California Air Resources Board

Background

California Climate Investments uses billions of Cap-and-Invest dollars to fund projects that reduce harmful emissions, protect public health, strengthen local economies, and support natural environments. California Climate Investments is funded by proceeds from the sale of State‑owned allowances from quarterly Cap‑and‑Invest auctions that are deposited into the Greenhouse Gas Reduction Fund (GGRF). On a yearly basis, the State distributes the money from the GGRF to programs administered by different State agencies. Any program that is paid for using money from the GGRF is a California Climate Investments program.

Senate Bill (SB) 862 (Committee on Budget and Fiscal Review, Chapter 36, Statutes of 2014) requires the California Air Resources Board (CARB) to develop guidance on quantification methods and reporting for all State agencies that receive appropriations from the GGRF. Quantification methods are designed to estimate the greenhouse gas (GHG) benefits and co-benefits[1] from funded projects. The resulting quantification methodologies (QM) and calculator tools are developed to:

• Support calculating the estimated GHG emissions reductions and applicable co-benefits for individual projects.
• Apply to the project types proposed for funding.
• Provide uniform methodologies that can be applied statewide at the census tract scale and are accessible by all applicants.
• Use existing and proven resources or methodologies, where available.
• Include the expected time period of over which GHG emissions reductions and co-benefits from projects will occur.
• Identify the appropriate data needed to calculate GHG emissions reductions and co-benefits.

Given several years of historical and anticipated future GGRF funding to transit-focused programs, and CARB’s role in quantifying and reporting on funded projects, it is important to update and maintain the supporting methods, data, and default values used for estimating potential benefits and impacts associated with proposed projects. Developing robust, transparent, and repeatable transit methods to support California Climate Investments ensures that CARB can appropriately estimate and report on project benefits; allows administering agencies to better understand project benefits, tradeoffs, and related equity implications; and helps to ensure that GGRF dollars are invested in ways that maximize benefits to priority populations, GHG emission reductions, and the advancement of the State’s long‑term decarbonization and climate resilience goals.

Objective

This project focuses on evaluating existing data and methods and updating or proposing new data and methods to support quantifying estimated benefits from transit-related projects funded through California Climate Investments programs—with a specific focus on any benefits to priority populations. This work will include, but is not limited to, updating the transit default values for adjustment factors related to transit dependency, average trip length, and average fare—core components used across multiple transit-related QMs supporting programs such as the Affordable Housing and Sustainable Communities Program, Clean Mobility Options Voucher Pilot Program, Low Carbon Transit Operations Program, and Transit and Intercity Rail Capital Program. This includes, at a minimum, reviewing the most recent California Household Travel Survey and National Transit Database data to update the default values, and evaluating other relevant and recent research and data that may support new or updated methods.

These default values were originally developed under a previous contract (agreement number 16TTD004) using data from the 2013 California Household Travel Survey and the 2017 National Transit Database. While some National Transit Database values were updated in 2021, the transit dependency adjustment factors have not been updated since the original technical report.

Key deliverables from this project will include updated lookup tables; an evaluation of relevant new or updated methods; use of methods and values in an easy-to-use Excel-based tool or similar easy application; an associated methodology report; and a method and script enabling CARB staff to maintain these values and resources going forward.

In this project, the contractor shall:

• Evaluate current literature, methodologies, tools, databases, and other publicly available resources to support standardized and defensible methodologies to estimate GHG emission reductions and other co-benefits from transit projects consistent with California Climate Investments requirements and guidance and with a focus on priority populations and potential equity implications.
• Develop methods, or repurpose previous methods, to update default look up values used in CARB’s transit QMs and to support accompanying Excel-based calculator tools.
• Provide methods, scripts, documentation, and/or guidance such that CARB staff can easily update and maintain the default lookup values and other deliverables in the future when new data becomes available.
• In coordination with CARB and as applicable, develop recommendations on possible future improvements to CARB’s transit quantification methodologies, data sources, default assumptions, and calculator tools, including opportunities to enhance accuracy, transparency, ease of use, and alignment with evolving State climate, equity, and transportation-planning priorities.

Scope of Work

Task 1: Review of literature and existing methods, resources, and databases

The Contractor shall conduct a comprehensive review of:

• Outcomes from the previous CARB QM contract.[2]
• Most recent California Household Travel Survey and National Transit Database data.
• Metrics and resources used by CARB, the California Department of Transportation (Caltrans) and other agencies, as appropriate.
• Additional academic and grey literature documents, metrics, resources, and data—with a focus on potential metrics to determine benefits to priority populations.

