California is counting on new housing to help wean drivers off their cars — but a new UC Berkeley and UCLA study finds the state's current local housing plans would cut per-capita driving by less than 1 percent, a fraction of what's possible, because cities aren't putting the homes in their most walkable, transit-rich neighborhoods.

The report, "Projected Transportation Impacts of California Housing Plans," released August 6 by UC Berkeley's Terner Center and the UCLA Lewis Center for Regional Policy Studies, is the first to grade where cities are actually planning to build against the state's climate math. Its verdict is split: the regional bodies that hand out housing targets did their part, steering more homes to lower-driving cities — but the cities themselves, which pick the actual parcels, largely didn't return the favor. The result is a 0.9 percent projected drop in per-capita vehicle miles traveled, against a state target of a 25 percent cut by 2030 and a demonstrated ceiling of 6 percent if homes were sited to minimize driving.

California wrote car-reduction into law. The Air Resources Board's 2022 Scoping Plan leans on a 25 percent per-capita cut in vehicle miles traveled — VMT — by 2030 to hit the state's climate targets. The theory behind it is simple: build homes in neighborhoods where people can walk, bike, or take transit, and residents drive less. The state's own housing blueprint calls for 2.5 million new homes by 2030.

The new study tests whether the housing California is actually planning will deliver those driving cuts. Researchers at Berkeley's Terner Center and UCLA's Lewis Center standardized the site inventories that 366 jurisdictions — 77 percent of the state's population — filed with the Department of Housing and Community Development for the current Sixth Cycle of Housing Elements, then modeled how much driving those planned homes would add or subtract. They assumed new residents would drive like current residents of the same neighborhood do.

The headline number is small. Built as planned, the homes would trim statewide per-capita VMT by 0.9 percent by 2030 — real, but a sliver of the 25 percent the Scoping Plan assumes. Terner's earlier work found that if the same 2.5 million homes were sited solely to minimize driving, the cut could reach 6 percent per capita. The gap between 0.9 and 6 is the story.

Where that gap opens is the study's sharpest finding. California allocates housing in three steps: the state projects how much each region needs, regional governments split their share among cities and counties, and each city decides which parcels get the homes. The analysis found regional governments did the climate-friendly thing — sending more housing to cities and counties where people already drive less on average. But inside those cities, local governments did not, on average, steer sites toward their own lower-VMT, transit-served neighborhoods.

"Many existing neighborhoods do have opportunities for people to be able to drive less," Zack Subin, the Terner Center's associate research director for housing and climate and a study co-author, told Streetsblog. "There's very clearly an opportunity to … solve the housing shortage by directing new housing to these places."

The report stops short of naming a single culprit for the local-level shortfall, noting each city faces its own constraints. But Subin points to a support gap. "[Cities] can't just do it on their own," he told Streetsblog. "The state really needs to step up in terms of, not just guidance, but high quality data and technical assistance."

That reframes the usual housing argument. A city can hit its state-assigned unit count and still whiff on the climate payoff if it zones for growth on its car-dependent edges instead of near its rail stops and commercial cores. The study also notes a limit on its own numbers: the researchers modeled the site inventories cities filed, but did not analyze the additional rezonings some jurisdictions have committed to — which, the report says, differ substantially in some cities, such as Los Angeles — and which could shift the results.

The takeaway isn't that housing fails to cut driving; it's that the current planning process captures only a fraction of the benefit sitting on the table. The state sets the targets and the regions distribute them, but the parcel-level decisions that determine whether a new apartment sits by a transit stop or a freeway offramp still belong to city halls — and, the data suggest, those city halls need better tools to make the climate-smart call.