At a Transportation Commission webinar on measuring transportation impacts, Jeremy Ketchum, division chief for environmental analysis at Caltrans, summarized how SB 743 and CEQA guide project-level transportation and air-quality reviews.

Ketchum said SB 743—signed in 2013—and subsequent CEQA guideline updates led the state Office of Planning and Research (now Office of Land Use and Climate Innovation, LCI) to adopt vehicle miles traveled (VMT) as the standard metric for land‑use project transportation impacts. Caltrans adopted guidance in 2020 and issued two primary documents, the Transportation Analysis Framework (TAF) and Transportation Analysis under CEQA (TAC), to guide district-level review and statewide consistency.

“SB 743 required LCI to identify new metrics for evaluating and mitigating transportation impacts under CEQA,” Ketchum said, noting Caltrans chose to focus on induced VMT consistent with the LCI technical advisory. He told commissioners that headquarters reviews focus on consistency with the TAF and TAC and that a risk assessment early in project development determines whether a project can be screened from SB 743 analysis or requires more intensive study and mitigation.

Ketchum explained typical screening: “Project types that are typically screened include rehab, maintenance, repair projects that improve the condition of existing assets.” By contrast, capacity‑increasing projects generally require analysis for induced VMT. He described the decision flow: scope technical studies during the environmental phase, identify mitigation to reduce impacts below significance, and if significant impacts remain prepare a statement of overriding considerations.

On methodologies, Ketchum said applicability of tools is determined by project context: the National Center for Sustainable Transportation (NCST) calculator applies only in counties inside metropolitan statistical areas and to certain project types (for example, lane additions exceeding about a mile). Where the NCST tool is inapplicable, Caltrans uses regional travel‑demand models or, when neither tool is appropriate, qualitative methods.

Ketchum emphasized that both the TAF and TAC are being updated and Caltrans is working on additional guidance for rural counties. “Headquarters review is focused on consistency with the TAF and TAC,” he said, adding the agency continues to review tools and consider updates for rural contexts.

Ketchum also reviewed the air‑quality analysis sequence required under NEPA and CEQA and federal and California Clean Air Acts. He described how traffic outputs feed emission estimates using CARB emission factors and EMFAC, and how projects in nonattainment or maintenance areas must follow interagency consultation with EPA, FHWA, CARB, air districts and regional planners. Projects identified as Projects of Air Quality Concern (POAC) require hotspot dispersion modeling (for PM2.5/PM10 and CO) using screening protocols and dispersion models such as CALINE4 and AERMOD; FHWA issues the formal transportation conformity determination before final environmental documents are issued.

Ketchum closed by reiterating that mitigation—beginning with avoidance and project design to limit induced travel—is required where impacts are found, and that where mitigation cannot fully address significant impacts, districts prepare statements of overriding considerations for headquarters review.

Caltrans’ presentation included timeline references: SB 743 was signed in 2013, CEQA guideline updates and OPR/LCI technical advice were released in December 2018, and statewide implementation of SB 743 guidance occurred July 1, 2020. Ketchum said the TAF and TAC released in 2020 are under revision and new releases are expected.