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New Trends in Transportation and Land Use Scenario Planning

Appendix C. Case Studies

Case Study 4: Southern California Association of Governments (SCAG)


SCAG is an MPO representing six counties that comprise half the population of California (see Figure 1). SCAG is the largest MPO in the United States, serving 19 million people in 6 counties and 189 cities. SCAG's size makes it unique in terms of resource availability and staff capacity. However, its size also presents significant challenges for coordinating local jurisdictions and creating regional consensus.

Figure 1. Map of SCAG region.27

Figure 1. Map of SCAG region.

In 2004, SCAG used scenario planning in a very successful and well-documented process. The process was known as the Compass Blueprint effort.28 Compass Blueprint is SCAG's largest and most successful outreach effort to date. It helped build support for new, regional integrated land use and transportation strategies, and helped SCAG build credibility with elected officials and other stakeholders.

Based on its positive experience with the Compass Blueprint effort, SCAG continues to use scenario planning to build support for progressive planning that considers the regional effects of local actions and policies. Because the Compass Blueprint effort has been well-documented, the focus of this case study is the upcoming Sustainable Communities Strategy (SCS) scenario planning process that SCAG will undertake, as required by California's Senate Bill (SB) 375.29

Overview of SCAG's Scenario Planning Effort

SCAG is currently preparing for a scenario planning effort that will be used to develop the region's SCS and long-range transportation plan (LRTP) update. SCAG plans to use scenario planning for the SCS to facilitate a regional dialogue about environmental, financial, quality of life and travel-related impacts of development patterns and transportation investment decisions.

In preparation for the scenario planning effort, over the next several months, SCAG intends to:

SCAG will then lead a regional scenario planning effort to help determine how best to bridge the gap between the emission reduction target and projected emissions based on current plans. Scenario development and analysis for the SCS will be conducted through a series of sub-regional workshops.

SCAG intends to engage the workshop participants through a "chips" exercise in which participants will place development on a map of the sub-region using chips that represent different development types. During workshops, stakeholders will assign these types to the region using 5.5-acre grid cells. Different combinations of development types and geographic distributions represent alternative scenarios. Using these development types as the building blocks for scenarios will help stakeholders understand the "look and feel" and implications of their choices, while enabling a detailed analysis of a very large region.

SCAG worked with a consultant to develop 17 customized development types as part of the Envision Tomorrow suite of planning tools for the Compass Blueprint effort.30 SCAG staff believes that these typologies are a good representation of existing and potential development in the region. Each development type represents a mix and intensity of development and includes a high level of detail about building types, density, design, costs, rents, tax revenue, energy and water use. The development types represent human-scale elements such as building mix and design. They also provide a way to translate that level of detail to the regional scale for analysis.

SCAG staff will simultaneously model the development patterns using a customized version of Envision Tomorrow software. Workshop participants will then evaluate the pros and cons of several scenarios at each workshop and the scenarios will be refined through a series of three to four iterative workshops in each sub-region over an eight- to ten-month period. The process is documented in Figure 2.

Figure 2. Scenario Building Process.31

Figure 2. Scenario Building Process.

Although GHG emissions will be a central focus of the SCS scenario planning effort, many other impacts related to growth and development, such as congestion and land consumption, will also be modeled so that a full picture of each scenario is offered to stakeholders for evaluation.

Ultimately, the sub-regional preferred scenarios will be combined to form a preferred scenario for the whole SCAG region. Policies and strategies for the preferred scenario will be included in the SCS plan and LRTP, as required by California's SB 375.

SCAG's ability to implement the preferred scenario is limited because local jurisdictions control land use decisions. However, certain tools and regulations will help yield land use decisions that are consistent with the SCAG's plan. For example:

Key Findings

The following are key findings from SCAG's efforts:

The real-time analysis that SCAG plans to provide at the SCS workshops advances the process used in 2004, where analysis was not available in real-time. Real-time analysis will make the workshops more interactive and deepen the potential to explore alternative scenarios.

Challenges and Success Factors

SCAG identified the following challenges and success factors:

Key Documentation

SCAG Growth Vision Report (2004), the Comprehensive report on Compass Blueprint efforts and associated growth vision:

SCAG State of the Region Report (2007), which details the performance of Southern California since 2000 as compared to several key indicators:

Draft guidelines by SCAG for the development of the SCS:

One-page overview of SCAG 's approach to address SB 375:

White Paper: Conceptual Land Use Scenario Methodology (developed by Fregonese Associates):


27 Map from SCAG site at

28 For additional information on SCAG's Compass Blueprint effort, see

29 Senate Bill 375: California enacted a state law in 2009 requiring the California Air Resources Board to set greenhouse gas emission reduction targets for regions in California, and requiring regional transportation plans to either demonstrate compliance with those targets, or requiring MPOs to develop a SCS that will be used to achieve compliance with the target.

30 Envision Tomorrow software was built by Fregonese Associates, an Oregon-based consulting firm. The tool allows users to quickly create and evaluate land use scenario using 'market-feasible' and prototype buildings. The tool works at both the neighborhood and regional scales and also offers an additional Scenario Builder extension for ArcGIS and a Return on Investment model. For more information on Envision Tomorrow and Fregonese Associates, see

31 Graphics from Fregonese Associates.

32 SCAG has developed a methodology for modeling GHG emissions. Rather than simply assuming a linear relationship with VMT, SCAG's method incorporates vehicle speed (through the 4-step travel model) and also models emissions from intra-zonal trips based on development type.

Updated: 10/20/2015
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