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Transportation and Climate Change Clearinghouse

Integration into Transportation Decision Making

1 - Overview and Summary Analysis


This report, conducted for the U.S. Department of Transportation's (USDOT's) Center for Climate Change and Environmental Forecasting (CCCEF) and the Federal Highway Administration (FHWA) by a project team from the USDOT's Volpe National Transportation Systems Center, is part of ongoing work to highlight actions and initiatives undertaken by states, Metropolitan Planning Organizations (MPOs), and local areas to incorporate climate change considerations as part of the transportation planning process.

At the current rate of growth, transportation's share of human-produced greenhouse gas (GHG) emissions in the U.S. will increase from 28 percent currently to 36 percent by 2020. When Congress, environmental groups, and others look for solutions to climate change, transportation is often considered to be a major source of the problem. USDOT must be able to participate in and contribute to these discussions to ensure that policies balance the need for reductions with other transportation goals.2

The complex nature of transportation and climate change issues poses challenges for state, regional, and local transportation decision-makers. State departments of transportation (DOTs), MPOs, counties, cities, and local transportation providers have primary responsibility for transportation planning and decision-making. Decisions range from working with elected officials to set policy to selecting major capital investments in roads, public transit, railways, ports, and airports to traffic management, tolls and pricing, and parking. State, metropolitan area, and local agencies make decisions that have a major impact on choices by residents and businesses to use one mode of travel rather than another, and to guide the land development that greatly determines travel patterns and distances.

In 1999, the U.S. Department of Transportation established the CCCEF to take a leadership role in addressing the growing policy issues associated with climate change and variability. Since its formation, the CCCEF, with a membership of eight operating administrations and the Office of the Secretary, has promoted comprehensive multimodal approaches to reduce greenhouse gases and prepare for the effects of climate change on the transportation system while advancing USDOT's core goals of safety, mobility, environmental stewardship, and security.

The USDOT formed the CCCEF to become the focal point within USDOT for information and technical expertise on transportation and climate change through strategic research, policy analysis, partnerships and outreach.

Stakeholders interviewed in the development of the current CCCEF Strategic Plan confirmed that there is a critical national role for the USDOT and the CCCEF to play on climate change and identified working with state, regional, and local agencies as a top priority. The Strategic Plan includes the following strategy as a top priority:

State and Local Transportation Planning: Focus on initiatives with State and local transportation planning agencies through outreach, capacity building, and other collaboration.

As part of this strategy, the CCCEF is conducting research to develop a better understanding of how climate change considerations can successfully be incorporated into statewide, regional, and local transportation planning efforts.

In the absence of current Federal regulations or related guidance to address climate change, states, metropolitan areas, and local governments are taking aggressive independent actions -- setting targets for reducing their GHG emissions, developing strategies to respond to the impacts of global warming and extreme weather, adopting policies to promote renewable energy, and developing climate action plans to reduce emissions. To date, 32 U.S. states and Puerto Rico have adopted climate action plans, six have plans in progress, and 46 states have completed GHG inventories.3 At the local level, 911 U.S. mayors have signed the Conference of Mayors Climate Protection Agreement4 committing to:

  • Strive to meet or beat the Kyoto Protocol targets in their own communities, through actions ranging from anti-sprawl land-use policies to urban forest restoration projects to public information campaigns
  • Urge their State governments, as well as the Federal government, to enact policies and programs to meet or exceed the GHG emission reduction target suggested for the United States in the Kyoto Protocol -- 7% reduction from 1990 levels by 2012
  • Urge the U.S. Congress to pass bipartisan GHG reduction legislation, which would establish a national emission trading system

States such as California are initiating new policies and regulations to reduce GHG emissions through the transportation planning process. California Assembly Bill 32 (2006) requires the State to reduce (GHG) emissions to 1990 levels by 2020 through a broad range of local government, transportation, and other strategies5 . Under California Senate Bill 375,6 the California Air Resources Board will set regional targets for reducing GHG emissions. The cities, counties, and MPOs participating in development of regional plans are expected to link regional land use and transportation planning to reduce GHG emissions from vehicle trips. Each metropolitan area will develop a "sustainable community strategy" in its regional transportation plans to meet the GHG reduction targets.

Other states are forming multi-state regional and inter-regional coalitions to reduce GHG emissions through emissions trading, clean energy development, and other programs. Regional efforts such as the Conference of New England Governors and Eastern Canadian Premiers (NEG/ECP), the Northeast Regional Greenhouse Gas Initiative (RGGI), and the West Coast Governors' Global Warming Initiative are underway to address emissions. The activities of the NEG/ECP are reviewed in detail in a case study in this report.

