National Institute of Justice National Institute of Justice. Research. Development. Evaluation. Office of Justice Programs
Crime Solutions.gov
skip navigationHome  |  Help  |  Contact Us  |  Site Map   |  Glossary
Reliable Research. Real Results. skip navigation
skip navigation Additional Resources:

skip navigation

Program Profile: CCTV in Philadelphia (Pa.)

Evidence Rating: Promising - One study Promising - One study

Date: This profile was posted on June 08, 2011

Program Summary

A program to install closed-circuit television cameras at different locations in the city of Philadelphia. The program is rated Promising. Camera implementation had no significant impact upon the amount of serious crime in the target area but did significantly reduce the number of crime events and disorder type crimes. There were mixed results with respect to displacement/diffusion of benefits across evaluation sites.

Program Description

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.

 

Program Theory

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.

Evaluation Outcomes

top border

Study 1

Serious Crime

The hierarchical linear modeling (or HLM) analysis of serious crimes found that camera implementation had no significant impact upon the amount of serious crime in the target area. Serious crime decreased slightly after camera implementation (by about five percent), but this drop was not statistically significant. While the average indicated no significant reductions in serious crime, there was considerable variation in outcomes for individual sites. For instance, serious crime was reduced and there was evidence of a diffusion of positive benefits to surrounding streets at four sites. The authors also noted that the base level of serious crimes was very low and perhaps too low to show any significant effect of the cameras.

 

Disorder Crime

Camera implementation significantly reduced disorder crime in the target area. After camera implementation, the average expected disorder crime count for the target areas was 16 percent lower, after controlling for all other variables. While the average indicated significant reductions in disorder crime, there was considerable variation in outcomes for individual sites. For instance, four sites experienced no reduction in disorder crime after implementation.

 

All Crime (Serious and Disorder Combined)

The implementation of cameras significantly reduced the number of crime events within the target areas. The months following the implementation of the cameras saw a statistically significant 13.3 percent reduction in expected crime counts after controlling for the other factors. While the average indicated significant reductions in all crime, there was considerable variation in outcomes for individual sites.

 

Displacement

There were mixed results with respect to displacement/diffusion of benefits across evaluation sites.

bottom border

Evaluation Methodology

top border

Study 1

Ratcliffe, Taniguchi, and Taylor (2009) used a quasi-experimental design that incorporated “before” and “after” measures of crime in experimental and comparable control areas. They used reported crime data independently collected by the police. These crimes were divided into two categories, “serious” and “disorder” crimes; crimes that could not be affected by CCTV were excluded from the analysis. The authors noted the low volume of serious crime at each camera site, which made it difficult to detect significance for the study's findings. The follow-up period was nine months for most sites (for a few sites, the period was slightly longer).

 

Although the 18 cameras were installed at 12 sites, the close proximity of some of the cameras led the researchers to construct eight evaluation sites. The treatment areas consisted of those areas that mapped the actual viewsheds of the cameras. Buffer areas surrounded these viewshed areas (approximately a 500-foot zone), and were the places to which crime would likely be displaced or, alternatively, that would benefit from a diffusion effect. The control areas were defined as the police districts surrounding the displacement areas.

 

The study assessed a time series of monthly crime incidents for 32 months for eight locations. The data was analyzed using hierarchical linear modeling and weighted displacement quotient. Controls were incorporated for seasonality and long-term trends in the crime data. Only crimes occurring in the carefully defined viewshed of cameras were included in the analysis for main effects.

 

The analysis accounted for the displacement/diffusion of benefits.

bottom border

Cost

top border
There is no cost information available for this program.
bottom border

Evidence-Base (Studies Reviewed)

top border
These sources were used in the development of the program profile:

Study 1
Ratcliffe, Jerry H., Travis Taniguchi, and Ralph B. Taylor. 2009. “The Crime-Reduction Effects of Public CCTV Cameras: A Multi-Method Spatial Approach.” Justice Quarterly 26(4): 46–70.
http://jratcliffe.net/papers/Ratcliffe%20et%20al%20%282009%29%20Crime%20reduction%20effects%20of%20CCTV%20cameras.pdf
bottom border

Additional References

top border
These sources were used in the development of the program profile:

Ratcliffe, Jerry H. 2006. Video Surveillance of Public Places (Problem-Oriented Guides for Police, Response Guides Series No 4). Washington, D.C.: Center for Problem-Oriented Policing.

Ratcliffe, Jerry H., and Travis Taniguchi. 2008. CCTV Camera Evaluation: The Crime-Reduction Effects of Public CCTV Cameras in the City of Philadelphia, PA, Installed During 2006. Philadelphia, Pa.: Temple University.
http://www.threatanalysis.com/misc/CCTV%20-%20Philly.pdf
bottom border

Related Practices

top border
Following are CrimeSolutions.gov-rated practices that are related to this program:

Closed Circuit Television (CCTV) Surveillance
Public surveillance systems include a network of cameras and components for monitoring, recording, and transmitting video images. The ultimate goal of installing public surveillance cameras is to reduce both property and personal crime. The practice was rated Promising for reducing overall crime and property offenses (i.e. vehicle crimes), but rated No Effects on impacting violent crime.

Evidence Ratings for Outcomes:
Promising - One Meta-Analysis Crime & Delinquency - Multiple crime/offense types
Promising - One Meta-Analysis Crime & Delinquency - Property offenses
No Effects - One Meta-Analysis Crime & Delinquency - Violent offenses
bottom border


Program Snapshot

Gender: Both

Geography: Urban

Setting (Delivery): Other Community Setting, High Crime Neighborhoods/Hot Spots

Program Type: Community Crime Prevention , Crime Prevention Through Environmental Design/Design Against Crime, Situational Crime Prevention, General deterrence

Current Program Status: Active