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Transportation Planning and Sustainability Guidebook

Chapter 3: State of the Practice

Section I: US practices in planning for sustainable transportation

A survey of the state Departments of Transportation (DOTs) was conducted by Georgia Institute of Technology from Fall 2008 to Spring 2009 to characterize current activities in sustainable transportation (see questions below). The survey indicated that various state DOTs appreciate the importance of sustainability in their external and internal activities, and can point to specific initiatives, largely environment-related, that demonstrate their interest in or commitment to sustainability. Agencies are clearly focused on a range of activities with various levels of engagement in sustainability practice. Examples of planning and analysis tools to address sustainability in transportation planning include scenario planning, GIS, prioritization and performance measurement, climate action plans, health impact assessments, green rating systems, and others.

Survey Questions: Sustainability and Transportation Planning

1. What policies has your board, agency, or department head enacted regarding environmental stewardship? These could be very broad policies relating to overall agency activities, or something as specific as how roadsides are maintained. If such policies exist, what was the reason for their adoption (if known)?

2. Which units of your agency are responsible for the different initiatives? From your experience were there any barriers or difficulties encountered in implementing the initiatives?

3. Has the inclusion of environmental stewardship considerations changed the institutional structure of the organization - for example, was a new position, team, or department created?

4. Are the policies/programs coordinated with any other DOT departments or with outside agencies/local governments?

5. Are the eventual outcomes of these programs/policies measured or monitored? If so, what indicators or measures are used? How often does this measurement occur? Who receives this information within the organization? Are there any examples of where this information was actually used to change program characteristics?

6. Does your department address other aspects of sustainability in the planning process? Economic development? Land use? Quality of life or social equity? Other? Please explain.

 7. Has the inclusion of these other sustainability considerations changed the institutional structure of the organization - for example, was a new position, team, or department created?

8. Are the policies/programs coordinated with any other DOT departments or with outside agencies/local governments?

9. Do these programs/policies involve measuring or monitoring sustainability? How? How often?

10. Do you know of any examples in other DOTs that are good examples of sustainable planning practices?

Each DOT has a unique package of policies or programs, but all the state DOTs address environmental planning in some way. Recently, green initiatives and climate change plans have been receiving attention across the country. In terms of economic sustainability, project prioritization methods are becoming more desirable as state DOTs attempt to maximize outcomes with relatively limited resources. The high level of prior activity in environmental (stewardship) initiatives is likely the result of federal legislative priorities in that area, although the current financial crisis may be shifting the balance towards economic initiatives. State DOTs are least active in social sustainability (beyond environmental justice policies and public involvement processes) and struggle to find appropriate performance measures to monitor social impacts. The survey also indicates that state DOTs have relatively little knowledge about peer activities addressing sustainability in transportation, but they are interested in sharing their experiences and learning from their peers. In the absence of a broad overarching sustainable development strategy, peer exchanges or other support resources such as online outreach materials could be valuable learning resources for agencies. Some level of coordination between and among state agencies would be necessary for states to address sustainability more comprehensively.

The following sections describe the state of the practice, with specific practices in each area described in more detail in Chapter 5: Case Studies. Best practices are those practices that are models for other transportation agencies and have been recognized by FHWA, AASHTO, or peer agencies.

Environmental Sustainability & Climate Change Initiatives

A majority of state DOT environmental initiatives began in response to federal requirements of the National Environmental Policy Act (NEPA) or national transportation reauthorization acts. The environmental initiatives range from roadside planting/mowing practices and wetland banks to early environmental screening and comprehensive environmental management policies. Just under half of the survey respondents reported a CSS program or approach to project development. Other environmental management best practices fall into two categories: early environmental screening and green or climate change initiatives.

State DOTs reported a wide range of green initiatives - from growing biodiesel crops and purchasing a more energy efficient vehicle fleet to greenhouse gas emissions budgets and climate action plans. Specific examples from the survey are described in Table 3-1. Climate change, an important piece of environmental sustainability, is gaining attention across the country. During the survey from 2008-2009, almost one-third of the state DOTs reported involvement with a climate change initiative. By 2011, over 35 states had climate action plans and more than ten had adaptation plans; state and regional transportation agencies typically contribute to those plans (77). Climate change initiatives possibly represent new concepts to transportation-environment planning because they are examples of comprehensive and collaborative approaches. It is important to note that most of these initiatives were stimulated by state policies (like a greenhouse gas budget) or a governor's directive. Both Vermont (VTrans) and California (Caltrans) have released climate change plans, and Oregon DOT collaborated on the Oregon Climate Change Adaptation Framework, which was released in December 2010 and assesses climate impacts to transportation and other critical infrastructure.

