Design for Communities PDF

CHAPTER 4 Design for Communities D esign and planning is the process of bringing a vision to the point of implementation. The professional considers a broad range of concerns in the synthesis of a design concept: the physical aspects of the site itself, the vision or program of the client, the d...

CHAPTER 4 Design for Communities D esign and planning is the process of bringing a vision to the point of implementation. The professional considers a broad range of concerns in the synthesis of a design concept: the physical aspects of the site itself, the vision or program of the client, the designer’s own creative inclination, the concerns of the community, and the interests of the end-user. The public’s interests are represented by a variety of public authorities who regulate and oversee the development process. Land development ordinances act as a set of minimum standards or guidelines, and few can be applied to a specific site or project without some adjustment or accommodation. These standards represent a local view of the minimum requirements for land development and should not be confused with a measurement of design quality. Quality design and development typically need to go beyond the minimum threshold of the ordinance. Site design professionals must balance the client’s objectives with the community’s standards and expectations, which are composed of stated, tangible parameters as well as unstated expectations and intangible elements. In addition, the interests of the enduser of the project must be kept in mind. The end-user usually is not included in the discussions that drive the design process. To arrive at a design solution that will satisfy a client, the various regulatory agencies, and still satisfy a future user, the designer must be a student of design outcomes and performance as well as design synthesis. Site Layout The most obvious feature of the site is how the proposed project lays upon the land, that is, how the buildings and facilities are organized. The site design is determined first by the land itself and then, in varying degrees, by the values of the developer, the requirements of local ordinances, community standards, and the nature of the project as these elements are perceived and balanced by the designer. The parameters that go into a site layout are diverse, but some important design practices and standards can guide the professional. The designer’s analysis and sensitivity to the site informs the entire design process. An awareness of the site might include its history, its place in a larger landscape ecosystem, its real estate value, and its local political or economic importance. Redevelopment may be the preferred environmental strategy because it involves the reuse of already disturbed land; in a sense, this option is recycling the site. Redevelopment projects should attempt to restore function wherever possible. Honoring particularly important historical aspects of a site should be considered when appropriate. Defining the role of the site in the larger landscape fabric is critical. In developing a new site, the environmental functions of the site should be preserved, and the design should minimize the impact of development. 73 74 Chapter Four FIGURE 4.1 This storefront conforms to the standards of the community. Recognition of the impacts of urban sprawl and an increasing awareness of smart growth alternatives are beginning to have an impact on site development practices. There is no simple, one-size-fits-all solution to the problems of urban sprawl or the challenges of smart growth, but the range of solutions available to designers will continue to grow with the sophistication and needs of the marketplace. Much has been said and written about the homogeneity of the modern built landscape: every place looks pretty much like every other place. However, many communities have established an identity, if not clear standards. In these communities even the mundane is made to meet community expectations. Note how a common business has adapted to local standards in Fig. 4.1. Residential Site Design The primary objective in residential and community site planning is to provide a desirable place to live for the intended users. Different parameters will be applied and different elements will be selected depending on who the end-user is to be. Developments targeted toward young families with children, for example, include features that would be out of place in a project designed for empty-nesters. House size, lot size, common space, and recreation facilities will be quite different, but some commonalities are found in all quality residential developments. In Save Our Lands, Save Our Towns, Thomas Hylton (1995) describes 10 rules of quality development for communities (Table 4.1). In essence Hylton and others have found Design for Communities 1. A sense of place 2. Human scale 3. Self-contained neighborhoods 4. Diversity 5. Transit-friendly design 6. Trees 7. Alleys and parking lots to the rear 8. Humane architecture 9. Outdoor rooms 10. Maintenance and safety Adapted from Hylton (1995). TABLE 4.1 Characteristics of a Quality Community that quality involves careful adaptation of traditional, even archetypal, forms of community design with important accommodations for modern life. The most desirable communities allow maximum pedestrian access to schools, work, shops, and the like but also provide easy transit in and out of the neighborhood. The presence of human scale streets and buildings, the softening and tempering effects of trees, and the diversity of social and architectural aspects are commonly considered to be important aspects of a community. Although security and safety are often cited as important, achieving these through hardening of buildings and sites is not desirable. Suburb and exurb neighborhoods often have little connection except through arterials, which may have provision for pedestrian movement or bicycle traffic. This isolation of neighborhoods can work against development of a sense community. This isolation reflects a process in which discrete parcels of land are developed without regard for adjacent parcels subject to future development or even existing development in many cases. Such an arrangement necessarily increases vehicle use and reduces “walkability”; traffic on arterial roads increases, contributing to local congestion and the attendant issues of longer commutes and reduced air quality. Local streets should be designed with a coherent pattern of circulation, and the project layout should be sensitive to the land and not require substantial alteration and a loss of character. Houses or residential units should be arranged to provide variation and visual interest. After the style and affordability of houses, lot layout and character is the most important element of the typical residential development project. The number of lots is of critical concern to the developer, and lot size and character are important to buyers. In a competitive residential market, developers may compete on the basis of price, quality, or the character of their units or amenities. Valuable lot amenities include the presence of trees, lot shape and size, views, and access to water (Table 4.2). It is important to begin to identify home sites early in the site analysis. Generally this is done using topographic mapping of the site and walking the entire site to identify valuable locations