Designing for Public Safety


Eyes on the Street

Crime Prevention Through Environmental Design (CPTED): Natural Surveillance

Think of a bustling city street that you know and love which feels safe at night. We’ll call this “Bonum Avenue.” On Bonum, sidewalks are filled with shoppers. People sip coffee in outdoor cafes or relax on benches in the shade, casually observing passersby. Storefront displays overflow on to sidewalks attended by shop owners who greet customers by name. Upper-story residents and office workers open their windows facing the street—often with bay windows offering a broad view—and run downstairs for a last-minute dinner ingredient or casual client meeting. Alleyways feature locally painted murals and can be seen at night because of functioning streetlights.

Now think of a different street, which is similar to Bonum Avenue, but some different decisions were made over recent years. We’ll call this hypothetical thoroughfare “Malus Street.” On Malus, several streetlights are out of service. Sidewalks are barren of outdoor seating, and there are few people to people-watch. Storefront displays feature small windows, but there has been little attention paid to window displays or other connections with passersby. While there are still upper-story residents and offices, some meet the streets with blank walls instead of windows. Alleyways are poorly lit, with hidden nooks and crannies, concealing a variety of clandestine activities.

In most ways, Bonum Avenue and Malus Street may be identical. Indeed, residents may remember that only a few years ago, Bonum felt much like Malus does today. They may have the same roads, sidewalks, and other infrastructure; the same number of nearby residents; the same building types; and even perhaps similar crime rates. But the experience of the two is completely different, in ways that are obvious to everyone. Not only does Bonum feel more pleasant, it feels safer. The difference is Natural Surveillance.

Natural Surveillance is the first and best-known concept of Crime Prevention Through Environmental Design (CPTED), a set of strategies focused on using the design of the built environment in this order to discourage illegal activities. Natural Surveillance, coined “Eyes on the Street” in Jane Jacobs’ 1961 classic Death and Life of Great American Cities, is based on a simple and intuitive concept: people feel safer in public when they know that many other people are around to see them. That basic idea is common sense, and the reason that cautious people don’t tend to spend time in dark, abandoned alleys at night. On a less extreme note, it’s also why Bonum Avemie may be thriving while Malus Street may fail even in the face of substantial investment.

Natural Surveillance is neither a panacea nor a replacement for law enforcement. When the chips are down, we’ll always need police to maintain law and order. But police should be considered the last line of defense. The first are ordinary people, going about their daily activity, subconsciously keeping watch for each other. In a walkable city commercial district, this often requires a wide variety of visitors at different times of the day and night. In a quiet residential neighborhood, where everyone knows everyone else, this manifests in a very different way (e.g. people sitting on porches). Either way, the bottom line is the same. When a neighborhood or district feels less than safe, police enforcement is only one part of the strategy to address it. The built form—how it’s designed and programmed—is also key, if we want our public safety efforts to be sustainable.

This is the first of a series of postings on Crime Prevention through Environmental Design (CPTED). Stay tuned for more. Updates will include additional principles of CPTED, updates from ASH+LIME’s work on the Public Safety Element of the Pine Bluff (AR) Comprehensive Plan, and an interview with retired Dallas Police Officer Shane Owens, an ASH+LIME consultant.

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