Creating Defensible Space 3°ÄD_¥sD_¥s BOOKMOBIÿÿÿþ = 6 *6 :6 J6 Z6 j6 z6 Š6 š6 ª6 º6 Ê6 Ú6 ê6 ú6 6 6 *6 :6 J6 Z6 j6 z6 Š6 š6 ª6 º6 Ê6 Ú6 ê6 ú6 6 6 *6 :6 J6 Z6 j6 z6 Š6 š6 ª6 º6 Ê6 Ú6 ê6 ú6 6 6 *6 :6 J6 Z6 j6 z6 Š6 š6 ª6 º6 Ê6 Ú6 ÍŸ < MOBI ýé% Á\
U.S. Department of Housing and Urban Development Office of Policy Development and Research Creating Defensible Space
Creating Defensible Space by Oscar Newman Institute for Community Design Analysis Contractor: Center for Urban Policy Research Rutgers University Contract No. DU100C000005967 U.S. Department of Housing and Urban Development Office of Policy Development and Research April 1996
The opinions expressed in this book are those of the author and do not necessarily reflect the views of the U.S. Department of Housing and Urban Development.
FOREWORD The appearance of Oscar Newman’s Defensible Space in 1972 signaled the establishment of a new criminological subdiscipline that has come to be called by many “Crime Prevention Through Envi ronmental Design” or CPTED. Over the years, Mr. Newman’s ideas have proven to have such signifi cant merit in helping the Nation’s citizens reclaim their urban neighborhoods that we at HUD’s Office of Policy Development and Research asked him to prepare a casebook to assist public and pri vate organizations with the implementation of Defensible Space theory. Information about this pro cess is presented for three distinct venues: in an older, small, private urban community; in an existing public housing community; and in the context of dispersing public housing throughout a small city. This monograph is very special because it draws directly from Mr. Newman’s experience as a con sulting architect. Indeed, we asked the author to share with us both his perspective on creating viable change and his personal observations on key lessons learned. By publishing Creating Defensible Space, PD&R is pleased to be part of the continuing growth and evolution of Defensible Space as both a criminological concept and a proven strategy for enhancing our Nation’s quality of urban life. Michael A. Stegman Assistant Secretary for Policy Development and Research iii
CONTENTS ■ ILLUSTRATIONS ..................................................................... ix ■ ACKNOWLEDGMENTS ............................................................ xiii ■ INTRODUCTION ..................................................................... 1 What this book is about and who it is for .......................................................................................... 4 Rationale for selecting the three case studies..................................................................................... 4 Case Study One: The Five Oaks community in Dayton, Ohio .......................................................... 5 Case Study Two: The Clason Point project, South Bronx, New York City ....................................... 5 Case Study Three: Dispersing public housing in Yonkers, New York ............................................... 6 Presentation format............................................................................................................................. 7 ■ Chapter I: Defensible Space Principles ........................................ 9 The concept ........................................................................................................................................ 9 Evolution of the concept..................................................................................................................... 9 The private streets of St. Louis......................................................................................................... 13 The effect of housing form on residents’ ability to control areas .................................................... 14 Summary of the effect of buil ding type on behavior ....................................................................... 17 The effect of building type on residents’ control of streets.............................................................. 18 Social factors and their interaction with the physical ...................................................................... 23 v
Creating Defensible Space The suitability of building types to lifestyle groups ........................................................................ 27 Factors influencing crime and instability......................................................................................... 28 ■ Chapter II: Mini-neighborhoods in Five Oaks, Dayton, Ohio ............... 31 Initiating the process ........................................................................................................................ 37 Initial presentations to city staff and the community....................................................................... 38 Community participation in designing mini-neighborhoods ........................................................... 43 Traffic studies ................................................................................................................................... 46 Description of the Five Oaks mini-neighborhood plan.................................................................... 46 The alley problem in Dayton............................................................................................................ 51 Allied measures for stabilizing the community ............................................................................... 51 Evaluation of the modifications ....................................................................................................... 55 Limits to the application of the mini-neighborhood concept........................................................... 59 ■ Chapter III: The Clason Point Experiment ..................................... 65 Redefinition of grounds ................................................................................................................... 69 Resurfacing of buildings .................................................................................................................. 71 Redevelopment of the central area ................................................................................................... 72 Effectiveness of the modifications ................................................................................................... 74 Learning from experience ................................................................................................................ 78 vi
