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This article compares the two developments - Radburn in Fair Lawn, New Jersey, and Kentlands in Gaithersburg, Maryland - that exemplify the American Garden City and New Urbanist paradigms, respectively. Through a morphological case study and quantitative analysis, the paper examines how their goals and prescriptions were realized in suburban residential developments and how they differ from each other. In the end, Radburn and Kentlands are not so completely opposed as they initially appear. They share the underlying goal of a walkable residential environment, and their prescriptions are very similar. However, in terms of walkability, Kentlands' interconnected grid cannot resolve the conflict between automobiles and pedestrians. Additionally, overemphasis on variety in housing types and styles in Kentlands, probably common in New Urbanism, may work against the marketability and long-term success of such planned suburban communities. Their similarities in scale, development density, mixed land use scheme, and block plan allow us to try complementary shuffling of the individual elements in both sets of prescriptions.

Radburn and Kentlands are test sites and incomplete realizations of the two elaborate planning and design models that were considered innovations in the 1920s and the 1990s, respectively: The American Garden City and New Urbanism. Nonetheless, they provide an opportunity to compare two paradigms that many today consider diametrically opposed. In the end, the two paradigms, which may look different to those traveling in cars, have much in common, especially from the viewpoint of pedestrians.

Radburn was a product of thoughtful planners who wanted to introduce the Garden City concept to America. This group of planners formed a discussion circle, named the Regional Planning Association of America (RPAA). In addition to the Garden City concept, they had foreseen the adverse effect of the automobile on residential environments and proposed solutions for it. Their ideas were realized by the City Housing Corporation (CHC), a private development company. However, Radburn, CHC's second project, turned out to be a financial failure due to the Depression. After the world wars, only the alluring term of "garden suburb" survived in the market, and the conventional development pattern has prevailed in American suburbs.

New Urbanists, who realized the harmful effects of the conventional development patterns, have developed design solutions to overcome the problems of the sprawling, automobile-addicted conventional suburbs. They are opposed to the disconnected street system using cul-de-sacs and hierarchical roads and adopted their solutions from traditional American suburbs of the early 1900s built on a gridiron street system. Ironically, the earlier Radburn planners were opposed to a gridiron street system because of its dullness and lack of safety in residential environments.

At first sight, New Urbanists seem to have adopted opposite prescriptions to those of the CHC planners. Furthermore, some argue that conventional, low-density suburbs are inherited from Radburn (Van der Ryn & Calthorpe, 1986). Whether or not they are influenced by New Urbanists, planners in the current generation tend to recognize Radburn for the introduction of its individual elements -including cul-de-sacs, the hierarchical street system, and the superblock concept-rather than for its sophisticated integration of these elements. For them, it is more important that these are the elements that New Urbanists are trying to avoid.

However, as New Urbanist paradigms are now enthusiastically accepted as a way to provide a walkable society, Radburn was considered an innovation for the same goal of walkable residential environments in its own time (and still may be). It is interesting that the two seemingly opposite sets of prescriptions were developed to achieve the same goal. Here, some questions follow. How different are the two sets of prescriptions? Do they really differ at all? If they differ, are the New Urbanist prescriptions sufficiently better than those of the American Garden City concept to warrant abandoning the old wisdom? We try to answer these questions by comparing the two representative developments for each paradigm-Radburn and Kentlands.

The discussion starts with a historical search and comparison of the two underlying paradigms-the American Garden City and New Urbanism-in relation to Radburn and Kentlands. The next section compares the morphological aspects of the two developments, including form, land use, housing, street pattern, accessibility, block plan, and open space. Additional discussions of market acceptance, which the morphological analysis cannot incorporate, and conclusions follow.

Radburn and Kentlands: Prototypes of the American Garden City and New Urbanism

As mentioned above, certain principles and philosophies underlie both developments. We begin our analysis with a brief history and description of the Radburn and Kentlands paradigms-that is, the American Garden City and and New Urbanism, respectively.

Radburn as an American Version of the British Garden City

Radburn was developed in the late 1920s and early 1930s by a group of planners who hoped to build a fullfledged Garden City. Clarence Stein and his colleagues began with the planning principles espoused some 25 years earlier by Ebenezer Howard in 1902 (Southworth & Ben-Joseph, 1997). The Garden City model has been highly influential. In the early 1920s it captured the imagination of American planners such as Lewis Mumford, Clarence Stein, Henry Wright, Benton Mackaye, Clarence Perry, Stuart Chase, Charles Whitaker, and Alexander Bing who, in 1923, formed a discussion circle known as the Regional Planning Association of America (RPAA; Parsons, 1990).

Ebenezer Howard envisioned the Garden City as a highly planned community that would combine beneficial aspects of city and country living. Beyond this quality-of-life aspect, his proposal included a comprehensive vision ofsocial reform based on the collective ownership of land (Ward, 1992). In his vision, the Garden City was self-contained. Garden City residents would not have to commute; a majority would have the opportunity to work within a few minutes of their homes. An unpublished diagram from Howard's papers shows detailed section design concepts of the Garden City (Ward, 1992, p. 5). Education, recreation, shopping, and civic facilities would be located near residential areas. No resident would live more than a third of a mile from the community's center, making the proposed Garden Cities eminently walkable. Large public open spaces, at the center and on the periphery, would provide healthy recreational opportunities and promote civic spirit. Howard did not specify street standards or building form, although his diagrams suggest large blocks and a hierarchical street pattern.

As Stein (1947) noted in the celebration speech for the 10th birthday of Greenbelt, Maryland, the CHC efforts were an American modification of Howard's Garden City. However, according to Geddes Smith, to create a "Town for the Motor Age" (quoted in Stein, 1957, p. 44) was more an innovation than a mere modification. This innovative neighborhood design triggered a flow of planning philosophy back to Europe, including Britain, where the Garden City concept originated.