or site features. Identification of home sites and related issues 75 76 Chapter Four Open space feature Mean score Adjacent to wet pond 4.44 Adjacent to natural area 4.27 On a cul-de-sac 3.83 Adjacent to golf course 3.67 Adjacent to public park 3.10 Adjacent to dry pond 2.05 TABLE 4.2 Homeowner Preference for Proximity to Open Space Features will drive the planning and design of the site. Home sites are identified by determining where it would be nice to live; it is fundamentally a simple process. A good location is a combination of the surroundings, access, amenities, and more subjective concerns such as desire for a sense of neighborhood or security. In the development of sites for more affordable homes, lot size tends to be smaller and the linear feet of road per unit lower. Hillside lots tend to be irregular in shape, reflecting the physical aspects of the site. The lot configurations are designed to encompass a desirable living space in a more difficult development condition. Lot configurations may range from tight clusters that leave large undeveloped portions of the site as open space to individual lots with dwelling units separated by varying degrees of distance. In either case the sites and layout are designed to minimize impact and maximize site value. The layout of a residential development is part of an overall community design. Communities are more than a collection of houses; they include recreation facilities, schools, shopping centers, workplaces, and religious institutions. Not all projects include all of these features, but it is appropriate for designers and developers to consider how the proposed project will relate to existing or future features. The next section highlights one successful regional approach to community planning and development. Emerging Practices The Connecticut River Valley has been inhabited for thousands of years, and its rich, fertile soils and climate and river aspect have attracted people to the valley. From 1951 to 1972, the land in the Connecticut River Valley converted from farmland to development tripled, and projections indicated that this trend would continue. However, existing ordinances and planning regulations did not provide the protection residents felt they needed. The river valley area comprises 19 towns in three counties. No coordinated effort existed to direct development or the construction of infrastructure on which future development would be attracted. In addition, the features and attributes considered the most desirable (rural character, views, access to open space, and river front) were the first features to be compromised. In the 1980s the Massachusetts Department of Environmental Design for Communities Management (DEM) established the Connecticut River Valley Action Program to develop a regional approach to planning and conservation that would preserve the scenic, historic, and environmental qualities of the area and still allow for development. Among the tools developed by DEM was the Agricultural Preservation Restriction (APR) program, which encouraged rural landowners to sell their development rights to the state. In cooperation with other state agencies, the DEM increased support for agricultural activities by providing training in integrated pest management and intensive farming practices to make the agricultural use of the land more effective, more profitable, and more sustainable. The action program has been most widely recognized, however, for publication of Dealing with Change in the Connecticut River Valley: A Design Manual for Conservation and Development (Yaro et al., 1988), which describes plausible and effective rural design parameters and policies that have very broad application. The Center for Rural Massachusetts, under a grant from the DEM, developed the manual from a concern that the only way to avoid a hodge-podge of low-density suburban development and “islands” of preservation was to develop a comprehensive approach to development and preservation. Complete faith in land preservation efforts will ultimately be unsatisfactory due to the limits of preservation resources. Reliance on unregulated market forces was surely not an acceptable alternative. From the outset the center recognized that the development and design process would have to encompass both concerns in a practical fashion. Design guidelines based on preserving the character of the region and those elements most prized by its residents also provided for viable residential and commercial development. Much of this process involves turning classic planning tools upside down. For example, it is common for zoning to require a commercial shopping center to be set back 100 or even 200 ft from a public right of way. This arrangement forces the shopping center into the familiar “strip” with a sea of parking and macadam in front of it. The center’s recommendations were to require a maximum setback of 25 ft from the public right of way, locating all of the parking behind or alongside the building. It also encourages people to walk from store to store and brings the stores into a more “human” scale, akin to the old downtown area. This arrangement is more in keeping with the character of the existing towns and streetscapes of the valley. Merchants accepted the new design because it gave them two places to advertise (front and back entrances). Landscape requirements for commercial development eliminated the classic “juniper and bark mulch” plantings in favor of native plants and wildflowers. Residential development is encouraged through density bonuses to form clusters and preserve open space. The developer can use the density bonus to purchase development rights sold to the state by local farmers. As a result, a developer of a residential project might be able to build 15 houses in a cluster on 12 acres of ground rather than being restricted to 10 or 11 units. The density bonus encourages the builder to “cluster” the 15 houses on a small portion of the site, leaving the rest of the site in open space. Although these ideas were not new or unique, the Connecticut River Valley program was able to develop broad support among residents and landowners. Public meetings were held and ideas from the design manual were discussed. The manual identifies eight different landscape types and illustrates possible development scenarios ranging from development under traditional zoning to development under these rural landscape planning guidelines. Sample ordinances for the municipalities to consider and adopt are also included. The successful effort by DEM has been linked to several factors: (a) the public had a vested interest in preserving the character of the area in which they lived and owned 77 78 Chapter Four land; (b) the Center for Rural Massachusetts dealt with the municipalities and the residents in developing design guidelines that represented the values and objectives of the residents; (c) the plan was practical, encouraging development consistent with the guidelines and stating performance requirements in a straightforward manner; and (d) the information was communicated in a readable, friendly style, using graphics and photos, easily understood by any interested person rather than the “legalese” and “technobabble” used in most documents of this type. The guidelines suggested by the center have been adopted by most of the municipal governments in the Connecticut River Valley, and the region has become