City of Carlsbad planning commissioners received a technical briefing Nov. 5 on vehicle miles traveled, the metric California requires for transportation impact analysis under CEQA.

Jason Gelderd, engineering manager for the City of Carlsbad, and consultant Katie Cole of Fehr & Peers walked the commission through why VMT replaced the older level-of-service (LOS) approach and how the city applies thresholds and screening criteria adopted in a 2020 resolution. "VMT is what we commonly refer to and it's just the amount of driving that's generated by a project," Gelderd said.

Cole said the state-directed shift to VMT (per SB 743) is intended to reduce greenhouse gases, promote infill and encourage active transportation. "I like to think of VMT as my odometer," Cole said. For CEQA purposes, Carlsbad evaluates residential projects on VMT per person (citywide average) and employment projects on VMT per employee (regional average).

The city’s adopted thresholds require a residential project to be at least 15% below the citywide VMT average to avoid a significant impact; employment projects must be 15% below the regional average per employee, Cole said. She noted other use-specific thresholds (industrial at average, regional retail on net-area VMT) and screening criteria—including proximity to transit, redevelopment that reduces net VMT, and 100% affordable housing, which research shows tends to produce fewer trips.

Cole illustrated the analysis with a hypothetical village project that combined residential and office uses: the residential component measured about 82% of the city average (no mitigation required), while the office component measured 92% of the regional average (a small but material impact requiring mitigation).

On measurement, staff said the city’s interactive VMT maps are derived from the SANDAG regional travel demand model; SANDAG updates roughly every four years and was expected to adopt a new regional plan in December. Cole noted other acceptable inputs: local travel surveys, CalEEMod modules for air-quality analysis and anonymized connected-vehicle big-data from vendors such as StreetLight and Replica.

Commissioners pressed staff on monitoring and reliability. Gelderd and Cole said mitigation measures are drawn from the city’s VMT guidelines and CAPCOA recommendations, are selected by applicants and reviewed by staff for technical adequacy. "Because we already monitor transportation demand management through the ordinance, we'll put the mitigation measures inside that plan," Gelderd said, describing enforcement via the city’s TDM program.

Commissioners asked whether electric vehicles affect the metric. Cole replied that EVs are not part of the CEQA VMT transportation metric: "EVs are considered in the state CEQA document as part of other resource areas," she said, noting EVs are analyzed under GHG and air-quality sections rather than VMT, which focuses on travel behavior and land-use efficiency.

Commissioner Foster suggested requesting rideshare trip data from companies such as Uber for local parking and curbside planning. Staff said the city could request that vendor data but cautioned about representativeness and records-request implications; Cole added rideshare trip logs are often less useful for VMT because they can add circulating vehicle miles (drivers entering and leaving trips). For VMT analysis, staff recommended using anonymized big-data vendors that infer home and work locations and overall travel patterns.

Cole also warned that a previously used small-project screening number (110 average daily trips) was undermined by recent litigation in San Diego County, so applicants must now provide evidence when seeking small-project screening. The presentation concluded with no public testimony and a commission discussion of next steps.

What’s next: staff will continue to review incoming project VMT studies for technical adequacy and apply the city’s guidelines and TDM monitoring program when mitigation is required.