the built environment as a crime deterrent : a reexamination of defensible space

Abstract 0 The value of defensible space (access by strangers and opportunity for residents to observe public areas) in a variety of household types was examined. Comparison of matched samples of households (one somple consisting of people who had been victims of acrime and one where they had not), using both observation and interview data produced mixed results. Defensible space was eflective in deterring crime in indoor public areas, but not in outdoor areas. Defensible space was found to have a slight impact on people’s feeling of responsibility for public areas.

THE BUILT ENVIRONMENT AS A CRIME DETERRENT A Reexamination of Defensible Space

ALAN BOOTH University of Nebraska

efensible space refers to ‘‘a model for residential environ- 1 ments which inhibits crime by creating the physical ex- pression of a social fabric that defends itself’ (Newman, 1973: 3). More specifically, Newman proposes that certain physical features of public areas around the home can encourage feelings of responsibility for what goes on in these areas by drawing out “latent territoriality“ and “a sense of community.” Individuals who feel responsible for activities in public areas are more likely to challenge the comings and goings of strangers or to intervene (personally or by calling authorities) when a crime is in progress and by doing so, deter crime.

AUTHOR’S NOTE: A more detailed report of this project is available from the author. Address requests to Alan Booth. Sociology Department, University of Nebraska, Lincoln, NE 68588.

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Newman (1973: 50) delineates four ways in which public areas can be designed so that nearby residents feel responsible for them:

(1) subdivide large public areas into smaller areas toward which resi-

(2) position windows to allow residents to survey public areas (3) locate residences adjacent to public activities that do not provide

a threat, such as small parks frequented by adults or playgrounds used by small children

(4) construct public areas in ways that give strangers the impression their activities will be observed and, if necessary, challenged by residents.

dents can adopt proprietary attitudes

It is possible to conclude from Newman’s highly illustrated discussions that the built environment may encourage crime in public areas in two ways: first, by permitting nonresidents (including people with criminal intentions) to have easy access to public areas; and second, by limiting the opportunities residents (or their representatives) have to observe activities in public areas adjacent to their home. Public areas are sidewalks, streets, alleys, empty lots, playgrounds, and parks. In multifamily units they include hallways, lobbies, stairwell, recreation areas, parking space, and laundry rooms. In short, public areas are any area shared by residents of a building, block, or neighborhood.

How do accessibility and opportunities to observe, facilitate crime? Highrises, for example, have many entrances and exits to enable people to enter and exit from any point. A hallway in a highrise typically has two stairwells and two to three elevators. Parking lots associated with multiple-family units are often not enclosed. A criminal has the opportunity to enter at will, commit a crime and exit undetected. Another dimension of accessibility is whether or not there are stores, parks or other public facilities which draw people to the vicinity. Such facilities may encourage crime by drawing large numbers of strangers to the vicinity, which makes the areas more difficult to monitor. On the other hand, if such facilities draw mostly locals, it could serve to provide greater surveillance of public areas. Jacobs (1961) argues that the surveillance provided by the passerby is an important deterrent to

Booth / DEFENSIBLE SPACE 559

crime. Newman (1973: 109) is not so sanguine about this feature of the built environment and insists that only certain types, (e.g., those not frequented by adolescents,) may provide the necessary surveillance. It is evident that the presence of public facilities may be as much an element of the opportunity to observe as it is of accessibility.

The opportunity for residents to observe public areas is also related to the size of the area. Newman argues that playgrounds, parks, and parking lots should be no more than 400 feet in diameter-the maximum distance human activity is clearly discernible. At 400 feet, a resident can usually decide, for example, whether two people are having a conversation or someone is being held up. In addition, for people to develop a feeling of responsibility for a public area, residents must be able to observe a public area before using it. This gives the individual a chance to judge whether the area is safe before being committed to its use. This means being able to observe public areas from several directions and from at least 50 feet away. In addition, police and security guards should be able to see clearly the area from the street, in the course of patrol.