These multistate, statewide, regional, and local initiatives represent a broad range of innovative transportation planning - the process for considering goals, setting priorities, assessing alternatives, determining trade-offs between climate change, energy, and a range of transportation goals, and reaching decisions on multi-modal transportation policies, investments, and strategies. Ultimately, these evolving efforts are beginning to have important impacts on how State DOTs, MPOs, and transportation agencies responsible for roadways, railroads, public transit, airports, ports, and nonmotorized transportation serve their jurisdictions.

For example, under the New York State Energy Plan, MPOs in the State are required to conduct a GHG energy analysis as part of the transportation planning process for "regionally significant" transportation projects and plans. The Houston area MPO is involved in regional planning to adapt the transportation network to prepare for the impacts of climate change, and in the Seattle metropolitan area, the MPO is considering GHG emissions in long range transportation and land use planning.

Although the number of State and local initiatives continues to grow, there has not been a systematic effort at the national level to survey, assess, and document innovations and successes, and provide information to assist states and MPOs who are interested in incorporating climate change considerations into transportation planning processes.

This report contributes to improving the national base of knowledge on how and why state, regional, and local organizations are integrating climate change within their transportation planning processes. The report builds on earlier research by the CCCEF on statewide and regional transportation7 :

  • "Greenhouse Gas Reduction Through State and Local Transportation Planning" (companion to this report)
  • "Assessing State Long Range Transportation Planning Initiatives in the Northeast for Climate and Energy Benefits"
  • "Integrating Transportation, Energy Efficiency, and GHG Reduction Policies: A Guidebook for State and Local Policy Makers"

This report focuses on the following areas:

  • Inclusion of GHG reduction as a broad goal in long-range planning
  • Consideration of climate change/weather impacts in long-range planning
  • Consideration of GHG reduction in vision or scenario planning
  • Analysis of GHG reduction through data collection, analysis, or modeling
  • Coordination among states, cities, and counties in developing their GHG reduction plans and/or inventories
  • Building consensus through public involvement and outreach to stakeholders

This report provides case studies and summaries of presentations from two panels of State and regional experts at a national research meeting of the Transportation Research Board (TRB) on Transportation, Land Use, and Air Quality, and the annual conference of the Association of Metropolitan Planning Organizations (AMPO).

Case Studies

This report includes three cases studies by innovative planning and policy organizations: an MPO, a State DOT, and a regional and bi-national organization of states and Canadian provinces:

  • Puget Sound Regional Council ( Seattle metropolitan area MPO): long-range planning that considers the GHG emission implications of alternative transportation investments and land use strategies, working in partnership with Seattle , King County , and Washington DOT;
  • New York State DOT (NYSDOT): policies and programs to work with MPOs to measure the GHG emissions of major transportation projects;
  • Conference of New England Governors and Eastern Canadian Premiers (NEG/ECP): examines how a bi-national and super-regional approach can be used to develop multi-sectoral policies, targets, and actions to support State, regional, and local transportation planning to meet emissions reduction targets. The case study considers the range of approaches taken by selected States, provinces, or regions within the bi-national area.

Expert Panels

As part of the research for this report, the CCCEF organized and sponsored two panels of experts to exchange information on innovative current practices, barriers encountered, and lessons learned:

  • TRB Conference on Land Use, Transportation Planning, and Air Quality ( Orlando , FL )
    • º Puget Sound Regional Council ( Seattle area MPO)
    • º NYSDOT
    • º NEG/ECP
    • º Gulf Coast Study
  • AMPO Annual Conference ( Little Rock , Arkansas )
    • º Boston Region MPO and Central Transportation Planning staff
    • º National Capital Region Transportation Planning Board (TPB) ( Washington , D.C. , area MPO)
    • º Puget Sound Regional Council

Report Overview

This report discusses how the case study areas and those represented by panelists consider climate change, including emissions reductions strategies and impacts of extreme weather on transportation systems, in transportation planning through:

  • Collaboration and partnerships with transportation and non-transportation agencies
  • Policies
  • Outreach
  • Technical methods and tools

The report also considers the extent to which climate change considerations are becoming a factor in State, regional, and local transportation investments and other decisions that reduce GHG emissions. The report examines the prospects for the future, including technical or institutional challenges to overcome, and lessons learned to assist peer States, regions, and localities that are interested in considering climate change within their transportation planning processes.

