAQ Volume 4a: The Pedestrian Environment., 1000 Friends of Oregon, 1993.
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will occur. The process of developing the regional land use forecast typically accounts
for all the factors that can shape the distribution of growth, and their inherent
uncertainties; thus, generally, it would be difficult to identify growth redistribution
impacts from land use measures that are not reflected in the regional land use forecast.
If it is felt that there are growth distribution impacts not reflected in the baseline, or in the
case of a land use measure initiated expressly for air quality purposes, quantifying the
impact of the control measure would need to be done on a case-by-case basis by
knowledgeable local and regional planners. In a few regions that employ formal land use
models like TRANUS or MEPLAN to aid in the forecasting process, the models can be
used to some extent to forecast the impact of some policies and programs. However, the
most widely used land use model, DRAM/EMPAL, cannot generally be used to forecast
the impact of most land use policies, such as zoning or development incentives. All
regional land use models could be used only to show the redistribution of regional
growth; micro-scale urban form changes are generally not recognized in zone-based
models.*
The impacts of policies and programs on micro-scale urban form changes are not
accounted for in developing the regional land use forecast because they are not typically
measured. Quantifying these impacts will require expertise by local and regional
planners. For example, the effectiveness of incentive programs that encourage developers
to include certain design or land mixing elements into projects will depend greatly on the
type of incentive and the market forces in that city at that time. Local planners will be in
the best position to credibly estimate the impact of these types of programs on urban
form.
One issue that could complicate efforts to quantify the impact of land use policies and
programs on growth distribution is the impact on regional growth totals. Currently,
nearly all MPOs assume a fixed amount of population and employment growth for the
region. States often determine these figures and require MPOs to use them. Under the
assumption of fixed regional growth totals, growth controls and development incentives
simply rearrange new jobs and housing within the region. However, it is possible that
some land use policies and programs could actually change regional growth totals from
the state's official forecast. For example, very strict growth controls could limit the
regional population in-migration, or strong infill incentives could lure additional growth
to a region. In the latter case, emission reduction benefits from sustainable development
might be offset by a greater increase in the region's population and VMT. Trying to
account for changes in regional growth totals would probably be difficult both politically
and technically. If land use measures were thought to be causing a change in regional
growth totals, it would raise questions about whether other cities in the state were gaining
or losing growth as a result. Given these difficulties, it is likely that metropolitan areas
will continue to assume fixed regional growth totals.
* For a full discussion of these issues, see Evaluation of Modeling Tools for Assessing
Land Use Policies and Strategies., 1991. See also Abraham and Hunt, 1998.
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3.4.4 Time Frame for Change
It is very difficult to draw any conclusions about the length of time that will be needed for
sustainable land use policies and programs to have an impact. As mentioned earlier, the
most commonly used land use models are not very sensitive to land use policy changes,
so they cannot be employed to estimate the impact of land use measures over time. The
effectiveness of specific implementing mechanisms will depend heavily on local market
conditions. In general, those interviewed as part of this work assignment and WA09 felt
that policies such as urban growth boundaries that attempt to promote infill by restricting
new development on the urban edge may not have any impact until available greenfields
land becomes scarce. Direct incentives to build on infill sites or near transit stations may
have an impact more quickly.
A number of regions have used travel and emissions models to show how alternative
future land use scenarios could reduce emissions, including the MPOs in Denver,
Portland (Oregon), Boston, and San Diego. But these scenarios are typically developed to
illustrate the full range of possibility and bear little relation to actual land use policies.
Most of the interviewees we asked about this issue felt that a realistic land use measure
would not show a significant emissions benefit for at least a decade and possibly two or
three. But clearly more research is needed to understand how sustainable land use
policies can shape urban form over time.
3.5 Measuring the Impact of Urban Form Change on Travel and
Emissions
Once the impact of a land use measure on urban form has been quantified, the next step is
to quantify the impact of the urban form change on travel and emissions. As described
earlier, the existing process is to use the official regional land use forecast as input to a
standard four-step regional travel demand model. The model produces a forecast of
VMT, vehicle starts, and average speeds that is used in an emissions model.
Quantifying the travel and emissions impact of a land use measure can be done in several
ways. Although there will also be many uncertainties involved in this calculation, there is
a large body of research and some existing analytical tools to rely upon. The complexity
of these tools and the cost and effort needed to use them can vary considerably.
In general, there are three ways in which land use can affect the travel and mobile source
emissions in the modeling process.
1. By shifting trips to non-automobile modes, land use can reduce regional VMT
and reduce vehicle starts. This can be accomplished by locating housing,
employment, or retail in areas more accessible to transit, or in closer proximity
to each other to facilitate walking or bicycling. Infrastructure and urban design
changes can also increase the non-automobile mode share by making transit,
walking, or bicycling more attractive options.
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2. By bringing trip origins and destinations in closer proximity, land use can
reduce vehicle trip lengths and hence regional VMT. This can be accomplished
by locating housing, retail, and employment in closer proximity to reduce the
distance of automobile trips. However, since this does not affect the number of
vehicle starts, it generally has less impact on emissions than diverting trips to
alternative modes.