Another dimension of the opportunity to observe public areas is whether residents are able to observe public areas numerous times in the course of their daily activities. This is achieved when windows (especially in high-use rooms, such as kitchens), doors, balconies, or porches overlook public areas. Not only do opportunities to observe increase the chances of intervention once a crime is in progress, but a criminal who can discern that a public area is under nearly constant surveillance by locals is less likely to enter the area with the intent of committing a crime. He will know his chances of being caught will be higher.

The evidence Newman provides in support of his argument is limited. In a comparison of two public housing units, one a high rise with high accessibility and limited opportunites to observe, and a low-rise project with greater defensible space, he found the high rise to have a greater number of robberies, malicious mischief and a variety of other felonies, misdemeanors and offenses. However, in a multiple regression analysis, many of


the design variables he proposes do not explain much variance in crime. For example, elevator visibility, lobby visibility, and whether the entrance is facing the street, each have betas of less than .lo, and together, explain less than 1% of the variance in robberies in an equation that includes a variety of social and economic variables (Newman, 1973: 240). Variables that reflect the opportunity to observe other public areas, such as parking lots, play areas, hallways, and the like, are not included in the analysis. Nor are the number of directions or the distance from which public areas can be observed. The opportunity to observe public areas from windows, doors, and porches, in the course of daily life is not examined. Surveillance from adjacent public areas is not assessed, nor are such dimensions of accessibility as size, fences, and so on. Perhaps the most severe omission in his study is the exclusion of some direct assessment of the social psycho- logical dimensions-feeling responsible for what goes on in public areas.

In spite of the sparseness of the evidence supporting Newman’s claims, the work has had influence on housing policy and some consider it to be “the most influential contemporary statement of urban designers” (Reppetto, 1976). While others have called attention to the importance of design in creating a secure house environment (see Rainwater, 1966) and, in particular, to the salience of opportunities to observe (Gold, 1969; Jeffery, 1977), perhaps Newman’s is one of the most comprehensive statements on the deterrence of crime through design features of the built environment.

There have been a number of studies attempting to test the veracity of the defensible space concept. Typically, however, these studies focus on only one aspect of the concept, and often the results are conflicting. For example, a number of studies compare housing types such as multiple-family and single-family homes, or high-rise and low-rise apartment units (Baldwin and Bottoms, 1976; Gillis, 1974; Hagan et al., 1978; Mawby, 1977; Reppetto, 1976, Waller and Ohikiro, 1978). Simple comparisons of building types, however, do not take into account the extent to which each type permits its residents to observe public areas or


allows strangers easy access. The lack of attention to design details may account for the conflicting results obtained by the dwelling-type comparison studies. Gillis (1974), Hagan et al., (1978) and Waller and Ohikiro (1978) find a relationship between crime and dwelling type, but Baldwin and Bottoms (1976), Mawby (1977a) and Reppetto (1974) do not.

Several studies focus on accessibility. Duffalo (1976) shows that convenience stores located on streets with less access to a major transportation route are not as likely to be robbed. Molumby (1976) and Fisbie et al., (1977) show that people in dwelling units on streets with poorer access are less likely to be the victim of a crime. Other studies (Waller and Ohikiro, 1978; Reppetto, 1974) examine whether the presence of stores, parks, schools and other public facilities influence residential crime, and these studies conclude they have no effect. The studies that examine opportunity to observe are fairly uniform in finding that this variable tends to deter crime. Some of these studies, however, narrowly define this variable as the opportunity to see a dwelling from neighboring homes or from the street (Waller and Ohikiro, 1978; Reppetto, 1974). Other investigations are concerned with the way in which street lighting and shrubs detract from or enhance opportunities to observe public areas (Molumby, 1976; Fisbie et al., 1977), while Mawby (1977a, 1977b) examines the role of opportunities to observe in deterring telephone-booth vandalism and a variety of offenses in shopping areas. None systematically examine the many dimensions of opportunities to observe public areas that Newman proposes.

The piecemeal approach of prior research evaluating New- man’s proposals, the conflicting findings of some of these studies, and the weakness of Newman’s original study, led the writer to undertake a study to evaluate the idea further.