Table 3-1. Summary of Environmental Sustainability Best Practices
DOT Practice Description
OregonContext Sensitive and Sustainable SolutionsDecision-making framework that combines context-sensitive design with sustainability principles (
Delaware&TennesseeGIS-based environmental screeningStatewide GIS data used to identify environmental issues during the planning process; requires GIS data from multiple state, regional, and local agencies
FloridaEfficient Transportation Decision-makingProcess to anticipate environmental problems early on through partnership with resource agencies, public involvement, and GIS-based environmental assessment (
PennsylvaniaLinking Planning and NEPATraining program to educate employees on linkages and overlaps between planning and NEPA in order to streamline both processes ( )
VermontEnergy and Climate Change Action PlanPreventative measures to address impacts of air quality and climate change, including both mitigation and adaptation approaches; involves coordination with local governments, state agencies, and neighboring states (
CaliforniaClimate Action ProgramActive climate change mitigation and adaptation measures in response to state legislation; includes greenhouse gas reduction strategies, sea-level rise assessment and habitat-connectivity study (
OregonClimate Change Mitigation Policies and PracticesEfforts to address climate change through both internal and external practices that address vehicle miles traveled and system efficiencies; formed a Climate Change Executive Group and Climate Change Technical Advisory Committee to establish priorities and guide ODOT activities; recognize importance of land use planning and multi-modal planning for mitigation (
IllinoisSustainability ProgramInitiatives to improve agency's internal sustainability (energy efficiency, emissions reduction, recycling) and be a model for local governments

Performance Measurement

Performance measurement is a tool for transportation agencies to monitor and assess progress toward sustainability. Approximately 60% of the DOTs reported that they use performance measures or indicators related to the environment, economy, and/or quality of life. However, many of the DOTs lacked a formal or comprehensive system for tracking these measures. Notably, the Texas DOT (TxDOT) recently worked with the Texas Transportation Institute on a project to develop sustainability indicators for the agency's strategic plan (the technical report was published in April 2009). The project resulted in 13 sustainable transportation performance measures that relate back to goals in TxDOT's strategic plan. For example, for TxDOT's "improve air quality" goal, the related sustainability objective is to reduce adverse human health impacts, which is related to the following performance measures: daily NOx, CO, and VOC emissions per mile of roadway. In addition to the performance measures framework, the technical report provides TxDOT with methodologies for evaluating the measures using readily available data inputs, and defines a process for benchmarking, indexing, and monitoring the measures. A few case studies demonstrate how the measures can be applied to rural, urban, and suburban contexts (30). Several other state DOTs provide good examples of performance measurement, with Minnesota DOT's system being cited most often in the survey. See Table 3-2 for these examples.

In addition to tracking performance, sustainability-related indicators were cited as an important means for assessing and prioritizing transportation projects. Approximately 20% of the DOTs were using or developing indicators for project prioritization. For example, Caltrans uses the concept of the System Management Pyramid (SMP) is to guide project prioritization and influence investment decisions (see Figure 3-1). The base of the pyramid is system monitoring and evaluation, which is achieved by collecting and tracking transportation system performance measures. Caltrans collects performance measures related to safety and security, system preservation, mobility/access, reliability, and customer satisfaction at the state level. The measures are used to identify areas of deficiency (or opportunities for improvement) and the pyramid is then used to assess potential solutions. In addition to being used during development of the statewide transportation plan and improvement programs, the SMP has been used to prioritize projects for economic stimulus funding. Additional examples of indicator use are provided in the discussion of economic and financial sustainability. Indicators are also commonly used to compare and assess transportation and land use scenarios. Indicator frameworks for project prioritization provide an opportunity to develop robust sustainability measurement systems, though it must be noted that most indicator frameworks for state DOTs are not explicitly linked to sustainability goals.

System Management Pyramid from top to bottom: System Completion and Expansion, Operational Improvements, Intelligent Transportation Systems (Traveler Information/Traffic Control, Incident Management), Smart Land Use and Demand Management/Value Pricing, Maintenance and Preservation, System Monitoring and Evaluation. Goals of Prevention and Safety guide all aspects of the Pyramid.
Figure 3-1. Caltrans' System Management Pyramid

Table 3-2. Summary of Performance Measurement Frameworks and Reporting
DOT Practice Description
TexasSustainable Transportation Performance MeasuresFramework for sustainability measures that correspond to goals in TxDOT's strategic plan; current selection of measures was limited by data availability (
MinnesotaPerformance-based Planning&ProgrammingFramework using clear policy priorities, performance trend data, and performance forecasting to guide investment decisions; measures cover both internal and external activities (
WashingtonGray NotebookQuarterly report of goals and measures organized around WSDOT's five legislative and strategic policy goals (safety, preservation, mobility/congestion relief, environment, and stewardship) and a “Performance Dashboard” of key indicators; transparency and organized presentation make it useful for internal tracking and external accountability (public review)(
IowaResults IowaAnnual report and online monitoring system that outlines performance goals and measures, and assesses which targets have been met; measures used to adjust allocation of resources and identify investments in priority corridors (
MissouriTrackerQuarterly report of measures for eighteen outcome areas covering environmental responsibility and economic development since 2005; an additional goal added in 2009 to track impacts of stimulus funding (
California State and Regional MeasuresReports on performance goals and measures at both the regional (Blueprint Planning reports) and state level (annual reporting on 9 performance outcomes from the California Transportation Plan) ( and

Sustainability Plan or Program

As of 2010, only five state DOTs and the District of Columbia DOT had a formal sustainability plan or program (Table 3-3). Sustainability plans and programs are important because they provide a comprehensive and coordinated way to address sustainable transportation within the agency and across complementary state agencies. International best practices were also examined; most notably, the New Zealand Ministry of Transport's sustainability-centered long-term plan. Oregon DOT has released the first two volumes of its Sustainability Plan, which is the US example most similar to New Zealand's plan. London's strategic freight plan was also developed with a sustainability focus. It is very clear from these efforts that the accomplishment of more sustainable transportation outcomes must be a function of a comprehensive multi-faceted approach. New Zealand and London's plans are described in more detail in Chapter 5.