3. Land use can affect congestion levels and vehicle speeds. The impact of vehicle
speed on emissions depends on the pollutant. In general, emissions per mile are
greatest at low speeds and high speeds, and lowest at moderate speeds.
It will generally be more difficult to quantify a travel and emissions benefit from micro-
scale urban form changes than from growth redistribution. Most empirical studies of the
land use/transportation relationship have focused on the impact of density and transit
access. Because higher densities often occur in conjunction with greater land use mixing,
and pedestrian-friendly urban design, it is difficult to separate the impacts of each of these
factors. Some studies have succeeded in isolating the impact of land use mixing. Urban
design is more difficult to study in isolation, and very few studies have been able to
credibly quantify its impacts on travel.
3.5.1 Using Regional Travel Demand Models to Quantify Land Use Benefits
One option for quantifying the impacts of urban form change would be to use the regional
travel demand model. This is the standard four-step model (possibly with other steps
added as enhancements), typically created and run by the MPO. While running a full
metropolitan travel demand model requires extensive time and effort for data collection,
model calibration, and validation, it may be relatively easy for an MPO to test alternative
land use scenarios in conjunction with the evaluation of a regional transportation plan or a
major investment study. A typical regional travel demand model could be used to
quantify at least some of the impact of a redistribution of population or employment
growth.
Metropolitan travel demand models can vary considerably in their sophistication and their
ability to forecast the travel impact of urban form changes. For example, if population
growth is shifted to TAZs that are located in areas with higher transit service, one would
expect the travel demand model to forecast an increase in transit use. The extent to which
the model does this depends on how the mode choice module is structured. Less
sophisticated mode choice modules might capture TOD benefits only through a slight
reduction in total transit travel time. A more sophisticated model might show lower
transit walking access time, higher densities around transit stations, and lower vehicle
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ownership levels as a result of TOD.* Similarly, shifting some of the retail or office
employment growth to TAZs that are located closer to residential areas, or to TAZs with
better transit access, should reduce vehicle use in the forecast. More sophisticated
models include walking and bicycling options in the mode choice module, and these
mode shares should increase if more destinations are accessible by foot or bike. In
simpler models that generate only vehicle trips, a higher density of local shopping
destinations would reduce only the vehicle trip generation rates. **
A number of metropolitan areas have used regional travel demand models to evaluate the
transportation and air quality impacts of alternative land use scenarios. For example,
studies in Baltimore, Seattle, and Portland have used regional models to show a reduction
in VMT from more compact growth patterns.*** The most comprehensive studies, done
in Portland, show significant congestion and emissions reductions resulting from more
compact and transit-oriented growth. However, the scenarios being evaluated in many
regions represent the extremes of future urban form, and assume full regional
participation. Modeling more realistic land use changes, or changes that occur only in
portions of the region, may show more ambiguous results.
The distinct advantage of using a single regional travel demand model for measuring the
impact of land use is that the model usually covers a geographic area roughly consistent
with the nonattainment area. Emissions are measured across the entire nonattainment
area. A local impact in urban form can have secondary impacts in other parts of a region,
such as affecting congestion levels; only a regional model can account for these impacts.
The limitations of these models are well known. Because they are based on a system of
analysis zones that are typically no smaller than census tracts, they cannot account for
micro-scale changes in land use, such as land use mixing at the site or block level. And
because they are designed primarily for evaluating large highway and transit
infrastructure improvements, they typically do not accurately reflect bicycle and
pedestrian travel. Therefore, in order to quantify the impact of micro-scale land use
changes, some alternative tools must be employed.
3.5.2 Improving Models to Better Capture Land Use Benefits
* Purvis, Charles, L., Incorporating Land Use and Accessibility Variables in Travel
Demand Models., Presentation at the ASCE Specialty Conference on Transportation, Land
Use and Air Quality, May 1998.
** Harvey, Greig and Elizabeth Deakin, A Manual or Regional Transportation
Modeling Practice for Air Quality Analysis, prepared for the National Association of
Regional Councils, July 1993.
*** The Effects of Urban Form on Travel and Emissions: A Review and Synthesis of
the Literature, Draft Report, 1998.
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The ability of a standard regional travel demand model to capture the benefits of
sustainable land use can be enhanced by increasing the model complexity, employing
additional model variables, or supplementing the model with other software packages.
Pedestrian Environmental Factors
One option is to enhance the standard travel demand model with some measure of the
pedestrian environment at the zonal level. The Portland, Sacramento, and Montgomery
County areas have incorporated a "pedestrian environmental factor" into their models.
This factor has been shown to improve the mode choice and auto ownership elements of
the models.
However, it is unlikely that this type of model enhancement would be able to fully
capture the micro-scale benefits of land use. Since the factor is a composite rating for the
entire zone, it may not be useful for changes that occur in only a small part of a zone.
Also, because all models are designed to forecast trips between zones and not within
zones, many short walking and bicycling trips are never captured in a travel demand
model even with measurements of the pedestrian environment.