We surmounted deficiencies of earlier research by assessing accessibility and opportunities to observe, using measures that cover more dimensions of the two concepts than did earlier studies. Like the original study, crime is the dependent variable. It is assessed through victim survey rather than official reports, as in the original survey, thus adding to the breadth of the study of

562 CRIMINOLOGY I FEBRUARY 1981

defensible space. In addition, information on whether residents feel responsible for what goes on in public areas was obtained, allowing us to investigate whether accessibility and opportunities to observe are related to people’s feelings of responsibility for public areas. A matched sample design allows us to control for a number of social and economic variables while examining the relation between defensible space and crime over a wide range of housing types.

RESEARCH PROCEDURES

In order to understand the influence of the environmental factors that Newman suggests are important in predicting crime, we compared two matched samples of urban households. In one sample, the residents had been victims of vandalism or burglary some time during the 18-month period prior to the study, and in the other sample, the residents had not been victims of the offenses. The households were matched on type of dwelling (single-family; duplex; apartment); minority status of residents (white, nonwhite); household composition (husband-wife; husband-wife-child; single person; other related individuals); years in school (past high school training; no past high school education); and age (under 60, 60, and over).

The households were part of the 1978 Nebraska Annual Social Indicators Survey; an annual survey of a random sample of 1800 noninstituionalized adults, 18 and over. Among the questions asked were: “During the last 12 months, did anyone break into your house or apartment and steal something?” and “During the past 12 months, has anyone unlawfully damaged or vandalized this property?” All those answering in the affirmative who lived in Omaha or Lincoln were included in our study. The characteristics of each victim household outlined above were examined and a search made of all other survey respondents from the same city who had identical characteristics, except having been a victim of crime. From among all of the matches, one was selected at random. This resulted in 73 matched pairs of households, the


residents of one, the recent victim of a burglary or vandalism. Since the original sample from which these subsamples were drawn is random, we also have a probability sample of victim and nonvictim households. The design eliminates the need to control for contaminating factors such as SES and household composition, as they are controlled by the matched sample feature. Trained observers were sent out to assess the design features of the dwelling and surroundings and to reinterview the respondent from the initial survey from which these subsamples were drawn. The observers had no information on which households had been vandalized or burglarized and they were assigned households on a random basis.

Upon arrival at a study household, the observer enumerated all of the public areas adjacent to the dwelling unit and, if the unit was an apartment building, all of the community areas in the building which contained the residence. After enumerating them, systematic information was obtained for each one: whether it was enclosed by shrubs, fences, or other structures; whether the area was locked or guarded; the number of people using the area; signs of use such as debris, defacement, and wear; whether the area could be seen from a public street; the distance and number of directions from which the area could be observed before use; the number of windows, balconies, porches, and doors in the dwelling unit from which the area can be seen; the number of public facilities (commercial establishments, parking lots, parks) immediately adjacent to the public area; and the size of the public area.

From these observations, we constructed variables reflecting the major components of Newman’s proposal. Each variable is constructed by counting the number of community areas for each household that either favor access by strangers or limit opportunities for residents to observe. From the observation data, five measures of accessibility and six measures of opportunities to

observe were created as follows:

Accessibility no boundaries (fences, shrubs, and the like)


0 one or more dimensions greater than 400 feet 0 three or more people present 0 signs of use (debris, defacement, wear) 0 bounded by public facilities

Opportunity to observe 0 cannot be seen from street 0 cannot be seen from more than one direction before using 0 cannot be seen from more than 50 feet away before using 0 cannot be seen from door of dwelling 0 cannot be seen from window of dwelling 0 cannot be seen from porch or balcony of dwelling

The observers, who were also trained interviewers, attempted to interview the household members who were part of the original survey. After three callbacks, we were able to obtain interviews from 37 of the 73 pairs. We interviewed residents in order to examine the relationship between the measures of accessibility and the opportunity to observe obtained by our staff, and the residents’ judgment of these variables. The central question on the accessibility of each public area was: “Do you or other members of your household feel too many strangers use the -T’ Questions on the opportunity to observe the community areas were in a similar vein: “Do you or other members of your household feel you have enough opportunity to see what’s going on in - before you use it?” “Do you have a clear view of the - from the most frequently used door in your home?” All variables were coded as dummy variables. This was done for analytical clarity and to meet the distributional requirements of some of the modes of analysis used in this paper.