a model of effective rural planning. Lot Layout Alternatives The rapid expansion of suburbs and edge cities has had several impacts. The cost of housing has continued to rise in real terms over the last 30 years, and affordability has become a major issue in some communities. Rapid development also has been criticized for consuming agricultural land, reducing environmental quality, and abandoning urban centers to poverty and other social ills. These complaints generally are grouped under the umbrella of urban sprawl. Most of these issues require a shift in public policy and political will that is outside the scope of the site design professionals’ immediate influence, but development practices have grown to embrace concerns of environmental quality, density, and affordability. As developers respond to the growth and resettlement patterns of the population, concern over the environment and interest in sustainable development and quality communities will continue to grow. The key to a successful residential design, regardless of the cost of the housing, lies in how effectively the design creates a sense of place and relates to the end-user. Some sites have natural features that may be worked into the design. Other projects must rely on the combination of housing type and landscape architecture to create a feeling on the site that attracts and holds residents. The familiar grid layout of post–World War II residential development is no longer the preferred approach in most communities. Contemporary site layouts rely on more curvilinear street designs and a greater mix of building styles and types than are found in those early suburban projects. The focus of contemporary residential site design is on balancing the number of dwelling units and the development costs with the interests of the community and the environment. This has been described as a quality-of-life approach. Numerous projects have demonstrated that quality development can be affordable and efficient. When all costs are considered, large lot developments consume more resources than they contribute to a community. The trend in development is toward higher densities generally consistent with the goals of the various smart growth initiatives around the United States. Varied densities and housing types have replaced the familiar uniform density and housing types of the past in some communities. Work done by the National Association of Home Builders (1986), Randall Arendt (1991), Andres Duany, and others have all found that smaller lots and cluster type developments have equal or greater initial and resale value than traditional residential development. Small lot development usually refers to projects with 6 to 12 units per acre. Resistance to higher densities is common in communities with the more traditional density of 1 to 4 units per acre, but many buyers find the higher densities attractive as long as amenities and privacy are sufficient. The primary target market includes young professionals, couples without children, and empty-nesters, but there are successful small lot communities for every demographic target. Small lot development Design for Communities tends to work best on relatively flat sites. Small clusters are an ideal way of reaching a gross density while preserving important open space features of a site. Site layout is critical to project success and should be focused on lifestyle amenities, emphasizing outdoor living and privacy. Small lot development, especially lots with unusual configurations, work best in more sophisticated real estate markets (Kreager, 1992). A recent survey of consumer preferences found that more than half of those who said they expected to build a new home in the next 10 years cited “green” features such as energy efficiency and sustainable materials as very important considerations. This number rose to more the two-thirds among those under 30 years of age (NAHB, 2008). Grid Layout The grid layout shown in Fig. 4.2 is an efficient way to subdivide property, but it can be monotonous, especially for residential areas. The key advantage of the grid layout is maximizing lots per linear feet of street. The relative ease in finding one’s way provides a certain level of comfort for many people, but the straight streets often invite higher vehicle speeds, especially when wide cartways are used. Curvilinear streets are far more interesting visually and may help to manage vehicle speeds, but they are somewhat less efficient with regard to lot count. In addition, finding your way through some of these communities can be confusing. This may be of concern in particular in communities designed for older residents. Alternatives to the traditional grid layout are shown in Figs. 4.3 and 4.4. A variety of lot configurations have evolved with higher densities to accommodate the smaller lot size and traditional or familiar housing types. Four configuration types are common. Some projects use a combination of strategies; others design around a single lot and housing type. Deep, Narrow Lots The deep, narrow lot configuration allows for a familiar lot and house pattern with the garage and front of the house facing the street (Fig. 4.5). Lots typically range from 3000 to 4800 ft2, about 6 to 8.5 lots per acre. The typical 40-ft wide lot allows for about FIGURE 4.2 Grid layout. 79 80 Chapter Four FIGURE 4.3 Alternative grid layout. 10 ft of side yard, which leaves 20 ft for garage and 25 ft for house. Garages are close to the front of the lot, often in front of the house facade to maximize the amount of yard space behind the house. This tends to create an unattractive street view of all garage doors. The deep, narrow lot provides minimal backyard privacy, especially in housing with two or more floors. This may be offset by paying special attention to the location of windows in adjacent units and to visual landscape barriers, but it is difficult to anticipate the location of windows and site lines in projects in which different housing models are possible. Wide, Shallow Lots The wide, shallow configuration allows for a standard-width house and garage and has the feel of a traditional neighborhood (Fig. 4.6). The wide, shallow lot gives a feeling of a larger lot with more space between units because its longest dimensions are along the Design for Communities FIGURE 4.4 Alternative grid layout. FIGURE 4.5 Deep, narrow lots. 81 82 Chapter Four FIGURE 4.6 Wide, shallow lots. street frontage. These lots generally yield about 6 to 7 units per acre with lot sizes from 3500 ft2. In general, these lots are not as desirable as the deep, narrow lot because of the increased lot costs and lack of useful yard space. Development costs may be higher as well because there are fewer units per linear foot of road and utilities. An increase in lot width of 20 ft will result in almost a 50 percent increase in utility costs per unit over the deep, narrow plan. The backyard of the wide, shallow lot offers little privacy, especially if two-story homes are constructed. Privacy can be increased with the use of fencing and landscaping. Alley Houses Another small lot layout alternative is a return to the use of alleys behind the houses, a common configuration in the past (Fig. 4.7). Garages were located in the back of properties and access was over a common alley usually 16 to 18 ft wide. The alley design allows for lots of 3300 to 4500 ft2, yielding 4 to 8 units per acre. Many older, desirable