INDEX Model
Another alternative is to use some form of spreadsheet-based analysis tool to enhance a
regional travel demand model. As described in Appendix C, a related EPA project has
been attempting to measure the benefits of infill development using the INDEX model.
This model combines GIS mapping capabilities with spreadsheet analysis and some
assumptions about the land use/transportation relationship from empirical studies. A
proposed development can be described in detail with INDEX, including such factors as
block length, land use mixing, parking, pedestrian features, and transit accessability. The
INDEX model, combined with a regional travel demand model, produces estimates of the
traffic, energy use, and emissions that result from the development.*
This process of combining a regional travel demand model with a tool like INDEX
requires considerable effort, and it would probably not be feasible to repeat it on a case-
by-case basis. If the EPA-sponsored efforts could develop some general estimates of the
emissions benefits of particular urban form changes, then it might be possible to apply
these results to other control measures. The work currently being done is testing the
sensitivity of the INDEX model to variations in the size, location, and type of land use
mixing in a project. This may be an important tool to distinguish between the benefits of
growth distribution and micro-scale urban form changes.
3.5.3 Off-Model Calculations
* The Transportation and Environmental Impacts of Infill versus Greenfield
Development: A Comparative Case Study Analysis, Review Draft., 1991.
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The other option is to estimate the impact of urban changes outside of the regional
modeling process. Using some professional judgement and empirical research, the
forecast of regional VMT or trips would be adjusted to account for a control measure.
For example, the air agency for the San Francisco Bay Area estimated the emissions
benefits of its program to promote more transit-oriented development. They assumed 200
additional housing units at each of the region's 75 rail transit stations. Based on the
regional household travel survey, each of these households was estimated to contribute
0.5 fewer trips per day than if the household were not located near a transit station. After
calculating the total emissions reduction, the agency took credit for only 20% of the
benefit to account for the uncertainties involved.
Several regional air agencies in California use a software tool known as URBEMIS7G to
estimate the emissions impact of particular projects. The software is primarily used as
part of an environmental review. It incorporates standard trip generation rates and some
assumptions about the vehicle fleet, average speed, etc. The latest version of the software
also allows the user to account for specific land use and urban design features that can
reduce travel and emissions, based on empirical studies of the land use/transportation
relationship.* While the emission reduction from any individual project would be quite
small, this type of tool could possibly be used to estimate the impacts of land use and
design features that were incorporated into a group of projects.
The danger in calculating travel and emission impacts off-model is that there may be
secondary impacts of a local land use change that are not captured. For example, it's
possible that a mixed-use development on an infill site could increase walking mode
shares locally, but because the site becomes a popular regional attraction, it would cause
shoppers to drive farther than they currently do. Or the development could increase local
congestion levels to the point where they negate the emission reduction due to increased
walking. These secondary effects are difficult to measure without a region-wide model.
The nature of land use measures can also make them difficult to evaluate in isolation.
Some regions feel that individual control measures have little impact in isolation, but the
synergistic effects of a combination of measures is greater than the sum of the parts. In
other cases, the benefits of several individual measures might overlap, and the cumulative
impact is less than the sum of the parts. The only way to consistently treat these
interactions would be to evaluate all measures under a single modeling framework.
3.6 Summary
Table 1 summarizes some of the points made in this chapter. It is important to keep in
mind that the conclusions drawn here reflect some simplifying generalizations about
policies, urban form, travel behavior, and technical methods.
* URBEMIS7G Computer Program User's Guide, Version 3.1, prepared for San
Joaquin Valley Unified Air Pollution Control District by Jones & Stokes Associates,
August 1998.
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Table 1
Land Use Measures Summary Points
Land Use
Measure
TOD
Infill
Jobs/Housing
Balance
Land Use
Mixing
Neotraditional
Design
Implementing
Mechanisms
State Development
Incentives
Local Growth
Controls
Local Incentives
State Growth
Controls
State Development
Incentives
Local Growth
Controls
Local Incentives
State Growth
Controls
State Development
Incentives
Local Growth
Controls
Local Incentives
Local Growth
Controls
Local Design
Controls
Local Incentives
Local Growth
Controls
Local Design
Controls
Local Incentives
Effect on
Urban Form
Mostly Growth
Redistribution
Some Micro-
scale Impacts
Mostly Growth
Redistribution
Some Micro-
scale Impacts
Growth
Redistribution
Mostly Micro-
scale Impacts
Mostly Micro-
scale Impacts
Effect on
Travel
Mode Shift to
Transit
Mode Shift to
Transit/
Walk/Bike
Shorter Trip
Lengths
Shorter Trip
Lengths
Mode Shift to
Walk/Bike
Shorter Trip
Lengths
Mode Shift to
Walk/Bike
Reflected
in
Baseline?
Somewhat
likely
Somewhat
likely
Likely
Somewhat
unlikely
Unlikely
Ability to
Quantify
Benefits
Less
difficult
Less
difficult
Less
difficult
More
difficult
More
difficult
###
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4. Conclusions
Land use measures can provide an effective strategy to reduce mobile source emissions.
