The California Transportation Commission solicited a road safety data analysis, then said last month that it couldn’t recommend a vehicle weight fee in part because the analysis didn’t prove vehicle weight affected whether people were mangled or killed in crashes — even though the numbers that could prove such a connection in California do not exist.

“We don’t have that data for enough crashes in California,” said Julia Griswold, who leads the UC Berkeley team contracted to carry out the analysis.

The California Highway Patrol collects crash information in the Statewide Integrated Traffic Records System, or SWITRS. Griswold and other researchers at Berkeley’s Safe Transportation Research and Education Center, or SafeTREC, worked off of SWITRS with a budget of around $500,000 from the state. SWITRS typically doesn’t specify the make, model and trim of vehicles — all critical information to determine a car’s weight.

Because of that, the researchers didn’t even attempt a “causal” analysis; they just looked at trends.

Ultimately, the California Transportation Commission said that without direct proof that heavier vehicles were driving up death rates in the state, commissioners would not recommend a weight fee.

Justin Behrens, a spokesperson for the commission, said the recommendation language in the commission’s report was meant to be neutral.

In the commission report to the Legislature that was based in part on the academic findings, the staff wrote, “The Commission does not recommend implementation of a passenger vehicle weight fee. While some other academic studies have found a potential relationship between growing passenger vehicle size and negative safety outcomes for vulnerable road users, the statewide analysis conducted for this study does not show a clear causal relationship between the two.”

Griswold said a heavier vehicle demonstrably makes a crash more dangerous to everyone outside the vehicle: “That’s just a fundamental of physics.”

Behrens wrote in an email that it was unclear what outcome a passenger vehicle weight fee would have on reducing fatalities and injuries, and so it couldn’t recommend implementing such a fee at this time. An economist, he noted, also told the task force that any charge would have to be fairly high to shift consumer car purchases.

Marc Vukcevich, a task force member and the director of state policy at the transportation advocacy nonprofit Streets for All, was surprised by what he perceived as the commission’s downplaying the established safety risks of heavier vehicles.

The outcome of the task force was “a shame,” Vukcevich said. “I think the (commission’s) final report was worded very carefully to not really say anything at all.”

Why study vehicle weight?

Since the 1980s — when the federal government carved out exceptions to fuel economy standards for pickup trucks, SUVs and minivans — the size of the U.S. passenger fleet has ballooned. As outlined in the initial academic report commissioned by the task force, the average pickup truck in the mid-1980s weighed about 3,500 pounds; by 2022, the average pickup weighed more than 5,000 pounds. In the past, sedans were by far the most popular passenger vehicle. In 2026, SUVs and pickup trucks account for a majority of new passenger vehicle sales in the U.S.

Over the past 20 years, pedestrian severe injuries and deaths have skyrocketed. In California, about 1,000 pedestrians die in collisions every year.

Part of the blame goes to the increased size of vehicles. As Griswold said, the force of a crash is related to both speed and mass. All things being equal, a larger car is more dangerous in a collision than a smaller car. California has a goal to enhance road safety, and lawmakers are interested in potentially curtailing dangerous vehicle sizes.

But the state can’t directly control vehicle design, which is regulated at the federal level.

In light of this, Assemblymember Chris Ward, D-San Diego, authored AB 251, which required the California Transportation Commission to head up a task force on vehicle weight and road safety. Under the bill — signed into law in October 2023 — the task force would produce a report describing its findings and any recommendations to the Legislature. The commission recruited academics to undertake a data analysis to inform that report, and the task force first met in December 2024.

A representative for Ward said he was not available for an interview. But, as archived by CalMatters’ Digital Democracy project, Ward described his intentions in a committee meeting in 2023.

He said that California didn’t have enough information to determine exactly how a fee might be implemented, and “I want this to be a very thoughtful and evidence-based policy should we actually get to that.”