Table of Contents ■ Chapter IV: Dispersed, Scattered-Site Public Housing in Yonkers ........ 81 Design principles.............................................................................................................................. 86 Problems in controlling the design process...................................................................................... 92 Selection of residents ....................................................................................................................... 97 Training of residents ........................................................................................................................ 97 Results .............................................................................................................................................. 99 Evaluation....................................................................................................................................... 101 ■ REFERENCES..................................................................... 109 ■ Addendum A: Defensible Space Guidelines Used in Yonkers RFP .......... 113 Background................................................................................................................... .................. 113 Definitions ..................................................................................................................................... 114 Selection of proposals .................................................................................................................... 115 Zoning ............................................................................................................................................ 115 Design criteria ................................................................................................................................ 115 Selection of proposals .................................................................................................................... 117 Proposal evaluation criteria .......................................................................................................... 118 ■ Addendum B: Tenant Training Course ........................................ 121 Tenant relocation ............................................................................................................................ 121 Home maintenance ......................................................................................................................... 121 vii
Creating Defensible Space Interpersonal relations ............................................................................................................... 122 Safety/security ........................................................................................................................... 122 Community resources ............................................................................................................... 123 viii
ILLUSTRATIONS ■ Chapter I: Defensible Space Principles Figure I–1: Overall view of Pruitt-Igoe in St. Louis...................................................................... 10 Figure I–2: The architect’s vision of how the 3d floor communal corridor in Pruitt-Igoe would be used ....................................................................................... 10 Figure I–3: The actual 3d floor communal corridor of Pruitt-Igoe ............................................... 11 Figure I–4: Vandalism in Pruitt-Igoe ............................................................................................. 11 Figure I–5: Pruitt-Igoe in the process of being torn down............................................................. 12 Figure I–6: Carr Square Village ..................................................................................................... 12 Figure I–7: Graph of increase in crime with building height ........................................................ 13 Figure I–8: Aerial view of typical closed streets in St. Louis ....................................................... 14 Figure I–9: Single-family houses and the nature of spaces ........................................................... 15 Figure I–10: Walkup buildings and the nature of spaces ................................................................. 16 Figure I–11: The elevator highrise and the nature of spaces ........................................................... 17 Figure I–12: A four-city-block row-house development.................................................................. 18 Figure I–13: A four-city-block garden apartment development ...................................................... 19 Figure I–14: A four-city-block highrise development...................................................................... 20 Figure I–15: A highrise and a walkup built at the same density ...................................................... 21 Figure I–16: Comparison of two walkups subdivided differently ................................................... 22 ix
