Cluster Subdivisions

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Cluster Subdivisions

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The typical postwar development operator was a man who figured how many houses he could possibly cram onto a piece of land and have the local zoning board hold still for it. Then he whistled up the bulldozers to knock down all trees, bat the lumps off the terrain, and level the ensuing desolation. Then up went the houses, one after another, all alike.

John Keats, The Crack in the Picture Window¹

In recent years there has been a search for alternatives to subdivision design practice, which has become conventionalized since World War II. Metropolitan areas have burst forth onto the surrounding countryside, which has been consumed in the wave of suburban development. The "look-alike" pattern of these developments is familiar. Architecture, street pattern, setback, and yard spacing are unvaried. While the phenomenon has been the cause of much comment, criticism, and despair, it has also been a boon to the nation's cartoonists.

The whole problem has been well summed up by William L. Nelson, who observes:

From the standpoint of community design, the scattered disorganization of subdivision development completely destroyed any sense of community cohesiveness; aesthetically even the gracefully curving streets with regularly set back ranch houses began to have a look of neatly landscaped sterility not much less monotonous than the rows of rectilinear streets of the past; the lots designed large enough to handle individual sewage disposal accentuated the sprawling, [and] were often larger than the homeowner wished to maintain. . . .

(Source: Letter to Planning Advisory Service)

It is in this context that the "cluster" subdivision has been heralded as a major breakthrough in suburban development. Planning Advisory Service has received a number of inquiries relating to the merits, the legal basis, and the appropriateness of the cluster subdivision. The publicity given to the "cluster" has aroused a great deal of curiosity, but it has left many questions unanswered and has not spelled out the details.

Several different kinds of schemes have been called "cluster subdivisions." As yet, few have actually been constructed. In exploring the problems involved, Planning Advisory Service has drawn on published plans and commentary and has supplemented this often sketchy information by getting in touch with planners and lawyers who were known to be actively concerned with this type of development. The compilation of their responses has not proceeded along statistical lines, but is rather a presentation of varying points of view. This approach was necessary because each of the respondents has been faced with differences in the layout of the proposals that have come to his attention, the physical characteristics of the area, and the legal underpinning.

What Is a Cluster Subdivision?

There are two features that distinguish what is thought of as a "true" cluster subdivision. The first is a characteristic of design and site planning in which several houses are grouped together on a tract of land. Each cluster of houses serves as a module, which is set off from others like it by an intervening space that helps give visual definition to each individual group. The second characteristic of the cluster subdivision, as it is often proposed, is the presence of undeveloped land that is held for the common enjoyment of the neighboring residents or the community at large.

The conventional method of laying out a subdivision to conform to the lot size requirements of zoning is illustrated in Figure 1a. The technique is ubiquitous and is equally applicable to a grid or curvilinear street system. Each lot is a module. Within it, the structures may be of varied design or virtually identical. When large lots are used it is easier to retain the original character of the land, and much of the open space can be preserved. With small lots, where coverage is greater, siting requirements are apt to be more critical, and may possibly result in drastic alteration of the natural landscape. There are no common areas except for publicly provided recreational facilities and streets, which are used for circulation, parking, and sometimes for play.

Cluster design is illustrated in Figure 1b. The structures are usually oriented toward one another around a crescent, a square, or in an irregular fashion. In many cases the realization of a cluster will necessitate the reduction of frontage requirements, as would happen when lots are wedge-shaped.

Lot size has a bearing on the effectiveness of the cluster itself as a module. With the same structures, the results obtained in using small lots or large lots are demonstrated in Figures 2a and 2b respectively. When small lots are used, the cluster design may be nothing more than a novel method of utilizing the land intensively, but it is hardly an improvement over conventional subdivision design practice. Large lots, with the buildings placed close together, will mean that each group of structures will be distinguishably distant from similar neighboring clusters.

Common land is a feature of many of the proposed cluster subdivisions. In principle, it does not differ from cases where common land has been set aside at the rear of the individual parcels for the enjoyment and use of the owners of abutting property and possibly the community at large. Figure 3a illustrates this kind of scheme. The open space has the effect of separating a house from its neighbor immediately to the rear. But. in this arrangement, the homes are not oriented to produce any sense of community, nor is there any reason to expect that such a layout would improve the streetscape. However, open space in the interior of a block may have its advantages.

In the Far Northeast section of Philadelphia, this type of pattern results where row houses are permitted in what was formerly a 5,000-square-foot single--family district. The zone change is conditional on the dedication of block interiors to form a continuous park strip along stream valleys.