neighborhoods using this configuration still exist in cities throughout the United States. By locating the garage in the rear, the streetscape is all house fronts: no driveways and no garage doors. The paved alley increases development costs somewhat, but many traditional neighborhoods using the alley layout have narrower streets and lots that offset the additional cost of the alley. Some municipalities resist the alley arrangement because of increased maintenance; in other cities the alleys are not public rights of way but are held in common by the neighbors through an access easement and maintenance covenant. Projects with alleys provide ideal utility corridors. Z-Lots The term Z-lot refers to a zero lot line layout in which the house is placed on or very near to one property line (Fig. 4.8). In some configurations the lot lines may jog around Design for Communities Alley FIGURE 4.7 Alley houses. FIGURE 4.8 Z-lot configuration. the building to create a more interesting space. Such lots are said to resemble a “z,” hence its name. The z-lot is often slanted relative to the street to increase the appearance of lot width. Houses are designed to increase light and maximize privacy by strategically locating windows and entranceways. Some z-lot developments provide special maintenance easements or even condominium-type arrangements to provide access to buildings for maintenance. Easements along lot lines may be difficult for z-lot configurations. Connectivity In traditional urban and early suburban development, neighborhoods were commonly assembled on a pattern determined by preexisting conditions (earlier development, topographic features) and by the local planning authority. As development occurred, it extended the existing pattern of streets and related infrastructure. In 83 84 Chapter Four recent years residential development has become more cellular in nature, with individual developments commonly located along a road that acts as an arterial collector. This collector is often arterial in function but not design. Isolated groups of homes connected only by arterial roads, often without allowances for pedestrian, bicycle, or other alternative transportation, work against the evolution of neighborhoods and limit access to community amenities to those in automobiles. Site designers should look for and evaluate ways of connecting to existing neighborhoods and street systems, although resistance to this sort of connectivity has occurred on occasion. The most common concern seems to be that connecting neighborhoods will increase “cut through” traffic. This should be addressed by the use of traffic calming devices and street design to manage vehicle speeds to increase safety, a sense of neighborhood, and reduce the value of connected streets as cut through paths. Cluster Designs Cluster designs allow the same number of units on a tract but group the units into clusters of greater density, thereby preserving more open space (Fig. 4.9). A density bonus is sometimes provided to recognize and encourage the preservation of open space. Cluster development can reduce the visual impact of new development on a community as FIGURE 4.9 This clustered residential development illustrates some of the opportunities for conserving open space. Design for Communities Allows same number of units in smaller space for more open space Reduces visual impact on existing community Allows for open space buffers between incompatible uses Preserves important natural functions of landscape Contributes to “rural” character of area Is sensitive to the character of the site Establishes a benchmark for future projects TABLE 4.3 Cluster Design Attributes well as reduce the environmental effects. Table 4.3 lists some attributes of cluster designs. This configuration allows developers to utilize the land yet preserves valuable natural areas, agricultural land, riparian zones, and so forth. Cluster developments are usually welcomed because they minimize the impact of the development and are sensitive to the rural character, the nature of the site, and the values of the community. Effective and successful cluster developments may also serve to establish a quality threshold for other future projects. Cluster designs have become more common in recent years (Fig. 4.10). Allowances for Easements and Rights of Way Allowances for easements and rights of way in higher-density developments may require more planning and thought than for less dense projects. With smaller front and side yards, easements may take a significant portion of the street side of individual lots. Utility easements may restrict planting large trees or building fences. Some utilities prefer that easements be located outside of the cartway to reduce the cost of maintenance and repair. In 1 37 2 36 3 35 4 34 33 5 32 6 29 31 7 28 30 26 24 14 21 22 19 18 FIGURE 4.10 Examples of possible cluster design layouts. 11 12 15 16 20 23 10 9 8 27 25 17 13 85 86 Chapter Four other cases the proximity of one utility to another may require extraordinary construction methods and increase development costs. Easements along the back of the property are possible for some utilities, but access is required, which may affect the use and enjoyment of the lot. Many small lot projects are designed to allow utilities to be installed within the public right of way of the street, usually between the curb and sidewalk. Still other projects provide a utility corridor easement across front lawns and restrict the amount and type of landscaping that can be used. Affordable Housing Design The cost of new development is a concern for many communities. Zoning and land development ordinances are prescriptions for development. Development costs are a function of many factors but among them are the local development standards. Planners and designers know that local development standards can be very prescriptive and can raise the development costs of a project. In turn, these costs are built into the sales price of homes, pricing key people in the community out of the market. Many communities have found that developments produced using their local standards are not consistent with the character of the community and contribute to unwelcome sprawl. Homes in many older communities continue to command high market prices. Many features that contribute to the continuing attraction and market value of these older homes would not be allowed under current ordinances and practices. Many of the standards for community development today were refined after the Second World War. Street width, lot size, setbacks, and many other aspects of postwar community development were modeled on the grid street pattern and lot layout. Developments with wider streets and larger lots reached their peak in the 1980s, and their popularity has been sustained to this day. The growing awareness of environmental impacts, increased energy costs, cost of the initial development, and life-cycle costs of unnecessary pavement and oversized lots has encouraged a shift toward more affordable and lower impact design without sacrificing public safety or function. Affordable housing remains a concern of many communities. Affordability can be improved dramatically by specific changes in development standards and local practices such as those listed in Table 4.4. Table 4.5 lists some elements of better residential site design. Urban Infill Planning and site design is generally focused on new