Table 3-3. Summary of Sustainability Plan/Program Best Practices
DOT Practice Description
Oregon Sustainability Plan Three volume plan that will outline goals, actions, and performance measures for internal actions and external system management to achieve a sustainable transportation system; Volume 1 (defining sustainability) released in January 2009 and Volume 2 (internal operations) released in Fall 2010; Volume 3 (managing statewide transportation network) under review (
PennsylvaniaSmart TransportationPartnering with other agencies, states, and local communities to make financially, environmentally, and socially sustainable decisions; includes a public education campaign and a handbook co-authored by New Jersey DOT (
MassachusettsSustainable Development Principles, Commonwealth Capital Review, Mobility PartnershipStatewide sustainable development principles adopted to guide policies, programs, and infrastructure investment decisions; partnering to coordinate transportation service planning and delivery
CaliforniaSmart Mobility FrameworkPilot project with EPA to create a sustainability assessment framework for transportation policy, planning, and programming; currently being tested for corridor analyses but will be used to assess regional and state efforts as well (
Washington StateSustainability Plan and Progress ReportAnnual plan update and progress report on sustainability targets and emerging issues (
Washington, D.C.Sustainability PlanCollaborative effort of all DOT units that describes eight priority areas for promoting sustainability; includes recommended actions, measures and targets for each priority area (

Transportation and Land Use Coordination

Due to the local control of land use decisions, state DOTs have limited opportunities to influence land use policy. For the most part, state DOTs influence land use through access management policies, basically limiting the number of access points to state-supported roadways in order to manage growth. Twenty-two of the surveyed DOTs reported that they address land use coordination and one-third of them reported using access management as the primary tool. Those states (seven respondents) with Smart Growth legislation or comprehensive planning requirements are better able to plan for land use impacts and respond to changes in land use. A number of state DOTs are engaging in coordinated transportation and land use planning in various ways (Table 3-4). Each initiative involves coordination with other state-level agencies and/or local governments.

Table 3-4. Summary of Coordinated Transportation-Land Use Best Practices
DOT Practice Description
MontanaSystems Impact Action Process (SIAP)Transportation Impact Analysis tool and coordinated development review process for determining impacts and required mitigation ( )
PennsylvaniaLand Use and Transportation for Economic Development (LUTED)State and regional agencies coordinate efforts for land use, transportation, economic development, and conservation to make effective investment decisions; DOT's Sound Land Use Implementation Plan is updated annually ( and
CaliforniaRegional Blueprint Planning ProgramGrant program for collaborative regional visioning and scenario planning that integrates transportation, land use, housing needs, resource protection, and other issues; communities shape their Blueprints process through selection of performance goals (
New JerseyNJ Future in Transportation (NJFIT)Effort coordinated with NJ's Office of Smart Growth to emphasize re-investment and transformation of existing transportation infrastructure; produced nationally recognized programs including Transit Villages and Mobility and Community Form (
New York StateSmart PlanningSmart Growth educational and training programs and planning assistance for local and regional transportation agencies; website to facilitate communication (
North CarolinaNC Interagency Leadership Team (NCILT)Coordinate transportation and land use planning efforts among several state and federal agencies; initiatives include a statewide action plan and development of a comprehensive shared GIS database (

Green Transportation Standards

State DOTs are currently leading or contributing to several initiatives to implement green standards for transportation facilities. Green infrastructure is an important lever for promoting sustainability. For the most part, the state DOTs have developed rating systems modeled after the U.S. Green Building Council's Leadership in Energy and Environmental Design (LEED) rating system for buildings. The LEED system, while not required, has led to marked improvements in the sustainability of buildings. LEED certification has become a great marketing tool for new developments due to positive public perception. Green standards and certifications for transportation projects could likewise stimulate innovative and sustainable design and improve the carbon footprint and image of the transportation industry. Table 3-5 describes some of the rating systems that were active or in-development by 2011. In addition to the tools listed in the table, FHWA has developed a sustainable highways self-evaluation tool (refer to page 2 for more information). With all of the options out there, it is not important which tool is chosen but that a tool is being used and customized to the agency.

