Program Goals/Program Components
The city of Philadelphia, Pa., installed 18 closed-circuit television (CCTV) cameras at various locations in the city between July 2006 and November 2006 to help reduce crime. These cameras are monitored by the Philadelphia Police Department.
Of the 18 cameras, eight were pan, tile, zoom cameras. These cameras can be controlled by a remote operator so that they can tilt up and down, pan around the surrounding area, or zoom in on a particular segment of the viewing area or “viewshed.” These images are viewed in real time by a police officer. Images are recorded digitally and stored for up to 12 days. These cameras provide good-quality images that allow a license plate to be read up to a block from the camera or for street activity to be viewed up to three blocks away. In Philadelphia, the officer monitoring these images is located at police headquarters.
The remaining 10 cameras were Portable Overt Digital Surveillance System cameras. They do not allow for real-time image viewing. These cameras are moveable, the recording system is located in a bullet-resistant unit, and the camera emits a flashing strobe light to attract the attention of people in the area. The images can be viewed by patrol officers with equipment designed to access a wireless link. Images can be stored digitally for up to 5 days. The retrieval of images from these cameras can be time-intensive: it requires the help of a city street engineer and can take up to two hours.
The underlying theory for the effectiveness of CCTV is deterrence theory, which predicts reductions in crime resulting from potential offenders’ perceptions of increased risk of detection and capture.