development. With the growing concentration of people living in and moving to cities, it is appropriate that the concern of designers include the sustainable redevelopment of existing neighborhoods. There is a robust but quiet effort in cities to restore, revitalize, and preserve urban neighborhoods everywhere. The deconstruction activities mentioned in Chap. 2 are part of that. Some cities have experienced suburban flight, often leaving urban areas with infrastructure designed for much larger populations than they currently support. Some trends, such as the portion of baby boomers retiring without adequate savings, expected increases in immigration, the cost of suburban housing, and the attraction of urban areas to young professionals and students, suggest renewed interest in an urban lifestyle. Demolition of vacant or poorly maintained buildings offers opportunities for redevelopment. Attracting retail into cities can be a mixed blessing, but supermarkets and similar stores are commonly seen as desirable and do not always compete directly with Design for Communities Standard Single family detached Single family attached or townhouse Lot size 4500–5000 ft2 3500–5000 ft2 Lot width (minimum) No minimum to 50 ft No minimum to 16 ft Lot coverage (maximum) 40–50% 50–75% Setbacks, front 10–20 ft 5–20 ft Back 5–15 ft 5–10 ft Side each/total 5/10 ft 0/5 ft Right of way width 35–40 ft 30–50 ft Cartway width* 18–28 ft 22–32 ft *9ft minimum travel lane on low volume local street, 8ft for each parking lane. Adapted from Welford Sanders, Judith Getzels, David Mosena, and JoAnn Butler, Affordable Single Family Housing, Planning Advisory Service Report No. 385 (Washington D.C., American Planning Association, 1984); Welford Sanders and David Mosena, Changing Development Standards for Affordable Housing, Planning Advisory Report No. 371 (Washington D.C., The Joint Venture for Affordable Housing, American Planning Association, 1982), and Steven S. Fehr, “Reducing Land Use Barriers to Affordable Housing,” Planning Series No. 10 (Harrisburg, PA, Planning Services Division of the Bureau of Community Planning, Pennsylvania Department of Community Affairs, 1991). TABLE 4.4 Development Standards for Affordable Residential Design Narrower, shorter streets Smaller lots with less restrictive setbacks and lot width requirements Increase allowable lot coverage Use effective stream buffers Increase infiltration of storm water Use grass lined swales instead of pipes and paved gutters TABLE 4.5 Elements of Better Residential Site Design smaller neighborhood stores, especially specialty shops. Vacant lots can be put to use as community gardens, pocket parks, or additional parking (Figs. 4.11 and 4.12). Many older neighborhoods were built before the automobile became the ubiquitous feature that it is today. In such places, narrow streets and the absence of off-street parking make parking and the resulting congestion a particularly unpleasant aspect of urban living. By using vacant lots to provide parking for residents, some congestion can be removed from the residential street and encourage an active pedestrian street life. Commercial and industrial development can be a bit more problematic. In the past, factories often were constructed within walking distance of housing. This circumstance has resulted in local residents resisting industrial and some commercial redevelopment. Other issues also constrain the redevelopment of urban property for nonresidential 87 88 Chapter Four FIGURE 4.11 A neighborhood parking area was created by removing a blighted building. The parking is reserved for residents and authorized visitors using a parking tag system. (See also color insert.) FIGURE 4.12 A neighborhood park created in the space where a vacant home once stood. (See also color insert.) Design for Communities uses. Older roads, for example, often have turning radii that are challenging to modern delivery vehicles, and urban sites sometimes have insufficient parking for employees. These situations increase local traffic congestion and increase parking competition. The structure of many older buildings simply is not compatible with modern industrial and commercial uses. Older buildings tend to have lower ceiling heights and smaller rooms than are desired for modern industrial, warehousing, or even commercial uses. These limitations aside, robust and successful redevelopment and revitalization efforts are under way in many cities. Making these efforts sustainable is an important challenge. Design for Security In recent years there has been increasing awareness of the role design of public spaces plays in crime prevention and security, particularly as part of efforts to improve distressed communities. Crime prevention through environmental design (CPTED) is most successfully conducted in conjunction with other community efforts, such as community policing and neighborhood awareness. Rob White (1998) of the University of Melbourne observes that there are two schools of thought regarding CPTED. One approach studies how places can be designed and built to be safer simply to create better quality places. The other he describes as “situational prevention,” that is, remedial work addressed to specific trouble or hot spots. Although environmental conditions may encourage or discourage crime, design alone is not the answer. Thefts are higher near schools and rapes are higher near hospitals because of predictable routines that create opportunity. To discourage crime, we must create environments that make it hard for criminals to do their work and that encourage other acceptable or desirable activities. Design is part of a larger strategy that must include management and social and community development. There is no single formula for the design of defensible space. A thorough understanding of the physical and social environment of a neighborhood is required: What is the physical layout? Who is coming and going? Who belongs and who doesn’t? What are the dynamics of the problem? Is it traffic? Automobile or pedestrian? Night or day? What are neighborhood routines? Design solutions for problems faced by communities range from improving security and safety elements to helping to increase neighborhood identity and pride. Adam Graycar (1998) has observed that crime is not an equal opportunity endeavor; where you live, how you live, and who you are have a great deal to do with your chances of becoming the victim of a crime. Not all crime is considered equal either. Predatory crimes such as homicide or assault are more serious and less common than drug- related crimes and violence and theft. Graycar observes that crime requires three necessary elements: a likely offender, a target, and the absence of a capable guardian. The capable guardian refers to all social, political, and design strategies used to prevent crime (Table 4.6). Situational CPTED focuses on providing physical evidence of the capable guardian by creating spaces that reduce criminal opportunity and increase the risks and effort required. A community that is aware of what is going on within it and where activities in pubic space are readily observed is less likely to have a crime problem primarily because the community itself, through its interaction and behavior, represents a capable guardian. Much of the CPTED effort is geared toward physically modifying space, but this effort should be a product of community desire and interest. The