Table 3-5. Summary of Green Transportation Standards
DOT Practice Description
NYSDOTGreenLITES (Leadership In Transportation and Environmental Sustainability)First completed rating system; applied internally to DOT projects to recognize sustainable practices, encourage innovation, measure performance, and identify areas for improvement; certifications and awards will be announced annually (
U of Washington, CH2M Hill, WSDOTGreenroads Sustainability rating system for highways that includes 76 credits in 7 categories, including 11 required credits; draft version being tested and calibrated; roadway developers will be able to apply for official certification or use the system for guidance (
Public-private initiative with support from EPA, FHWA, Maryland DOT (MDSHA)Green Highways Partnership (GHP)Voluntary partnership to share information and provide guidance for developing more sustainable roadways (
Public/private team from Oregon and WashingtonSustainable Transportation Access Rating System (STARS)Rating system for transportation projects, plans, and employer programs that is under development
University of Wisconsin with Wisconsin DOTBE2ST rating systemApproach based on triple bottom line that uses qualitative measures to screen road projects and then rates a project with quantitative measures. Incorporates LCA (environmental) and LCCA (economic).
Lochner EngineeringSustainable Transportation Environmental Engineering and Design (STEED)Checklist for sustainable highway/roadway projects that should be applied during planning, environmental assessment, design, and construction phases; able to track how projects change (

Economic or Financial Sustainability

In terms of economic sustainability, there is prevailing concern about the future of transportation funding, and many state DOTs are exploring ways to prioritize transportation investments to better meet user needs and maintain the system. The financial crisis confronting infrastructure may overshadow a number of other critical issues. Almost 60% of state DOTs referenced the importance of funding and prioritization of financial resources. One DOT explicitly stated that funding is the key issue for future study. To aid in assessing and prioritizing transportation projects, several DOTs are using scenarios and/or indicators to examine the type and magnitude of impacts (see Table 3-6). Performance indicators offer a relatively objective means for comparing transportation projects or investment packages and determining how they will contribute to the DOT's vision and goals. Beyond performance measurement, one of the fundamental challenges this century is defining a sustainable funding mechanism for transportation, one that would likely involve tax or user-cost financing and public/private partnerships.

Table 3-6. of Economic and Financial Sustainability Best Practices
DOT Practice Description
Montana Performance Programming Process (P3) Decision process for funding allocations based on asset management principles, scenario planning, and strategic goals ( and
Oregon Investment Scenarios Oregon Transportation Plan assesses seven policy scenarios and three investment scenarios to determine system performance outcomes of different levels/types of investment (
Illinois Program Menu Develops funding packages based on different emphases (eg. system preservation or capacity for economic development) and use iterative process to allocate all available funding and meet statewide transportation needs
Montana Highway Economic Assessment Tool (HEAT) Enhanced benefit-cost analysis tool for projects that accounts for system impacts at state, corridor, and project level; considers traditional mobility measures in addition to economic and resource impacts; tool is customizable to each state's goals and data availability ( and
Illinois Lifecycle Costing Process to assess present and future roadway condition and prioritize improvement projects; based on a facility's cost over its lifetime rather than just the upfront capital costs

Challenges in addressing sustainability

One of the most important challenges faced is the necessity of institutional change for developing and implementing effective sustainable transportation policies and programs. Over 60 percent of the DOTs reported that a new team, position, department, or arrangement resulted from incorporation of a new environmental sustainability initiative. A few of these changes (usually reorganization or combination of departments) occurred in the 1970s as a result of federal legislation, but many have occurred within the last decade. Common institutional changes include:

Another commonly cited issue was prioritizing funds for new initiatives when existing programs are already competing for limited funds. The issue is compounded by concern (usually unfounded in the long term) that green design or CSD will add costs to projects. Yet another issue is institutional inertia, which relates to the arduous task of getting the different DOT divisions on-board with new or innovative policies. Similarly, local governments are often resistant to new policies, particularly ones that they perceive as a threat to their power. Overcoming the internal or external resistance often takes leadership, coordination, education and time. There are unique challenges for large, decentralized DOTs like Texas and California, which must try to coordinate activities across all districts while still maintaining sufficient flexibility to address the districts' different priorities. For example, it may be difficult to address the issues of both rural and urban districts with just one policy. The case studies (Chapter 5) provide examples of how transportation agencies have started to address these challenges.

Section II: International practices and emerging practices in planning for sustainable transportation

Sustainability Policies and Research Strategies

Sustainable transportation initiatives at the sub-national or local level are strongly influenced by national policies and regulations. As stated earlier, the US does not have overarching policy guidance for sustainable transportation. Europe and New Zealand offer examples of what a national policy could look like and how it could influence agency and research and development plans at sub-national levels. The New Zealand and the Randstad (i.e., the Netherlands) examples are also very relevant to state or regional policymaking because of similar geographical scales and relationships among transportation agencies at different levels.