The first experimental American Garden City was Sunnyside Gardens, which was inserted into a few city blocks in the borough of Queens in New York City. The designers introduced extended shared commons inside the blocks instead of the traditional lot subdivision, which would be a partial realization of communal land ownership in the Garden City. But the designers soon had to recognize the limitations of the gridiron street system as a setting for safe motor-age living (Stein, 1957).1

After the success of Sunnyside Gardens, their first small development in New York City, Clarence Stein and his colleagues at the RPAA were eager to create a wholly new development on vacant land, rather than try to shoehorn their development into an existing urban grid. They were concerned about the monotonous and dull suburban landscape created by the gridiron street system. In 1927, CHC-the company that financed and built much of Radburn-purchased about 2 square miles for a new Garden City in the rural borough of Fair Lawn, New Jersey.

In addition to following the British concept of the Garden City, resolving the ever-increasing conflict between pedestrians and vehicles was a new challenge for the Radburn plan. The design solutions can be summarized as follows (Stein, 1957):

1. Use of superblocks and the integration with Perry's neighborhood unit concept (3 or 4 superblocks constitute a neighborhood unit).

2. Hierarchical street system, in which each type of street has its own specialized functions, including service lanes, secondary collector roads around superblocks, main thoroughfares to link the traffic of various sections, and highways to connect to outside communities.

3. complete separation of pedestrian and vehicle paths by using cul-de-sacs and pedestrian-only paths in a superblock.

4. Interior parks (at the center of superblocks) as the backbone of pedestrian movement, jointly forming a continuous park system.

5. Houses turned around to make living rooms and bedrooms face toward pedestrian paths and parks and service rooms face service lanes.

When it was first built in 1928, Radburn was well received by planners and the public. However in 1929, a few months after the earliest residents moved in, the Depression began. Although the CHC had planned to sell off 1 square mile of land to help finance the development, as the Depression worsened they were forced to sell more than anticipated. As a consequence, development was scaled back. In 1934 the company declared bankruptcy.

In the end, the CHC developed 149 acres instead of 1 square mile. According to one local history, when its population peaked in 1964, Radburn sheltered 5,000 residents (League of Women Voters, 1994). Currently, the boundary of the Radburn community is defined by the Radburn Association; it encompasses about 2,900 residents in 674 units on 149 acres. Radburn contains local retail stores, a school, and recreational facilities, but lacks industry and a full complement of neighborhood services shown in the 1 square mile of the original town plan. Thus, the development fails to meet the Garden City ideal of integrating work, home, neighborhood services, and civic centers within a compact, walkable community. Located some 12 miles from Manhattan, Radburn is instead a bedroom community.

Although Radburn was an innovative residential development, it was a financial failure. Construction in the U.S. was almost dead until the end of World War II, and postwar residential development did not incorporate the innovation. Even for Roosevelt's Resettlement Administration (RA) new town developments in the 1930s, only Greenbelt, Maryland, among the three completed new town developments followed Stein's design for Radburn. The other two developments-Greendale, Wisconsin, and Greenhills, Ohio-were different (Parsons, 1990). Borrowing from Radburn by later new town developments was mostly piecemeal adaptation (Birch, 1980).2 While there were some efforts to promote the Radburn idea, the innovative scheme was not attractive to private developers in the postwar period. Rather, private developers paid attention to the financial success of the Levittowns, which seemed to be a prototype of subsequent conventional suburban developments (Girling & Helphand, 1994).

Kentlands as a New Urbanist Prototype

We chose to compare Radburn with Kentlands because it is one of the older New Urbanist developments and because it has a comparable suburban location. Kentlands is built on an old estate within commuting distance of Washington, DC; at 13 miles, it is almost the same distance away from this city center as Radburn is from Manhattan. Its rush-hour commuting time is similar to that of Radburn. From Kentlands to downtown Washington takes approximately 35 minutes by train, after a 4-mile bus ride.3

The mixed-use Kentlands project was begun in 1989. The present developer, the Greater Seneca Development Corporation, took over from the original developer in what they describe as a friendly foreclosure. For the most part, Greater Seneca continues to follow the master plan for the 356-acre community devised by New Urbanist planners Andres Duany and Elizabeth Plater-Zyberk (DPZ).

The New Urbanist or "neotraditional" paradigm challenges not only the prescriptive design standards and regulations governing suburban design, but also its implicit values. It represents a true value shift from contemporary suburban planning: Both its critics and its proponents claim that New Urbanism looks to the past, which the CHC model denied, for design solutions to contemporary problems.

In brief, New Urbanists decry the destructive influence of the automobile on modern life. They believe that dense communities with a wide variety of housing types, mixed land uses, and good transit connections can reduce Americans' reliance on the automobile. Like the early Garden City proponents, New Urbanists believe that compact planned communities promote a more wholesome lifestyle and foster civic values.

Some of the New Urbanists' basic principles are in line with CHC's; however, they go beyond Garden City proponents in prescribing urban form. New Urbanists believe that towns can be designed through highly detailed codes. Although there is much discussion about particulars, the New Urbanists generally adhere to a set of core design standards and principles. Some of the prescriptions and principles most relevant to our discussion are the following:

1. Streets should form an interconnected grid, allowing both vehicles and pedestrians free range. The street system should maximize rather than limit the choice of routes.

2. Streets should be carefully designed to reflect their primary importance as public spaces. Narrow street widths, sidewalks, and shallow setbacks help create the sense of an outdoor room that promotes neighborliness.

3. Neighborhoods should contain a mix of housing types to create a more diverse community. Apartments, town houses, and single- and twofamily homes should be intermingled rather than segregated by zoning.

4. Localities should encourage new development or redevelopment at higher densities to help make this housing mix possible. Higher densities are also essential to promoting public life, encouraging greater transit use, and supporting neighborhood businesses.

5. Land uses should be mixed to diminish reliance on the automobile. Homes, shops, schools, offices, and civic buildings should all be within a short walk, preferably within a quarter of a mile.