In Figure 3b both characteristics of the cluster subdivision have been combined: the siting of homes in a group so that they have a focus of orientation, and the separation of each such cluster by common land for the use and enjoyment of nearby residents or the community.

The opinion of the respondents to Planning Advisory Service's inquiries was that the use to which the common land is put is dependent on a host of factors. These include the characteristics of the site, its size and location, the needs of the future residents, and the community's need for public areas. The use that was most frequently mentioned was the preservation of the land in its natural condition, especially where there are prominent features such as stream valleys, ravines, and stands of trees. Other suggestions were parks and playgrounds, special recreational facilities, "buffers," and lawns. Most of these uses would also achieve distance between the groups of structures.

Precedents

The cluster concept is a contemporary adaptation of some old principles. The interplay of urban and rural life has been a recurring ideal from the days of the medieval village, when the agricultural base of the community had to be close at hand. Ebenezer Howard emphasized the desirability of having city and country in close proximity, although economic necessity was less compelling than in an agrarian society.

The cluster idea differs from these precedents in that it is the group of houses rather than the town that is enveloped by the natural environment. The greenbelt was the means by which this ideal was realized during the Middle Ages and according to the preaching of Howard. Now the principle is echoed in the cluster, which is a modern adaptation within the development pattern of the American metropolis. In the true cluster, an interlacing system of parks and natural areas can assure that each house lot is adjacent to undeveloped land. Even though there is no greenbelt in Radburn, park land is always close at hand.

The reservation of common property is a tradition, almost taken for granted, which was inherited from the Old World, and practiced in the very earliest colonial period. The village "green" or "common" so frequently encountered in New England towns is a holdover from the days when these patches of ground served as a protected refuge for cattle or as a training ground for the militia. Today the New England common is often a useful and aesthetically splendid park that is sacred in the threat of possible encroachment.

Other design features used at an earlier time are not found in the proposals for cluster subdivisions. One is the cul-de-sac, a means of access rather than a street for circulation, which is intended to serve a limited number of dwelling units. Some proposed clusters utilize this principle, even if the roadway is just a crescent resembling the customary turnaround of these access roads.

Proposals

The cluster subdivision has been hailed as a possible solution to two problems that plague almost every rapidly growing community on the expanding fringes of our metropolitan areas. The first problem is the disappearance of the open countryside; the second, the high cost of "big-lot" land development.

An article in House & Home (September 1959) has pointed out some of the advantages claimed for cluster subdivisions:

1. Cluster layouts preserve the rural character of the land by retaining stretches of open fields and stands of trees, and by leaving brooks, hillocks, and similar natural assets undisturbed.
2. Cluster layouts reduce development costs for areas zoned for big lots by cutting road and utility costs ... [and] ... by allowing the developer to bypass natural obstacles in the site.
3. Cluster layouts meet "big-lot" zoning requirements based on density control....

Other amenities that can be designed into the cluster layout, according to House & Home, are planned privacy, excellent play areas for all ages, and better parking facilities.

Since the cluster subdivision is far from standardized at this early date, caution must be used in drawing any sweeping generalizations based on the analysis of a few proposals. One difficulty encountered in this exploration is the scarcity of drawings that show in detail the topography, landscaping, types of structures to be built, utility systems and, in many cases, scale and orientation. Some of the publicized plans are only schematic.

A "True" Cluster. One proposal, which has been frequently reprinted, is designed by Myron X. Feld of Stephen Sussna Associates for Raritan Township, New Jersey (The American City, July 1959; House & Home, September 1959; New York Times, January 3, 1960). The grid layout as originally submitted to the planning board by the subdivider is illustrated at lower left in Figure 4. This plan, designed to be built on steep, hilly terrain, would have contained 94 lots of about 50,000 square feet serviced by approximately 12,000 feet of new roads. The consultants improved the plan by employing a curvilinear pattern (lower right of Figure 4) providing for 96 lots with a small saving in road length. However, Feld states that "any development with lots side by side and back to back is still residential and inconsistent with the rural character that these communities would like to maintain."

An alternative plan, the "cluster," shown at top in Figure 4, was developed in order to overcome these difficulties. On the same tract of land, 15 clusters of six lots arranged in a semicircle around a central plaza, were connected by two sweeping roads, with a reduction in total length of roads to about 6,000 feet. Maintaining approximately the same number of building sites, the initially large lot sizes were reduced to 3/4 acre. About half the acreage was to be left as natural undisturbed park or commons to act as a green barrier between clusters.