A previous contract evaluated how CARB could update two default adjustment factors used in the transit and connectivity (TAC) methods and in CARB’s QMs for estimating emission reductions from transit projects. The default values developed under this previous contract used data from the 2013 California Household Travel Survey and the 2017 National Transit Database.

• The first, an “A” factor, is used to account for transit dependency in estimating ridership gains. The factor is used to indicate the share of riders of transit projects who are not transit dependent and therefore could be expected to have driven in the absence of the project.
• The second, an “L” factor, is a required input for the estimated length of an average unlinked[3] transit passenger trip associated with the proposed project. The factor is used to determine the number of passenger-miles traveled by unlinked trip. While some National Transit Database values were updated in 2021, the transit dependency adjustment factors have not been updated since the original technical report.

In this project, the Contractor shall focus, but not limit, their review on data in the newest version of California Household Travel Survey and the National Transit Database to evaluate if the default factors for transit ridership and the default trip lengths for vehicle type and transit agency should be updated, respectively. The Contractor will review any additional relevant, recent research—in addition to the latest California Household Travel Survey and National Transit Database—to support updates to the existing methods and default values or to proposed recommended new methods and values. The Contractor shall focus additional research on existing or new metrics to discern potential equity implications of projects, at a census tract level and broken out by priority population designation.

Interim Deliverable

• Technical Memorandum summarizing findings, methodological and/or data gaps, and possible approaches for quantification—including a complete list of references/resources reviewed. The memorandum should also include a comparative analysis of existing methodologies being used by other California State agencies, noting points of alignment and diversion from one another, as applicable.

This deliverable is required before the contractor can continue to work on other tasks.

Task 2: Develop draft methods and tables

Building on the deliverable outlined in Task 1, the Contractor will develop draft methods, or repurpose previous methods, to update default values used in CARB’s transit QMs. The Contractor will incorporate the methods and values into an easy-to-use Excel-based tool or similar easy application with an associated methodology report—consistent with CARB guidance and requirements.

Any draft methods and supporting documentation developed shall include detailed equations and calculation steps; required inputs and default values; data sources and assumptions; uncertainty and sensitivity considerations; and alignment considerations with existing California Climate Investments, CARB, and other State agency requirements, guidance, and standards.

Any resulting or proposed metrics should be calculated at the census tract scale, at minimum. The output should also be aggregable to the project level (i.e., sum of project’s impact across the census tract(s) impacted by the project) and broken out by priority population designation (i.e., sum of project’s impact on census tract(s) designated as disadvantaged communities, low-income communities, etc.).

The Contractor shall also provide a draft method, script, documentation, and/or guidance such that CARB staff can easily update and maintain deliverables in the future when new data becomes available.

Interim Deliverables

• Draft QM and Calculator
  • Provide updated, or propose new, default lookup values.
  • Create user‑friendly spreadsheets, calculators, and/or modular scripts that apply the methodologies and default lookup values.
  • Ensure the deliverables are accessible to various end users, including small transit agencies and users with limited technical capacity.
  • Include built‑in documentation, instructions, and example scenarios.
• Produce a comprehensive draft report describing all methods, assumptions, data sources, etc. not described in the Draft QM and Calculator. This includes detailed documentation on how to maintain and update the deliverables.
• Deliver all draft reports, methodologies, calculators, scripts, datasets, and documentation, where applicable.

These deliverables are required before the contractor can continue to work on other tasks.

Task 3: Test and evaluate draft methods and tools

Using the draft methods, default values, and calculator tool developed under Task 2, the Contractor will apply the quantification approach to a sample of 15–20 previously funded transit projects. The selected projects must reflect the diversity of project types, geographies, and priority population contexts relevant to California Climate Investments transit and related programs. The purpose of this task is to validate the draft methods, assess usability, and identify areas requiring refinement before finalization.

The Contractor shall:

• Select a representative sample of past projects, ensuring coverage of:
  • Rural, suburban, and urban contexts.
  • Projects located within and outside priority population census tracts.
  • A range of transit modes and project types.
• Run the draft calculator and methods to generate test outputs for each selected project, including:
  • Estimated GHG emission reductions.
  • Estimated co-benefits, as applicable.
  • Census-tract–level and priority-population–specific outputs.
• Evaluate equity implications of the proposed metric components, including but not limited to:
  • How updated default values affect estimated benefits in priority population areas.
  • Whether the methods meaningfully differentiate impacts across demographic or geographic contexts.
• Conduct sensitivity testing on key assumptions and default values to assess, for example:
  • How changes in input values influence results across different project types.
  • Whether certain project types or priority population areas are disproportionately affected by methodological changes.
  • The robustness and stability of the proposed methods.
• Compare results to past quantification outcomes, including but not limited to:
  • Differences between the new draft methods and the methods used at the time the projects were originally funded.
  • Identification of systematic shifts (e.g., consistently higher or lower estimates).
  • Discussion of whether differences reflect improved accuracy, updated data, or methodological changes.
• Document findings, including but not limited to:
  • Observed strengths and limitations of the draft methods.
  • Recommendations for refinements to improve accuracy, usability, transparency, and equity considerations, if applicable.