However, in order to better recognize sustainable land use practices in the air quality
planning process, a number of technical, institutional, and regulatory issues need to be
addressed. As discussed in Chapter 2, there are three general options for recognizing the
emissions benefits of sustainable land use: include the measure in the SIP baseline, adopt
the measure as some type of SIP control measure, or show an emissions reduction from
the measure to support a conformity determination. A critical factor in assessing these
options is the extent to which the measure is already reflected in the regional land use
forecast.
The interest in sustainable land use results primarily from efforts to reduce traffic
congestion, promote economic vitality, preserve recreational open space and agricultural
lands, protect threatened species, and use infrastructure funds more efficiently.
Sustainable land use activities may have a beneficial impact on air quality, but that is
rarely their primary intent. Thus, most sustainable land use activities are being
considered as part of a local and regional planning process, and are included in the
regional land forecast. These measures could still be used for explicit emissions credit if
the baseline does not completely reflect their impact.
It is also possible that land use measures could be initiated by air agencies expressly for
air quality purposes. The research conducted under WA09 and this project suggests that
this is rare. However, if such a measure were implemented, it might not be reflected in
the baseline and could potentially serve as a SIP control measure.
4.1 The Baseline Option
A forecast of regional emissions may be reduced by improving the procedures for
quantifying land use impacts in the baseline scenario. It is important to keep in mind that
the process for developing the SIP baseline and conformity analyses already accounts for
some of the effects of land use policies and programs. Emissions benefits from land use
measures that are reflected in a baseline cannot be used for explicit credit, neither in the
SIP nor as a conformity determination control measure. With this in mind, there may be
ways to better incorporate some land use measures into the baseline that are not normally
reflected in the baseline.
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What is typically reflected in the baseline?
The benefits of a land use measure are likely to be reflected in the baseline if (1) the land
use forecast includes the urban form change caused by the measure and (2) the travel
modeling captures the benefits of the urban form change. As discussed in Chapter 3, this
is likely to be the case for measures that result in a redistribution of regional growth
between zones. Thus, measures that simply cause growth redistribution are generally not
good candidates for explicit emissions control measures.
The types of measures that would typically produce growth redistribution include infill
development, transit-oriented development (TOD), and jobs/housing balance measures.
The implementing mechanisms that produce these types of changes include state and
regional growth controls and local growth controls. In general, the more likely it is that a
policy will affect actual growth distribution, the more likely it will be reflected in the
baseline. For example, in regions affected by state-mandated growth control policies, the
regional land use forecast that underlies the baseline will almost certainly reflect any
impact of the policy on growth distribution.
What is typically not reflected in the baseline?
The baseline land use forecast will probably not reflect micro-scale urban form changes
like urban design and land use mixing. Nor is it likely that most travel and emissions
models capture the full impact of these types of changes. So land use measures that
produce micro-scale urban form changes are better candidates for explicit credit. In
addition, the baseline might not reflect a measure that was initiated expressly for air
quality purposes by the air agency.
The types of measures that would typically produce micro-scale changes include mixed-
use development and neotraditional design measures. Some infill and TOD measures
could also produce micro-scale urban form changes as a secondary impact. The
implementing mechanisms that can produce these types of changes include local
government incentives and design controls. Many transportation modelers have indicated
that the emissions benefits from micro-scale urban form changes will typically be very
small and difficult to quantify.
In reality, many land use measures will produce both larger-scale growth redistribution
and micro-scale urban form changes. This could lead to a scenario in which some of the
benefits of a measure were accounted for in the baseline, and other benefits were not. In
such a case, the only way to take credit for the change as an explicit control measure
would be to separate the impact of the two types of urban form changes. This may be
difficult to do and would probably require a high level of approximation.
Can land use be better incorporated into the baseline?
It may be possible to modify the baseline forecasting process to account for land use
measures that would not otherwise be reflected in the baseline. For example, there are a
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number of improvements that can be made to regional travel demand models so that they
better account for micro-scale factors like the pedestrian environment.
Incorporating in the baseline the impact of land use policies and programs that are not
included in the regional land use forecast would be a significant departure from current
practice and probably not advisable. Since policies and programs included in the baseline
are not subject to the control measure enforceability and documentation requirements,
this option could lead to credit for a land use measure that does not get implemented.
While in the long run this would cause problems for showing conformity or ROP
requirements, credit for activities that are not included in the regional land use forecast
should be done using explicit control measures.
Issues for EPA
The advantage of taking "implicit credit" for land use measures in the baseline is that it
would be relatively easy for air agencies or MPOs to do. Taking emissions credit by
improving the existing regional travel demand model would also minimize the possibility
of double-counting benefits. Because of the limitations of the current models, however,
this option will probably not provide much emissions credit.
4.2 The SIP Option
Land use measures not reflected in the baseline could be used to show emission
reductions as a SIP control measure. As described in Chapter 2, the existing EPA
guidance for both EIP and VMEP programs can apply to land use measures. As most
land use measures rely on local government implementation rather than direct state
control, the VMEP option may be more attractive to many regions. However, the
emissions reduction allowed under VMEP is limited to 3 percent of the inventory for each
criteria pollutant.