New Zealand

New Zealand has taken the lead in developing a coordinated national policy for sustainability. The New Zealand Transport Strategy (NZTS) 2008 establishes a set of targets to be achieved in transportation over the next 30 years. NZTS 2008 was strongly influenced by climate change and energy policy. Sustainability is explicitly part of their future vision: "people and freight in New Zealand will have access to an affordable, integrated, safe, responsive and sustainable transport system." The plan's targets reflect the stated vision and include halving per capita greenhouse gas emissions from domestic transport by 2040, increasing rail's share of freight to 25 percent of tonne-kilometers by 2040, and widely using electric vehicles. While setting targets is not necessarily unique for transportation plans, NZTS 2008 is set apart because the targets will be statutorily enforced through the Government Policy Statement on Land Transport Funding, which establishes short-term system goals that will be achieved by prioritizing funding over the next six to 10 years. In addition to the statutory funding statement, NZTS will also be evaluated through a Transport Monitoring Indicator Framework, which is being made available to the public via an online interactive version. The framework provides a procedure to monitor progress towards the objectives, sector outcomes, and targets in the Transport Strategy and Government Policy Statement. It provides a tool for evaluating the effectiveness of the current policy and for guiding future decisions. Last but not least, it also provides accountability (31).

European Union

The European Union is also recognized as a leader in coordinating sustainability at a high level through the Common Transport Policy (CTP) and the Framework Program (FMP). The goal of a "common" transport strategy is to remove barriers to free movement of goods and people throughout the EU by promoting a balanced network and sustainable development patterns. The CTP establishes targets and goals for transportation for the EU as a whole (which are translated down to the member states), but like the United States the goals are not mandatory. The CTP was established in 1992 with the express goal of using transportation to balance economic development. It has evolved over time to reflect an increasing commitment to sustainable transportation and a broader focus. In 2001, policy directives were released as a white paper called "Keep Europe Moving - Sustainable mobility for our continent." The 2001 policy emphasized mode shifts to more sustainable alternatives like transit, biking, and walking. In 2007, the European Commission released a "Green Paper: Towards a new culture for urban mobility" that reflects a commitment to sustainable energy and modes for transportation. Green papers (discussion papers on a specific subject area) and White papers (proposals for EU community actions on a particular topic) are a primary means of communication between the EC and member states (32). The FMP establishes the priorities and funding for the European Union's research, technological development and demonstration activities over a five year period, and is designed to complement the EU's priorities as reflected in the CTP (33). The FMP is carried out by government offices, universities, and private consultants in the Member States. In addition to the EU's efforts, individual member states, like Germany, Sweden and the Netherlands, have been recognized for innovative approaches to sustainable transportation (34).

The Randstad

The Randstad, an area consisting of the Dutch cities of Amsterdam, Rotterdam, The Hague and Utrecht, has a population of approximately 7.5 million. When combined with contiguous urban areas, the Randstad is one of the largest metropolitan areas in Europe. The Dutch government has identified an aggressive sustainability initiative called the Urgent Randstad Programme and the Randstad 2040 Strategic Agenda consisting of three major themes: Accessibility and economic dynamics; Climate-proof delta; and Quality of life and a good climate for residence, business and leisure.

From a research perspective, the Minister of Transport, Public Works and Water Management, the Minister of Housing, Spatial Planning and the Environment, and the Minister of Economic Affairs have developed a long-term research program called "Sustainable Accessibility of the Randstad (2008-2040)". The themes established for funding research in this program include:

Relevant sustainability perspectives in the context of the Randstad research program include: connecting at different scale levels, the synergy between urban development and infrastructural networks, and the interconnectivity of infrastructure networks. The research program will further address questions on the region's sustainability. Which gaps in our knowledge appear if we reason from the future perspective being outlined? And how can these gaps be filled? How exactly is the accessibility of the Randstad defined and quantified from a network perspective? To what extent and in what ways are the internal and external accessibility of the Randstad affected by climate change, the new water level and the energy transition? Like the EU's program, the Randstad's program integrates research and planning at multiple scales and across multiple sectors.

Spatial Analysis and Planning

Spatial planning is defined as a "self-conscious collective effort to re-imagine a city, urban region or wider territory and to translate the result into priorities for area investment, conservation measures, strategic infrastructure investments and principles of land use regulation" (35). The purpose of spatial analysis is essentially to explore potential development pattern scenarios with respect to economic development and smart growth principles. In particular, it is concerned with physical places (and their attributes) and the networks that connect them. Like scenario-building, it is a tool for informing policy and regulatory decisions. Further, it can help coordinate public policies among multiple government units and enhance regional competitive advantage by developing and leveraging a "collective asset base" (35). Spatial planning can be used to promote sustainable development by balancing environmental preservation, economic feasibility, and social equity. In terms of sustainable transportation, development scenarios require or enable certain transport projects. Spatial planning ties together the way that space is planned and used (where development happens and its form) and how people/goods can access the facilities and services that they need (36).

The general components of a spatial analysis include assessing existing conditions; evaluating internal and external relationships (linkages); performing a land suitability analysis; performing demographic projections by cohort (age, sex, income class, et cetera); investigating future development scenarios; and creating visualizations of potential patterns. A Spatial Plan is different from a traditional land use plan because it emphasizes the coordination of spatial impacts from multiple decision makers. It results in an identification of key areas of change and critical issues with the spatial development, and defines clear goals for outcomes in multiple areas. Further, spatial planning can promote mutual learning and information sharing in a collaborative, iterative political process. Unlike land use plans, the generation of scenarios is guided by an understanding of spatial development trends, market demands and needs, and environmental, economic, and social impacts. By working within a collaborative environment, stakeholders from different sectors (local government, transportation agencies, businesses, et cetera) can build ownership of the strategy and develop joint mechanisms for implementation (37).