In this example of a "true" cluster, one of the goals was to incorporate amenities that were beneficial to the community and to the future residents of the development. Among the features to be included were provisions for off-street parking, and a landscaped plaza. The interior area was to be preserved in its natural condition as a "wanderland." Although the illustration does not show these developments in detail, it is evident that where there is a large proportional reduction in lot size, there is a great deal of flexibility for choosing from among a number of desirable space "consuming" alternatives for the use of the common property.

Economies in the length of streets and utilities are realized by reducing frontages of the individual lots and by building upon superblocks and eliminating the need to serve the interior acreage. Further savings can be achieved by siting the clusters to avoid natural obstacles such as boulders or streams, thus reducing the cost of site preparation and helping to preserve the rural character of the land.

Density Control. One of the essential characteristics of the cluster subdivision is the preservation of some part of the tract in its natural condition or the development of a park. A developer may achieve this effect by electing to leave some areas free of structures where he would be entitled to build under the zoning regulations. However, most developers feel compelled to build the maximum allowable number of structures on a tract. Some ordinances permit the subdivider to reduce building lot sizes below the specified requirements on the condition that the residual parcels gained by using smaller lots will be devoted to a common area that is free of structures. This method is, in effect, a way of controlling density while allowing flexibility in layout, as was demonstrated in the Sussna proposal. Ordinarily, minimum lot area per dwelling is required, but density can also be controlled by specifying a maximum number of family units per area.

One zoning ordinance that employs this technique is that of Rockaway Township, New Jersey (1959), which allows lot area (but not lot width) to be reduced if the following conditions are met (these provisions are not specifically designed for clusters):

1. The lot size is not reduced less than 12.5%.
2. The population density is no greater than if the tract were developed with 20,000 square foot lots.
3. The subdivider dedicates for public purposes the same percentage of the entire tract as that by which the lot area has been reduced.
4. The area dedicated for public purposes is in a location and shape approved by the Planning Board.
5. No area to be dedicated for public purposes shall be less than ten acres.
6. The plan on the reduced lot sizes is only permitted if it is mutually agreeable to both the township and the subdivider.

Figure 5a is the original proposal and Figure 5b illustrates the effect of the density control provisions.

The result, from a design point of view, may in no way resemble what is commonly thought of as a "cluster" subdivision. (In fairness to the designer, this development was not intended to be a cluster subdivision.) Although the community and the subdivision may be improved by dedication of sizable tracts within the development, there is little to distinguish this plan from that of the conventional subdivision.

In this case the parcels are dedicated for park and school sites, with a portion reserved for an enlarged shopping center. When the saving in land is to be used for what is clearly a public purpose, it is reasonable to ask whether such density control is not just a method of getting around the areal requirements of the zoning ordinance, since public facilities will be needed whether the lot size is 20,000 square feet or 17,500. In other words, by awarding free land to the municipality for public purposes, the subdivider is allowed to build more houses than he could if there were no change in the lot size requirements and if the city accepted full responsibility for the provision of school and park sites. This type of concession has the effect of increasing density beyond what was originally anticipated.

"Golf Course Subdivisions." Closely related to the cluster idea is the so-called "golf course subdivision" exemplified in Figure 6. The fairways are located in the interior of the blocks. Homes are built in the conventional side-by-side manner, but the rear lot lines adjoin the golf course itself. One reason for building this type of subdivision is the additional value imputed to each lot, which, according to a study by the Urban Land Institute has been estimated at approximately $2,000 for an average lot (Urban Land, September 1958). When the common area — in this case, a golf course — is a revenue-producing property or so increases the value of adjacent property, there seems to be no compulsion to reduce lot area requirements as a "bonus" for providing the facility. In suitable situations, the heightened property values, stabilized over a period of time, seem to be reason enough for departing from conventional site design practice.

Mixed Housing. A further development of the cluster idea leads to the conclusion of varied housing types on the tract of land under consideration. A multi-family building is in one sense a very tight cluster of dwelling units. Figure 7 illustrates a plan set forth by Nelson-Ball and Associates combining single-family detached houses, row houses, and a high-rise apartment building.

This subdivision would have a total of 130 dwelling units, 5,700 linear feet of streets, and 6,300 linear feet of sewer mains, and would feature a pitch--and-putt golf course. Under existing zoning regulations, the same tract could be laid out in a curvilinear pattern with 108 lots and 11,400 linear feet of streets and utilities. Density is actually increased in the example shown, although more land is free for community use. The proponents of the development claim that smaller lots (with common land) and variation of housing types conform more closely with what is actually desired.