Existing Requirements
Adding a land use measure under either the EIP or VMEP option will require the air
agency to estimate compliance and programmatic uncertainty. Compliance uncertainty
addresses the degree to which governments adopt implementing mechanisms in support
of sustainable land use. Programmatic uncertainty addresses the degree to which urban
form, travel, and emissions change as a result of the implementing mechanisms. Due to
the nature of the development process, the level of programmatic uncertainty will
typically be very high. Land development is strongly influenced by fluctuations in market
demand. And most land use policies do not guarantee that any changes will occur, since
local officials can choose to ignore the policies.
Disadvantages of the SIP Process
Since most nonattainment SIPs address only a five- to seven-year horizon at the most,
they offer little opportunity to recognize the longer-term benefits of land use unless
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measures are included in a Maintenance Plan. In addition, for land use measures initiated
expressly for air quality purposes, it may be difficult to use the SIP process as an
incentive for local governments to participate in measure implementation. While local
governments in some regions are heavily involved in efforts to reduce pollutants like
fugitive dust, in other regions there is little burden placed on local governments to reduce
mobile source emissions. Thus, there may be little opportunity to reduce the burden for
those that commit to sustainable land use activities.
Issues for EPA
Taking credit for land use measures in the SIP process raises the prospect of double-
counting benefits already reflected in the baseline. Air agencies typically have a poor
understanding of the land use and travel demand forecasts that form the baseline. To
ensure that land use measure benefits are surplus, air agencies will need to better
document the land use and travel forecasts that make up the baseline. Additional EPA
guidance may be needed regarding the form of this documentation. However, it should
be recognized that any new requirements may make the adoption of land use measures a
less attractive option.
To adopt, as a control measure, land use policies and programs that are not included in
the regional land use forecast, the state would typically need assurances from local
governments that the actions would be implemented as expected. The form that this
assurance should take is not clear under the existing guidance.
4.3 The Conformity Option
Land use measures that are not reflected in the baseline could be used to show an
emissions reduction in support of a transportation conformity determination. The MPO
estimates the emissions that will result from the implementation of a long-range
transportation plan, and these emissions must be within the mobile source emissions
budget established in the SIP. Estimates of emissions can be reduced by factoring in the
impact of control measures, thus providing "credit" for the measures.
Advantages over the SIP Process
As described in Chapter 2, the conformity option has several advantages over the SIP
process. Most importantly, conformity addresses a longer time period than the SIP, and
thus better matches the time needed to realize the benefits of land use measures. The
conformity requirements for interagency consultation bring together all relevant local,
regional, and state agencies in a frequent and regular forum. Any difficulty in showing
conformity will focus the participants specifically on strategies to reduce mobile source
emissions. Since this process is being conducted in conjunction with a new regional land
use forecast and transportation plan, it provides a good opportunity to consider the impact
of land use. Finally, because it is linked to future transportation funding, the conformity
process may offer an opportunity to provide incentives to local governments to adopt land
use measures.
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Existing Requirements
The Conformity Rule specifies that emission reductions from projects like TCMs that are
not "regionally significant" may be estimated with reasonable professional practice, rather
than incorporating them into the regional travel demand model. The Rule defines the
type of implementation commitment needed to include a control measure in the
conformity determination. Measures that require regulatory action (i.e., zoning or other
growth control mechanisms) generally must be already adopted by the local government,
or must be included in the SIP, or the SIP must contain a letter of commitment from the
implementing authority.
Issues for EPA
There are several issues that EPA may wish to address with respect to land use measures
in the conformity determination. While the requirements for including control measures
in the SIP and conformity determination are essentially the same, at least several air
agencies perceive that there is less accountability for measures adopted to show
conformity than in the SIP. There is also a potential to double-count control measure
benefits that are already reflected in the baseline. Currently, it would be difficult for a
reviewer to detect this double-counting because there is little requirement for
documenting the baseline land use forecast and the policy assumptions that underlie it.
As with SIP measures, additional EPA guidance may be needed regarding documentation
of the baseline land use assumptions.
4.4 Summary
In summary, the first critical issue with respect to policy options for land use measure
credit is whether the regional land use forecast includes the control measure. Nearly all
examples of current sustainable land use activities are occurring primarily for reasons
other than air quality, and these are likely to be included in the regional land use forecast
to the extent that they are having an impact. Then the issue becomes the extent to which
the emissions benefits of the measure are reflected in the output of travel and emissions
models. Many of the micro-scale changes may not be reflected, and could be used for
additional emissions credit. Care must be taken to avoid double-counting benefits that
are already reflected in the baseline.
For control measures that are not reflected in the regional land use forecast, the key issue
with respect to credit is obtaining the commitment needed to assure that the land use
measure will be implemented. If these commitments exist, then the important issues
relate to evaluating the inherent uncertainties of urban form change and quantifying the
travel and emissions benefits. Again, care must be taken to avoid double-counting
benefits that are already reflected in the baseline. Table 2 presents a summary of these
issues.
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Table 2: Sustainable Land Use Policies and Programs
Process for Adoption
Included in Regional
Land Use Forecast?
