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VMT v. GHG: Identifying the Six Percent Gap

By: Bill Higgins on Feb 29, 2020
The purpose of this article is to explain that there is a six percent gap between the Greenhouse Gas (GHG) emission reductions called for by the Air Resources Board in the Scoping Plan and the emission reduction targets set under SB 375.  Put another way, the regional SB 375 targets are not enough to achieve the reductions California needs from cars and light trucks to meet its stated goal.  
Here are the main reference points from ARB in identifying the gap and identifying what should be done about it.  
1.  General Framework 
SB 375 requires Metropolitan Planning Organizations (MPOs) to adopt Sustainable Communities Strategies that integrate land use and transportation planning to achieve per capita GHG reduction targets for passenger vehicles. The targets are developed through a comprehensive bottoms-up process between the MPOs and ARB. In contrast, the light duty VMT reductions in the Mobile Source Strategy scenario provides a top-down framework for how transportation efficiencies put California on a trajectory to meet climate goals. Thus, the SB 375 process provides one mechanism to pursue the needed reductions, but additional policies are also needed to promote improved land use outcomes, increased use of ZEVs, and greater mobility options.  See Mobile Source Strategy, pages 47 and 50.  
2.  VMT Reduction in Mobile Source Strategy (2015)
The scenario incorporated into the Mobile Source Strategy assumes a 15 percent reduction in vehicle miles traveled (VMT).  (See Mobile Source Strategy, page 36-37; model details on page 166).  ARB later equated this to a 7.5 percent reduction by 2035; and a 15 percent reduction by 2050. (For example: ARB SB 375 Workshop Presentation, slide 19). Thus, ARB equates the 7.5 percent reduction in VMT (the metric used in the Mobile Source Strategy) to a 25 percent reductions in per capita GHG emissions (the metric applied to sustainable communities strategies under SB 375).  See also ARB Scoping Plan, page 75.
3.  Scoping Plan (2017)
The Scoping Plan notes that the Mobile Source Strategy “identifies the need for statewide per capita greenhouse gas emissions reductions on the order of 25 percent by 2035.”  See Scoping Plan, page 75. ( See also, Page 78, stating that the Mobile Source Strategy includes a 15 percent reduction in total light-duty VMT from the business as usual--or BAU--scenario in 2050).  
4.   SB 375 Targets (2018) 
Stronger SB 375 GHG reduction targets will enable the State to make significant progress toward this goal, but alone will not provide all of the VMT growth reductions that will be needed.  Scoping Plan. ARB developed a set of SB 375 Regional Targets that range from 13 to 19 percent (among the larger MPOs). The percentage is sometimes referred to as a collective 19 percent target because that rate applies to more than 80 percent of the state population in the largest metropolitan areas.  
4.   Ergo, The Six Percent Gap  
There is a 6 percent gap between the 25 percent reductions in the Scoping Plan and the highest (19 percent) regional targets under SB 375.  The Scoping Plan notes that the targets "enable the State to make significant progress toward this goal, but alone will not provide all of the VMT growth reductions that will be needed. See Scoping Plan, page 75. 
5.  Why Weren’t the SB 375 Targets Set Higher?
The Scoping Plan directed that the SB 375 targets be "more stringent."  (See Scoping Plan, Table 17, p 103).  ARB notes that there are many external factors outside of the authority of an MPO that affect how people choose to drive. For example, the cost of gas significantly affects how people choose to drive, but MPOs no authority impose higher fees or taxes on gas. Thus, ARB acknowledges that partnerships between governmental agencies will be necessary to achieve the state goals. Here is how ARB has acknowledged these external factors: 
  • Discussions among a broad suite of stakeholders from transportation, the building community, financial institutions, housing advocates, environmental organizations, and community groups are needed to develop the needed set of strategies to achieve necessary VMT reductions.  See Scoping Plan, page 75.

  • [O]ther factors . . . such as gas prices and employment, play a significant role in influencing personal travel behavior and affect SB 375 implementation.  . . . Given that these trends will continue to change over time, policymakers must think through what tools and practices will allow each region to meet its goals despite continued variability. See SB 150 Report, page 24.

  • California – at the state, regional, and local levels – has not yet gone far enough in making the systemic and structural changes to how we build and invest in communities that are needed to meet state climate goals. To meet the potential of SB 375 will require state, regional, and local agency staff and elected officials to make more significant changes across multiple systems that address the interconnected relationship of land use, housing, economic and workforce development, transportation investments, and travel choices. See SB 150 Report, page 6.