DESIGN FACTORS

In relation to the total volume of residential development, very few developments have employed the cluster principle — the close grouping of houses set off from similar groups by an intervening space held in common ownership or by the public. It is premature to base judgments on the few finished products that exist in scattered locations, especially when each of these subdivisions has such an individual character.

Therefore the approach will be to identify the groups that have an interest in any residential development, and to see whether a cluster subdivision has the potential for satisfying all interested parties. It is possible to indicate which factors have a bearing on cluster design and to point out the possible objectives that may be accomplished in a cluster development by examining the claims that have been made.

Interested Parties

In judging a proposed subdivision, it would be well to review the impact that it will have on all interested parties. The effects of a cluster design may become more apparent when weighed against the conventional form of development.

Foremost among groups interested in the final form of a new subdivision are the eventual residents of the development. Generally, these are people interested in having an attractive place to live. Often they are city dwellers who have felt a strong desire to live in the suburbs where they can be near open space which they, and especially their children, can enjoy. They will look for a metropolitan location which is as convenient as possible for the family. In addition, potential residents of a new subdivision will seek good schools, recreational facilities, and convenient shopping. Although prospective homeowners may not be aware of alternative methods of site design, it is probable that they will appreciate superior layouts when they see and experience them. If the cluster subdivision indeed fulfills the claims of its proponents, it should be a persuasive factor in the housing market.

All of these considerations must be examined in the light of a family's ability to pay, and most buyers will seek economy in cost and maintenance. As the future residents are not on hand during the planning and building stages of a new development, their interests must be considered and protected prior to their arrival.

The property owners already established in areas adjacent to the proposed subdivision will also be interested in the eventual form of the new development. Among their objectives will be the preservation of amenities that were previously found in the neighborhood. It is not an unfamiliar thing to hear long-time residents of an area lamenting their loss resulting from the destruction of field, hill, and vista that accompanies the erection of a new subdivision. Persons with a constructive outlook will be concerned with the form that the new subdivision will take. With development, new amenities can be created in the neighborhood that will provide residents with visual and active enjoyment. The interests of nearby residents will be expressed in existing zoning regulations, which may be reflective of the desire to maintain property values. But in the light of contemporary construction techniques and costs, the zoning ordinance should be examined to see if it will actually allow the desired result. Innovations in siting may go a long way toward creating interesting attractions when the motif of housing design has become so standardized.

Recognizing that there is a housing shortage and that there exists a widespread desire for suburban living, entrepreneurs — subdividers and developers — are interested in making a profit. To do so they must have a product that is salable in a competitive market. The entrepreneur, therefore, will be concerned with the standards embodied in subdivision regulations and zoning ordinances, since they have a bearing on costs and design possibilities. In addition to the profit motive, the developer may wish to create an outstanding product as a means of satisfying his pride and performing a service to the community.

It is now fully recognized that the community, acting through the local government, has a stake in any form of development that takes place within its boundaries. It will be concerned with the health, safety, and general welfare of its citizens, and — equally important — the cost of those responsibilities that are accepted by the government. The community expresses its intentions by setting up standards for development, by staking out areas of public interest, and by striving to keep public expenditure at a minimum. At the same time, the community should take steps to insure that new development will continue to be desirable in years to come and that property values will be maintained, providing a continual flow of tax revenue.

The planning agency, in concert with other departments of the local government, is probably in the best position to determine the effect that any proposed development will have on all the interested parties. In considering a new subdivision, it will have to determine whether the proposal conforms to the intent of the existing regulations, and whether the existing regulations will permit the best possible form of development.

The inhabitants of the region form another group that shares an interest in the form of development that occurs. These are people who will witness change, for the better or for the worse. As passers-by, they are concerned with the visual impact of new development on the landscape. Where natural features exist, they will be interested in knowing whether they can continue to enjoy the view of hills, streams, fields, and forests. Finally, the use of the land will influence the economic activity of the entire region. Both on the local and the regional level, provision should be made for circulation and for protection of what is justifiably the public interest; through the instrument of the comprehensive plan.

Determinants of the Tract

Any tract of land in its natural state has characteristics (topography, soil conditions, prominent features, and orientation) that will suggest a particular form of development. Some persons advocate doing the least violence to the site as it exists in its predeveloped state; at the other extreme are those who favor any development within the limits of modern engineering technique — that is, practically no limit at all.