Land Use Measure
Urban Form Impacts
Models Reflect Travel
and Emissions Benefits?
Candidate for Additional
Control Measure?
Issues for EPA
Adopted Outside the Air Quality
Planning Process
Likely
TOD
Infill
Jobs/Housing
Balance
Mostly Growth
Redistribution
Likely
Probably Not
How to prevent
double-counting of
benefits already
reflected in
baseline?
Mixed-Use
Neotraditional Design
Mostly Micro-Scale
Changes
Unlikely
Possibly
How can models be
improved to better
account for emissions
benefits of measure?
How to prevent
double-counting of
benefits already
reflected in baseline?
Initiated Expressly for
Air Quality Purposes
Unlikely
TOD
Infill
Jobs/Housing Balance
Mixed-Use
Neotraditional Design
Growth Redistribution &
Micro-Scale Changes
No (if not in regional land
use forecast)
Possibly
Appropriate commitment
is needed from local gov't
to assure measure
implementation.
How to estimate the
uncertainty of urban form
change?
How can models be
improved to better
account for emissions
benefits of measure?
How to prevent double-
counting of benefits
already reflected in
baseline?
###
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5. References
Abraham, JE and JD Hunt, Policy Analysis Using the Sacramento MEPLAN Land Use
Transportation Interaction Model, submitted for presentation at the 1999 TRB
conference, July 1998.
Assessing the Emissions and Fuel Consumption Impacts of Intelligent Transportation
Systems (ITS), US EPA, December 1998.
Babsin, Marc, Mary Hill, Laura Melendy, Megan O'Neill and Elizabeth Deakin, Real
Estate Trends and Transit-Oriented Development: A Compendium for 21
Metropolitan Regions, Working Paper 688, Institute of Urban and Regional
Development, University of California at Berkeley, June 1997.
Bay Area '9 7 Clean Air Plan and Triennial Assessment, Volume 1, Bay Area Air Quality
Management District, December 17, 1997.
Clean Air Communities, Clean Air Act Advisory Committee, US EPA, August 7, 1997.
Conformity Determination of the 1994 Baltimore Region Transportation Plan and the
1999-2003 Transportation Improvement Program, Prepared by the Transportation
Steering Committee, the Metropolitan Planning Organization for the Baltimore
Region, July 1998.
Economic Incentive Program Rules, US Environmental Protection Agency, 40 CFR Part
51, 1994.
The Effects of Urban Form on Travel and Emissions: A Review and Synthesis of the
Literature, Draft Report, prepared by Apogee/Hagler Bailly for the EPA Urban and
Economic Development Division, April 17, 1998.
Emission Inventory Requirements for Ozone State Implementation Plans, U.S. EPA
Office of Air Quality Planning and Standards, March 1991.
Evaluation of Modeling Tools for Assessing Land Use Policies and Strategies, prepared
by Arlene S. Rosenbaum and Brett E. Koenig of Systems Applications
International, for the EPA Office of Mobile Sources, August 1997.
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Guidance on Incorporating Voluntary Mobile Source Emission Reduction Programs in
State Implementation Plans (SIPs), Memorandum from Richard D. Wilson, October
24, 1997.
Harvey, Greig and Elizabeth Deakin, A Manual or Regional Transportation Modeling
Practice for Air Quality Analysis, prepared for the National Association of Regional
Councils, July 1993.
Indirect Source Review Program, Implementation Guidelines, Prepared by the
Sacramento Metropolitan Air Quality Management District, February 1995.
Johnston, Robert A., Caroline Rodier and Melanie Choy, Transportation, Land Use, and
Air Quality Modeling, date unknown.
Land Use Distribution Element of the Regional Growth Management Strategy, San Diego
Association of Governments, February 1995.
LUTRAQ Volume 4a: The Pedestrian Environment, 1000 Friends of Oregon, 1993.
Methodologies for Estimating Emission and Travel Activity Effects ofTCMs, Prepared for
US EPA by Systems Applications International, July 1994.
Ozone Attainment Demonstrations, Memorandum from Mary D. Nichols, March 2, 1995.
Phase II Attainment Plan for the Baltimore Region and Cecil County, Maryland
Department of the Environment, April 1998.
Preliminary 2020 Cities/Counties Forecast - Technical Update, San Diego Association
of Governments, February 26, 1999.
Purvis, Charles L., Incorporating Land Use and Accessibility Variables in Travel
Demand Models, Presentation at the ASCE Speciality Conference on
Transportation, Land Use, and Air Quality, May 1998.
Sacramento Area Regional Ozone Attainment Plan, Sacramento Metropolitan Air Quality
Management District, November 15, 1994.
State Implementation Plans; General Preamble for the Implementation of Title 1 of the
Clean Air Act Amendments of 1990, US Environmental Protection Agency.
Task 6: An Analytical Framework for the Evaluation of Air Quality Transportation
Control Strategies, Working Draft Report, Prepared under NCFIRP 8-33,
Quantifying Air Quality and Other Benefits and Costs of Transportation Control
Measures, by Cambridge Systematics, Inc., April 1997.