Spatial analysis and planning have been implemented in Europe for several decades, but have only recently been discussed in the United States. The European Commission's commitment to spatial planning is embodied in the policy document European Spatial Development Perspective: Towards Balanced and Sustainable Development of the Territory of the European Union, which was agreed upon at the "Informal Council of Ministers responsible for Spatial Planning" in Potsdam (May 1999). The Netherlands is an example of spatial planning's deep roots. The Dutch have produced national spatial planning policy documents since 1960, and the concepts have influenced national, provincial and local policy. In January 2001, the government approved the Fifth National Policy Document on Spatial Planning 2000-2020, which established a new spatial development approach based on criteria for "spatial quality". The criteria are spatial diversity, economic and social functionalities, cultural diversity, social equality, sustainability, attractiveness and human scale. The criteria are intended to be guiding principles for sub-national plans, investment programs, and regulations. The document also contains four spatial frameworks to conceptualize future development scenarios:

Sustainability Footprint

Wackernagel and Rees developed the ecological footprint in 1996 as an environmental accounting tool. Since then, there have been a growing number of applications of the ecological footprint concept in infrastructure decision-making. For example, the ecological footprint has been measured for a county-level transportation network in current and future time periods (38) and applied to assess the sustainability of ports (39), building construction (40), and alternative fuels which are part of broader infrastructure systems (41). Footprint analysis has also been applied at the planning level to assess highway systems for their progress toward sustainability (42), and at the policy level as in the use of ecological footprint to explore alternative policy scenarios in a city-region in Ireland (43).

Figure 3-2 presents a simplified depiction of the sustainability footprint concept, developed and applied to evaluate the Atlanta Metro and Chicago Area highway systems (42). The sustainability footprint is defined as the rate of change of system performance as a function of the environmental costs associated with attaining that level of system performance (e.g., the costs can be measured as the consumption of natural resources and generation of wastes). The model was applied to compare the relative progress of the Atlanta Metro and Chicago Area highway systems toward sustainability in the 1996 to 2006 period. The application used QOL as the system performance measure. QOL was measured as a reduction in congested travel during this period. These reductions were then compared with fossil fuel consumption and emissions generation of the respective highway systems in the same period to determine which metro area system was offering a higher QOL to system users at a lower expense to the environment (i.e., with lower fuel consumption and emissions generation). A higher QOL increase with lower fuel usage and emissions indicates more progress toward sustainability. Different measures can be used in the Sustainability Footprint to capture the most relevant issues to the users of any particular system(s) under consideration.

Visual depiction of Sustainability Footprint, with resource usage (like fossil fuel consumption) on the Y axis, waste generation (like emissions generation) on the X axis, and quality of life (like percentage congested travel) on the Z axis. The example plots points for two stakeholders, City A and City B, in 1996 and 2006. Points are formulated as: A1996=(XA1996, YA1996, ZA1996).
Figure 3-2. Visual depiction of Sustainability Footprint method
(Source: Amekudzi et al. 2009 (42) )

Multi-Criteria Evaluation of Plan and Project Alternatives

In contrast to single objective decision-making methods, such as cost-benefit analysis, Multi-Criteria Decision Making (MCDM) tools can take into consideration a wide range of different criteria simultaneously, making the tool appropriate for sustainability evaluation. There are several applications of multi-criteria methods for alternatives analysis in planning and project development (62,72,73). Multi-Criteria decision making is especially useful when making preference-based decisions over alternatives that have multiple, usually conflicting attribute (74). Because of the multi-dimensional nature of sustainability (i.e., involving system performance, economic, environmental and social decision criteria), multi-criteria methods are well suited to evaluating competing alternatives for sustainability. Essentially, when a multi-criteria approach is applied to evaluate multiple alternatives, each alternative is evaluated across several criteria, e.g., mobility, safety, cost of transportation, NOx exposure, etc. The total value of these criteria is determined, either through a weighted sum, weighted product or other method. For each alternative, scores and weights are assigned for each criterion. The scores reflect how well the particular alternative is faring with respect to a decision criterion, e.g., economic sustainability, and the weight reflects the relative importance of the decision criterion. For example, Jeon et al., (2010) evaluated three land use-transportation plan alternatives or scenarios in the Atlanta Metro Region to determine the relative value of each alternative based on functional system performance, environmental impact, economic impact and social impact. Performance measures were developed for each of the criteria. The performance measures were based on the regional transportation goals of the Metro Region: (1) improving accessibility and mobility; (2) maintaining and improving system performance and preservation; (3) protecting and improving environment and quality of life; and (4) increasing safety and security. Examples of performance measures used for transportation system effectiveness were the average freeway speed, and average vehicle miles traveled per capita. Similarly, environmental sustainability indicators included daily emissions of volatile organic compounds (VOCs) and oxides of nitrogen (NOx), two precursors for ozone. Social equity was captured by equity of exposure to emissions. Each of the land use/transportation alternatives was scored on each of these performance measures, the measures were normalized, weighted and aggregated to develop an overall sustainability index (62). This process is explained in more detail in Case Study 9.  Since the measures can also be aggregated for each sustainability dimension, e.g., economic, environmental, social sustainability or system performance, the analysis results could also be evaluated for tradeoffs among these four dimensions, allowing the analyst to distinguish among dominant and non-dominant alternatives. A tool, the Sustainability Diamond Visualization Tool, was developed to help with visualizing trade-offs and thus the relative effectiveness of each plan alternative from the viewpoint of each evaluation criterion. The tool is described in more detail and displayed in Case Study 9, but in general it shows, for each plan alternative, four indices related to each evaluation dimension: system performance, environmental sustainability, economic sustainability and social sustainability, and an overall comprehensive sustainability index. Using this tool, one can compare the relative sustainability of competing plans as well as evaluate the tradeoffs among these plans. Examining such tradeoffs can facilitate with determining superior alternatives to promote sustainability in the region.