Land, on the other hand, can range from relatively characterless but buildable terrain to parcels that are liberally studded with interesting natural features, but which might have the effect of inhibiting development. For example, in the flat lands of the midwestern states, there may be no compelling determinants of the site to suggest that homes be built in clusters. On the other hand, rolling terrain might be characterized by heavily wooded areas, relatively steep slopes, water courses, and prominent rock outcrops. This kind of terrain would indicate, first, that the entire character of the area would be altered through expensive grading and indiscriminate leveling of forests, and, second, that such an operation would be uneconomical. In this case, natural features would suggest the desirability of clustering the structures, for aesthetic reasons and for economy.

Technical Determinants. Zoning ordinances, subdivision regulations, and building codes reflect the technical requirements that are necessary for the health, safety, and general welfare of the residents of a particular area. In a fundamental and direct way, lot area requirements may be derived from the technicalities of sanitary engineering; yard requirements from adopted standards for light and air, and for protection against fire; off-street parking from the necessity of providing a workable circulation system, and so forth.

In all cases the technical requirements necessary to achieve an adopted standard should be embodied in the community's regulations, but it may be discovered that the standards embodied in code and ordinance are considerably in excess of the technical necessities. Large-lot zoning is a case in point. In contemplating a cluster development, it may be entirely reasonable to relax the adopted regulations to the minimum which is imposed by technology. For example, in a particular cluster design, yard requirements based on standards for light and air and fire protection may be achieved equally well through innovations in orientation, building materials, and housing design, without strict adherence to existing yard requirements.

A particular problem that arises in connection with the cluster subdivision is the establishment of proper individual lot sizes when public sewer and water facilities are not available. Opinion among the respondents to Planning Advisory Service's questionnaire ranges from the conviction that individual sewage disposal systems should be contained within the lot to the opposite viewpoint that the common open space could be used for drainage fields.

The principle variables in planning for sewage disposal are design, topography, soil, lot size, and the possibility of connection to the community system. The most widely held view is that the individual lot should remain the standard for independent sewage disposal systems, especially where there would be any conflict with the use of the open space due to surface runoff, pollution, odor, and maintenance operations.

Proper planning, regardless of the type of subdivision, will reflect the technical requirements necessary to accommodate the activities that are expected to occur in any particular development. But other considerations are also taken into account in planning.

Social Determinants. Social values are by their nature reflected in the processes of planning and politics. Over and above the technical requirements mentioned, zoning incorporates an elusive but valid idea concerning a way of life. In more familiar terms, one speaks of neighborhood character, its preservation, or possible changes that may occur. Residents may wish to perpetuate attributes of existing development in new subdivisions. For example, in large-lot zoning, where the land area is far in excess of the needs of independent sewage disposal systems, the zoning requirements may in no way be derived from accepted technical requirements.

In many cases, existing regulations do not permit a cluster subdivision, even though such development would achieve an effect similar to that which is sanctioned by the community. Several attempts have been made to draw up regulations that would enable cluster subdivisions to be built. These will be discussed in a later section.

Objectives of Cluster Subdivisions

In the absence of widespread experience with cluster development, we must evaluate the claims of its proponents from illustrations and commentary that have appeared in periodicals. Of the proposals reviewed, the objectives vary, and it is evident that there are limitations in each case. Furthermore, choices may have to be made between mutually exclusive goals.

What advantages are claimed for the cluster subdivision?

Preservation of the Rural Character of the Land. The proponents of the cluster claim that it preserves the rural character of the land by retaining the natural features of the tract, including wooded areas. Some would go so far as to say that the cluster is a way of saving the open countryside. The cluster subdivision is not a greenbelt, however, and according to present thinking it can be built up to at least the density that is possible under conventional zoning. In most cases this density would not be considered open countryside.

The first new development in an area, cluster or otherwise, may give the illusion of being in the open country, but it is always possible for subdivisions to follow, swallowing up the open country. On the other hand, careful planning of a cluster subdivision will allow rural features to be retained if only on a small scale. Grouping structures in concentrations does allow larger portions of the tract to remain undisturbed, just as large-lot zoning (say 3- or 4-acre plots) implies that large portions of the property will be left in their natural condition, whether woodland or pasture. At higher densities the cluster is a promising method for the retention of the rural characteristics of an area. In many cases the pleasing natural features of the land will coincide with the portions needing the greatest degree of site preparation if developed. Thus, the developer and the community may have added incentive to approve the cluster idea, knowing that the rural character will not have to be completely sacrificed.