Children are particularly at risk as pedestrians

While the researchers affiliated with the task force didn’t definitively prove that larger vehicles are the primary cause of the rise in pedestrian and cyclist fatalities in California over the last 15 years, they did unearth some disturbing information. “Children pedestrians are 82% more likely to be killed if struck by a SUV versus a sedan,” they wrote. The trend could have been related to both weight and to visibility. SUVs have more blind spots than smaller vehicles, and smaller bodies are more likely to slip unseen into a blind spot.

The researchers also found that from 2010 through 2022, “SUVs are the fastest growing vehicle type involved in crashes (197% ped, 171% bike) followed by sedans (183% ped, 171% bike) and pickup trucks (166% ped, 152% bike).” Larger vehicles are safer for the people inside them, but they tend to be more dangerous for everyone else.

Most serious crashes still involved a sedan, at least in part because sedans remained the most common vehicles on the road even as their popularity decreased in new sales. SUVs and pickups make up the majority of new registrations, but the shift hasn’t fully percolated through the state’s fleet because Americans tend to hold on to their vehicles for more than a decade.

David Brownstone, an economist at UC Irvine, also analyzed how a weight fee might impact user behavior. He determined that only a sizable fee might discourage significant numbers of people from purchasing larger, more dangerous vehicles. Among other downsides, higher costs might disproportionately affect lower-income Californians. And a smaller fee, such as 10 cents per pound, he wrote, wouldn’t do much to change behavior.

But researchers concluded that a small fee could have a positive impact even if it didn’t discourage drivers from purchasing larger passenger vehicles.

“While the $0.10 per pound fee would not substantially shift consumer behavior,” they wrote, “it is estimated to generate $1.2 billion per year in 2040 if applied only to 2024 vehicles and newer. These resources could be used to improve road safety through infrastructure improvements and other investments, creating a virtuous cycle whereby fees shift purchasing behavior towards safer form-factor vehicles and fee proceeds improve safety through changes to the built environment.”

Car fees are controversial in California

The commission considered the weight fee with a troubling backdrop: California faces a transportation funding crisis. The gas tax is not the powerhouse it once was, in part because of the rise of electric vehicles and greater fuel efficiency.

With decreasing revenue from the gas tax and increasing costs, Behrens said that over the next decade, the state will face a $216 billion shortfall. The commission has projected that it will need $757 billion over those years, with $34 billion of that going toward street safety projects and “active transportation” focused on pedestrians, cyclists and other non-motorized travelers.

A vehicle weight fee could conceivably help fill that gas tax gap, but it wouldn’t make a significant dent, Behrens said.

“Since it is unlikely that the funding shortfall or even the $34.1 billion need for complete streets and active transportation improvements could be adequately addressed with a passenger vehicle weight fee alone, it is important that the Legislature consider a fee in the broader context of California’s need for a sustainable funding mechanism for transportation infrastructure,” he wrote.

State lawmakers are still far from deciding on how to address the long-brewing collapse of road funding.

On the task force, neither Vukcevich nor Griswold expected a full-throated endorsement of a vehicle weight fee from the California Transportation Commission: It’s politically loaded.

Griswold pointed out that former Gov. Gray Davis tripled vehicle registration fees in 2003 — which the Los Angeles Times reported cost the average driver $158 more annually. He was recalled. The winner in that election, Arnold Schwarzenegger, had repeatedly hammered Davis on the “car tax.”

Still, the final report from the commission surprised Vukcevich. He was incensed that the commission had suggested that vehicle weight has a “potential” relationship with fatalities, when the relationship is proven.

It took decades, he said, “to prove causation when it comes to cigarettes and lung cancer. So the fact that we couldn’t prove causation in a much more messy, uncontrolled environment like our roadway system made sense to me,” he said. “But it also didn’t seem like a reason not to act on a pressing issue.”

The state has said that more active transportation projects would save lives, but money to pay for those improvements has been scarce. And according to the California Office of Traffic Safety, about 10 people die in car crashes every day.

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