Over the last decade, a wealth of new planning and policy decisionmaking processes, design guidance, and support tools have emerged to help better understand, quantify, and reframe transportation system performance. Once focused primarily on mobility, DOTs, MPOs, and local governments are advancing a whole systems approach to achieving mobility, livability, and sustainability goals. While the profession has yet to produce a single all-encompassing 'livability model' or reach consensus on livability performance measures, there have been several advances in this area in recent years. MPOs and local governments are incorporating new performance measures into transportation planning that include broader sustainability indicators. New analytical methods are emerging that better demonstrate the relationship of the built environment on a variety of factors such as:
Analytical tools can be very powerful in demonstrating the interrelatedness and interdependence of systems and desired outcomes. The tools aid in the planning and decisionmaking process used by the public, agency staff, and policymakers to incorporate livability considerations into traditional transportation decisionmaking. Implementing livability principles requires integrated planning processes to reframe the conversation on how transportation projects can help achieve broader community goals. Examples include:
While there is a need for more research and development in tools, performance measures and decisionmaking processes - as evidenced by requests for such research on behalf of the National Cooperative Highway Research Program, the Transit Cooperative Research Program, and EPA - some noteworthy examples at the State, regional, and local level that demonstrate these new approaches and analytical tools.
Integrated planning processes that incorporate the full range of issues relative to creating more sustainable and livable communities is an emerging area of practice. While comprehensive planning has been around for more than half a century, primarily in local and county plans, in practice it often gets bogged down into specialized disciplinary silos of transportation, land use, housing, economic development, environment etc. This misses the opportunity to integrate specific policies and plans and leverage investments in support of broader community goals. Another challenge is the ability to integrate planning efforts across geographic scales and jurisdictional boundaries - from States or mega regions to corridors or subarea plans. New approaches to address these issues of scale and cross-disciplinary integration are becoming more mainstream.
Scenario planning is an example of an integrated approach that helps communities to develop a range of "what if" scenarios to analyze different growth and transportation strategies and their relative impacts on a range of community livability goals. Scenario planning engages participants in defining a desired vision for their future, and understanding the tradeoffs and implications of each alternative growth scenario. Successful scenario planning efforts typically lead to new policy development in the form of comprehensive plans, long range transportation plans, community blueprints, housing strategies, land development codes, transit systems plans, green infrastructure and environmental plans, or climate action plans.78
Most successful scenario planning efforts involve the community during visioning to develop meaningful indicators that are relevant and unique to community context. Whether trying to demonstrate reductions in VMT based on walkable development patterns, quantifying financial impacts of development on long term financial stability, comparing energy and infrastructure needs of compact versus dispersed development patterns, or creating peak oil price scenarios to test influences on travel demand and travel behavior, quantitative and qualitative analysis is an important part of the equation. Scenario planning processes have resulted in several notable community visions at various scales including Envision Utah. A 2007 study identified over 80 scenario planning projects from 50 metro areas, but noted that there was room for improvement in public participation, methodologies, and institutional structure.79 The new FHWA Scenario Planning Guidebook provides a framework that transportation agencies can use to tailor a scenario planning process to meet their needs.80
As new planning tools and processes emerge, there is a growing shift away from evaluating transportation system performance based simply on levels of service (congestion) and safety alone. The focus on livability and sustainability goals creates a new lens through which communities can evaluate transportation investment decisions in light of a host of other community goals. Doing so ties that transportation system's performance to other community goals such as growth management, location efficient housing, community service provision, etc. Another example is measuring accessibility overall - transit, auto, or other - for different segments of the population, including access for people with disabilities. This type of analysis can help to illuminate key environmental justice issues such as the predominance of poverty rates which are highly correlated to access to automobiles in rural areas.
Another example is using sketch-planning tools that measure VMT/VMC (Vehicle Miles of Capacity) to assess transportation needs. The Florida DOT District 4 is supporting the SR 7 Collaborative in conducting network and corridor based studies that help evaluate transportation system performance in a different way. Analyses on this project identified multimodal project alternatives to reduce areawide VMT. This analysis resulted in recommendations to complete the local street networks and enhance connectivity; increase transit, bicycle and pedestrian quality of service; and implement corridor management and operations strategies in lieu of significant roadway widening for this major arterial. This network based approach helped to demonstrate how a traditional roadway capacity project may have increased speeds and reduced congestion - but in doing so actually increased areawide VMT - which was seen as counter to other community goals. The final set of project recommendations helped achieve improved network mobility gains without increasing VMT.81
Linking the built environment to public health issues such as obesity is another emerging area that overlaps with transportation system performance. The Centers for Disease Control and Prevention has conducted research that directly links local policies and the physical environment to daily choices that affect people's health. One study, "Recommended Community Measures for Preventing Obesity in the United States," developed 24 strategies to encourage healthy eating and active living, with measures provided for each strategy to help communities track their progress over time.82 For example, people living in suburban neighborhoods typically drive to work or drive their kids to school because there are no walkable destinations located nearby. Communities that want to improve public health and reduce levels of obesity can evaluate transportation system performance by measuring how many walkable community patterns exist, or what percent of the population is located within walking distance to a transit route. Geographic Information Systems (GIS) planning tools enhance the ability to quantify and measure the variables of the built environment and relate them to other socioeconomic trends.