6. Plentiful transit connections should support compact development.

Radburn and Conventional Suburbs

Calthorpe (Vander Ryn & Calthorpe, 1986) argued that "Levittown inherited many of the planning ideas of Radburn" (p. 229) and viewed Radburn as a low-density development and the beginning of the conventional suburban development pattern (Van der Ryn & Calthorpe, 1986).4 However, there are no similarities between the two design concepts: We cannot find any superblocks, pedestrian-only paths, or emphasis on shared open space in the series of Levittowns.5 Rather, we find parallel rows of segmented, privatized gardens and monotonous ranch-style houses. In terms of density, Levittown's homes were 750 square feet (livable area only) on lots of 6,000 to 7,000 square feet, while Radburn's were 1,300 square feet (2 stories) on lots of 4,500 square feet, which means that Radburn's net dwelling unit density was roughly SO% higher than Levittown's (Girling & Helphand, 1994).

Chronologically, Radburn was developed between traditional and conventional suburban developments, but it was not replicated in conventional suburban developments. Rather, some piecemeal adaptations, including cul-de-sacs and hierarchical roads, are found in conventional suburbs. The Federal Housing Administration in particular promoted postwar housing with this kind of piecemeal adaptation. As a result, these elements became another generic street type in conventional suburbs (Mohney & Easterling, 1991). However, the real merit of Radburn comes from the integration of its elements (Lee & Stabin-Nesmith, 2001). The combination of cul-de-sacs, hierarchical; treets, pedestrian ways backboned by interior parks, and good pedestrian linkages to common destinations such as the school, the shopping center, and the transit station promotes the residents' walking and viability on the pedestrian ways. Therefore, accusations that Radburn is the prototype for conventional suburban development are somewhat misguided.

There is a negative aspect to cul-de-sacs, as we can readily observe in conventional suburbs. Duany et al. (2000) point out that conventional suburbs based around cul-de-sacs and curving roads result in a complete loss of autonomy for children. The cul-de-sacs are the cause of this loss of autonomy, and Radburn seems to attract criticism for the adoption of cul-de-sacs in its plan. However, cul-de-sacs in Radburn are fully interconnected with children's activity places and allow children to walk there freely. Children thus gained full autonomy in Radburn.

The New Urbanists' standpoint is certainly one of opposition to conventional suburbs. However, contrary to the assertions of some New Urbanists, conventional suburbs did not evolve from Radburn. At least Radburn cannot be identified as the origin of conventional suburbs simply because of its introduction of cul-de-sacs and hierarchical road systems. Except for some piecemeal adaptations of certain elements, Radburn failed completely to serve as a prototype for postwar suburban developments. Rather, the American Society of Planning Officials, an official government group and the most influential planning association at that time, promoted anti-Radburn policies of single-lot, large, individual-yard residential zoning (Birch, 1980).

The American Garden City, and New Urbanist Principles

The American Garden City and New Urbanist paradigms are both concerned with how to deal with the car in the residential environment. The paradigms share many underlying goals-such as the provision of open space, walkability, and a compact development-although they propose very different means of achieving those goals. A summary of the comparison between these paradigms is presented in Table 1 in terms of their backgrounds, goals, prescriptions, and results.

This brief introduction to the American Garden City and New Urbanist paradigms serves to outline the two planning approaches and to show where there may be concurrence and disagreement. Our case study of Radburn and Kentlands should illuminate some of these similarities and differences. The discussion that follows is meant to help the reader determine whether these differences are ultimately significant and what the implications may be for New Urbanist development schemes.

Comparison of Radburn and Kentlands

Both Radburn and Kentlands show how the principles of their respective paradigms can be applied successfully on a small scale, and thus offer important lessons for planners who hope to modify current suburban development patterns. Our comparison is based on a morphological analysis.6 Specifically, we employ here the analytical framework used by Michael Southworth (1997). This analysis tries to elaborate some of Southworth's methodology in a more quantified form to allow a precise comparison, with some modifications to units of measurement.

Form and Pattern

Kentlands was planned for a 356-acre site surrounded by conventional suburban developments. Designed as a community for about 5,000 residents and 1,600 dwelling units (du), construction was begun in 1989. In 2001 it is almost built out. Gross density is 4.78 du/acre (14 persons/acre), which is much higher than that of conventional suburbs generally. Net density for single-family detached homes is 7.44 du/net acre.

The original plan for Radburn, with a population of 25,000 was not completed, and it shrank to a 149-acre residential district. Currently, it is difficult to distinguish the area of the original Radburn development from later developments surrounding it. There now exists only a vague boundary formed by the Radburn Association (that is, the homeowner's association). For this analysis, we take the Radburn community to be the area of the Radburn Association. Currently, 674 dwelling units are situated in the area, housing 2,900 residents. The resulting density is 4.52 du/acre (19 persons/acre). Net density for single-family detached homes is 7.9 du/net acre. Although Kentlands is twice the size of Radburn, in terms of development density the two communities are comparable (see Table 2).

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Kentlands' grain of development is much finer than that of the surrounding conventional suburban developments (see Figure 1). Although the difference in Radburn is not as distinct as it is in Kentlands, we can easily see that Radburn is also more densely built than its surrounding areas. The built form of Kentlands exhibits a variety and an unsystematic mix of grains, rather coarse in some places and rather fine in others. However, it produces neighborhood clusters having unique characteristics. On the other hand, Radburn exhibits an even arrangement of grains. They are aligned in a systematic way, and instead of variety among the clusters they exhibit similarity and an even and replicated pattern.

Land Use Pattern

The overall mixes and arrangements of land use patterns in Radburn and Kentlands are quite similar (see Figure 2). Kentlands, like Radburn, made its neighborhood educational and recreational facilities the focal point for the development. The Radburn elementary school is situated at the northeast corner of a superblock, at the wide end of the interior park. The Kentlands elementary school and a related children's center, providing day care and after-school programs, are located at the southwest corner. Kentlands' extensive parks and recreational facilities supplement the dawn-to-dusk care provided by the school and the children's center. However, the facilities are isolated beyond a boulevard, while the elementary school in Radburn is open to the interior park and recreational facilities.

Radburn's shopping and office district is located in the middle of the development; it borders Fair Lawn Avenue, a major crosstown street with a variety of building types and sizes. In the original Radburn plan, each of the three neighborhoods was to have its own shopping center, as well as its own elementary school (Stein, 1957). As a result of the Depression and the bankruptcy of the CHC, the scaled-down Radburn development plan resulted in a central location for neighborhood retail activities. Radburn's Plaza Building and the adjacent buildings form a small cluster and provide a limited number of neighborhood-oriented retail facilities to both Radburn residents and others.

