This document provides an overview of Crime Prevention Through Environmental Design (CPTED) strategies. It discusses research showing that natural surveillance, access control, and territorial reinforcement can reduce crime. Specifically, it notes that (1) houses with better natural surveillance were less likely to be burglarized, (2) access barriers like fences reduced crime, and (3) signs of ownership and maintenance strengthened territoriality. The document uses examples to illustrate how design can be used to apply these CPTED principles.

1. A Quick Review of CPTED Strategies (Crime Prevention Through Environmental Design) By: Russell James, J.D., Ph.D., Asst. Professor, Dept. of Housing & Consumer Economics, University of Georgia

2. The criminal’s SAT questions Surveillance (Will I be seen?) Access (Can I get in and out)? Territoriality (Does anyone care what happens here?)

3. Research Surveillance (Will I be seen?)

4. “burglarized houses had less visual access to immediately neighboring houses than did non-burglarized houses” Brown, B. (University of Utah), Altman, B. (University of Utah). 1983. Territoriality, defensible space and residential burglary: an environmental analysis, Journal of Environmental Psychology, 3(3), 203-20.

5. “Convenience stores experienced mean annual robbery rate reductions after installation of CCTV systems (-23%); installation of video cameras with monitors (-54%)” C. Casteel (UCLA) & C. Peek-Asa (UCLA). 2000. Effectiveness of crime prevention through environmental design (CPTED) in reducing robberies. American Journal of Preventative Medicine, 18, 99-115, p. 110

6. Office beverages available with payment on an “honor” system. Picture above payment instructions rotated weekly. Payments were higher when picture of eyes was posted. M. Bateson, D. Nettle & G. Roberts (2006). Cues of being watched enhance cooperation in a real-world setting. Biology Letters 2, 412–414.

7. Two groups with two computer backgrounds. Each person receives $10. Computer question: Do you want to share any of it with another (anonymous) participant? A B K. J. Haley (UCLA), D.M.T. Fessler (UCLA). 2005. Nobody’s watching? Subtle cues affect generosity in an anonymous economic game. Evolution and Human Behavior, 26, 245–256

8. K. J. Haley (UCLA), D.M.T. Fessler (UCLA). 2005. Nobody’s watching? Subtle cues affect generosity in an anonymous economic game. Evolution and Human Behavior, 26, 245–256

9. Research Access (Can I get in and out)?

10. “Burglarized houses had fewer fences and locked gates surrounding the yard than did non-burglarized houses.” Brown, B., Altman, B. (1983). Territoriality, defensible space and residential burglary: an environmental analysis, Journal of Environmental Psychology, 3(3), 203-20.

11. Preventing access by adding chain link fencing and lighting to lower levels of this parking garage led to 50% drop in reported crime. Tseng, C.-H. (Ohio State U.), Duane, J. (Ohio State U.), & Hadipriono, F. (Ohio State U.). 2004. Performance of Campus Parking Garages in Preventing Crime. Journal of Performance of Constructed Facilities, 18(1), 21-28.

12. Territoriality (Does anyone care what happens here?) Research

13. “burglarized houses had fewer symbolic barriers characteristic of primary territories (i.e., fewer markers depicting the identity of the territory owners)” Brown, B. (University of Utah), Altman, B. (University of Utah). 1983. Territoriality, defensible space and residential burglary: an environmental analysis, Journal of Environmental Psychology, 3(3), 203-20.

14. In a study of 400 convenience store robberies, one significant difference between robbed and non-robbed stores was distance from nearest graffiti S. A. Hendricks, D. P. Landsittel, H. E. Amandus, J. Malcan, & J. Bell. (1999) A matched case-control study of convenience store robbery risk factors. Journal of Occupational and Environmental Medicine, 41(11), 995-1004

15. “Does it pass the SAT?” Visual Examples Surveillance (Will I be seen?) Access (Can I get in and out)? Territoriality (Does anyone care what happens here?)

16. Will I be seen?

17. Surveillance: FAIL

18. Can I get in and out?

19. Access: FAIL

20. Does anyone care what happens here?

21. Territoriality: FAIL

22. Does anyone care what happens here? Territoriality: FAIL

23. Can I get in and out? Access: FAIL

24. Does anyone care what happens here?

25. Territoriality: FAIL

26. Access: Can I get in and out?

27. Territoriality impacts Access If no one cares what happens here, is it less risky to try opening the door with a crowbar or bolt cutter?

28. Access barriers alone can be overcome Surveillance + Access + Territoriality (SAT) work together

29. ACCESS: Does the fence make it harder to get in and out?

30. SURVEILLANCE: Does the fence make it less likely I will be seen when attempting to break in through a back door?

31. Surveillance + Access + Territoriality may impact each other.

32. Does anyone care what happens here?

33. The fence says “Maybe”. Everything else says “No”

34. Does anyone care what happens here?

35. TERRITORIALITY: High level maintenance. Defined borders.

36. Short decorative fencing can enhance territoriality inside the fence without disconnecting from the surrounding neighborhood

37. Short decorative fencing can enhance territoriality inside the fence without disconnecting from the surrounding neighborhood

38. Short fencing, even if solid, creates no surveillance problems.

39. As fences get higher, the access barrier increases, but the risk of visually disconnecting from the neighborhood also grows

40. Does anyone care what happens here INSIDE the fence?

41. Does anyone care what happens here OUTSIDE the fence?

42. High fences may diminish territoriality outside the fence

43. High solid fences Indicates lack of territoriality outside of walls Reduces natural surveillance Can anyone see what happens outside the fence?

44. High solid fences Indicates lack of territoriality outside of walls Reduces natural surveillance Does anyone care what happens outside the fence?