Economy. The flexibility permitted by cluster design may be the source of considerable economy in the initial investment and maintenance costs. In the first place, land that is thought to be unbuildable, or difficult to develop, may command a lower price than prime building land, or land used intensively for some other purpose, such as agriculture. However, the cost of raw land of this type may rise once it is realized that the potential liability of poor but aesthetically pleasing land can be turned into an asset.

Secondly, the need for extensive site engineering is reduced if the subdivider suffers no penalty by leaving some portions of the tract in the natural state. The best sites for building can be used for the clusters, obviating the need for extensive grading; trees can be left where they stand, enhancing the subdivision. Because a relatively large proportion of the tract in a cluster subdivision need not be served by streets and utilities, their linear footage can be substantially reduced from what would be needed in the conventional subdivision. In the "true" cluster designs reviewed, the length of these facilities has been reduced from 40 to 50 per cent.

Incorporation of Special Facilities. Most of the cluster designs reviewed include either special features for the benefit of the residents or sites for public facilities. These distinguishing characteristics of the cluster can vary considerably both in the activity that is accommodated and in the formality of the arrangements.

If the facility is used by and benefits only the owners of abutting properties, it is similar to "pooling backyards" for a common purpose which would be merely an extension of what each lot owner might choose to do on his own land. The limits placed on the feature or activity occurring in "pooled" backyards would be the same as those placed on accessory uses in that zone. When the facilities are constructed and used in common, there is the further problem of legal responsibility for the tenure and maintenance of the common property (a point to be discussed in a later section).

A second type of situation exists when a special facility is designed and constructed where the land is subdivided, but operated as an entity separate from the residences themselves. An example would be a golf course, a swimming pool, or tennis courts provided for the residents of the subdivision, or operated on a commercial basis whether or not the service area coincides with the development itself. In the latter case, permission to include the facility in the development would seem to depend on whether or not it is allowed as a principal use in that district. The question of reducing the lot area requirements to accommodate the area needed for the facility would have to be considered individually in each case. As yet there are few precedents upon which to rely, or even evaluate.

If there is a public interest in the tract, the solution would be to dedicate the land, which would then be subject to the same control as any other municipal enterprise.

In all cases, judgment in relation to a special facility should be based on the criterion of whether the community — the residents and the public — is better off as a result. Undoubtedly there will be conflicts of interests, for there is bound to be a variety of opinions as to what is "good," what is needed, and what is wanted. It is unlikely that any limited tract of land could accommodate the pet projects of all the interested parties. The potentialities of the cluster subdivision for accommodating special facilities do not make it a cure-all for environmental deficiencies. Alternative uses for the common land should be examined and the choice made before the wheels are set in motion.

Variety in Design. The cluster represents a departure from the conventional practice of laying out lots side by side, with rear property lines adjoining. In change there is variety. If, however, cluster subdivisions are built on a large scale, there is no guarantee that a similar type of monotony will not result, especially if but a single housing design is used with the usual minor variations. What is sought by house buyers is identity — individual expression — rather than variation for its own sake. Even in the monotonous subdivisions constructed in past years, identity exists within the walls of the dwelling. On a larger scale, identity cannot be formulated, but must grow out of a forceful plan for the subdivision, the locality, and indeed, the region. The cluster, rather than the individual house, then becomes the module of boredom.

The cluster does open up an avenue of flexibility that will enable site planners, landscape architects, and subdividers to take greater advantage of the site characteristics. But in this discussion it should be assumed — until it is otherwise demonstrated — that housing types will have no more variety than in any other subdivision. Nevertheless, design possibilities are unlimited; and insofar as each cluster would be somewhat secluded from its neighbor, these subdivisions may encourage more interesting architectural treatment. A developer might turn a different architect loose on each cluster within the context of his overall plan. Another possibility is for a cluster of six houses to have six designs that could be repeated in other clusters. The most significant thing about the design opportunities in cluster subdivisions is that the cluster itself is a small planning unit which allows each grouping to be treated individually.

Privacy and Sociability. It is claimed that both privacy and sociability can be realized in the cluster subdivision. Actually, this achievement is completely a matter of siting within the group and the design of the houses themselves. Beginning with the principle that distance increases privacy and proximity encourages sociability, it is possible for both characteristics to be incorporated in a cluster. In a semicircular design the facade of each house is brought closer together than if the houses faced the street directly, and oriented toward a focus common to all houses in the group. Siting in this manner is more likely to encourage social relationships within the cluster. There are some who would take positive measures to promote social intercourse among neighbors, but with the caution that certain forms of contact can become irritating.