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The Transportation and Environmental Impacts of Infill versus Greenfield Development:
A Comparative Case Study Analysis, Review Draft, Criterion, Inc. and Apogee
Research, December 17, 1997.
Transportation Conformity Rule Amendments: Flexibility and Streamlining; Final Rule,
US Environmental Protection Agency, 40 CFR Parts 51 and 93, August 15, 1997.
Transportation-Related Land Use Strategies to Minimize Motor Vehicle Emissions: An
Indirect Source Research Study, prepared by Deborah A. Dagang and JHK &
Associates for California Air Resources Board, June 1995.
Technical Methods for Analyzing Pricing Measures to Reduce Transportation Emissions,
US EPA, August 1998.
Tools for Reducing Vehicle Trips Through Land Use Design, San Diego Air Pollution
Control District, January 1998.
URBEMIS7G Computer Program User's Guide, Version 3.1, prepared for San Joaquin
Valley Unified Air Pollution Control District by Jones & Stokes Associates, August
1998.
Ventura County 1994 Air Quality Management Plan, Appendix R-94: Transportation
Control Measure Documentation, Ventura County Air Pollution Control District,
1994.
###
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Appendix A Interviewees
Charles Baber, Baltimore Metropolitan Council
Ben Cacatian, Ventura County Air Pollution Control District
Dennis Canavan, Montgomery County, Maryland
Diane Franks, Maryland Department of the Environment
Andy Hamilton, San Diego Air Pollution Control District
Paul Kavanaugh, San Diego Association of Governments
Dave Mitchell, San Joaquin Valley Unified Air Pollution Control District
Brian O'Sullivan, Puget Sound Air Pollution Control District
Steve Smith, South Coast Air Quality Management District
Bob Stern, New Jersey Department of Environmental Protection
Steve Tracy, Local Government Commission, Sacramento, California
Tim Trahimovich, City of Redmond, Washington
Mike Winter, Sacramento County, California
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Appendix B Sustainable Land Use Internet Web Sites
Smart Growth Network
http: //www. smartgro wth. org
Transportation Action Network
http: //www .transact. org
Sustainable Communities Network
http://www.sustainable .org
Growth Management Institute
http: //www .gmionline .org
U.S. Department of Energy, Center of Excellence for Sustainable Development
http://www.sustainable.doe.gov
The U.S. Conference of Mayors, Joint Center for Sustainable Communities
http ://www .usmayors.org/uscm/sustainable/sj -7 .htm
National Governors Association, Center for Best Practices
http: //www .nga. org/Center/Activities/SmartGrowth .asp
Presidents Council on Sustainable Development
http: //www. whitehouse .gov/PC SD/
National Trust for Historic Preservation
http://www.nthp.org
Planners Web: Sprawl Resource Guide
http://www.plannersweb.com/sprawl.html
Center for Neighborhood Technology
http://www.cnt.org
Oregon Transportation and Growth Management Program
http://www.lcd.state.or.us/issues/tgmweb/about/index.htm
BUILDER Online, July 1998 special report on Sprawl
http ://builder .hw .net/monthly/1998/j ul/covstory/spraw!4 .htx
City of Austin, Smart Growth Initiative
http://www.ci.austin.tx.us/doorstep/98/10/smartgrow .htm#anchorl055467
New Jersey Pinelands Comprehensive Management Plan
http: //www. state .nj .us/pinelands/cmp .htm
Smart Growth in Maryland
http: //www. op. state .md .us/smartgrowth/
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Appendix C Related Work Efforts
A Methodology to Establish SIP Creditability of Infill Development
This is an ongoing contract with Apogee/Hagler Bailly and Criterion under EPA's Office
of Policy (OP). Preliminary work performed is described in a draft report entitled The
Transportation and Environmental Impacts of Infill versus Greenfield Development: A
Comparative Case Study Analysis. This study uses regional travel demand modeling to
compare the travel and emissions impacts between a hypothetical development located on
an infill site and on a greenfield site. Models were run for three case studies, in
San Diego, California; Montgomery County, Maryland; and West Palm Beach, Florida.
Each case study consisted of modeling a hypothetical large development as if it were
located on an actual infill site, and then modeling the same development as if it were on
an actual greenfield site. The development size remains the same in both locations, but
the density and street patterns are consistent with the surrounding urban form at each
location. In each case, the MPO travel demand model was used to simulate the travel
impacts of the development. Environmental impacts (including NOx and CO2 emissions)
and energy use were estimated using a GIS-based model called INDEX.
All three case studies show that locating the development on the infill site results in lower
vehicle use and lower vehicle emissions. VMT per capita at the infill sites was roughly
half that at the greenfield sites. NOx emissions were 27 percent to 42 percent lower at the
infill sites, even though congestion at one infill site was higher than the greenfield site. It
should be noted that the INDEX model uses simplified per-mile and per-trip emissions
factors, not the standard vehicle emissions models. Further work is continuing under this
contract. The same simulation methodology will be used in different cities (Baltimore,
Dallas, and Chicago) to explore the sensitivity of the earlier results to changes in project
scale, land use type, land use mix, location, transit accessibility, etc.