In contrast, the Kentlands plan relegates retail and office activities to the edge of the development. The few stores and office buildings have very large footprints and are surrounded by large parking lots.8 Similar to Radburn, Kentlands' shopping center serves a larger area than the planned community. However, in terms of scale, these retail facilities serve as a regional shopping center, while Radburn's is only neighborhood based. One distinctive variation in Kentlands is that along with the conventional shopping center, a viable street shopping strip is provided to fill the gap between the regionalscale retail and community needs.

In both developments, residents can walk to a neighborhood shopping area, since most of the residents in both Radburn and Kentlands are located within a 0.5mile radius from the shopping center. Using median value, Radburn residents live at a 0.19-mile radius from the shopping center, while Kentlands residents live at a 0.36-mile radius.9 These statistics reveal that more than half of Kentlands residents live beyond the 0.25-mile radius that is accepted as a pleasantly walkable distance from a shopping center.

One of the main issues concerning New Urbanist principles is the mix of land uses, and even the mix of building uses. New Urbanists argue that a neighborhood should contain a variety of housing types and land uses to be viable places for various activities, including living, shopping, and working (Bressi, 1994). Their utopian goal is a community in which people of different incomes, ethnicities, races, and ages are evenly mixed. Furthermore, Duany et al. (2000) emphasize that the designer's role is "only [to] provide the ingredients and conditions most likely to lead to a mixed-use future" (p. 190). This intention is well shown in the land use plan of Kentlands.

Although there was no explicit argument concerning land use mix, Radburn seems to contain a mix of commercial, recreational, and public land uses and a mix of housing types, although they are not arranged in the same way as in Kentlands. Rather, they are grouped into several blocks and arranged in a systematic way around a focal point. Specifically, there is a cluster of commercial buildings very close to the transit station, and multifamily housing and town houses surround the commercial area within a 0.25-mile radius from the transit station. Finally, single-family detached houses (still in a relatively high density) surround the high-density housing area. This provides a good example of the TransitOriented Development (TOD) land use scheme, which is one of the main features of New Urbanism.

Housing

Kentlands' 1,507 housing units are divided among 467 single-family residences, 508 town houses, 292 multifamily condominiums, and 240 multifamily apartments (see Figures 3b, 3d, 3f, and 3h). In Kentlands, the different housing types are commingled on the same blocks, whereas in Radburn each pedestrian block (that is, a block divided by pedestrian paths) contains mostly the same type of housing. In addition, Kentlands exhibits more variety in housing type and lot size. Even granny flats are allowed. Radburn's 674 housing units include 469 single-family residences, 48 town houses, 64 units in 32 two-family homes, and 93 rental apartments (see Figures 3a, 3c, 3e, and 3g). The percentages of each housing type in both developments are shown in Figure 4. While they are not generally commingled on the same blocks, they often face each other on the same street. As shown in the statistics, the proportion of single-family detached homes in Kentlands (31%) is much lower than in Radburn (70%). In the end, Kentlands exhibits a more even mix of housing types than Radburn.

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Radburn houses have a few common styles, and their facades are rather plain, except on some Tudorstyle homes located at the northwest corner of Radburn that were built later than the original homes. The first and main set of homes, built in 1929, were rather standardized houses following the Radburn concepts. The studied informality of the English landscape style helps to blend most of the Tudor and other styles together behind a heavily screened landscape. Radburn's single-family detached houses (1,086 square feet) tend to have smaller footprints than Kentlands' houses (1,594 square feet), as Radburn homes were built at a time when singlefamily homes were smaller.

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Kentlands exhibits a set of housing types similar to those of Radburn, although Kentlands homes exhibit more variety and the exteriors are more ornate. The styles are based on those popular in Maryland and Virginia. From the outset, Kentlands homes have been designed and built by several different builders. The variety of developers and types of housing on residential blocks gives Kentlands a more diverse streetscape than Radburn. The sizes, plans, and styles of the single-family homes vary considerably. However, DPZ created a design code especially for Kentlands that controls many of the architectural elements and maintains a clear delineation between private, semipublic, and public spaces. Builders and homeowners must abide by the code, which specifies elements such as front porches and picket fences to promote neighborliness. The results are that each Kentlands residential block is a unique ensemble. Consequently, varieties of stylish homes characterize the streetscape of the community in Kentlands, while full-grown trees and well-organized greenery along the interior parks distinguish the community appearance in Radburn.

Street Pattern and Circulation Design

In both Radburn and Kentlands, the street pattern differs considerably from that of conventional suburbs. First, Radburn's streets are hierarchical and use many short and straight cul-de-sacs inside the superblocks. However, they are very different from the bewildering streets in conventional suburbs, with disoriented, disconnected, and long cul-de-sacs attached (see the area adjacent to Kentlands in Figure 5). They are carefully interwoven with pedestrian pathways and produce well established connections between residences and trip destinations. Radburn's cul-de-sacs are mainly 30 feet wide, with the larger collector streets circling the superblocks ranging from 60 to 70 feet wide. The paved area is limited to 18 feet, which makes the private yards appear to extend another 6 feet. The streets on the south side of Radburn, added in the 1940s, were laid out in more traditional patterns.

Radburn's elaborate pedestrian network combines sidewalks, underpasses, and parklands to create a unified network. The walkways extend for over 8 miles (Schaffer, 1982). Yet, with the Radburn design, when traversing the community one needs to cross very few streets. Stein considered intersections to be a key point of conflict between pedestrians and vehicles and tried hard to avoid such conflict. The result of his considerations was a superblock with cul-de-sacs. Children and adults can reach a park, pool, playground, or school without crossing a street.10

In contrast to conventional suburban street patterns, Kentlands' streets are based on New Urbanist grids. Interconnected and carefully adapted to the rolling topography, they enable both vehicles and pedestrians to easily reach all common destinations within the development, such as the school or shopping center. There are also separate jogging and bicycle trails within the parks. Although there are many straight and parallel streets and right-angle intersections, each section has a unique pattern.