Climate change considerations can shape the selection of investments and strategies resulting from a region's transportation planning process. Transportation planning can be viewed as a critical means to address what is variously described as the "three legs of the stool" for reducing GHG emissions: vehicle technology, vehicle fuels, and vehicle mile travel reduction. More recently, analysts and advocates have added a "fourth leg" to the stool: improved efficiency of the transportation system through technology, pricing, or other means. Transportation planning can play a critical role in addressing all of these elements - energy and vehicle efficiency, travel behavior changes, and system management - individually and in combination.

The case studies and panel summaries focus on how States and MPOs are considering climate change at key stages of their transportation planning process:

  • Long Range Planning
    • º GHG reduction as a broad goal in regional vision planning and the development of transportation and land use scenarios over time periods that range from 30 to 40 years
    • º Long-range planning to prepare transportation systems for and adapt to the impacts of climate change and extreme weather
    • º As part of the Federally-required long range transportation plans that all areas over 50,000 population must prepare, identifying goals, needs, investments, costs, and revenues over a 20-25 year period.
  • Forecast, Data, and Performance Measures
    • º Carbon dioxide (CO2) reduction in vision or scenario planning
    • º Analysis of reductions through data collection and modeling
  • Public Involvement and Coordination
    • º Coordination among States, cities/counties, and transportation authorities on GHG inventories and reduction plans and transportation plans
  • Project Selection and Decision-Making
    • º Investments and strategies that reduce CO2
    • º Along a spectrum of choice ranging from reviewing and screening proposed projects to using GHG emission reductions as a project selection criterion

As discussed in this report, integration of climate change considerations within the transportation planning process is rapidly evolving - the States and MPOs reviewed will continue to make rapid changes, and many of their peers will likely undertake similar planning initiatives.


The following summary presents key observations based on the case studies and panel summaries in this report. Insights from the panels are based both on the presentations and the ensuing discussion with the audiences of researchers and senior planners from peer MPOs. As the transportation planning processes studied in this report evolve, they will continue to provide insights for peer States, regions, and cities that are considering following similar paths.

Table 1 presents a summary of approaches being undertaken by the agencies reviewed in the case studies and represented on the two panels. The entries in the table identify initiatives undertaken that the study team considered to be innovative and of significant potential interest to peer agencies considering how to incorporate climate change within their planning.

Table 1: State and Regional Transportation Planning and Climate Change: Summary of Major Aspects of Transportation Planning Processes

Table 1: State and Regional Transportation Planning and Climate Change: Summary of Major Aspects of Transportation Planning Processes. If you are a user with disability and cannot view this image, call 800-853-1351

X = In place or pending
A = Anticipated

The role of targets to reduce GHG emissions within transportation planning process:

  • The transportation planning process can be adapted to focus on the feasibility of meeting CO2 emission reduction targets through transportation and land use policies, investments, and other strategies.
  • PSRC and TPB provide examples of how vision and scenario plans can be used to engage stakeholders and decision-makers by presenting a range of possible emissions reductions for a metropolitan area over a long time horizon and beginning to identify critical regional choices and trade-offs required to meet reduction targets.
  • The MPOs reviewed are supported by formal State, regional, city, or county Climate Change plans with reduction targets, actions, and dates in place; are conducting early planning; or are developing policies that could support future plans and targets to reduce GHG emissions.
  • The NEG/ECP member States and provinces have GHG or Climate Change plans in place with targets or are developing plans, supported by the voluntary targets set collaboratively by the governors and premiers for the U.S.-Canadian northeastern region.

The need for realistic policy advocacy:

  • As suggested by panelists in discussion with peer MPOs at the AMPO session, there is an important role for MPOs to play nationally in the policy debate about what can realistically be accomplished through metropolitan area transportation planning and complementary land use planning, and more broadly at national, statewide, and local levels with city, county, and modal authority partners.

Key initial stages: policy development and supportive regulations:

  • The examples reviewed in this report demonstrate the role regulations can play as key mechanisms for State, regional, and local agencies to translate political support and policies into concrete actions to reduce emissions or respond to climate change impacts.
  • The NYSDOT case study describes an early application by a State of regulations and policies to implement the State Energy Plan, which requires MPOs to conduct a GHG energy analysis as part of its transportation planning process for plans and "regionally significant" projects.
  • TPB conducted modeling to forecast GHG emissions from land use and transportation scenarios in response to policy direction from its Board, building on technical capabilities in place to meet existing conformity requirements of the Clean Air Act Amendments.

