Do Surveillance Cameras Reduce Crime?
Many cities, businesses, and individuals have installed Closed-Circuit TV (CCTV) cameras for surveillance purposes. London in particular, has installed thousands of surveillance video cameras. New York City with more than 4000 video cameras in just Manhattan, has adopted many of the same strategies as London, and cities across the US are on a comparable path. These cameras make many people feel safer, but this technology can make other people concerned with a perceived loss of privacy.
The investment required for a surveillance camera can be significant. Some of these cameras can cost up to $ 60,000 each, and that is before the cost for human resources to monitor the output is considered. JP Freeman, a security market analyst company, projects that the US will annually invest 21 billion dollars in these systems by 2010. The market for CCTV systems in the US increased by almost 700 percent from 1980 to 2000.
Do the experiences to date, show that surveillance cameras improve the public's safety? Because of the political agendas in play, with the camera industry bias in favor and civil libertarian groups biased against, the answer is clouded with hyperbole.
For example, the headline from a news article about a study conducted by the University of California "Center for Information Technology Research in the Interest of Society" (CITRIS) read "SF SURVEILLANCE CAMERAS DO NOT STOP VIOLENT CRIME". However, this CITR study found that the cameras were very effective in reducing property crimes within 100 feet of the cameras, resulting in a reduction of 24 percent, but that fact was buried in the news article.
The CITRUS study was very thorough and is frequently cited as evidence that surveillance cameras do not work, even though the study found significant positive effects from the cameras. However, because those results may not be consistent with the agenda, those results are often not reported.
There is also bias from industry groups, since they make their money from selling cameras. The newest technology in camera surveillance is the use of computers to interpret the data. This is a kind of artificial intelligence that is called "video analytics", and is potentially beneficial for efficient use of surveillance cameras, but this technology has sometimes been significantly oversold by the surveillance camera industry. This technology works best in less complex environments, such as a warehouse or loading dock that should be idle. Video analytics works much less well in busy environments like a crowd at a shopping mall.
"Some of the claims that are made are just ridiculous," says Oliver Vellacott, CEO of IndigoVision, a British company that develops video analytics technology. "It's important not to believe all the ridiculous hype and nonsense about what analytics can deliver."
It has been demonstrated many times that camera recording can be used to solve crimes. The Chicago Police Department estimates that the web of cameras installed in their city has been an important tool, resulting in more than 1,200 arrests since 2006. The Dallas Police Department has reported more than 1,700 arrests in a similar period from their camera system. We have all seen the news reports about the 2005 London Terrorist bombings of the subways. Without the camera systems, where officials were able to track the movements of the perpetrators, it is very likely that it would have taken much longer to solve those crimes.
Surveillance works best when there is a system observing the camera output. But human time is expensive, and this is where video analytics can be important. If a computer can screen many cameras, and have the human review only the probable events, then a single human can monitor many more cameras. It is also more rewarding for the human not to watch camera output from eventless images. But we should keep our expectations realistic.
If we believed Hollywood, camera systems with this kind of artificial intelligence have almost mystical power. The truth is that it is very difficult for a computer to interpret many environments, at least with today's level of technology. However, a computer system equipped with video analytics software, teamed with a skilled human, can effectively monitor many cameras.
Chicago has hired IBM to install camera systems with video analytic software. "That's really going to just throw our camera network into hyperdrive," said Kevin Smith, a spokesman with the Chicago's Office of Emergency Management and Communications (OEMC). "Ultimately I think what this software might be able to do is simply recognize suspicious behavior and alert our operations people and, at times, our crime detection specialists as to what it sees." Chicago is installing surveillance cameras on all of their buses and subways to provide mobile eyes on the city. Once their mobile broadband system is in place, the data will be available in near real-time. Chicago is the world leader in the application of video analytics on this scale.
Surveillance cameras can be a deterrent to crime. In a study of convenience stores, CCTV surveillance showed impressive results. A sample of 81 stores were studied for 1 year before and and 1 year after the installation of CCTV camera surveillance systems. The rate of robbery decreased by 53 percent after the cameras were installed. The New York City Housing Authority estimates that the CCTV systems have reduced crime by 36% in their public housing. Baltimore (17%), Dallas (11%) and Philadelphia (37%) also report improvement in the rate of crime because of their downtown camera monitoring systems. However, not every city reports improvement. Washington DC, for example, says that their cameras have proven ineffective. In a British study, of 14 British cities that utilized a CCTV system, the systems had little effect on crime in six of the cities.
The conclusion is that a successful camera surveillance program requires more than just installing hardware. An effective program comprehends that a camera that is not monitored, is a dumb piece of hardware, and the camera system will lack credibility. Dallas uses retired and light-duty officers for their camera monitors. Smart systems (video analytics) can make human monitoring much more efficient. Over time, as camera systems successfully address crime, the deterrence effect of the cameras will improve. This is the message from London and New York.