In spite of the interconnected grid system, Kentlands also exhibits a well-organized street hierarchy, including boulevards, residential streets, and alleys. The boulevards collect the traffic from the streets and connect to the regional thoroughfares. The residential streets (with 50-foot rights of way) are narrower than those of conventional suburban developments and the collector streets in Radburn (60-70 feet). Kentlands' alleys, with 26-foot rights of way, are within the same range as Radburn's cul-de-sacs and theoretically serve as the same type of buffered play area and semipublic social space. Most of the streets in Kentlands are narrower than the streets encircling the superblocks in Radburn.

To analyze the street patterns of Radburn and Kentlands in a more quantitative way, we calculated the geometry of the pattern, the total lineal length of the streets, and the number of blocks, intersections, access points, and loops or cul-de-sacs per unit area (2,000 by 2,000 feet), following Southworth (1997). Comparative analysis of the street patterns reveals that Kentlands has much denser vehicle ways and more varied orientations than Radburn. Kentlands has 24,000 lineal feet of street, while Radburn has just 16,000; 50 intersections, while Radburn has only 26; and 37 blocks, while Radburn has only 10. For vehicles, Kentlands certainly exhibits a more interconnected street system than Radburn. These factors allow vehicles more route choices and constitute a finer-grained network (see Figure 6).

In terms of access from outside, Radburn has 11 entry points and Kentlands has 22. However, Kentlands is more insular when the entire site is compared, while Radburn's superblocks are intermingled with nearby blocks without noticeable boundaries. Finally, Radburn has 18 cul-de-sacs and one loop, and Kentlands has 11 cul-de-sacs or loops. If we consider cul-de-sacs and loops to constitute a disconnected suburban street form, then we can describe Radburn as a more discontinuous suburb than Kentlands.

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When we consider pedestrian ways along with vehicle ways, the figures are much different. Radburn has 14,000 feet of pedestrian-only ways and Kentlands 11,000 feet. Radburn thus provides more pedestrian ways. When these are combined with the vehicle ways, Radburn has 30,000 lineal feet of street compared to Kentlands' 35,000 feet. In Radburn, interwoven pedestrian ways divide blocks inside superblocks. If we consider this level of segmentation, Radburn has 48 blocks, while Kentlands has 72. The size of the blocks in Radburn is much smaller in these terms. Radburn has 37 more intersections between pedestrian ways, whether pedestrian-only ways or streets with sidewalks, at the pedestrian block level compared to the superblock level, while Kentlands has only 19 more. Overall, Radburn has a total of 89 intersections, which is comparable to Kentlands' total of 99 (see Figure 7).

Radburn has a total of 15 access points including 4 pedestrian connections, and Kentlands has 30 access points including 8 for pedestrians. If we consider the streets in terms of their pedestrian connectivity, the number of cul-de-sacs and loops decreases. Radburn has 11 cul-de-sacs and loops (19 for vehicle connections) and Kentlands has only S cul-de-sacs (11 for vehicle connections). These statistics indicate that the degrees of interconnectivity and network density in Radburn and Kentlands are comparable as far as pedestrians are concerned. One big difference remains: the orientation of the pedestrian ways. Although in Radburn these are clearly oriented to connect trip destinations, the orientations in Kentlands vary considerably path by path and produce a slightly confused pattern. Although the street system in Kentlands is based on a grid, pedestrian networks in Radburn more closely resemble the traditional grid.

Pedestrian and Vehicle Access

In order to compare the pedestrian and vehicle accessibility of common destinations in Radburn and Kentlands, we measured air distances and network distances for both vehicles and pedestrians from every lot to the destinations using GIS. To adjust for the size of the destination facilities, the distances are measured to the nearest points of the boundaries of the facilities. Also, since the two sites have different sizes, the absolute measure of the distances might produce misleading comparisons. To overcome this problem, we calculated ratios of driving and walking distances to air distance to each destination. These ratios reveal the efficacy of vehicular and pedestrian connectivities in a relative sense compared with the absolute air distance to the destinations. As a more direct measure of the relative efficacy of pedestrian and vehicular networks, we report the ratios of walking to driving distances. The mean values are given in Table 3.

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For shopping centers, the mean walking distance to their boundaries is 1,316 feet in Radburn and 2,311 feet in Kentlands. These statistics reveal that the shopping center is more accessible in Radburn than in Kentlands in an absolute sense. However, the shopping center in Kentlands is located at the north corner of the site, while the shopping center in Radburn is located in the center of the site. Also, as Kentlands is twice as big as Radburn, the overall mean distances are longer in Kentlands.

In order to adjust the effects of different development size, we calculated the ratios of driving distance to air distance and walking distance to air distance. This size-adjusted measure still reveals an interesting difference. The ratios in Radburn (drive/air: 1.38; walk/air: 1.26) are lower than in Kentlands (drive/air: 1.47; walk/ air: 1.33). We can interpret these results to mean that Radburn residents located 1 mile (air distance) from the shopping center should drive 1.38 miles to get to it, while Kentlands residents should drive 1.47 miles. In terms of walking, Radburn residents at the same location should walk 1.26 miles, while Kentlands residents walk 1.33 miles. Overall, these statistics mean that to reach destinations located at the same air distances, Radburn residents walk or drive a shorter distance than Kentlands residents. In a sense, the network system in Radburn is more efficient for both pedestrians and vehicles than the system in Kentlands. Although Radburn's street system makes much use of cul-de-sacs, its efficiency with regard to accessibility is better than Kentlands' street system based on interconnected grids. However, the ratios of driving distance and walking distance are comparable (Radburn: 1.09; Kentlands: 1.10). This means that the driving distance to the shopping center is about 10% greater than the walking distance in both Radburn and Kentlands. This is because each development incorporates pedestrian-only connections in the site plan.

For schools, Radburn's mean air distance (1,627 feet) is somewhat greater than Kentlands'(1,477 feet). The relative closeness of the school in Kentlands applies to both driving and walking distances. However, the drive/air ratio in Radburn is much higher (1.78) than in Kentlands (1.30), while the walk/air ratios are comparable (1.27 and 1.25). This difference is reflected in the walk/drive ratios (0.72 in Radburn; 1.04 in Kentlands). This is due to the use of the superblock and the location of the elementary school, which is situated at the north end of the interior park in Radburn. Interestingly, on average, driving distances are shorter than walking distances in Kentlands. This result demonstrates that in Radburn the link to the school is thoughtfully designed to promote walkability for children.

