Study gives split verdict on crime cameras

In San Francisco, they appear to reduce larceny but not violent offenses


A long-awaited study of San Francisco's installation of surveillance cameras in high-crime areas shows that the effort fails in its primary goal of reducing homicide and other violent crime, but succeeds in reducing such offenses as burglary, pickpocketing and purse-snatching.

The study found that the program, started by Mayor Gavin Newsom in 2005, is hampered by a lack of training and oversight, a failure to integrate footage with other police tactics, inadequate technology, and what may be fundamental weaknesses of cameras as devices to stop violent crime.

The 184-page study, which was called for by the Board of Supervisors in 2006, was conducted by the UC Center for Information Technology Research in the Interest of Society. It represents one of the most thorough reports on public surveillance, a trend that has swept the nation in recent years.

San Francisco's camera program is different from other cities' because, in a nod to privacy concerns, police in San Francisco are not allowed to monitor cameras in real time; investigators must instead order footage after a crime is reported.

Researchers examined everything from camera locations and police requests for images to the number of times the images were used to bring charges.

"We find no evidence of an impact of the cameras on violent crime," the report stated. "Violent incidents do not decline in areas near the cameras relative to areas further away and we observe no decline in violent crimes occurring in public places."

The report examined only the cameras obtained by Newsom. It did not address cameras separately used by the San Francisco Housing Authority. They are in the agency's housing developments.

The report theorizes that the camera program's goal of deterrence may be at odds with violent crime, which is "often committed outside the bounds of rationality." In addition, the cameras have not had a "feedback cycle" - criminals have not seen immediate consequences to lawbreaking under the cameras' gaze.

Property crimes were another matter. Statistics showed that within 100 feet of camera locations, felony property crime fell 24 percent, with the change driven by decreases in larceny that targeted people, homes and cars.

The report quoted police as saying footage had helped them bring charges against crime suspects in six cases, and had been helpful in other cases.

"Officers and others note that despite poor image quality, the camera footage has been useful in criminal investigations ... more often footage is helpful in establishing a sequence of events for a crime or placing witnesses at a scene," researchers wrote.

A jumbled system

The report was critical of the way a hodgepodge of city agencies combined to administer the program. It said the program had no dedicated manager, and that officers and attorneys got no training on how to view the footage. The clarity of the footage, the study said, could be greatly improved if San Francisco bought more data storage space.

The cameras San Francisco bought and installed for $700,000 are high-resolution but produce so few frames per second that the footage appears choppy, making it difficult to identify things like license plates, the report said.

Movies and video games are shot at 24 to 30 frames per second, a speed that is "seamless to the human eye," the study notes. The San Francisco cameras can go up to 12 frames per second, but are set at three to four frames per second, which provides far less information than seamless filming. In a story published last year, The Chronicle found some of the San Francisco cameras were operating at even slower speeds.

The city told researchers that increasing the frame rate and retaining the images longer - a month rather than the current week - could cost $3 million.

This content continues onto the next page...