Creating Defensible Space Figure I–17 : Crime rates by social and physical variables .............................................................. 23 Figure I–18: Variations in crime rate by socioeconomic groups ..................................................... 26 ■ Chapter II: Mini-neighborhoods in Five Oaks, Dayton, Ohio Figure II–1: Map locating Five Oaks and downtown Dayton ........................................................ 31 Figure II–2: Typical street in Five Oaks ......................................................................................... 32 Figure II–3: Deteriorated two-story walkup in Five Oaks ............................................................. 34 Figure II–4: Street in Five Oaks with various building types ........................................................ 34 Figure II–5: Map of Five Oaks’ internal streets and boundaries .................................................... 35 Figure II–6: Map of Five Oaks showing percent of renters ........................................................... 36 Figure II–7: Map of Five Oaks showing percent of African-American renters .................................. 36 Figure II–8: Map of Five Oaks showing percent of vacancies ....................................................... 37 Figure II–9: Greek cross plan for ideal mini-neighborhood .......................................................... 43 Figure II–10: Overly large cul-de-sac layout ................................................................................... 44 Figure II–11: Schematic showing ideal access to mini-neighborhoods........................................... 45 Figure II–12: Mini-neighborhood boundaries of Five Oaks ............................................................ 46 Figure II–13: Mini-neighborhood plan for Five Oaks showing location of gates and entries into mini-neighborhoods ........................................................... 47 Figure II–14: Hammerhead turn at end of street .............................................................................. 48 Figure II–15: Proposed portal markers for mini-neighborhoods ..................................................... 48 Figure II–16: Actual position of portals as installed ........................................................................ 49 Figure II–17: Proposed gates defining mini-neighborhoods............................................................ 49 x
Illustrations Figure II–18: Gates as actually installed .......................................................................................... 50 Figure II–19: Gates across the rear alleys ........................................................................................ 51 Figure II–20: Residents making improvements to their homes ....................................................... 54 Figure II–21: Renter and homeowner children playing together ..................................................... 56 ■ Chapter III: The Clason Point Experiment Figure III–1: Clason Point from street before modifications ......................................................... 66 Figure III–2: Interior grounds before modifications ...................................................................... 67 Figure III–3: Composite of fear maps produced by residents........................................................ 68 Figure III–4: Six-foot fencing defines collective rear yards .......................................................... 69 Figure III–5: Collective front yards defined by the new curbing................................................... 69 Figure III–6: Vandalized tiles and mailboxes in a highrise............................................................ 70 Figure III–7: Small play nodes ....................................................................................... ............... 70 Figure III–8: Wall of sample surfaces ............................................................................................ 71 Figure III–9: The central area before modifications ...................................................................... 72 Figure III–10: Plan for the conversion of the central area ............................................................... 73 Figure III–11: The central area as modified ..................................................................................... 73 Figure III–12: Revised plan of Clason Point.................................................................................... 74 Figure III–13: Internal walk at Clason Point before modifications ................................................. 75 Figure III–14: Internal walk after modifications .............................................................................. 75 Figure III–15: Before and after photographs of Clason Point ......................................................... 76 Figure III–16: Residents’ response to 6-foot fencing....................................................................... 77 xi
Creating Defensible Space Figure III–17: Play node for young children ................................................................................... 79 Figure III–18: Aerial view of a small portion of Clason Point ........................................................ 79 ■ Chapter IV: Dispersed, Scattered-Site Public Housing in Yonkers, NY Figure IV–1: Map showing concentration of public housing ........................................................ 81 Figure IV–2: The School Street project in Yonkers ....................................................................... 82 Figure IV–3: Map locating Yonkers relative to New York City ..................................................... 82 Figure IV–4: Aerial view of east Yonkers ...................................................................................... 83 Figure IV–5: The Schlobohm project in Yonkers ........................................................................... 83 Figure IV–6: The Mulford Gardens project in Yonkers ................................................................. 84 Figure IV–7: Typical site plan for a 12-unit site ............................................................................ 85 Figure IV–8: Typical site plan for a 24-unit site ............................................................................ 86 Figure IV–9: Typical site plan for a 48-unit site ............................................................................ 88 Figure IV–10: Sketch of a group of row-house units ....................................................................... 88 Figure IV–11: Fencing-off of the rear yards in Yonkers .................................................................. 89 Figure IV–12: Typical garbage dumpster serving public housing ................................................... 90 Figure IV–13: Individual garbage cans along the walks .................................................................. 90 Figure IV–14: Completed scattered-site units in Yonkers ................................................................ 92 Figure IV–15: Residents’ initial improvements to front yards ....................................................... 100 Figure IV–16: Residents’ later improvements to front yards ......................................................... 100 Figure IV–17: Residents’ later improvements to rear yards........................................................... 101 xii