Concerning parks, Radburn and Kentlands both have parks within comparable mean air distances (Radburn: 289 feet; Kentlands: 283 feet), and in terms of walking distances, both communities have comparable accessibility (Radburn: 410 feet; Kentlands: 396 feet). The parks in both Radburn and Kentlands are very accessible to residents. However, in terms of driving distances, Radburn has a much greater mean distance (935 feet) than Kentlands (461 feet). As a result, the walk/ drive ratios are extremely low in both Radburn (0.09) and Kentlands (0.06). This may be due to the use of culde-sacs and the superblock concept in Radburn; the scattered arrangement of parks in Kentlands would aggravate the discrepancy. In contrast with the ratios for shopping centers, the ratios of walking and driving distance to air distance for parks are higher in Radburn (1.51) than in Kentlands (1.39). This means that Kentlands has a more efficient arrangement for the use of parks than Radburn.

Although Southworth (1997) interpreted the number of intersections in a unit area as a measure of interconnectedness, it also serves as a measure of conflict between pedestrians and vehicles. Compared with the conventional suburban street pattern, New Urbanist developments generally have longer streets and more intersections (which make New Urbanist developments more costly to build and maintain). Thus, the New Urbanist pattern provides more alternatives for drivers and is potentially more explorable than the conventional suburban street pattern of loops and lollipops. However, the greater number of crosswalks also means that the movement of pedestrians is more frequently impeded. This is especially true for children and bicycle riders.

This condition is quantified in Table 3. For each destination, the mean number of street crossings was calculated. As expected, the overall figures are smaller in Radburn than in Kentlands. To go to the shopping center, on average Kentlands residents must cross a street 5.2 times while Radburn residents must cross a street only 2.4 times. To go to school, on average children must cross a street 5.2 times in Kentlands but only 3.9 times in Radburn. The figures for Radburn would be much smaller ifwe considered only the three original Radburn superblocks rather than the current Radburn Association area. The difference is magnified in the figures for access to parks (Radburn: 0.4; Kentlands: 1.6).

The number of street crossings is basically related to safety, especially for children.11 Also, bicycling on the pedestrian ways in Radburn is extremely safe, because there is almost no chance of encountering an automobile. However, safety issues for children bicycling on the interconnected streets in Kentlands are not clear, even though the streets are well designed, and automobile speed is reduced by the narrow streets.12 We should be cautious about conflating the freedom of movement of vehicles and pedestrians. Finer street grids with more intersections would create less, rather than more, walkable environments.

Public Open Space

Radburn's formal park and recreation network encompasses 23 acres (16% ofthe site). The three large parks are landscaped in an Olmstedian style, providing long, green vistas. The Radburn Association also provides a number of facilities: two swimming pools, four tennis courts, four baseball fields, three playground areas, a community center with a gymnasium, and an outdoor stage. Its soccer field and baseball fields serve the larger community. The Radburn open spaces are heavily programmed; families can enroll their children in a preschool program or summer camp or can participate in various cultural activities. The Radburn parks and other common spaces are animated by residents who pass through on the way to shopping, transit, or school; the spaces are enlivened by casual encounters among adults and children who share many activities and common interests.

The superblock concept gives a degree ofownership to the homes surrounding each park, creating a functional subneighborhood unit. Officially, the Radburn parks are private spaces, but they are not fenced or gated and thus are generally accessible to the wider Fair Lawn community, at least on foot. The homes overlooking the superblock parks and recreational fields provide surveillance, making these parks potentially safer than other more public parks.

Kentlands residents enjoy a similar or even higher level of recreational programming than Radburn residents, and this may help to foster the communal spirit. Its park system consists of 100 acres (28% of the site), and each public open space varies in size, shape, and usage. Except for the greenways and lakes in the middle of the site, open spaces of various sizes are scattered around. Among these, the recreation center provides the main gathering and recreation space in Kentlands. Kentlands parks are mostly open to the streets and are designed to function like the squares in European cities. This configuration provides extra vitality (at least at the recreation center), compared with the tranquility of the interior parks in Radburn. Another major difference between Kentlands and Radburn is in the ownership of the open spaces. A significant share in Kentlands' recreational spaces has been deeded to the municipality. The City of Gaithersburg owns and maintains three major public spaces: Quarry Park, the Village Green, and the Kentlands Recreation Center.

Unit and Block Plan

Block plans in Radburn and Kentlands are compatable in terms of size and basic configuration. Radburn's superblock is defined by streets and is about 30 acres. However, the actual "block" unit is defined by pedestrian ways and is about 220 by 400 feet. Kentlands' block widths are about the same as Radburn's, but the lengths vary (see Figure 8). A typical lot in Radburn (45 by 100 feet) is about the same size as the lot of a small detached house in Kentlands (44 by 100 feet). Kentlands' row houses, on about 2,200-square-foot lots, are mixed with single-family detached houses in the same block. As a result, the similar size blocks in both Radburn and Kentlands serve a similar number of units.

Initially, the Radburn plan was intended to provide dual frontages for each house. One entrance would face the pedestrian side, giving quick access to the parks and pedestrian network, while the other entrance would provide convenient service and vehicle access from the cul-de-sac. Internally, the unit plan follows the dualaccess scheme, with the living room, porch, and as many bedrooms as possible facing the garden on the pedestrian-alley side, while the kitchen, garage, and cellar storage are easily accessible from the service lane (Stein, 1957). However, despite the designers' intentions, the pedestrian entrance has decreased in importance; in fact, many homeowners have allowed that access to become blocked (see Figure 9c). Instead, the service-lane entrance has evolved into the primary entrance to the unit, and the service lane has become an active area for vehicles and pedestrians (Figure 9a). As a result, the intended front yard became a back yard. These changes by the residents demonstrate the difficulty of maintaining two main entrances for pedestrians and vehicles.