Transportation Impacts of Micro Scale Urban Design Elements: Data Collection and
Modeling Needs
This 1998 joint DOT (FHWA)/EPA (QMS and OP) funded project will bring together
current knowledge and recent research concerning the ability to appropriately reflect the
transportation impacts of various micro-scale urban design elements (e.g., sidewalk
width, building setback, street grid type, etc.). A report from the contractor conducting
the study, Parsons Brinckerhoff, should be available in late 1999. The report will explain
procedures to estimate how land use development strategies and site design elements
affect travel behavior and will give examples from selected MPO experience.
Particularly useful for MPOs will be a product that will relate specific urban design
changes to auto ownership, trip generation (or tour or activity generation), and mode
choice for use in current travel demand models.
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Air Quality Impacts of Regional Land Use Policies
This 1998 joint OP/OMS-funded grant to Robert Johnston at the University of California,
Davis will produce a document for policy makers at the national, state, and metropolitan
levels that illustrates the air quality benefits or deficits of regional policy scenarios that
affect land use development patterns. Policies that affect land use directly, such as
removing density caps on zoning around rail stations, and indirectly, such as travel
pricing or transit investment, will be simulated. A suite of models is under development
that utilizes earlier work done in the Sacramento metropolitan area. Numerous scenarios
will be evaluated and compared to the expected baseline out to the year 2015. Scenarios
having strong effects on region-wide accessibility and affecting demand for travel or land
significantly (e.g., new road capacity, major region-wide transit capacity expansion, or
strong travel and parking pricing policies) will be evaluated. In addition, plans call for
evaluation of scenarios that include land market pricing corrections, such as incentives for
infill development, and land development fees for raw land projects at the urban edge and
beyond.
The simulations of land use, transit, and travel pricing scenarios for the Sacramento
region using the regional MPO's travel demand model are complete. Part two of the
project is underway. This will evaluate the best two or three scenarios, using two urban
models that represent land development and travel, MEPLAN and an improved
TRANUS. These results will give differences that take into account land use pricing and
give indications of the magnitude of land use price differentials for the various outcomes.
Results will be compared to the less resource intensive modeling technique previously
used.
The Effects of Urban Form on Travel and Emissions: A Review and Synthesis of the
Literature
This is an ongoing contract with Apogee/Hagler Bailly under EPA's Office of Policy
(OP). The draft report offers a thorough summary of recent research on the effect of land
use on travel behavior. Studies fall into two general categories. Empirical studies
compare data collected from actual communities and try to distinguish how various land
use factors lead to different travel patterns. Simulation studies use computer models to
examine the impact of hypothetical land use patterns on travel and emissions.
The report concludes that changes in land use can reduce region-wide vehicle use and
emissions over a period of several decades. Using simulation models, several studies
have convincingly shown that modifying future development patterns in ways that make
them less dependent on automobile use will reduce VMT and emissions. The reduction
in emissions comes from shorter trip lengths and shifts to transit, bicycling, and walking
modes. While computer modeling has improved greatly in recent years, it is still subject
to some serious limitations. Zonal size generally precludes modeling the impact of
micro-scale design features, for example.
The report documents how numerous empirical studies have shown relationships between
specific land use factors and components of travel demand. For example, compact
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clusters of mixed-use development are correlated with reduced trip lengths. Similarly,
higher density communities of mixed land use are associated with higher shares of travel
by transit, bicycling and walking. The report acknowledges the methodological flaws that
limit the conclusions that can be drawn from empirical studies. Some, for example, do
not control for factors like income when comparing neighborhoods. A more fundamental
flaw is the fact that cross-sectional studies, by nature, cannot establish causality.
Evaluation of Modeling Tools for Assessing Land Use Policies and Strategies
This complementary effort was done for the EPA Transportation and Market Incentives
Group by Systems Application International (SAI). Its final report was issued in August
1997. The work was intended to assess how regional land use forecasting models are
able to incorporate specific land use policies. The report evaluates three commercial land
use models: DRAM/EMPAL, MEPLAN, and TRANUS. Each model was evaluated in
terms of how well it could account for policies designed to (1) increase development
densities, (2) increase land use mixing, and (3) modify design elements and infrastructure
to encourage alternative travel modes. The specific policies used to achieve these goals
were summarized as zoning, monetary incentives (such as subsidies to developers to
build in targeted areas), and non-monetary incentives (such as reduced parking
requirements).
The study concludes that DRAM/EMPAL, because it does not easily represent costs,
cannot model the impact of any of the three types of policies. MEPLAN and TRANUS
do include representations of development costs, and therefore can at least partially model
zoning policies as well as monetary and non-monetary incentives. The report points out
that all the models are seriously constrained by zonal size, however. They are usually run
using zones the size of several census tracts, or a single census tract at the smallest. As a
typical urban census tract is roughly one square mile, a model built on zones of this size
could possibly detect an increase in density within a half-mile of a transit station or transit
corridor; it could not detect smaller-scale land use changes. If the zonal system uses
aggregations of census tracts, even transit station-area densities could not be resolved.
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