Strategic Sustainability Assessment

Over time, the EU has established progressively strict requirements for environmental sustainability assessment in transportation. The 1993 Treaty on the European Union (EU) requires that "environmental protection requirements be integrated into the definition and implementation of other Community policies." Based on a later EU directive, Environmental Impact Assessment (EIA) is a prerequisite for transportation infrastructure projects. Most recently, Guidelines for Trans-European transport networks (TENs) required that the European Commission develop a methodology and tools for strategic environmental assessment (SEA). SEA is defined as "the formalized, systematic, and comprehensive process of evaluating environmental impacts of a policy, plan or program and its alternatives, including the preparation of a written report on the findings of that evaluation and using the findings in publicly accountable decision making" (44). SEA essentially expands upon EIA; it combines cost-benefit analysis (CBA) or multi-criteria analysis (MCA) with environmental goals, public participation, and impact prediction models (45). The general process for SEA begins with a screening process to determine whether such an analysis is necessary. Once the need for SEA is established, the scoping process begins. Scoping involves identifying the impacts to be evaluated (based on environmental objectives), selecting methods and defining terms, and establishing parameters such as the time horizon, alternatives, and geographical scale.

The next step is the multi-part impact assessment and evaluation, which can be accomplished with either a forecasting or backcasting approach. Guhnemann and Rothengatter (1999) define forecasting as working forward from proposed projects or policies to predict the impacts and end state (46). A backcasting approach to SEA would involve:

A backcasting approach is deemed appropriate when the planning time horizon is long because forecasting would lead to considerable uncertainty in the impacts and risks. The final step in SEA is incorporation of the impact analysis into decision-making. A public involvement process or a formal policy may provide the necessary oversight to ensure that SEA is considered. The SEA methodology can be applied at multiple scales. At the continental level it was applied in the project "Bottlenecks in the European Infrastructure" for the European Center for Infrastructure Studies. The purpose of the project was to identify major bottlenecks to determine investment priorities. At the state (national) level, the German Environmental Agency developed a methodology to assess a regional transportation plan based on environmental considerations (46).

Despite the advancements provided by SEA, there are certain criticisms. First, using CBA and MCA assumes that criteria are independent of each other and that the impacts are unidirectional. For example, this could translate as, "transportation impacts the environment but the converse is not true" (when, in fact, it is). Second, exogenous ("forgotten") variables are not accounted for even though they can have substantial impact. Finally, while SEA is helpful for choosing among project alternatives it is still not sufficient for assessing long-term, multi-step programs (45).

A Strategic Sustainability Analysis (SSA) is capable of addressing the criticisms of SEA and expands on the SEA concept to integrate economic and social implications into transportation planning. The term SSA was first coined in 1999 at a joint meeting of Organization for Economic Cooperation and Development (OECD) and the European Conference of Ministers of Transport (ECMT). SSA is a methodology for analyzing complex transportation decisions (a) with long-term time horizons, (b) interlinked with environmental, economic, and social systems, and (c) with a spatial scope above the project-level. Schade and Rothengatter insist that traditional transportation assessment methodologies are incapable of accounting for the complex system within which sustainable transportation decisions are made (45). There are two requirements for SSA: Integration and Pathfinding. Integration involves (1) integrating real systems into one model and (2) integrating impact prediction and impact assessment steps into the same or interlinked model. Integration allows for an iterative process of policy refinement. Pathfinding has two additional requirements. First, long-term policies should be driven by a vision and have identifiable goals. Second, the method should be capable of showing or investigating development paths from future vision to current situations (or backcasting). SSA is characterized as a dynamic, quantitative, and consistent methodology. Specifically, it is

Schade and Rothengatter identify two model-based approaches for SSA: the Economic Assessment of Sustainability Policies of Transport (ESCOT) model and the Assessment of Transport Strategies (ASTRA) model (45). The ESCOT model was developed by Germany as part of OECD's Environmentally Sustainable Transport (EST) project. ESCOT is a system dynamics model that integrates the five sub-models: macroeconomics, regional economics, transport, environment, and policy implementation. The user can manipulate thirteen policy measures (technical or behavioral in nature) and compare a business-as-usual scenario to desirable future scenarios (47). ASTRA was developed as part of the EU's 4th Framework Program to analyze long-term impacts of the EU's common transport strategy. It is a system dynamics model with four submodels: macroeconomics, environment, regional economics and land use, and transport. Relationships between models and internal feedback loops are integrated into one model platform. Policy packages can be assessed individually or compared against a base scenario. ASTRA can be operated in either a forecasting or backcasting mode and has the capability of using appraisal methods (like CBA or MCA) to compare alternative scenarios (48). ESCOT and ASTRA leave out one aspect of a comprehensive SSA: local impacts. Schade and Rothengatter suggest that this gap could be overcome by incorporating GIS analysis into the methodology.