Thinking long term: the role of vision planning and scenarios:

  • MPOs can use long-term planning horizons to examine how transportation and land use policies and actions might reduce GHG emissions. This can be over the 20-25 year horizon of long range plans, but also over the longer periods -- 30, 40, or even 50 years -- considered in regional vision and scenario plans.
  • MPOs can employ "back-casting" techniques to examine aggressive GHG reduction targets and work backwards to identify the potential policies, investments, and strategies that would be required to meet those targets.
  • As a key part of the planning process, MPOs can play an active role educating decision-makers and the public about realistic options, critical choices, and necessary trade-offs to meet aggressive goals.

Linking transportation to land use:

  • The MPOs reviewed in this report approach GHG emissions reductions as involving coordinated transportation and land use planning.
  • The PSRC planning process and vision plan are national models for how MPOs can attain GHG emission reduction targets with combined transportation and land use policies and programs.
  • TPB provides a very helpful example of how an MPO can evaluate transportation and land use scenarios to indicate the range of CO2 emission reductions possible over a long-term time horizon in a complex region (two States and the District of Columbia ).

Ultimate test: linking planning to decision-making:

  • Transportation planning provides a sound technical process for making decisions, including formulating policies, identifying investments, and developing strategies that can involve land use as well as transportation considerations.
  • The areas summarized in this report are taking the early steps necessary to establish broad support for considering climate change in State and regional transportation planning processes. These steps include:
    • º setting policies to reduce emissions (NY DOT, NEG/ECP, TPB, and PSRC)
    • º developing GHG plans with targets or linking to plans by partner governments (PSRC)
    • º developing new technical capabilities to forecast emissions from alternative transportation decisions (PSRC and the TPB)
  • Rigorous GHG analysis conducted early in the decision-making process can be translated into criteria as part of the screening or selection of investments in metropolitan or statewide transportation improvement programs (TIPs and STIPs). These criteria will require rigorous technical analyses to credibly forecast GHG impacts of alternative decisions combined with broadly based political and institutional support to pursue GHG emission reductions alongside traditional transportation goals, such as mobility, congestion relief, or safety, and other broader goals, including energy conservation or public health.

Need for realistic expectations:

  • The case studies provide early "reality checks" on the range of feasible reductions in CO2 emissions that DOTs, MPOs and their planning partners might accomplish through policies, investments, and other strategies that they might shape.
  • The MPOs in the NY DOT area identify possible limits of potential GHG emission reductions from major projects and the difficulty involved with estimating project-level emissions impacts.
  • The scale of GHG reductions from MPO-initiated actions may be small relative to the reductions possible from Federal or State policies directed toward energy and vehicle technology, including fuel economy standards, renewable fuels, advanced vehicle designs, cap and trade regulations, or carbon pricing.
  • As suggested at the AMPO peer exchange, as MPOs begin to examine the potential emissions reductions through regional planning and actions, initial limitations should not result in pessimism and inaction; MPOs should aggressively address energy and climate change issues with innovative planning, particularly over long time horizons.
  • Experiences of State DOTs, MPOs, and local authorities using transportation planning to consider climate change could be very helpful for informing future Federal and State policies and regulations.

GHG emission reductions can complement other regional goals (role of co-benefits):

  • GHG reduction activities are best pursued in combination with other regional goals, particularly air quality improvement, but also energy conservation, smart growth, open space preservation, congestion relief, and public health.

Important technical role for MPOs:

  • MPOs that are already modeling criteria pollutants from transportation, as required by the Clean Air Act Amendments for conformity, are in a strong technical position for refining or developing models that also analyze CO2 emissions.
  • Enhanced models that account for factors such as speed, vehicle mix, weather, and fuel type are necessary to accurately analyze CO2 emissions at regional, corridor, and project levels, as required for comprehensive transportation planning. PSRC is at the forefront of MPOs that are testing and refining some of these types of model improvements.
  • Future Federal or State requirements for MPOs to perform related analysis of GHG emissions will require additional staff and improved technical capacity, especially for smaller MPOs.

