SF Is Struggling to Reduce Traffic Deaths. Slow Streets Could Be an Answer

A new analysis of San Francisco’s Slow Streets shows the program meant to reduce and slow down vehicle traffic on certain residential roadways continues to deliver on one of its major promises — making streets safer for all users.

In a study relying on data from the city’s Department of Public Health, traffic safety advocate and data analyst Stephen Braitsch found that injury collisions on the network’s 32 miles of roadway have fallen 61% since it was made permanent in December 2022 compared to the previous 26 months. Citywide, the number of injury crashes rose 6% during the same period.

The analysis suggests that Slow Streets could represent what advocates say should be a key tool for the city as it struggles to make progress on its Vision Zero goal to reduce deaths and injuries in traffic collisions.

Braitsch said the numbers show the program, which uses a modest and relatively inexpensive set of interventions such as signs, roadway paint and plastic “soft-hit” posts on 18 different streets, “has been wildly successful at reducing vehicle crashes.”

Braitsch’s study on the site Transpo Maps, which builds on a 2022 analysis he undertook just before the city’s Municipal Transportation Agency voted to make Slow Streets permanent, also looks into how reduced access to the network’s roadways has affected the Fire Department’s emergency response times.

The verdict: The overall average response time for the Slow Streets network increased by 28 seconds — from 3 minutes, 46 seconds to 4 minutes, 16 seconds — since December 2022. That’s a 12% increase compared to a 5% rise in average response time citywide in the same time frame.

“When you look at emergency response times, it’s also really important to consider the fact that the Fire Department responding station can be up to half a mile or three-quarters of a mile away from an emergency scene on a slow street,” Braitsch said.

“So there’s many, many, many other streets that the Fire Department has to navigate before it actually gets to the actual slow street,” he said. “Nonetheless, we wanted to put that data out there so at least there’s a foundation from which a conversation can happen around this information.”

The Fire Department did not respond immediately to a request for comment on the study.

San Francisco started its Slow Streets experiment five years ago as a way of creating easily accessible outdoor recreation opportunities after stay-at-home orders were imposed at the outset of the COVID-19 pandemic.

The program started with 14 streets in the spring of 2020. The SFMTA expanded it to the current footprint of 18 streets and made the program permanent at the end of 2022. The agency aims to limit traffic to 1,000 vehicles a day or fewer and reduce speeds to 15 mph or lower on each street in the program.

Braitsch said the Slow Streets program stands out as an example of what the city can accomplish as it considers how to move ahead with its Vision Zero safety program.

San Francisco adopted Vision Zero in 2014 with the goal of eliminating traffic fatalities within a decade. While deaths declined at first, they have surged again in recent years. Forty-two people were killed in collisions last year, the highest total in nearly two decades.

“The success of Slow Streets is like a mini-Vision Zero achievement because it really checks so many of the boxes that Vision Zero as a concept is trying to achieve,” Braitsch said. “The more we can expand the program throughout the city, the sooner we’re going to get closer to achieving our Vision Zero goals.”

He also points to Slow Streets as a cost-effective safety solution that the city has shown it can deliver quickly and efficiently.

The current SFMTA capital projects budget — funding dedicated to everything from updating Muni’s fleet to upgrading traffic signals to street safety projects — includes about $8 million for Slow Streets investments through 2029. That’s about one-third of 1% of the total $2.5 billion capital budget.

“What I think really comes across is that the program has been extraordinarily successful at an extremely small investment, the cost of the materials and the time to implement them,” Braitsch said. “It’s such an insignificant cost in terms of materials and labor, but yet it has had such a significant impact on public safety.”

Other street safety advocates agree that the SFMTA should prioritize expanding Slow Streets and investing in other “traffic-calming” projects.

Robin Pam, a cofounder of Kid Safe SF, said, “What all of this data shows is that when we decide a street should be safer and intervene to do that, it works. We need a more comprehensive and systematic approach to improving safety on all of our streets, the same way we have on Slow Streets.”

Christopher White, executive director of the San Francisco Bicycle Coalition, said in a statement that Slow Streets is a key component to building a citywide network accessible to people of all ages and abilities.

“The city should be looking for every opportunity to expand the Slow Streets program to support local transportation within neighborhoods as well as crosstown connectivity,” he said.

Walk San Francisco has called on the city to adopt a long list of steps to slow down motor vehicle traffic on city streets, perhaps the most important factor in reducing serious injuries and deaths in traffic collisions.

Those measures include installing equipment like posts or pavement bumpers at high-injury intersections to force drivers to slow down during turns, timing traffic lights to keep traffic flow at or below speed limits and reducing the number of lanes on streets known to be particularly dangerous — such as the network of wide, one-way streets in the city’s South of Market neighborhood.

Jodie Medeiros, WalkSF’s executive director, said the new Transpo Map analysis “backs up what we know to be true: When drivers go safe speeds, there are dramatically fewer crashes. If drivers would slow down on all San Francisco streets, we’d immediately see dramatically fewer crashes — just like what’s happened on Slow Streets.”