In contrast to the desire for sociability, each family has a corresponding need for privacy. In urban living, privacy is achieved within the confines of the dwelling unit, whereas in a rural environment the presence of space allows outdoor seclusion as well. Between these extremes the potentiality of landscaping permits imaginative possibilities for the creation of open-air private spaces. As will be seen in Figure 8, the cluster layout facilitates the creation of private areas since the rear lot lines of the individual lots abut the common property rather than a neighbor's backyard. If the common is not intensively used, at least one orientation is effectively devoid of human activity.

Lot Size. Large-lot zoning is a method by which semi-rural character can be preserved and density kept low, thereby limiting the need for public services that are related to population rather than space, such as educational facilities. But large lots may impose upon the home owner a heavier burden of yard maintenance, which may be more extensive than desired. The proponents of the cluster subdivision claim that individual lots need not be so large, for the cluster achieves the same effect as large-lot zoning by leaving the intervening spaces in common ownership. This solves the problem of maintaining low density.

It is further claimed in some quarters that the smaller individual lots in a cluster subdivision correspond more closely with the maintenance burden which the homeowner is willing to assume. The fallacy is that someone must assume the responsibility for the common property. Unless it is dedicated to the public, the cost of the raw land and the expense of upkeep will eventually be passed on to the homeowner. There is some consolation in that the body responsible for the maintenance of the common property — either a property owners' association or the public — may be able to realize economies of scale in exercising control over an extensive tract of common land.

CLUSTER SUBDIVISIONS AND ZONING

The cluster subdivision is the exception rather than the rule. There are no zoning ordinances that spell out in detail the standards to be applied to the cluster, and a review of the few proposals available indicates that the layout and the objectives vary widely in each case.

In general, conventional zoning ordinances do not permit the construction of a true cluster. Many of them do permit planned developments of housing groups, however. There are enough similarities between these developments and the cluster subdivision to make a comparison between them worthwhile, and to see if group housing provisions can be adapted to allow the cluster.

Before the cluster became so widely publicized, "planned development provisions" were examined in detail in Zoning for Group Housing Developments, Planning Advisory Service Information Report No. 27, published in June 1951. More recently, these provisions were further reviewed in an article entitled "Zoning for Planned Residential Developments," by Eli Goldston and James H. Scheuer, published in the Harvard Law Review (December 1959).

Planned Development Provisions

Recognizing the sometimes restrictive effect of conventional zoning regulations, many jurisdictions have adopted some sort of planned development provisions that allow a reviewing authority broad discretionary powers based on standards which are, in most cases, set forth rather vaguely. New York State enabling legislation is cast along the following line:

The planning board may, when approving a plat and after a public hearing, make any reasonable change in the zoning regulations to have them conform with the plat of a new subdivision, provided this authority is given by the legislative body. It may also permit variations in density of population in accordance with a building plan not exceeding that permitted under the zoning regulations. The planning board can use its best judgment along the lines of the plan for the future development of the community, and apply the existing zoning ordinance to the new subdivision without having to go through the complicated procedure of amending the ordinance.²

Accordingly, the planning boards in this state may, at their own discretion and after a public hearing, modify the existing zoning ordinances within the limits that may be imposed by the local legislative body. With such a constitutional green light, the conditions of approval may be spelled out.

Regulation of planned developments can proceed in two directions. The first is to grant wide discretionary power to the reviewing authorities, which may include the planning board, the board of zoning appeals, and other municipal departments. The intent of the zoning ordinance as it stands, especially the provisions applicable to the zone for which the development is proposed, is used as a basis for modifying the existing regulations. In discussing review procedure, Goldston and Scheuer state:

It is assumed that whatever discretion the community has been willing to grant to its board of zoning appeals or planning commission, and whatever procedural safeguards it has established in the way of public hearings and written administrative determinations for other conditional uses ... should be sufficient for final decision on planned developments.

An alternative approach, which minimizes the role of the reviewing authority, is to spell out in detail the conditions under which planned developments will be permitted, and the standards that must be met by the developer.

There are dangers in employing either approach in the extreme. Without specific guidelines, total reliance must be placed on the good judgment of the persons in administrative positions. A lay board must have an adequate technical staff to review in detail an application for a planned development or to consider the consistency of a particular proposal with the city's master plan.

But ordinances have been held illegal, because administrative boards have been granted discretionary powers without clearly apparent standards. There always lurks the possibility of political pressure which can more easily sway decisions in the absence of specific regulations.