Scenario Planning by Backcasting

Scenario studies have been used by different industries in the United States since the 1950s. The methodology was advanced by the Rand Corporation under the leadership of Herman Kahn for the federal government to study scenarios under which nuclear war could begin. In the 1970s Shell Oil popularized scenario planning as a business tool to predict how consumers and countries would react to an oil shortage and then prepare for it (49,50). An early definition of scenarios calls them "hypothetical sequences of events for the purpose of focusing attention on causal processes and decision points" (51).

Modern scenario planning offers a method for citizens, government officials and other stakeholders to visualize and clearly understand potential trade-offs and interactions that occur amongst transportation and the social, environmental, and economic development resulting from growth. The FHWA views scenario planning as a way to enhance traditional modeling and assessment methods and improve transportation decision-making. "Scenarios are stories about future conditions that convey a range of possible outcomes" (52). Scenario planning allows a region to realistically evaluate a wider variety of potential futures and determine what the community wants the future to look like.

There are two types of scenarios: projective and prospective (49). A projective scenario starts from the current situation and extrapolates current (or highly probable) trends to produce future images. A prospective scenario on the other hand starts from a possible or desirable future situation and works backward to the present situation. Creating projective scenarios is forecasting (the predominant method in transportation planning) whereas creating prospective scenarios is backcasting. A main criticism of forecasts is their susceptibility to error due to uncertainty about future trends, particularly when the time horizon is long (25 years or more). However, improving the ability to accurately reflect past trends is a standard procedure in model calibration. The term "backcasting" was coined by Robinson (1982) and defined as "'working backwards' from a particular future end-point to the present to determine what policy measures would be required to reach that future." It is distinguished from other methods because it is "concern[ed], not with likely energy futures, but with how desirable futures can be attained" (53). Figure 3-3 shows a schematic of how a backcasting process works. Backcasting is growing in popularity in Europe as a methodology to investigate sustainable transportation scenarios (34,46,49).

Specific examples of backcasting applications to address sustainable transportation issues (namely climate change) include OECD's EST study (49), the European Parliament's scenario development for long-distance transportation (54), and Visioning and Backcasting for Transport Policy (VIBAT) studies in the UK and India (55,56).

Schematic of backcasting with the following steps: 1. Determine objective of study, 2. specify goals, constraints, and targets, 3. describe present state, 4. specify exogenous variables, 5. undertake scenario analysis, 6. determine implementation requirements, 7. undertake impact analysis. Step 1 feeds into Steps 2 and 3. Steps 2, 3, and 4 feed into step 5. At the end of the process (Step 7), there may be the need to return to Step 1 or Step 2 and revise objectives or goals.
Figure 3-3. Schematic of a generic backcasting approach
(Source: Adapted from Guers&van Wee 2004)

The examples cited above employ backcasting based on expert panel assumptions. However, it is possible to apply a participatory model to the development of transportation scenarios, particularly at the local level. "Interactive backcasting" describes backcasting as a recipe rather than a tool because it should enable "problem structuring rather than problem solving" (57). Based on this philosophy, interactive backcasting employs a mixture of methods (both quantitative and qualitative) to generate scenarios and explore pathways. To distinguish interactive backcasting from traditional backcasting, the approach places more emphasis on defining the future image than on analyzing how that future could be achieved. Interactive backcasting approaches have been developed in both Canada and the Netherlands for climate change projects (57).

Why can backcasting lead to more sustainable solutions for transportation systems? To begin with, transportation problems, particularly environmental ones are complex and long-reaching - they can take 25 to 50 years to manifest themselves and the impacts are long-lasting. Further, "fixing" transportation problems takes a long time because transportation infrastructure is expensive and turnover (of vehicle fleets, bridges, etc.) is not immediate. The complexity of transportation problems (namely, interactions of different systems and manifestations at different scales) makes it difficult to exact real change through incremental policies. Forecasting is limited to an extension of current practices whereas backcasting provides the freedom to explore the radical changes that are needed for transportation systems. Backcasting, particularly through a participative process, provides an opportunity to take an action-oriented rather than a passive approach and to develop desirable future images and effective policies for moving forward. Backcasting is an important process to inform policymakers in the selection of policy packages and implementation phases and important for the public in a social learning environment. The process and the outcomes of backcasting can help raise public awareness of sustainability issues for transportation and what is truly valued for the future. Further, it can provide a realistic view of what needs to be done in order to achieve a desirable future.

Updated: 03/27/2014
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