45. High solid fences Indicates lack of territoriality outside of walls Reduces natural surveillance High solid fences may create spaces with little surveillance or territoriality

46. Some high fences control access, but fail the S.A.T. by Blocking surveillance Sending a clear message that the area is dangerous, crime is accepted, and no one cares what happens outside the wall

47. Making the chain link fence opaque blocks surveillance and permits graffiti showing a lack of external territoriality.

48. With proper design and maintenance, high fences can limit access without damaging surveillance or territoriality

49. A high fence blocking access without damaging surveillance or territoriality

50. Spikes can add a visceral element of access reduction that is still decorative and residential

51. Of course, you can go too far with anything!

52. Window bars limit access, but may also send a negative territoriality message about neighborhood safety.

53. Glass block can create security similar to window bars but without the stigma

54. Most burglary entries do not occur through the front door, often because of natural surveillance.

55. Open access to side or rear entry points where there is no natural surveillance make for more attractive burglary entrances.

56. Access barriers to side or rear entrance can reduce the risk

57. A very short barrier may provide insufficient access control

58. As barriers rise, access is reduced

59. Tall opaque barriers limit access, but may also eliminate natural surveillance

60. The line of sight for entry points is critical.

61. Am I visible to outsiders here?

62. Am I visible to outsiders here?

63. Am I visible to outsiders here?

64. Am I visible to outsiders here?

65. Consider the sight-lines in this aerial shot of a new group of duplexes

66. Front Entrance / Windows Side Windows Rear Entrance / Windows What are the sight lines for the potential entry points in this unit?

67. 10 residences have sight lines to the rear entry What are the sight lines for the potential entry points in this unit?

68. 16 residences have sight lines to the front entry What are the sight lines for the potential entry points in this unit?

69. 11 residences have sight lines to side window What are the sight lines for the potential entry points in this unit?

70. Rear Entrance / Windows Side Entrance/ Windows Front Entrance / Windows What are the sight lines for the potential entry points in this unit?

71. 2 residences have sight lines to rear entrance What are the sight lines for the potential entry points in this unit?

72. 0 residences have sight lines to side window What are the sight lines for the potential entry points in this unit?

73. Zone outside residence where sight lines are covered by wooded area with link to walking trail What are the sight lines for the potential entry points in this unit?

74. Which residence has better SAT scores?

75. What natural surveillance issue best predicted convenience store robberies? C. Casteel (UCLA) & C. Peek-Asa (UCLA). 2000. Effectiveness of crime prevention through environmental design (CPTED) in reducing robberies. American Journal of Preventative Medicine, 18, 99-115, p. 110

76. C. Casteel (UCLA) & C. Peek-Asa (UCLA). 2000. Effectiveness of crime prevention through environmental design (CPTED) in reducing robberies. American Journal of Preventative Medicine, 18, 99-115, p. 110 Visibility from outside the store to inside the store was the most important sight line

77. C. Casteel (UCLA) & C. Peek-Asa (UCLA). 2000. Effectiveness of crime prevention through environmental design (CPTED) in reducing robberies. American Journal of Preventative Medicine, 18, 99-115, p. 110 Visibility from outside the store to inside the store was a more significant predictor of convenience store robberies than the number of clerks or the proximity to drug traffic, gangs, or subsidized housing.

78. At night, surveillance depends on lighting.

79. Of course, surveillance can be blocked by both darkness and solid barriers.

80. line of site; access out Lighting alone may not overcome natural barriers to surveillance

81. Lighting can also be important during the day, especially where lines of sight are limited

82. Neighborhood watch signs may improve territoriality by indicating that people care what happens in the area

83. Of course, if no one really cares about the area, then there is no real community ownership or territoriality, and a sign may not have the desired effect!

84. Territoriality fails when it appears that no one is maintaining an area. No one is claiming ownership. In short, no one cares what happens there.

85. What signals do you get that territoriality appears weak here?

86. Closed stairwells have low natural surveillance and easy access for both entry and escape

87. Combined with territoriality deficiencies, stairwells can create CPTED problem areas.

88. Design solutions can improve the natural surveillance for stairwells

89. Open stairwells have strong natural surveillance properties

90. All ranges of natural surveillance levels are possible for stairwells depending upon the design solution chosen

91. “replacing bathroom entrance doors with right-angle entrances permit the warning sounds of crime to travel more freely and reduce the sense of isolation” Auditory Surveillance Sommer, R. (1983). Social design: Creating buildings with people in mind. Englewood Cliffs, NJ: Prentice-Hall

92. Cul-de-sacs may limit access, making visiting cars more noticeable

93. Cul-de-sacs make automobile escape more problematic as there is only one exit route

94. Street closures can provide similar access results

95. Pedestrian traffic can also be limited with street closures

96. High rise buildings provide weaker surveillance of street level activity because of structural separation, distance separation, and sound separation. This separation also limits the sense of territoriality over street level activities.

97. Mid rise balconies create stronger surveillance and territoriality, connecting residents with street level.

98. Mid-rise balcony neighborhoods create safer street level areas with high levels of perceived surveillance and perceived territoriality

99. Presentation by Russell James III, J.D., Ph.D., Asst. Professor, Dept. of Housing & Consumer Economics, University of Georgia. Dr. James’ research has been published in a variety of housing and design related academic journals including: Environment & Behavior; Housing Policy Debate; Journal of Urban Planning & Development (ASCE); Journal of Performance of Constructed Facilities (ASCE); Housing, Theory, and Society; Housing & Society; Journal of the Community Development Society Please feel free to use any of these slides for any non-commercial purposes. All pictures used in this presentation are creative commons licensed, have been purchased with rights to allow this usage, are from MS PowerPoint or are the author’s own photographs. Citations for all creative commons licensed photos are in the notes to each slide.