The San Diego Police department has adopted a concept called Crime Prevention Through Environmental Design based on a set of four design and usage concepts that can lead to a reduction in the incidence and fear of crime, and an improvement in the quality of life: surveillance, access control, maintenance and territoriality fully described at https://www.sandiego.gov/police/services/prevention/tips/deter.
Surveillance involves the use of electrical and mechanical devices, and the location of physical features, activities, and people to provide good visibility in the environment. Creates a risk of detection for offenders and a perception of safety for legitimate users.
Access control employs electrical and mechanical devices, people, and natural measures to create a perception of risk to offenders and deny them access to targets. Also guides legitimate users safely through the environment.
Territoriality uses physical features and signs to define ownership and control activities in the environment. Delineates spaces with limited or no public access.
Maintenance allows the continued use of spaces for their intended purposes. Maintains the effectiveness of measures employed for surveillance, access control, and territoriality.