Recommendations for addressing any sensitivity results or discrepancies that indicate potential methodological weaknesses, unintended equity impacts, or areas where additional data, refinements, or safeguards may be needed.

Interim Deliverables

• Technical Memorandum summarizing:
  • Project selection rationale.
  • Key findings from testing and sensitivity analysis.
  • Identified issues or limitations in the draft methods or tools.
  • Recommended revisions to methods and default values prior to finalization.

These deliverables are required before the contractor can continue to work on other tasks.

Task 4: Develop final methods and tools

Following review and coordination with CARB and any applicable State agency staff on the deliverables outlined in Tasks 2 and 3, the Contractor will develop and return final materials. This includes, but is not limited to, any data, scripts, guidance, and other documentation on how to maintain and update the materials, where applicable.

Final Deliverables

• Final QM and Calculator
• Final default values presented in a tabular format
• Final comprehensive report, including but not limited to:
  • Underlying data, scripts, and guidance material to update and maintain the calculator.
• Provide training sessions for CARB staff and State agency partners.
• Final contract presentation to CARB staff.

All final deliverables must meet full ADA (Americans with Disabilities Act) requirements per Assembly Bill 434 and CARB guidance.

Minimum Expectations

Provided below are the minimum expectations at various phases of the contract. Expectations at the pre-proposal stage are applicable to all proposers, while the remaining three expectations are applicable only to proposers whose pre-proposal is selected. 

At the Pre-Proposal Stage

• Include the items listed in the application process 
• If applicable, provide a cultural humility statement in the pre-proposal.
• If applicable, provide a community engagement plan in the pre-proposal.

At the Beginning of the Contract

• All researchers must undergo cultural humility training (e.g., implicit bias training and racial equity training). Training should be completed or scheduled within 30 days of contract execution.

During the Active Contract Period

• The Contractor must submit Quarterly Progress Reports. These reports shall include plain-language summaries that can be posted publicly. CARB will provide the progress report template.
• The Contractor shall engage in frequent (e.g., monthly) consultation calls with CARB and key interested parties.
• The contractor shall submit Interim reports to keep CARB staff informed. These reports are expected at the end of each task, upon CARB staff’s request, to ensure that progress is being made.

Prior to Contract Close

• The contractor shall submit all data, analyses, and analytical resources generated during this project.
• The contractor shall satisfy the following requirements of the Draft Final Report (DFR):
• DFR will be copy-edited, reviewed, and approved by the Principal Investigator.
• Include a plain language summary in DFR
• Include an equity implications section in DFR
• If applicable, have the DFR reviewed by community representatives.
• The contractor must work with CARB to create plain-language outreach deliverables for the public, summarizing the results and impact of the project.
• The Final Report submitted to CARB must be in an accessible format aligned with WCAG Guidelines.
• The contractor will participate in a virtual or in-person seminar to present the project findings.
• Peer-reviewed publications should be publicly available (please budget for this expense; submission-ready publications shall be reviewed by CARB staff).
• Additional deliverables shall be determined in consultation with CARB staff.

Timeline

This project is anticipated to be completed in 12 months from the start date. Cost shall not exceed $145,000.

Scoring Criteria

Responsiveness to the goals and objectives outlined in the pre-proposal solicitation(15 points)

The pre-proposal should demonstrate a clear understanding of the policy objectives and research needs that CARB aims to address with this project while highlighting their expertise on the subject. The pre-proposal should consider various aspects of the need and identify or acknowledge any potential biases. It should outline, in sufficient detail, the proposed approach to meeting the requirements of the Solicitation. The pre-proposal must detail work that aligns with the objectives outlined in the Contract Solicitation:

• Evaluate current literature, methodologies, and publicly available resources to support standardized and defensible methodologies to estimate GHG emission reductions from transit-related projects consistent with California Climate Investments requirements and guidance, and with a focus on priority populations and equity implications.
• Produce recommendations to CARB on the quantification methods, documentation, and provide guidance that can be used by State agencies administering GGRF funds for transit-related projects. Develop updated default values, QM, calculator, and supporting documentation that compiles and/or builds on existing resources.
• Ensure recommendations and methods are consistent with existing California climate accounting frameworks, including those used by CARB and other State agencies, as relevant.