ACKNOWLEDGMENTS Firstly, I wish to thank Henry Cisneros, the Secretary of Housing and Urban Development, for his personal support and encouragement in having me prepare thes e case studies. Early in his administration, he recognized the importance of our work to housing authorities and cities across the country and prepared his own essay entitled: Defensible Space, Reducing Crime and Creating Community. The publication has received wide acclaim and distribution. He followed this by having me conduct a series of seminars for U.S. Department of Housing and Urban Development (HUD) personnel and his key staff and Assistant Secretaries to explore how Defensible Space technology could be utilized in various HUD programs. Michael Stegman, HUD’s Assistant Secretary for Policy Development and Research, initially suggested the idea for the three case studies. He then had me meet with Margery Turner, Deputy Assistant Secretary for Research, Evaluation, and Monitoring and with Dr. Hal Holzman to define the scope of the work. Hal Holzman served as HUD’s Project Officer, but more importantly, as my mentor and muse during the entire writing effort, he encouraged me to record experiences and speak to issues I would have otherwise hesi tated addressing. In Dayton, Ray Reynolds, the city’s former director of urban develop ment (now planning director for the city of Hollywood, California) bore the full responsibility of seeing the Dayton project through from start to finish. I describe his role in my discussion of Five Oaks. Suffice it to say, the project would not have been realized without his efforts. Others who were germane to the success of the Five Oaks project were: Jaruth Durham-Jefferson, superintendent of police, who brought me to Dayton and helped me at every stage; and Patrick Donnelly, Karen DeMasi, and Bernice Ganble, all residents of the community and professionals in their own right, who served to coordinate community participation during the xiii
Creating Defensible Space planning of the project and provided insights that helped me define the plan and write the case study. In Yonkers, Pete Smith, the director of the Yonkers Municipal Housing Authority, was my second conscience through my entire 8 years of working there. His role was difficult; as a long-time Yonkers resident, he knew everyone and identified with their concerns and resistance, but as executive director of the housing authority, he also identified with public housing residents and their plight in segregated highrise projects. He knew that what we were planning would help all public housing resi dents and would not be the destabilizing force everyone in the commu nity feared. Chief of police Robert Olson (now in Minneapolis) was helpful in calming the community’s nerves during the process, provided a police presence when it was needed, and had his men bring the com munity and public housing teenagers together when tempers flared. Clason Point in the Bronx, New York, was our first effort in modifying public housing projects using the Defensible Space theory. Even though housing authority management was skeptical, two men took to the idea, opened doors, and provided insights and assistance that gave access to data and to sites for experimentation. They were Sam Granville, director of management, and Bernie Moses, director of maintenance, both now retired. Within our offices, Joanna King, who has served as our institute’s administrator and my trusted editor for 20 years, continued her critical work in helping me produce this book. Allen Christianson, architect, pre- pared the final illustrations from my sketches, as he has in my previous books. Oscar Newman Hensonville, New York April 1996 xiv
Defensible Space Principles C H A P T E R ONE ■ The concept All Defensible Space programs have a common purpose: They restruc ture the physical layout of communities to allow residents to control the areas around their homes. This includes the streets and grounds outside their buildings and the lobbies and corridors within them. The programs help people preserve those areas in which they can realize their com monly held values and lifestyles. Defensible Space relies on self-help rather than on government interven tion, and so it is not vulnerable to government’s withdrawal of support. It depends on resident involvement to reduce crime and remove the pres ence of criminals. It has the ability to bring people of different incomes and race together in a mutually beneficial union. For low-income people, Defensible Space can provide an introduction to the benefits of main- stream life and an opportunity to see how their own actions can better the world around them and lead to upward mobility. Over the past 25 years, our institute has been using Defensible Space technology to enable residents to take control of their neighborhoods, to reduce crime, and to stimulate private reinvestment. We have been able to do this while maintaining racial and economic integration. The pro cess has also produced inexpensive ways to create housing for the poor, often without government assistance. In this chapter, I will briefly explain the origins and principles of Defensible Space and introduce the reader to the results of our various research projects. ■ Evolution of the concept: Pruitt-Igoe and Carr Square Village The Defensible Space concept evolved about 30 years ago when, as a teacher at Washington University in St. Louis, I was able to witness the newly constructed 2,740-unit public housing highrise development, Pruitt-Igoe, go to ruin. The project was designed by one of the country’s 9