key to CPTED is the involvement of the community. Designers working with communities become facilitators of the 89 90 Chapter Four Provide effective lighting Design to assure good lines of sight along streets and paths and near buildings Consider crime prevention when selecting plant materials Use traffic calming measures and circulation planning to reduce joy-riding Look for and anticipate escape routes Encourage people to observe streets and public spaces Use vandal proof materials and assure quick repair and replacement of damaged materials Restricting traffic on residential streets (one way streets, traffic calming) Increased evidence of formal and informal surveillance Restricting vehicle movement TABLE 4.6 Site Design Crime Prevention Strategies community’s goals. In most instances the budget for implementing a design is limited, so it is important to have the greatest impact for the resources available. To determine the scope of the problems and to develop a design strategy, the CPTED process usually begins with an assessment of the neighborhood. It may be difficult to determine the boundaries of the neighborhood and the study area, but it is important to have a finite area of consideration. Working with neighbors and local businesses, the CPTED team identifies the attributes and the problems of the neighborhood. The team looks for positive elements— points of stability such as schools, churches, or long-standing businesses—and locates these places on a map. Next, the problem areas are identified. CPTED teams may elect to map abandoned buildings, vacant lots, high-crime areas, homeownership, parking areas, poorly lit areas, traffic patterns, or anything else that contributes to the character and concerns of the neighborhood. From these maps and the juxtaposition of positive and negative elements, the CPTED team works with neighbors to identify and prioritize steps toward a better community. In general there are three aspects of defensible space design: territory, access, and surveillance. Territory refers to private and public space. Territory is established by drawing distinctions between spaces (Fig. 4.13). Distinctions can be accomplished by textural changes in pavements or walls, elevation changes (a step up or down), barriers such as walls or fences, visual barriers such as low fences or shrubs (Fig. 4.14), or psychological barriers such as consistent neighborhood organization or themes. When evaluating a space, ask yourself, “What could I get away with here? (Martin, 1997).” Access refers to providing and restricting access; in short, control. Street blocking is usually not the preferred method. Through streets provide access by pedestrians and vehicles. Some alternatives to blocking streets are intersection narrowing, “s” curves in streets, dual use streets, traffic calming devices, one way streets, turn restrictions, and bollards. Physical access can be restricted. This is known as “target hardening” and Design for Communities FIGURE 4.13 Fences and outdoor seating in this traditional neighborhood clearly delineate private from public property. FIGURE 4.14 Bollards and planting used in this city neighborhood separate pubic from private space and signal community activity and surveillance. 91 92 Chapter Four involves installing fences and gates or other restrictions. It is sometimes necessary as a preliminary or temporary design element to gain control. More subtle ways of communicating boundaries and a sense of territory or neighborhood include low fences or walls, colors, or signs that do not actually restrict access but signal to people that this area is set apart. Passing through these barriers signals a transition from one area to another. Such symbolic barriers provide an identity that both residents and visitors can see and that makes a sense of ownership more palpable. Space that does not indicate use or is not controlled within a neighborhood is an invitation to unwanted behavior and is at least an attractive nuisance. Surveillance refers to seeing and being seen. Windows and doors facing the street allow people to be seen both as observers and the observed. Points of congregation such as playgrounds and porches encourage residents to see and be seen, increasing the degree of visible surveillance in a neighborhood. Lighting is important, but the sense that there are eyes on the street is more likely to be a deterrent to unwanted activity. With the increased terrorist threat faced today, designers should expect to address security issues beyond crime in the site design plan, especially for public facilities. This may require consultation with a security expert or a design professional with specific security experience. The federal government has developed site security guidelines, but this is an emerging area of practice and the standards are still evolving. The General Services Administration developed a set of security standards in the early 1990s, and every federal facility was assessed and upgraded to minimum standards. More recent studies reported in 2008 by the GAO found that many facilities lacked sufficient security measures. Much of the focus of the standards deals with architectural issues, interior security, and technology, but site planning also plays an important role. Most state and local facilities and many private institutions that might also be targets for terrorists have little or no relevant security. In many cases the short-term answer has been target hardening, which creates a fortresslike feeling to public buildings. Public buildings and public spaces adjoining them are more than the sum of activities that take place within them. They represent the values and the character of the people, so they must remain accessible, attractive, and inviting. Security and safety are important concerns, but it is widely agreed that target hardening is not the first line of defense. The events of September 11, 2001, in Washington D.C. and New York City caused officials and designers to revisit security as a design element. Security planning and design is completely consistent with the CPTED principles: increased surveillance reduces opportunities to be unobserved and increases the risks of being caught; effective design limits opportunity for access and escape and protects the building and people. There are important differences though. Where crime may be directed to one or a few individuals per incident, terrorism is directed toward the greatest possible number per incident. Criminals look for a means of escape, but we have learned that terrorists may have no thought of escape. The common criminal and the terrorist look for different forms of vulnerability. It is a challenge for the designer to meet these objectives in a fashion that is more than simply hardening the facility. New facilities that might be the target of such attacks should incorporate security into the most basic design considerations. Redevelopment or retrofitting projects should be aware of the vulnerability of the site and make appropriate recommendations. It is likely that site designers will work in conjunction with security experts, but they should develop an awareness and expertise of their own as well. To not consider these issues in one’s design may be seen later, after an incident perhaps, to have constituted a breach Design for Communities in the standard of care expected from a design professional. Many of these concerns are not yet