Under California’s Cap-and-Trade program, the State’s portion of the proceeds from Cap-and-Trade auctions is deposited in the Greenhouse Gas Reduction Fund (GGRF). The Legislature and Governor enact budget appropriations from the GGRF for State agencies to invest in projects that help achieve the State’s climate goals. These investments are collectively called California Climate Investments. Senate Bill (SB) 862 requires the California Air Resources Board (CARB) to develop guidance on reporting and quantification methods for all State agencies that receive appropriations from the GGRF. CARB may review and update quantification methodologies, as needed. CARB developed quantification methodologies to provide project-level GHG estimates for administering agencies to use when selecting projects for funding. CARB’s quantification methods use a similar formula to measure GHG emissions reductions from both new bike share programs and new car share programs. That formula includes as inputs both average trip length per bike or car share trip, and an adjustment factor to account for trips that either would not have been previously made (induced new vehicle trips) or would substitute for non-private automobile trips (like transit or walking trips). This report summarizes outcomes from a literature review and analysis of shared mobility program data to (1) identify average trip length defaults for car share, bike share, and scooter share projects, and (2) determine whether and how the current adjustment factors used for car share and bike share projects could be modified to better reflect emerging data and methods for estimating VMT and greenhouse gas (GHG) emissions reductions from shared mobility programs.