Policy relevance/benefits to the State(10 points)

The pre-proposal must describe how the project will provide data, information, and/or products to support the objectives of this project in furtherance of CARB’s mission. 

The pre-proposal must provide details on how recommended or developed methods, calculators, and resources will be consistent with existing CARB guidance. More specifically:

• Support calculating the estimated GHG emissions reductions and applicable co-benefits for individual projects.
• Apply to the project types proposed for funding.
• Provide uniform methodologies that can be applied statewide at the census tract scale and are accessible by all applicants.
• Use existing and proven resources or methodologies, where available.
• Include the expected time period of over which GHG emissions reductions and co-benefits from projects will occur.
• Identify the appropriate data needed to calculate GHG emissions reductions and co-benefits.

Previous work (15 points)

The pre-proposal should demonstrate that the proposers have a team with the work experience or subject matter expertise required to successfully carry out the proposed project as described in the varying tasks. Additionally, the pre-proposal should describe how the project will build upon previous relevant work that was funded by CARB, other regional, state, and federal agencies (e.g., the U.S. EPA, U.S. Department of Energy). If the project includes an equity component and/or community engagement, proposers should describe prior experience in community engagement and provide letters of support, references, or a community impact statement detailing how their previous work has benefited communities.

Five points will be reserved for project teams that meet at least one of the following criteria:

1. The project team is multi-disciplinary.
2. The project team includes members from various universities, non-academic institutions, or community-based organizations.
3. The project team includes one or more members who will contribute significantly to the project (e.g., a principal investigator, co-principal investigator, or co-investigator, contributing 25% or more of their time) who have not worked with CARB in the past 5 years.

Technical merit (25 points)

The pre-proposal should clearly explain the logic and feasibility of the project’s methodology, spell out the sequence and relationships of major tasks, and explain methods for performing the work. The pre-proposal should include a clear description and plan for how each task will be completed. 

The pre-proposal should also explain how the proposed methods are robust and how the results will be validated. Pre-proposals will be reviewed for how well they address these areas:

1. Is the proposed measurement approach appropriate? Are the technologies being considered suitable, and will the proposed analysis yield relevant results?
2. Does the proposed work address all the deliverables outlined in the “Deliverables” section? If not, the proposal should not be considered for funding.
3. The review team will select only one pre-proposal for development into a full proposal. If this pre-proposal shows potential, what areas or topics should be prioritized or further explained in the full proposal?

Level and quality of effort to be provided(15 points)

The pre-proposal should describe how time and resources will be allocated and demonstrate how this allocation ensures the project’s success. Pre-proposal reviewers will evaluate whether supervision and oversight are sufficient to keep the project on schedule, and whether the distribution of time and resources is appropriate for activities such as research, evaluation, analysis, data reduction, computer simulation, report preparation, meetings, and travel.

Cost effectiveness (20 points)

Pre-proposal reviewers will evaluate if costs are appropriately allocated across different project tasks and stages and if the proposed work appears feasible within the requested budget.

Scoring Criteria Scoring Guidance

91-100 points. Exceptionally strong. The submission is technically strong, meets stated research objectives, is cost-effective, and has a high potential to be successfully completed.

81-90 points. Strong. The submission is technically sound.

71-80 points. Mixed. The submission has either strong technical merit or strong policy significance, but not both.

61-70 points. Weak. The submission is not sufficiently linked to the needs of the Board and offers limited technical merit.

60 points or below. Unacceptable. The submission is not linked to the interests or needs of the Board and lacks technical merit.

[1] "Co-benefits" include social, economic, and environmental benefits. CARB has developed several co-benefit assessment methodologies relevant to transit projects, including air pollutant emission reductions, vehicle miles traveled reductions, travel cost savings, and energy and fuel cost savings. For more information, see the California Climate Investments Co-benefit Assessment Methodologies webpage.

[2] Available on the California Climate Investments GHG Quantification Research webpage under “Transit Factors.”

[3] Unlinked trips are the number of times passengers board public transportation vehicles. Passengers are counted each time they board vehicles no matter how many vehicles they use to travel from their origin to their destination and regardless of whether they pay a fare, use a pass or transfer, ride for free, or pay in some other way. A person riding only one vehicle from origin to destination takes one unlinked passenger trip; a person who transfers to a second vehicle takes a total of two unlinked passenger trips; a person who transfers to a third vehicle takes a total of three unlinked passenger trips. Also called boardings.