A correlation matrix of the accessibility and opportunity to observe variables reveals that the outdoor variables are inde- pendent of one another, but measures for the indoor public areas are not. The correlation between observers’ judgments and residents’ perceptions of accessibility and opportunities to observe, are low and positive, indicating that these two means of assessing accessibility are tapping quite different dimensions, but that they are valid for purposes of our analysis of the built environment as a facilitator of crime.


FINDINGS

A simple cross-tabular analysis showing the percentages of the noncrime and the crime household samples which have environmental features that increase access to public areas by strangers or limit residents’ opportunities to observe such areas, reveals that for the outdoor public areas, the differences between the two samples are slight. In some cases the differences were not in the predicted direction. Thus the outdoor features of the built environment studied, with minor exceptions, do not seem to facilitate or impede burglary or vandalism.

The interview data concerning outdoor public areas generally conform to this finding. There is little difference between the crime and noncrime sample with respect to the features of the environment that, according to Newman, are supposed to impede or encourage crime. Moreover, the observation-based finding that public areas around victim households have more people in them, is not substantiated by the feeling among the residents that “too many strangers” use the area. Thus, both observational and interview data indicate that accessibility and opportunities to observe outdoor public areas are not important factors in whether or not households will be the victims of a crime.

The analysis for public areas inside apartment buildings shows quite a different picture. While the differences are small and not statistically significant, they are all in the direction which suggests that easy access and limited opportunity to observe, facilitates crime. The importance of this consistency is explored in sub- sequent paragraphs.

To see whether the numerous measures of accessibility and opportunity to observe actually coalesce around one another to form the proposed dimensions, a varimax factor analysis with an oblique rotation was used. Three factors emerged from the analysis of the observation data pertaining to public areas outside the household. The first factor is an “opportunity to observe” dimension that includes all of the variables in this category. Size loads highly on a second factor, along with whether the area is bounded. The remaining components of accessibility load highly on a third factor that seems to constitute a people dimension:


the number of people observed in the area, signs of heavy use, and whether or not the area had public facilities adjacent to it. Thus, accessibility appears to have two dimensions: first, the size of the area and whethe'r it is bounded; and second, the use of the area.

A factor analysis of the interview data yielded somewhat similar findings: whether or not the respondent could see a public area from the door loaded on the same factor as hislher opportunity to see it from windows. The respondents' opportunity to view the area before using it, however, loaded highly on a different factor as did reports of too many strangers using the area. With respect to public areas in muliple-family units, the high multicollinearity prevented the emergence of meaningful dimensions.

In order to assess the relative and overall influence of these dimensions on crime, scales based on factor coefficients were constructed and entered into discriminant analysis equation. The results of the discriminant analysis, using the opportunity-to- observe scale and the two accessibility scales based on the outdoor public area data, show that the opportunity-to-observe scale is negatively related to crime: the worse the opportunities to observe activities in public areas, the less the chance of being a victim of burglary or vandalism. The two accessibility scales, on the other hand, are positively related to crime: the households having areas highly accessible to strangers are more likely to be the object of crime. When the opportunity-to-observe scale is removed from the equation, the percent of households correctly classified is 54%. As the odds of being classified into one or the other sample are 5050, an improvement of 4% is small-only 8% of the possible total predictive power. The discriminant equations for the interview outdoor public area data were even less supportive of the central hypotheses-with low or negative opportunity to observe coefficients and correctly classifying only 52% of the households. Moreover, neither equation was statistically significant.

The high multicollinearity of the measures for public areas in apartment dwellings renders the discriminant coefficient rela-

Booth I DEFENSIBLE SPACE 567

tively meaningless. However, the percentage of correctly classified cases is not influenced by this property of the coefficients. The number of cases correctly classified is 61%. This proportion accounts for 20% of the potential prediction power of these variables and indicates that accessibility and opportunity to observe indoor public areas is an important deterrant to crime.