part of building codes or design standards. They may not even be on the client’s list of concerns, but they require the attention of the designer nonetheless. New facilities should ideally incorporate a setback from the street that allows for observation of all approaching vehicles or pedestrians. Federal recommendations for some types of facilities call for a minimum street setback of 100 ft and minimum lot sizes of 15 acres. Clearly this would limit the number of possible urban sites for these facilities. The setback, however, presents an aesthetic concern. Many involved in these decisions agree that it may be a mistake to think of and design for security first. An unadorned open space may facilitate surveillance, but it clearly speaks of a bunker attitude in terms of design. A well-thought-out design would reduce the need for distance as a security strategy by incorporating changes in elevation to make access with a vehicle more difficult and the site more pleasing. Other low barriers, ponds, grading changes, or strategically locating site furniture in the plaza can make a direct path by a vehicle impossible. To protect the building further, the building could be raised above street grade and the plaza used as a transition over the change in grade. The plaza should be designed to function as a public space and should be filled with activities. The key site design concern is access by pedestrians and vehicles. Security should provide for vehicles and pedestrians to be directed into specific patterns of approach through the site design. The points of access for pedestrians should be limited to provide a maximum amount of surveillance and control. Walkways should be set away from the building, and plant materials and landscape features should not obstruct a clear field of vision around the building. Approaches to entrances should be open but provide controlled access by vehicles. Hardened bollard systems may be used, but other methods such as changes in elevation, raised planting, or water features might produce the same effect without the hardened appearance. Separate entrance facilities for pedestrians and vehicles might be considered. The separate entrance isolates everyone entering the facility for a security check and could serve as a barrier to vehicles attempting to get to the entrance. The most common method of keeping vehicles away has been to rely on large planters or other heavy items, but large planters or tree masses may create blind spots or hiding places. Landscaping is recommended to be kept below 24 in. in the security surveillance area, but this limits the design’s aesthetic value and its potential to contribute to site security. Changes in grade are important design considerations in limiting vehicle access and controlling vehicle and pedestrian circulation. Site lines should be discussed in the planning stage so that tree masses, walls, and other features can be strategically located. It may be possible to require vehicles to change directions upon entering the site. This will require the vehicle to slow down and reduce the possibility of a ramming or rush to the building using a vehicle. Vehicle access should be on roads that are curvilinear to require vehicles to drive slowly. When barriers are called for that will stop a vehicle, the designer may consult Army TM 5-853-1 and TM 5-853-2/AFMAN 32-1071, Volume 2, for relevant design procedures. Parking should be kept well away from the building, and separate controlled parking may be advisable for key personnel. It is likely that new public facilities will not be built with public parking beneath them. Strict setbacks from the building should be observed for all vehicles. Loading and unloading areas should be large enough for needed queuing but not allow parking. Loading docks should be designed in consultation with the facility management. 93 94 Chapter Four Of course, all of this must be accomplished while meeting accessibility requirements and facilitating the smooth operation of the site. The site exterior should be well lit, avoiding dark places near the building. Lighting should be coordinated with exterior closed circuit television systems to keep obtrusive lighting to a minimum but also to avoid “hot” and “cold” spots that may reduce surveillance effectiveness. The combined effect of these measures creates a clear perimeter around the building with an obvious buffer effect to make terrorist or criminal acts more difficult but without the hardening appearance. Design professionals should be cautious, however: security is expensive. One should be careful with site development cost estimates if enhanced security costs are to be included. Lighting Lighting serves to improve security and way-finding, but it also provides important visibility to commercial sites and can be used to create special effects and feelings in the nighttime landscape. With the development of specialty lighting products and effects, lighting has become as creative as any aspect of site design and is a specialty of many designers. The design of site lighting is just as often performed by companies selling lighting equipment as by an ancillary service, however. Finding the right combination of products, lighting type, and distribution can be a complex undertaking. The purpose for the lighting is a critical consideration; for example, lighting for security or surveillance calls for a different strategy than designing for a more intimate space. Lighting is selected on the basis of the type of light, the distance from light source to object, the light of surrounding areas, and the nature of the activity being illuminated (Table 4.7). Many organizations have specific lighting standards or preferences that will influence design. The lighting industry introduces new products and capabilities all the time, and like so many other aspects of site planning, lighting requirements are often a matter of local ordinances. The distribution and brightness of light are the fundamental elements of lighting design. Distribution of light refers to how much light is cast over an area. Lighting for accent or to create a mood or feeling requires a lighter and more elegant touch. For such applications, the angle and position of the light is determined by the visual or aesthetic effect as opposed to assisting in way-finding or security. By uplighting, moonlighting, or backlighting objects, the designer can create a very different feel from the daylight landscape. Uplighting is most effectively used to feature objects that can be viewed from a limited point of view and is commonly used against walls or fences or in gardens that will be viewed only from one side. The light source is located low and is pointed toward the object and away from the viewer. This orientation lights the object without any glare to the viewer and produces an unusual effect because the eye is not used to seeing things lighted from below in nature. This method is effective at creating dramatic textures and contrasts in the night landscape. There are several methods for computing the effectiveness of different lighting choices. The point illumination method measures the illumination at a given point and is described as follows: E= I cosθ d2 Design for Communities Area Building exterior Activity Lux (lx) Footcandles (fc) Entry, active use Entry, infrequent use Vital location or structures Building surrounds 50 10 50 5.0 1.0 5.0 10 1.0 Bright