Creating Defensible Space most eminent architects and was hailed as the new enlight enment. It followed the plan ning principles of Le Corbusier and the Interna tional Congress of Modern Architects. Even though the density was not very high (50 units to the acre), residents were raised into the air in 11-story buildings. The idea was to keep the grounds and the first floor free for commu- Figure I–1: nity activity. “A river of trees” was to flow under the buildings. Each Overall view of Pruitt-Igoe, building was given communal corridors on every third floor to house a a 2,740-unit public housing project laundry, a communal room, and a garbage room that contained a garbage constructed in St. Louis in chute. the 1960s. Occupied by single-parent, welfare families, the design proved a disas ter. Because all the grounds were common and disassociated from the units, residents could not iden tify with them. The areas proved unsafe. The river of trees soon became a sewer of glass and garbage. The mail- boxes on the ground floor were vandalized. The corridors, lob bies, elevators, and stairs were dangerous places to walk. They became covered with graffiti and littered with garbage and human waste. The elevators, laundry, and community rooms were vandal- Figure I–2: The architect’s vision of ized, and garbage was stacked high around the choked garbage chutes. how the 3d floor communal Women had to get together in groups to take their children to school and go corridor in Pruitt-Igoe shopping. The project never achieved more than 60 percent occupancy. It would be used. 10
Chapter One: Defensible Space Principles was torn down about 10 years after its construction and be- came a precursor of what was to happen elsewhere in the country. Across the street from Pruitt- Igoe was an older, smaller, row- house complex, Carr Square Village, occupied by an identi cal population. It had remained fully occupied and trouble-free throughout the construction, occupancy, and decline of Pruitt-Igoe. With social vari- Figure I–3: ables constant in the two developments, what, I asked, was the signifi- The 3d floor communal cance of the physical differences that enabled one to survive while the corridor as it a ctually turned out, showing the other was destroyed? vandalism that ensued. Walking through Pruitt-Igoe in its heyday of pervasive crime and vandalism, one could only ask: What kind of people live here? Excluding the interior public areas of the development there were occasional pockets that were clean, safe, and well- tended. Where only two fami lies shared a landing, it was clean and well-maintained. If one could get oneself invited into an apartment, one found it neat and well maintained—modestly furnished perhaps, but with great Figure I–4: pride. Why such a difference between the interior of the apartment and Vandalism to the large number of vacant the public spaces outside? One could only conclude that residents main- apartments in Pruitt-Igoe tained and controlled those areas that were clearly defined as their own. as seen from the outside. Landings shared by only two families were well maintained, whereas corridors shared by 20 families, and lobbies, elevators, and stairs shared by 150 families were a disaster—they evoked no feelings of identity or control. Such anonymous public spaces made it impossible for even 11
Creating Defensible Space Figure I–5: neighboring residents to develop an accord about acceptable behavior in Pruitt-Igoe in the process these areas. It was impossible to feel or exert proprietary feelings, of being torn down, at a impossible to tell resident from intruder. loss of $300 million. Most of us have seen highrise apartments occu pied by middle-income people that function very well. Why then do they not work for low-income fami lies? Middle-income apart ment buildings have funds available for doormen, por ters, elevator operators, and resident superintendents to watch over and maintain the common public areas, but in highrise public housing, there are barely enough Figure I–6: Carr Square Village, a row-house development located across the street from Pruitt-Igoe. 12
Chapter One: Defensible Space Principles funds for 9-to-5 nonresident mainte nance men, let alone for security person nel, elevator operators, or porters. Not surprisingly, therefore, it is within these interior and exterior common public ar eas that most crime in public housing takes place. Given that funds for doormen, porters, and resident superintendents do not exist for public housing, the question emerged: Is it possible to design public housing without any interior public areas and to have all the grounds assigned to individual families? 12.7 10.0 16.2 14.514.512.0 Total 30.0 Total 41.0 Total 68.0 37.3 16.55.3 In interior public spaces On outside grounds Inside apartments Walkups (3 floors) Midrises (6–7 floors) Highrises (13–30 floors) Location of Crime in Walkups and Highrises ■ The private streets of St. Louis Also in St. Louis, I came upon a series of turn-of-the-century neighbor- hoods where homes are replicas of the small chateaux of France. They are the former palaces of St. Louis’ commercial barons—the rail, beef, and shipping kings. These chateaux are positioned on privately held streets, closed to through traffic. St. Louis in the mid-1960s was a city coming apart. The influx of people from the rural areas of the South had overwhelmed the city. It had one of the Nation’s highest crime rates, but the private streets appeared to be oblivious to the chaos and abandon ment taking place around them. They continued to function as peaceful, crime-free environments—nice places to rear children, if you could afford a castle. The residents owned and controlled their own streets, and although anyone was free to drive or walk them (they had no guard booths), one knew that one was intruding into a private world and that one’s actions were under constant observation. Why, I aske d, could not this model be used to stabilize the adjacent working and middle-class neighborhoods that were undergoing massive decline and abandonment? Was private ownership the key, or was the operating mechanism the closing-off of streets and the creation of controlled enclaves? Through research funded by the National Science Foundation (Newman, Dean, and Wayno, 1974) we were able to identify the essential ingredients of the pri vate streets and provide a model that could be replicated throughout the Figure I–7: Graph showing the relationship between the increase in crime and increased building height and that crime is mostly located within public areas. 13
