Following the lead of other major cities such as Paris and New York, San Francisco is examining lowering speed limits by as much as 10 miles per hour as part of its effort to achieve zero pedestrian traffic fatalities by 2020.
Lowering the speed limit reduces accidents, improves the chances of survival if someone is struck and reduces greenhouse gas emissions, supporters of the effort say.
San Francisco, which saw 21 pedestrian deaths last year, continues to garner support for its Vision Zero plan to eliminate traffic fatalities within the decade.
"We must do all that we can do to make sure that the streets are safer for our residents and a speed limit reduction may have a significant impact on achieving this," said Supervisor Eric Mar, who on Tuesday asked the budget and legislative analyst to examine lowering speed limits on San Francisco's streets.
"Cities around the globe are beginning to lower speed limits on city streets to 20 miles per hour in an effort to reduce accidents," Mar added.
San Francisco's speed limits vary from as low as 15 mph in school zones to as high as 45 mph. State law imposes a 25 mph speed limit in business and residential areas unless otherwise posted, and 15 mph in alleyways.
The report is expected to be completed sometime in the fall. It will specifically look at the number of deaths and serious injuries that could be prevented by reducing speed limits in certain areas by 5 mph and 10 mph.
The speed reductions may require state law to change, which is what New York officials recently pursued in order to have the authority to lower speed limits to 25 mph, a 5 mph reduction.
"Recent studies have found that small increases in traffic speeds can greatly affect the severity of accidents," Mar said. "Pedestrians being struck by a car traveling for example 20 miles an hour have a 95 percent chance of survival. At 40 miles per hour only 15 percent of the people hit by cars survive."
With the study, San Francisco joins a growing trend to reduce speeds to curtail fatalities in dense urban cities. Paris' Mayor Anne Hidalgo recently announced plans to impose speed limits of 30 kilometers per hour, about 19 miles per hour, on Paris streets. The United Kingdom is increasingly implementing 20 miles per hour zones.