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San Francisco to Study Lowering Speed Limit to 20 mph

| July 14, 2014
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A pedestrian waits to cross South Van Ness Avenue at 24th Street in the Mission. (Mark Andrew Boyer/KQED)

A pedestrian waits to cross South Van Ness Avenue at 24th Street in the Mission. (Mark Andrew Boyer/KQED)

With growing concern about pedestrian safety in San Francisco, and the city getting on board with a plan to end all traffic deaths within 10 years, Supervisor Eric Mar wants to study lowering speed limits to 20 mph, especially on streets with high collision rates.

“My hope is that as our Vision Zero process for San Francisco moves forward with engineering, enforcement and education, that we also look at policy changes like lowering speed limits, to save lives and make our streets safer,” said Mar.

Vision Zero is a plan to eliminate all traffic fatalities by 2024. Under the plan, the San Francisco Municipal Transportation Agency has identified the most troubling intersections and plans to undertake quick “cost-effective” measures to improve pedestrian safety.

Mar has asked the city’s budget and legislative analyst to look at three things: what the city can learn from London, New York and Paris, which have implemented 20 mph speed zones, how many lives could be saved, and the financial and environmental impacts of lowering speed limits.

London’s 20 mph speed zones have led to a steady decline in injuries and deaths, especially among children, according to one study. London’s program helped inspire San Francisco’s 15 mph school zones.

Many San Francisco streets have default speed limits of 25 mph, including those arterial streets that pedestrian advocates say by design act as auto speedways and pose the biggest pedestrian threat. Drivers often ignore the posted speed limits, and can travel upwards of 40 mph.

But there’s a life saving difference between 40 and 20 mph. A pedestrian is more likely to survive a collision with a car when the vehicle is traveling at 20 mph or under, says Nicole Schneider, executive director of Walk San Francisco.

“You can compare it to falling off a five-story building versus a one-story building,” Schneider said. “At 40 mph, you have a five percent chance of living. But at 20 mph you have an 85 percent chance of living.”

Some streets that could be targeted for speed reductions are in dense neighborhoods with high pedestrian injuries and fatalities, such as SoMa and the Tenderloin. Pedestrian advocates say safer designs and traffic calming measures on dangerous streets would need to go hand in hand with speed reductions.

SFMTA staffers found that 60 percent of pedestrian injuries and deaths occur on just 6 percent of streets. More than 100 pedestrians are “severely injured or killed” each year, and 800 are injured, they found.

“Reducing speeds in San Francisco is critical for the health and well-being of our community,” Schneider said.

Mar hopes to propose some policy changes once the data starts coming in in the early fall.

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Category: Transportation

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About the Author ()

Bryan Goebel is a reporter focused on transportation and housing issues. He was previously the editor of Streetsblog San Francisco and a producer and anchor at KCBS radio. He's a lifelong Californian and over his 20-year radio career has worked at stations in Barstow, Redding and Sacramento. Reach Bryan Goebel at bgoebel@KQED.org.
  • Rod King

    Great to see this movement taking off in the US as well.
    To see how the movement for lower speeds is going in the UK then take a look at http://www.20splentyforus.org
    Already most of our iconic cities are implementing a default 20mph speed limit.
    Good luck
    Rod King
    20′s Plenty for Us

  • richensf

    This will save lives and improve communities. It’s a no-brainer. Just make sure these streets become 20mph Green Wave streets, posted signage and all.

  • Akeem

    “Many San Francisco streets have default speed limits of 25 mph. Drivers often ignore the posted speed limits, and can travel upwards of 40 mph….But there’s a life saving difference between 40 and 20 mph. ”

    It seems like a moot point if the average person is already 15mph above the speedlimit anyway.

  • http://district5diary.blogspot.com/ Rob Anderson

    Still waiting for someone in the local media to acknowledge that 2012 UC study that found that the city’s method of counting cycling accidents was radically flawed:
    http://www.ncbi.nlm.nih.gov/pubmed/?term=Using+trauma+center+data+to+identify+missed+bicycle+injuries+and+their+associated+costs

    The implication of the study: that we really don’t know how safe/unsafe city streets are until the city has a sound method of counting accidents—all accidents, not just cycling accidents. If the city has been significantly under-counting cycling accidents, it may also be under-counting pedestrian accidents and motor vehicle accidents.

  • sebra leaves

    State laws trump city laws and the state has set the default limit at 25mph