Creating Defensible Space city. This was done in both African-American and white areas, and its implementation suc ceeded in stabilizing communities in transition. ■ The effect of housing form on residents’ ability to control areas Over the next few pages I will explain how dif ferent building types create spaces outside the dwelling unit that affect residents’ ability to control them. Firstly, I should explain what I mean by the dwelling unit: It is the interior of an apartment unit or home. That is the case whether the unit is one among many in a highrise building or sits by itself on the ground. I am interested in learning how the grouping of units in different types of building configura tions creates indoor and outdoor “nonunit” Figure I–8: spaces of different character. Aerial view of typical closed streets in St. Louis. For simplification, I have grouped all buildings into the three categories that capture the essential differences among them. These three categories are: single-family houses; walkups; and highrises. Single-family houses come in three basic types: detached houses; semi- detached houses; and row houses (row houses are also called townhouses). The fully detached building sits by itself, not touching any other build ing; the semidetached building has two single-family units sharing a common wall; and the row-house building has a few single-family units sharing common walls with other units, one on each side. Although all three types of single-family buildings look different, they share an essen tial common trait: Within the four walls of each type of building is the private domain of one family. There are no interior spaces that are public or that do not belong to a family. All the interior spaces, therefore, are private. Even the row house is subdivided into a series of distinctly pri vate spaces. There are no interior spaces within any single-family build ing—whether a row house, a semidetached building, or a fully detached 14
Chapter One: Defensible Space Principles house—that are shared by more than one family. The fundamental difference in the three types of single-family houses shown is the density at which they can be built— which is to say the number of units that can be put on an acre of land in each of these configurations. The upward limit of the detached house is about six units to the acre. The upward limit of the semidetached house is eight units to the acre, but this allows for a driveway to be put between each unit, something that could not be achieved in detached units • All interior spaces are within the private domain of the family. • All grounds around the private unit are for the private use of the family. • There is a direct abutment between private grounds and the sidewalk. • The domain of the house encompasses the street. at six to the acre. Row houses can be built at an upward limit of 16 units to the acre if one also wishes to pro- vide off-street parking on a one-to-one basis. When one looks at the grounds surrounding these three types of single- family units, one finds that all the grounds are private because they have been assigne d to each unit. Regardless of which type of single-family building we examine, each has been designed so that each unit has its own front and rear yard. The front yard of each unit also immediately abuts the street. If we attempt to categorize the grounds as either private, semiprivate, semipublic, or public, we would have to conclude that the rear yards are certainly private because they belong to individual fami lies and are only accessible from the interior of each unit. The front yards also belong to individual families, but because they are accessible from the street as well as from the interior of each unit their character is different. I have classed them as semiprivate because of this difference, but some people would say that they are really private. Looking at the next classification of building—the walkup—one finds that a radical new element has been introduced that totally changes the character of both the inside and outside of the building. We now have circulation areas within the building that are common because they are shared by a few families. The number of families sharing these common Figure I–9: Three types of single-family houses and the nature of spaces in and around them. 15
• Private space is within the apartment unit only. • The interior lobby, stairs, and corridor are semiprivate. • Grounds can be designated for one family but are usually shared by all the families in the building. • Only a small number of families (three to six) share the interior circulation areas and grounds. • The street is within the sphere of influence of the dwellings. Creating Defensible Space areas depends on how the entrances, corridors, and stairs are distributed within the building. In figure I–10, the walkup building is subdi vided so that six families share a common entry and interior circulation stair. Two families per floor share a common landing. Entrances from the common staircase usually exit to the outside Figure I–10: Walkup buildings and the nature of spaces in and around them. at both the front and rear. Such buildings are often called garden apartments. Walkups can be built at a density of 30 to 40 units per acre if they are 3 stories in height, and at a density of 20 to 30 units to the acre if they are only 2 stories in height. Three-story walkups were commonly built in the 1950s and 1960s, but as these are nonelevator buildings, the 3- story walkup has fallen out of favor with the decline in housing demand. Because the grounds surrounding 3-story walkups, front and back, belong to all the families living in the building, they cannot be consid ered private. The grounds in the front of the unit are also adjacent to a public street. For this reason I would categorize the grounds in front as semipublic space. The grounds at the rear of the unit are also not as- signed to individual families and the rear of the units are often used for parking. In such a case, the grounds at the back would also have to be considered semipublic. It is, however, possible to modify the design of the rear grounds to make some of the areas private and the remainder semiprivate, and I will demonstrate how to do that shortly. We come now to the last of our three building types: the highrise. These are elevator buildings and commonly come in two sizes, depending on the type of elevator used. The least expensive elevator is the hydraulic, but it has an upward limit of six stories. The electric elevator can comfortably 16