surroundings Dark surroundings 150–500 50–200 15.0–50.0 5.0–20.0 Along roadside Away from road 2–10 5 500–1000 10–20 6–13 4–10 5–10 6–40 20–40 10 200–600 50 200 200 10–20 0.2–1.0 0.05 50–100 1.0–2.0 0.6–1.2 0.4–0.9 0.5–1.0 0.6–4.0 2.0–4.0 1.0 20.0–60.0 5.0 20.0 20.0 1.0–2.0 Badminton Baseball, infield Baseball, outfield Basketball Football Field hockey Skating Softball, infield Softball, outfield Tennis Volleyball 200 110–300 100–200 100 100–1000 100–200 100 100–500 70–200 200–500 100–200 20.0 11.0–30.0 10.0–20.0 10.0 10.0–100 10.0–20.0 10 10.0–50.0 7.0–20.0 20.0–50.0 10.0–20.0 Buildings and monuments Bikeways Bulletin boards, kiosks Major roads Collector roads Local roads Walkways, open air Walkways, enclosed Park or garden walkways Steps in park or garden Stairways Gardens Garden features Loading areas Parking areas Outdoor athletic areas Source: Harris and Dines, 1998. TABLE 4.7 Recommended Levels of Illumination 95 96 Chapter Four where E = illumination on a horizontal surface, footcandles I = lamp intensity in lumens θ = angle between the fixture and a point on the ground d = distance from the luminaire to the point The point distribution calculation is useful for determining the constancy of light within its distribution but is a fairly effort-intensive method (Fig. 4.15). The average illumination method measures a more general distribution of light and can be described as follows: F= where luM LM F = average illumination, footcandles l = lamp intensity in lumens u = coefficient of utilization M = maintenance factor L = horizontal distance between fixtures W = width of the area illuminated To solve for L L= luM FW Designers should consider changes in the efficiency of the lamp, sometimes referred to as the maintenance factor, over its life. Some lamps may vary as much as 75 percent over their operating life. The maintenance factor includes variation as the light source ages as well as the effects of dust or dirt on lamp covers (Table 4.8). Maintenance factors Fixture Light pole d H R FIGURE 4.15 Point distribution calculation dimensions. Design for Communities Type of light Lumens/watt Life (hours) Florescent 70 High pressure sodium Color Notes 6000 Good color purity, white Affected by cold weather 130 16,000 Poor color purity, yellow to orange Washes out colors in landscape Incandescent 10 to 18 750 to 1000 Very good color purity, yellow Low pressure sodium 190 11,000 Poor color purity, pink to orange Metal halide 90 14,000 cool white Good color purity Mercury vapor 55 24,000 Cool white Tungsten-iodine 18 to 20 2000 Good color purity (Deluxe White) Washes out colors in landscape (gray) Strong in blue-green spectrum TABLE 4.8 Performance Characteristics of Different Sources of Light vary, but 50 percent is a common rule of thumb. Information on illumination and the coefficient of utilization is found in photometric information of the luminaire. Moonlighting is accomplished by using combinations of light carefully located high up in trees and other low wattage ground level lighting attached to branches and leaves from below. Moonlighting can create very dramatic effects and is especially good for transitions between lighted areas. The filtered light may provide adequate light for walking on a marked path and can be particularly beautiful. These effects can be difficult to achieve if there are more brightly lit areas nearby. Backlighting is sometimes used to feature a tree or shrub or other element with an unusual or visually pleasing silhouette. Care must be taken to minimize the risk of glare to the viewer, so the height and angle of the lighting is very important. Silhouette lighting can be achieved by uplighting a wall or surface behind an object. Indirect or bounce lighting is achieved by directing light to a surface that reflects the light into or on a desired area. The development of extruded fiber optic lighting and other products has introduced the possibility of drama and beauty into the night landscape. Commercial Lot Layout The layout of commercial sites is driven by the nature of the enterprise as well as the local ordinances and community practices and expectations. A key issue for the developer and tenants is location in the community; site selection is extremely important. The ideal commercial site seems to have a somewhat elusive but immutable character. Every community has sites that are successful despite a poor location and others that never succeed regardless of the tenant or business that locates there. A site analysis that 97 98 Chapter Four studies the development potential or the visibility and traffic past a site often cannot identify the underlying cause of success or failure from the bare facts. Some of the factors that contribute to the success of a commercial site are related to demographics: is the site located near enough to people with disposable income? Success is also correlated with the type of business or mix of tenants: is the business mix able to draw people either as a destination or on an impulse? Does the mix of tenants support each other and create a draw greater than any one tenant? Other aspects of site success are well within the scope of the site professional’s work. During the site analysis, the site location should be explored. Commercial development with retail shops usually requires a minimum of existing traffic at the proposed location. Very large retail projects may rely on becoming a destination themselves and be less concerned about existing traffic. In either case, existing intersections are prized locations for most commercial projects. Access to the project site is critical. Accessibility in this sense refers both to the ability of the customer or client to get into the shop or business and to the “visual access” of the site. Although there is not a fixed standard, many retail operations require a minimum number of parking places to be within a given distance from the door. One of the most lamentable aspects of retail development is the visual impact projects have on the community. Even small corner stores can bring a significant change in character to a neighborhood if not designed carefully. The most significant impacts are associated with automobile traffic and parking, but the intrusion of bright lights and noise can also be problematic. There is a strong preference on the part of retail operations to be able to show the available parking and its proximity to the door to the public. Retail operations often resist attempts to reduce the visual impact of parking (by putting it behind the building or screening it) in the belief that if customers do not see convenient parking they will go somewhere else. Except in smaller projects, in-fill, high-end, or theme-related retail projects, it is difficult to overcome this preference. The designer must also accommodate delivery and distribution traffic on the site. In most projects these activities are located behind the building, further complicating relocating the parking. The most important part of accessibility is visibility. Customers and clients generally need to see the development. Efforts to mitigate the visual impacts of development are complicated by the need of commercial projects to be seen. In most cases it is necessary for the site professional to find a design that meets both needs, and site screening should be carefully considered (Figs. 4.16 and 4.17). In many cases, no screening is required or expected, but as time pa