  • While no single agency or level of government alone bears the responsibility for this work; there is an important opportunity to partner across many agencies on taking collaborative action toward better results. See SB 150 Report, page 4.

  • Structural changes and additional work by all levels of government are still needed to implement regional strategies. Staff and elected officials of local, regional, and state government have critical authorities and roles to contribute . . .. But as a whole, all actors responding rationally to the incentives, political forces, and policy restrictions in front of them have not been able to enact the magnitude of change needed.  . . . The current structure of policies and lack of incentives will continue to produce and exacerbate the insufficient results unless shared responsibility, changes in authority or mandates and incentives, and strong, deliberate, collaborative action is taken to change them. CARB finds that this disconnect impedes progress on attaining the SB 375 targets and their co-benefits. See SB 150 Report, page 56.  
7.    What is the Plan to Address the 6 Percent Gap? 
The gap between what SB 375 can provide and what is needed to meet the State’s 2030 and 2050 goals needs to be addressed through additional VMT reduction measures such as those mentioned in Appendix C.   See Scoping Plan, page 79.  Appendix C includes a state commitment to “explore” ideas in two documents: Vibrant Communities and Landscapes (four pages) and Potential State-Level Strategies to Advance Sustainable, Equitable Communities and Reduce Vehicle Miles of Travel (five pages)
Vibrant Communities lays out a general land use comprehensive land use vision for the state of California that emphasizes controlled development. It recommends that the state to develop or implement the following programs: 
  • Work with local and regional governments to develop performance metrics for environmental, health, and equity outcomes associated with stronger land use policies.  
  • Develop quantitative and achievable goals to protect and limit the conversion of the State’s most productive lands.
  • Develop policies for infrastructure siting that are consistent with the State’s conservation, development, maintenance, mode shift, and population health goals
  • Explore and develop financing, regulatory, incentives, guidelines and other tools to support more efficient and more equitable development: 
  • Support transportation policies such as priced express lanes, road user charges, reduced parking requirements, and transit commuter incentives that promote infill development, but in a way that avoids impacts on low income drivers. 
The Potential State Level Strategies document focuses on VMT reductions specifically (in five pages) by providing a range of potential strategies to explore (acknowledging that each would require a great deal of study and outreach). These strategies are grouped into four categories:
  • Efficient, Equitable Development.  Explore strategies like transfer of development right programs, more funding for transit oriented development, rebates for low VMT projects,, property tax incentives to improve properties in distressed areas, reduced parking strategies, and creative infill financing for priority infill projects in a way that assures that they do not displace disadvantaged communities and are implemented equitably.  

  • Prioritize Equitable Investments.  Expand transit networks, capacity, and level of service.  Support base rapid transit, rail and bus guides, explore transit pass subsidies, increase transit safety and attractiveness.  Also support active transportation investments and road safety for bicyclists and pedestrians.  Support shared mobility, green construction, location efficiency, and research.

  • Equitable Pricing.  Explore the various options for pricing road driving, parking in ways that are fair to all income classes.  

  • Maximize Transportation System Efficiencies (Equitably).  Explore strategies related to telecommuting, transit incentives, and carpools, Promote econdriving educations, and promote technologies that can make roads more efficient. When possible, implement programs that will benefit low income households and offset high cost burdens. 

8.  What About SB 743?
The forthcoming statewide implementation of SB 743 is considered one of the strategies to address the six percent gap between the Scoping Plan and the SB 375 Targets.  Specifically, Table 17 (on page 103) in the Scoping Plan states the pathway to achieve the overall goal: further reduce VMT through continued implementation of SB 375 and regional Sustainable Communities Strategies; forthcoming statewide implementation of SB 743; and potential additional VMT reduction strategies not specified in the Mobile Source Strategy but included in the document Potential VMT Reduction Strategies for Discussion (Appendix C). 

See the CALCOG SB 743 Resource Page for more information on SB 743.  
Note that Table 17 (Scoping Plan, page 103) also includes the following actions for state responsibility
  • 1.5 million zero and hybrid light duty electric vehicles by 2025; 4.2 million by 2030  
  • Enforce advanced clean cars regulation 
  • By 2019, adjust performance measures used to select and design transportation facilities
  • Harmonize project performance with emissions reductions, and increase competitiveness of transit and active transportation modes (e.g. via guideline documents, funding programs, project selection, etc. CalSTA, SGC, Caltrans, CEC, OPR, local agencies.  
  • By 2019, develop pricing policies to support low-GHG transportation (e.g. low-emission vehicle zones for heavy duty, road user, parking pricing, transit discounts).  CalSTA, Caltrans, CTC, OPR, SGC, CARB