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In Kentlands, the planners employed a similar dualaccess scheme. Housing units are accessible from both the street and the service alley (see Figures 9b and 9d), although their functions differ from those in Radburn. It may take a long time to ascertain whether Kentlands residents will favor one entrance and disregard the other. However, some preliminary evidence from consumer surveys of the Kentlands development shows that children play in the service alleys (Bradford, 1993). In coming years, Kentlands residents, who are by necessity dependent on autos, may not use the street entrances as frequently as the alley doors, leading to the same problem with dual entrances as in Radburn.

The underuse of the pedestrian path side entrances in Radburn may be an effect of the lower population density and the smaller number of children compared to past years, but it may indicate a more widespread problem. It may be that the relatively low densities in contemporary suburbs makes the division of activity between two entrances inadvisable in any suburban setting, because it draws activity away from the main streets.

Related Issues

As we can easily see, one of the main ideals of the Radburn and Kentlands plans is the walkable suburb. This section deals with three related issues that are not dealt with directly in our analysis: the relationship between walkability and cul-de-sacs, walkability and transit uses, and market acceptance.

Walkability and Cul-de-sacs

Competition between vehicles and pedestrians is a longstanding issue in residential development. The Radburn plan was the first design solution to address this conflict (Southworth & Parthasarathy, 1997). This plan was the origin of many of the local regulations that now govern residential street design. These regulations led to a hierarchical and disconnected street pattern in conventional American suburbs. The obsession with safety eclipsed the other goals embedded in the cul-desac pattern, and thus suburbs have allowed the proliferation of cul-de-sacs without a concern for pedestrian connections, which was the main goal of the Radburn scheme.

The cul-de-sac has an intrinsic traffic-restricting nature, if it is the proper length. A cul-de-sac also fosters relationships among residents, which can discourage careless driving within the cul-de-sac. The 1939 FHA manual Planning Neighborhoods for Small Houses went so far as to state that houses on cul-de-sacs provide the most favorable living environment for families with small children because of the reduced traffic hazard. Unless automobile speeds are kept low, a street is hardly a safe place for young children to play. Our observation of contemporary Radburn confirms this argument. In the 300-foot-long cul-de-sacs in Radburn, vehicles and pedestrians can mingle without any conflict, as shown in Figure 9a. New Urbanist street systems are based on an interconnected grid that allows through traffic, and so one cannot argue that they are more desirable than Radburn's cul-de-sacs for families with young children.

Walkability in Regional Context and Transit Uses

New Urbanists argue that neotraditional designs can reduce the number of vehicle trips and trip distances. They believe that the mixed arrangement of land uses, the higher densities, and the greater number of route choices all contribute to reducing vehicle traffic. One study argues that by shortening trip distances, New Urbanist plans could reduce vehicular traffic by 43% relative to conventional suburban development (Bookout, 1992a). However, several subsequent studies on this efficiency issue did not confirm the arguments (Crane, 1996a, 1996b; McNally & Ryan, 1993). Also, at the regional level, transportation efficiency cannot be improved by on-site connection. Therefore, the remaining issue regarding the New Urbanist grid is its walkability and the possibility of improved social interaction at a local level.

New Urbanists also contend that their schemes will increase transit use. Schemes such as Calthorpe's (1989) "pedestrian pocket" place train stations at the center of their compact developments. Rail transit systems require certain minimum densities at both origins and destinations to be successful (Shaw, 1993). Even with a less expensive light rail system, rail advocates concur that rail transit requires high densities, multiple uses, and limited parking to be economically viable (Henderson, 1994). Cervero's (1994) study of several commuter stations in the Washington, DC, and Atlanta metropolitan areas demonstrates that coordinated joint development of transit stations and office development can be highly profitable to both the public and private sectors. The New Urbanist scheme may improve transit use once sufficient regional connectivity is obtained. However, before completion, possible gains in transit use are obtainable only through improved walkability and proper functional arrangements in the local context of trip origins.

Interestingly, Lee and Stabin-Nesmith (2001) have analyzed the 1990 census data and revealed that the number of transit users in the Radburn area is significantly higher than that in neighboring areas of Fair Lawn. They argue that the generic nature of the Radburn plan, including the TOD type of land use scheme and pedestrian-friendly site design, increases the attractiveness of transit use. This observation supports the New Urbanists' scheme, especially TOD. However, the success of these local efforts to create walkable and transitfriendly communities is predicated on changes in the current regional patterns ofland use and transportation.

Market Acceptance of New Urbanist Developments

The market needs to be interpreted by demand, supply, and the resulting price. First, for the demandside story, there have been several surveys to report consumers' preferences of New Urbanist elements. The success of New Urbanist developments hinges on whether their higher-density development is broadly accepted by the market. Bookout's (1992b) study shows that New Urbanist developments attract only a portion of the market (mostly households of single adults with or without children). Two-parent families with children under 18, major customers in the housing market, do not seem to be attracted to New Urbanist developments. To achieve widespread success, New Urbanist designers and planners must attract these customers. A survey in 1995 by the American LIVES service suggests that although two thirds of the respondents were dissatisfied with conventional suburban developments, only 21% embraced New Urbanist schemes (Rybczynski, 1998). Farnsworth (1998) surveyed more than 2,000 prospective home buyers from the western and southern United States and found that 34% of respondents preferred mixed-product neighborhoods to communities where expensive homes are separated from others. This series of surveys demonstrates that New Urbanist development still needs some improvement to be a major development pattern in American suburbs. However, Kentlands' success shows that there is a potential market for homes at higher densities than many more timid municipalities have allowed in the post-World War II era (Southworth & Parthasarathy, 1997).13

The success of Kentlands has attracted considerable numbers of private developers into the New Urbanist circle. While we can easily observe some developers' high enthusiasm for New Urbanist developments, the majority of suppliers still have some doubts about New Urbanist schemes. In particular, the current real estate industry structure hampers project financing for New Urbanist developments (Leinberger, 1998). Gyourko and Rybczynski's (2000) survey reveals that industry practitioners still perceive New Urbanist projects as riskier than conventional suburban development projects. The main reason for the high risk comes from the mixed-use nature of New Urbanist schemes. The mixed-use scheme raises the complexity of developments and development costs, and hinders the standardization of products. It requires good management skills and design expertise. This situation is very different from that in standardized conventional developments.