EPA recently completed a Guide to Sustainable Transportation Performance Measures. The guidebook identifies 10 performance measures (largely already in use by MPOs) that can readily be developed and applied in transportation decisionmaking. For each measure, the guidebook presents possible metrics, summarizes the relevant analytical methods and data sources, and illustrates the use of each measure by one or more transportation agencies.
The 10 profiled measures are:
The Partnership for Sustainable Communities has heightened the need for a set of indicators that can be applied consistently at different geographic scales across the country to track and monitor progress towards creating more sustainable communities. The Partnership is working to develop a preliminary set of outcome-based performance measures tied to the six livability principles. The Federal agencies are working with grant recipients in the areas of livability and sustainability on the use of performance measures and promoting their use among State, regional, and local agencies.
Virtually every effort to expand the use of performance measures in planning faces the challenge of data limitations. In some cases, data are not collected and reported at the geographic scale of interest. For example, there is no way for local governments to accurately measure the VMT of their residents on an annual basis without a household travel survey (which is costly and therefore performed infrequently) or access to vehicle registration data (which is confidential in many States). In other cases, necessary data may exist, but to produce useful metrics, it requires data processing that is beyond the capacity of most local governments. For example, finely grained datasets covering population, income, and transit service exist in most metropolitan areas, but combining these to measure equity in transit access can be challenging. Even when local and regional agencies develop sustainability performance measures, they may do so in ways that are inconsistent with other local and regional agencies, precluding comparisons among peers. Performance measures need to address meso-scale (regional system, watershed) goals for sustainability. Matters like water quality and habitat conservation may be best addressed at this scale.
EPA is currently conducting a research project to evaluate and test sustainable community performance measures. It will focus on identifying and overcoming the data challenges that prevent greater use of sustainability performance measures. It will identify national datasets that are instrumental to implementing performance measures, along with opportunities to apply local and State datasets to fill gaps in national data consistently. The project will then test the use of these datasets in a range of types of communities involved in regional sustainability planning.
Many Federal, State and local agencies are incorporating livability principles into their policies and design guidelines. Nearly all the documents reviewed include guidelines or performance measures for pedestrian and bicycle travel, and several include transit strategies. The local documents tend to encourage more innovative designs that foster placemaking and redevelopment, rather than just balanced multimodal travel. Some of them also incorporate 'green streets' practices to mitigate stormwater impacts. Several State DOTs have developed integrated planning, design, project development, or evaluation criteria. Some notable State DOT examples include:
Notable local examples tend to be from larger cities, but the concepts are applicable to smaller cities:
Transportation agencies can use a variety of tools to support development and use of performance measures and integrated planning processes. Many of these tools use existing GIS data and mapping capabilities - which most transportation and planning agencies are already adept at using.
While many scenario modeling resources also present data in easy-to-understand graphics and GIS mapping, there are several other visualization techniques in use by urban planning consultants. One of the most effective of these is photo-simulation, or 'before and after' photographs that show what a community's vision might look like in a specific place (see example in the Executive Summary). The photos of existing places are manipulated with photo editing software to produce photo-realistic visualizations of potential improvements to specific corridors or sites.94
Most current applications of travel demand models used to examine interactions between transportation strategies and land use are limited in assessing livability impacts. Most four-step travel models are unable to assess "intrazone" trips - the walk, bicycle, and short driving trips made in compact communities. However, several State DOTs and MPOs are improving travel demand models by incorporating land use variables, lifestyle considerations, GHG emissions evaluations, economic factors, and other variables. For instance, the Southern California Association of Governments (SCAG) is using scenario planning to reduce regional greenhouse gas emissions in response to California Senate Bill (SB) 375, which requires regional transportation plans to comply with California Air Resources Board emission targets. SCAG will model these emissions using a four-step travel model and a supplementary model of intrazonal travel. The scenario modeling will help the community to visualize development options and support regional analyses of energy, water use, open space, GHG emissions, and costs and revenues to local governments.95
While significant progress has been made in scenario analysis and modeling, underlying data needs, performance measures, and visualization, many challenges remain before these innovative approaches are as accepted as the conventional four-step travel modeling process. The challenges of data collection - especially for local walking and bicycling trips - are compounded by integrating transportation analysis with housing, environmental, economic, and energy planning. Performance measures need to be meaningful, understandable, easy to use, and based on readily available data; they also need to measure what matters to the community. Developing an acceptable process for identifying community values, and then establishing such values as part of creating a vision for the future, are critical initial steps in any integrated planning process. The goals, performance measures, data needs, and any visualization required to demonstrate concepts can then be based on issues that people care about. Making sure that agency and elected decisionmakers are involved throughout visioning, scenario building and analysis, selection of measures, and adoption of preferred scenarios will help ensure that related plans and projects get adopted, approved, funded, and built.