Overall, the discriminant analysis conforms to the cross- tabular analyses and indicates that for outdoor public areas, the accessibility strangers have to public areas has minor bearing on crime and that the opportunities residents have to observe such areas are not effective in reducing the incidence of burglary and vandalism. However, these dimensions are more important in public areas inside multi-family dwellings and are probably effective in diminishing crime.

It is, of course, possible that the variables proposed by New- man are not equally effective in preventing both vandalism and burglary. With this in mind, the vandalism and burglary subsets were analyzed separately. While these findings must be regarded as tentative because of the small number of cases, it appears that the two dimensions of defensible space deter both burglary and vandalism, and are somewhat more effective in the case of burglary.

Central to Newman’s hypothesis is the argument that people will develop a sense of responsibility for what goes on in an area if they observe it frequently in the course of their everyday life and if the area is not overrun by strangers. We were able to examine this hypothesis using a question from the interview: “Do you or, any member of your household feel responsible for what goes on in -T’ All 164 outdoor community areas enumerated and assessed by the observers for the 76 households responding to the interview, were analyzed. The public areas were divided into two groups on each dimension of accessibility and observability. Those that enhance accessibility (or observability) were aggre- gated into one group, and those that limit it were put into the other. For each group, the percentage the respondents felt responsible for was computed. The differences are small (aver- aging 9%) and with some exceptions, indicate that people are


more likely to feel responsible for areas that have limited accessibility and provide ample opportunity to observe. How- ever, the number of cases upon which many of the percentages are based is small, and therefore, the proportion may be unstable. While the findings do suggest that the built environment might have mild influences on feelings of responsibility, this inter- pretation must be regarded with caution.

CONCLUSION

Defensible space seems to be a viable concept in preventing burglary and vandalism in some areas (public areas in apartment buildings), but not in others. While strangers’ accessibility to community areas seems to make a difference in whether or not crime will be committed, the opportunity for residents to observe public areas seems also to play a role. It is of interest that other researchers find that the opportunity-to-observe dimension bears some, albeit slight, relationship to crime. We do not agree and a word about the reason for this difference is in order. Of the six prior studies, only two focus on public areas adjacent to a residence. Rather, they focus on the opportunity to view the doors and windows of the dwelling itself (Waller and Ohikiro, 1978; Reppetto, 1974) or on public areas detached from residence (Mawby 1977a, 1977b). The two studies that do assess opportunity to observe in public areas adjacent to residences (Molumby, 1976; Frisbe et al., 1977) examine the effect of street lighting, a factor not considered in the study reported here. Had the studies been more similar to our own, more consistency in the results could be expected.

Given the very high cost of reconstructing the built environment to meet defensible space criteria, our findings cast some doubt on the wisdom of such an expenditure, at least for outdoor areas. Of course, it is possible that accessibility and observability have more impact on preventing robberies or some other crime we were not able to examine with our data.

Part of the reason defensible space is not a very useful concept is that it is monolithic-relying almost entirely on physical


features of the environment and ignoring the social aspects of the milieu. The stability of the neighborhood, its composition and organization are social factors that are important in predicting crime. Perhaps when defensible space is applied in neighbor- hoods with limited residential mobility, low unemployment and a high level of community integration, crime deterrence is more effective. If social factors are prerequisites, then public policy should reflect these needs. As it is, however, defensible space is a sterile concept: void of the social reality which might make it work. Further research is needed to evaluate whether defensible space is more effective than this study would suggest in particular social milieux.

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DUFFALO, D. (1976) "Convenience stores, armed robbery, and physical environmental features." Amer. Behavioral Scientist 20: 227-246.

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Alan Booth is Professor of Sociology at the University of Nebraska-Lincoln. He has studied the e/fect of household and neighborhood crowding on pathology, drawing on data f i om a sample of Toronto families. Other research includes a comparison of Uniform Crime Report and victimization indices and a study of the effects of housing type upon family relations. Currently, he is engaged in astudy of the factors that cause divorce.

the built environment as a crime deterrent : a reexamination of defensible space

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