Chapter One: Defensible Space Principles go up to 30 stories, but it is usually used in 10- to 16-story apartment buildings. The 15-story building at the right has 195 families sharing common inte rior areas. Because of the large num ber of people sharing them, these interior areas can only be designated as semipublic or even public. Even the corridors on each floor ar e shared by 13 families and are acces sible from 2 sets of stairs and 2 elevators that are very public. For this reason I would have to designate • Private space exists only within the apartment units. • The interior circulation areas and the grounds are public. • There is no association between buildings and street. these corridors as semipublic, if not public. The outside grounds, because of their disassociation from any of the individual units, and the fact that they are shared by 195 families, can only be designated as public. ■ Summary of the effect of building type on behavior A family’s claim to a territory diminishes proportionally as the number of families who share that claim increases. The larger the number of people who share a territory, the less each individual feels rights to it. Therefore, with only a few families sharing an area, whether it be the interior circulation areas of a building or the grounds outside, it is relatively easy for an informal understanding to be reached among the families as to what constitutes acceptable usage. When the numbers increase, the opportunity for reaching such an implicit understanding diminishes to the point that no usage other than walking through the area is really possible, but any use is permissible. The larger the number of people who share a communal space, the more difficult it is for people to identify it as theirs or to feel they have a right to control or determine the activity taking place within it. It is easier for outsiders to gain access to and linger in the interior areas of a building Figure I–11: The elevator highrise and the nature of space in and around it. 17
Creating Defensible Space shared by 24 to 100 families than it is in a building shared by 6 to 12 families. ■ The effect of building type on residents’ control of streets If we examine the three building types from the viewpoint of residents’ ability to exert control over surrounding streets, we again find marked differences. Figures I–12, I–13, and I–14 graphically summarize the major differences between residents’ ability to control the areas around their homes and public streets. The three illustrations show the same four-block area of a city, each developed using a different building type. Figure I–12: A four-city-block row-house development. Only the central portion of the roadbed can be considered fully public. Figure I–12 is an illustration of a row- house development built at a density of 18 units to the acre. Each city block has been subdivided so that all the grounds, except for the streets and sidewalks, are assigned to individual families. The front lawns, because each belongs to an individual family, are desig nated semiprivate. The rear yards, which are fully enclosed, are private. In fact they are only accessible from the interior of the dwelling units. The close juxtaposition of each dwelling unit and its entry to the street contributes to the incorporation of the sidewalk into the sphere of influ ence of the inhabitants of the dwelling. This is further reinforced by the fact that their semiprivate lawn abuts the sidewalk, and the family car is parked at the curb. Residents’ attitudes suggest that they consider this sidewalk and parking area as semipublic, rather than public. Examining the entire four-block area, we find an urban fabric in which most of the outdoor areas and all of the indoor areas are private. In addi tion, a good portion of what is a legally public street is viewed by resi dents as an extension of their dwellings and under their sphere of 18
Chapter One: Defensible Space Principles influence: that is, the sidewalk and that portion of the roadbed on which their cars are parked. Because of the close jux taposition of the street to the private front lawn of each dwellin g, residents are con cerned about ensuring its safety and act to maintain and control it. In actual fact, only the very central portion of each street is truly public in nature. If the street were narrow, even the activity in this central portion would be considered accountable to neighboring residents. Figure I–13 shows the same four-block area, this time accommodating 3-story garden apartments built at a density of 36 units to the acre. The rear courts within the interior of each cluster have been as- signed both to individual families and to all the families sharing the cluster. The families living on the ground floor have been given their own patios within the interior courts, with access to them from the interior of their unit. These patios are therefore private. The remainder of the interior court belongs to all the families sharing a clus ter and is only accessible from the semiprivate interior circulation space of each building, making the remainder of the interior cluster semiprivate. The small front lawn adjacent to each building entry is the collective area for that entry’s inhabitants and is therefore semiprivate. As in the row-house scheme in figure I–12, all the entries face the street, but each entry now serves six families rather than one and is thus semiprivate rather than private. Parking again is on the street immediately in front of each dwelling. Because of the semiprivate nature of the grounds, the side- walk and street are not clear extensions of the realms of individual dwelling units. But even with all these limitations, the neighboring sidewalk and parking zone on the street are considered by many residents as areas over which they exert some control. Figure I–13: A four-city-block garden apartment development. The streets and grounds are encompassed within the domain of the multifamily dwellings. 19