Impacts/adaptation versus mitigation/reductions:

  • Phase 1 of the CCEF study, "Impacts of Climate Change and Variability on Transportation Systems and Infrastructure Gulf Coast Study" assessed the vulnerabilities of regional transportation systems to potential changes in weather patterns and related impacts. Phase 2 will include resources for planners and engineers working at the State, regional, and local levels.
  • MPOs such as the Boston Region MPO are approaching climate change by first raising public awareness of forecasted impacts, which may then build the future support necessary for regional transportation decisions to reduce emissions.
  • To date, MPOs actively considering climate change appear to be focusing either on adaptation of transportation facilities to global climate change and extreme weather, or on identifying investments and strategies to reduce GHG emissions.
  • As MPOs gain experience with climate change issues, it is likely that increasing numbers will be interested in pursuing both adaptation and reductions. A future challenge will be to balance pursuit of emissions reductions and preparation for impacts alongside other planning priorities since both may draw on the same limited resources.

Anticipation of possible future policies, regulations, or programs:

  • Federal and State policies and initiatives and major trends related to climate change and energy will have profound impacts on the ability of State DOTs, MPOs, and local governments to reduce CO2 emissions. Changes in these areas appear likely following the 2007 Supreme Court ruling that requires the EPA to determine whether CO2 emissions endanger public health and welfare and the priority placed by the Administration and Congress on developing new climate change policies.
  • MPOs should be prepared for the possibility that future Federal policy may entail regulatory actions requiring GHG reductions.
  • Models and staff will need to be enhanced to meet future Federal and State policies and regulations.
  • Currently, carbon monoxide, nitrogen oxides, and volatile organic compounds are included as criteria pollutants in air quality analysis; MPOs such as TPB and PSRC are exploring how they can expand this technical analysis to estimate GHG emissions.
  • MPOs, State DOTs, and regions that are already addressing or at least accounting for GHG emissions, such as those evaluated in this paper, will be well-positioned to respond to any future regulations.
  • State DOTs and MPOs interested in GHG emissions reductions should anticipate possible Federal and State policies, and develop local strategies that might amplify the results of these policies. For example, MPOs and States might anticipate shifts to alternative fuels by supporting investments in energy infrastructure. Similarly, increases in fuel prices, including from carbon pricing or cap and trade programs, might be anticipated with investments in alternative modes or land use policy to support compact development or improved jobs-housing balances. California 's Senate Bill 375 will provide a laboratory for one comprehensive state-based regulatory approach to reduce GHG emissions through coordinated regional transportation and land use planning.

Role of education and outreach:

  • Education and outreach are important components in all of the case studies and panel presentations.
  • The Boston Region MPO white paper represents a helpful example of an early effort by an MPO to raise the awareness of decision-makers, stakeholders, and the public of the connection between climate change and transportation, and to build support for future related planning and decisions.
  • The TPB conducted modeling of scenarios to raise the technical understanding of decision-makers and stakeholders of the range of GHG reductions that are possible considering land use and transportation scenarios examined in the past vision plan.
  • The NEG/ECP efforts are directed toward educating State and provincial-level leaders and stakeholders and building broad-based political support for future bi-national, multi-state, and multi-province policies, and related regional and local actions, to reduce GHG emissions.
  • The Gulf Coast study will help raise the awareness of the States, cities, MPOs, modal operators, and other jurisdictions in the multi-state region on the vulnerability of the region's transportation networks and the pressing need to plan for collaborative adaptation. The study provides a valuable model for approaching transportation adaptation in a large vulnerable area with complex and over-lapping jurisdictional responsibilities.

Importance of Partners and Champions

  • Partnerships are critical for successful GHG emission reduction strategies. Whether it is at the metropolitan, State, or multi-state level, partnerships help ensure "buy-in" and ownership of multi-jurisdictional and multimodal measures to realize significant GHG reductions.
  • While partnerships are important, political or community champions, including elected officials, are essential to move measures from plans to implementation. With concurrence of other stakeholders, champions can move stalled or complex measures forward and can bring more partners into the process.

Other Related Issues

  • Panelists and the discussants at the two workshops expressed interest in research and an exchange of information on the relationship between zoning and climate change impacts and national experiences integrating climate change into the environmental review process.

2 US DOT Center for Climate Change "Strategic Plan,"

3 US EPA Climate Change Site, last updated August 2008 (February 9, 2009)

4 U.S. Conference of Mayors Climate Protection Center (February 9, 2009)

5 California Air Resources Board, "Summary of AB 32 California's Climate Change Scoping Plan,"

6 California Senate Bill 375, September 30, 2008,; summary by the California Department of Transportation,

7 Available with other related research on the CCCEF web-site:

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