About Assembly Bill 43

California Assembly Bill 43 (AB 43) gives cities more flexibility when setting speed limits in business and residential areas. It allows cities to lower speed limits based on safety, land use, and the number of people walking or biking nearby—especially among vulnerable groups such as children, seniors, people with disabilities, and individuals experiencing homelessness.

The law also lets cities reduce speed limits in “business activity districts,” such as downtown areas. AB 43 took effect in 2022 and changed how traffic speed surveys are prepared and used.

Cities set speed limits using an Engineering and Traffic Survey (E&TS). This study measures how fast drivers typically travel—known as the “85th percentile speed,” or the speed at or below which 85% of vehicles drive. The survey also reviews road conditions, land use, and the area’s collision history.

San Rafael is taking a proactive approach to traffic safety by updating its E&TS in 2025. The City’s first step is to study the downtown area to identify streets where lower speed limits could improve safety.

The analysis considers the built environment, crash history, and how streets are used. Early findings were shared with the Bicycle and Pedestrian Advisory Committee in October 2024 and the Police Advisory and Accountability Committee in January 2025. Final recommendations will go to the City Council for approval, as required by AB 43.

After the downtown review, the City will evaluate other San Rafael streets that may benefit from lower speed limits. Once adopted, the final limits will be included in the City’s updated E&TS, which serves as the legal basis for enforcement through the Marin County Superior Court.

The 2024 Marin County Local Road Safety Plan found that downtown San Rafael has higher crash rates and that slower speeds would make streets safer for people walking, biking, or using mobility aids. Because of this, the first study focuses on downtown, where most injury and fatal crashes occur.

Starting with downtown also takes advantage of AB 43’s special provisions for “business activity districts,” helping calm traffic and create a more welcoming environment for visitors.

Future studies will look at other streets with:

• Heavy pedestrian or bicycle activity
• A history of frequent crashes
• Nearby schools, parks, or community centers
• High numbers of seniors, children, or other vulnerable groups

Speed is one of the biggest factors in how severe a crash is. A pedestrian hit by a car going 20 miles per hour has a 90% chance of survival. At 40 miles per hour, that chance drops to 50%. Even small reductions in speed can prevent serious injuries and save lives.

Lower speeds also reduce traffic noise and make streets more pleasant, walkable, and livable.