In terms of price, Tu and Eppli (1999) analyzed single-family home transactions in Kentlands and surrounding conventional subdivisions between 1994 and 1996 with hedonic price models and concluded that there is a 12% premium (approximately $25,000) for properties in Kentlands. Since the comparative prices are estimated using a constant quality home, this premium is due more to the overall site plan characteristics of Kentlands than to the quality of individual houses.

This market premium for a planned community is also found in Radburn. Lee and Stabin-Nesmith (2001) analyzed the 1997 tax assessor's file in Bergen County, NewJersey, and concluded that in 1996 there was a considerable premium (16%, about $27,000) for Radburn homes (priced around $200,000) compared with both pre-Radburn homes built in the 1920s on gridiron streets and post-Radburn conventional homes. This premium is due to the site characteristics, including wellorganized, pedestrian-friendly environments integrated with shared open space.

Along with the Kentlands case, these results indicate that Americans appreciate the integrated quality of the two planned communities in spite of their higher densities. This suggests that over a long term, suburban developments with even higher densities are marketable. The market still appreciates the integration of high-density development with attractive public space and a complete pedestrian network, as shown by their property value premiums. The two recent studies confirm this argument.

However, some differences between Radburn and Kentlands in market aspects have favorable implications for New Urbanist developments. On the demand side, New Urbanist developments suffer from an insufficient interest of the main group of home buyers (families with children). On the other hand, Radburn was planned for and still has a major portion of residents who are families with children or seniors. On the supply side, a high degree of variation in housing types and styles deters developers from establishing New Urbanist projects. On the other hand, Radburn requires few variations in products. Housing style in Radburn is not a major concern in development. Rather, the overall site plan and its functional integration are advantageous factors. Without elaborate architectural gestures, Radburn achieves market appreciation purely by its functional arrangement. That is, the Radburn scheme shows New Urbanists the way for improvements to achieve a better performance in the suburban housing market of America.

Conclusions

Although the formations of the American Garden City and New Urbanist paradigms have different historical and social backgrounds, both share the same goal of walkable residential environments in America. Their resulting prescriptions realized in Radburn and Kentlands have much in common. Their development densities, mixed land use schemes, and the degree of pedestrian connectivity are all comparable. Especially their block plans, using a dual-access scheme, are notably similar in scale and pedestrian connectivity. However, they certainly differ in the prescriptions of how to achieve walkability in a residential development. Radburn tries to separate pedestrians and vehicles wherever possible, whereas Kentlands puts both pedestrians and vehicles in the same street with some traffic-calming measures and sidewalks. The Kentlands scheme might vitalize the street sides as intended, but its safety is not clear. Inherently, a street for both vehicles and pedestrians cannot easily resolve the conflict between the two types of users. That is why the Radburn scheme was born 70 years ago. The short cul-de-sacs in Radburn are certainly sharable space both for vehicles and pedestrians (even for children). Kentlands cannot be argued to be better than Radburn in terms of walkability.

The mixed land use scheme in Kentlands goes beyond a simple mix of land use and housing types; it requires variety in housing style. As a result, pedestrian routes in Kentlands offer visual interest, with small-scale detail and variety as well as changing vistas and focal points. These visual qualities may not be maintained in other developments. Something functional beyond architectural gestures must draw pedestrians, especially for everyday trips. As discussed above, these architectural gestures backfire in the supply side in the market. In Radburn, there are no extraordinary architectural measures that encourage people to walk. Rather, Radburn residents walk because of the town's functional arrangement; the plan encourages them to walk, with its pedestrian ways cutting through the mid-block parks, its small number of crosswalks, and its close connections to frequent destinations.

The strength of Radburn's plan is such that it has endured with few changes for almost 70 years. In the 1990s, we find quite a few designers and planners who describe themselves as New Urbanists rejecting some of the central ideas of the Radburn plan. Some have suggested that the separate pedestrian ways are unworkable. Instead, they endorse the alley concept, believing that it allows more through traffic and mobility and promotes sociability, while still allowing for demarcation of public, semipublic, and private spaces. But overall, the empirical evidence for Radburn is quite persuasive: A New Urbanist plan is not necessary for promoting sociability, increasing transit use and reducing auto use, or creating a dense, mixed-use neighborhood.

The compatibility between the Radburn and Kentlands schemes indicates how to improve New Urbanist schemes. Integrating Radburn principles with New Urbanist principles in suburban (and urban) development can provide a good mix of residential environments and a wider variety of choices. Our analysis reveals that the Radburn and Kentlands schemes are compatible in terms of pedestrian movements and activities, in spite of differences in the main ideas about how to deal with pedestrians and vehicles. In particular, their basic elements (block schemes) are readily compatible. These conditions allow us to integrate individual elements.

The integration of Radburn elements with the New Urbanist schemes may improve the New Urbanist developments' current lack of market share. Consumer surveys show that families with children do not favor traditional-neighborhood-development neighborhoods (Bradford, 1994). One of the main concerns of parents in selecting a residence is whether there is a safe play environment that is readily accessible from the house. New Urbanist towns do not allow a sufficient buffer area for children's play adjacent to the home, nor do they provide much in the way of private outdoor space. For families, the Radburn model provides greater safety for children while achieving the higher density and pedestrian networks desired by planners.

We are not arguing for a complete rejection of the New Urbanist approach. Rather, we argue that New Urbanist developments need to provide a fuller range of residential environments to attract the whole range of potential customers. Planners and designers should consider the robustness of the Radburn plan, the positive experience of its residents, and its positive effects and integration with the larger community over the past 7 decades.

ACKNOWLEDGEMENTS

This study was partially supported by the Brain Korea 21 project. The authors thank Seong-Hee Kim, Joo-Ho Rhim, Barbara Stabin-Nesmith, and the Institute of Engineering Science at Seoul National University, for their helpful assistance in conducting this research. Thanks also to the anonymous referees who forced us to elaborate and clarify our arguments.

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