Creating Defensible Space Figure I–14 is the same four-block area shown in figures I–12 and I–13, but now developed as a highrise superblock at a density of 50 dwelling units to the acre. Each building entry serves 50 families by means of an interior circulation system consisting of a public lobby, elevators, fire stairs, and corridors. The grounds around the buildings are accessible to everyone and are not assigned to particu lar buildings. The residents, as a result, feel little association with or responsibility for the grounds and even less association with the surrounding public streets. Not only are the streets distant from the units, but no building entries face them. The grounds of the development that abut the sidewalks are also public, and, as a Figure I–14: A four-city-block highrise development. All the streets and grounds are public. consequence, so are the sidewalks and streets. This design succeeds in making public the entire ground surface of the four-block area. All the grounds of the project must be maintained by management and patrolled by a hired security force. The city streets and sidewalks, in turn, must be maintained by the city sanitation department and patrolled by city police. The placement of the highrise towers on the interior grounds has pro duced a system of off-street parking and access paths to the building that involves many turns and blind corners. Residents in such developments complain about the dangers of walking into the grounds to get to their buildings at night. The proclivity of landscape designers for positioning shrubs exactly at turns in the paths increases the hazards of these access routes. This problem does not arise in traditional row-house or walkup developments where building entries face the street and are set back from the sidewalk no more than 10 to 20 feet. Nor do these fears occur in highrise buildings whose entries face the streets and are only set back slightly from them. In these latter cases, residents are abl e to move in a 20
Chapter One: Defensible Space Principles straight line from the relative safety of the public street to what they can observe to be the relative safety of the well lighted lobby area in the interior of their buildings. Figure I–15 shows two housing projects located across the street from one another: a garden apartment complex on the right and a highrise on the left. Both projects are designed at the same density and with similar parking provisions (40 units to the acre and 1 parking space per unit). The highrise project has all building entries facing the interior grounds of the development. Parking has been designed as a continuous strip along the street, further disassociating the buildings from the street. The project on the right is only three stories in height and has all the buildings and their entries juxtaposed with the city streets or the interior streets and parking. Each entry faces the street and serves only 6 families, whereas the highrises have 60 families sharing a common entry. Small play and sitting areas have been provided near the entry to each walkup. This Figure I–15: A highrise and a walkup built at the same density. The project on the left is turned in on itself, away from the public street, while the one on the right brings the streets within the control of the residents. 21
Creating Defensible Space serves to extend into the street the sphere of influence of each of the six families. The residents in the walkup are a very short distance from the sur rounding streets, and because of the positioning of the building entries, play areas, and parking, the neigh- boring streets are brought within the sphere of influence of inhabitants. Another important lesson to learn from this comparison is that 2 radi cally different building configura- Figure I–16: Comparison of two ways to subdivide the same building envelope to serve the same number of families, but in radically different ways. tions can be produced at the same density: in this case a density of 40 units to the acre with 1-to-1 parking. This is a very high density that will satisfy the economic demands of high land costs. The walkup develop ment achieves the same density as the highrise by covering more of the grounds (37 percent ground coverage versus 24 percent). Municipalities that wish to reap the benefits of walkup versus highrise buildings must learn to be flexible with their floor-area-ratio requirements to assure that they are not depriving residents of a better housing option in order to get more open ground space that has little purpose. What is true for site design is also true for building design: The same build ing envelope can be subdivided in different ways to produce dramatically different results. For instance, figure I–16 shows two ways of configuring a three-story walkup. Both buildings serve a total of 24 families each. In the upper layout, all 24 families share 2 common entrances and 8 families share a common corridor on each floor, although access to the corridors on each floor is open to all 24 families in the building. In the lower design, only 6 families share a common entry, and only 2 families share a common landing on each floor. In the lower design, the smaller number of families sharing an entry and landing allows the families to control the public spaces better: They can more readily recognize residents from strangers and feel they have a say 22
Chapter One: Defensible Space Principles in determining accepted behavior. If this were a two-story building rather than a three-story building, it would have been possible, in the lower design, to give each family its own individual entry directly off the street and thus avoid having any interior public spaces at all. ■ Social factors and their interaction with the physical An understanding of the interac&sh