On the other hand, detailing standards may freeze cluster developments in a form that is acceptable when the regulations are drafted but may not be in the years to come. The best solution seems to be a set of appropriate standards for planned developments supplemented by some form of review, since it is impossible to anticipate all future innovations.

The reviewing authority may approve an application, reject it, or prescribe further conditions before granting approval. The major question is what factors should be spelled out in the regulations, for the intent of the zoning ordinance is not always clear, and determination of equivalents may be difficult when forms differ.

Among the provisions which have been included in ordinances allowing planned developments, the following seem applicable to the cluster subdivisions:

1. Density. Local regulations generally indicate that the density of the planned development shall be no greater than that which is allowed under conventional zoning. Occasionally a bonus is granted to the subdivider if he meets certain conditions laid down by the municipality, such as dedication of land for special purposes.
2. Minimum area. Many ordinances require a minimum size project for a planned development. The range runs from less than 1/4 acre to 50 acres, with 10 acres being the most common figure. The minimum project size can also be established by the number of buildings or dwelling units. A minimum area provision may be desirable to discourage the use of the exception for planned developments as a substitute for a hardship variance.
3. Character of development. A common but vague provision, which is found in most ordinances that allow planned developments, requires that the character of the project be substantially the same as would be allowed in the original zone, or at least that it shall not be detrimental to uses in that zone. The language is typified by these ordinances:

The proposed development must be designed to produce an environment of stable and desirable character.... (San Francisco, 1960)

(1) ... the uses permitted by such exception [planned developments] are necessary or desirable and are appropriate with respect to the primary purpose of the development; (2) the uses permitted by such exception are not of such a nature or so located as to exercise a detrimental influence on the surrounding neighborhood. (Chicago, 1957)

... such development will create an attractive residential environment of sustained desirability and economic stability, compatible with the character established for the area by the community general plan. (Mequon, Wisconsin, 1960)

General as these regulations may be, they serve as a basis for judgment in the light of facts that may be revealed while the project is being reviewed.

4. Location of open space. Open space may be designated in the comprehensive plan of the community or it may be included at the option of the subdivider. Few ordinances spell out any standards for. the location, or orientation of open space, but say merely that its appropriateness is one of the factors that will be reviewed.

The Chicago provisions state:

that the minimum lot area per dwelling unit requirements ... shall not be decreased by more than 15 percent ... and that there shall be available to each residential building and immediately adjacent thereto (including the land area upon which it is erected) the minimum amount of land area required for such building under the lot area per dwelling unit provisions.

By implication, some ordinances predetermine the character of the open space and its location by setting the conditions for the orientation and relationship of buildings where bulk is a significant factor. These regulations remove some of the flexibility which is given to the designer of a cluster subdivision where building mass is not as crucial as in the case of multi-family units.

5. Periphery. Many ordinances make specific provisions to assure that development at the edges of the project conform with the requirements of the original zone so that there will be a gradual blending between the character of the new project and that of uses outside it. This is done either by defining the permissible border of the "lot" in a planned development or by stating that certain dimensional requirements must be met on the edges of the project.

The Stamford, Connecticut, ordinance (amended to 1958) does both:

The parcel or each part thereof that is separated from every other part thereof by public streets, shall be deemed a lot for the purposes of these regulations.

No building contiguous to property in other districts shall have a front yard or a side yard less than specified in the Schedule of Requirements ... for the contiguous district, or a side yard equal to one half the height of the building; whichever is greater.

The Chicago zoning ordinance states:

that along the periphery of such planned developments, yards shall be provided as required by the regulations of the district in which said development is located.

6. Recreation areas. Few ordinances spell out the requirements for recreational facilities in detail. Instead, they often state that judgment will be based on the specifications of the comprehensive plan.

The San Francisco regulation states:

It must include provision for recreation areas to meet the needs of the anticipated population or as specified in the Master Plan.

Stamford, Connecticut, is more specific:

Areas for playground and other recreational purposes, appropriate in location, nature, and size to the type of residential development and the prospective population density thereof, but in no case consisting of less than a total of 200 square feet of space for each dwelling unit served, shall be designated.

7. Parking. Most ordinances require that the same provisions be made in the planned development as are called for in the original zone.
8. Single ownership. In order to insure overall planning of the project, and to guarantee that the development is built as planned, some ordinances require that application be made by a single owner or a coordinated group. Permission to undertake a planned development may be revoked if progress toward completion is unsatisfactory according to provisions agreed to by the developer and the local authorities at the onset.
9. Subsequent fragmentation of project ownership. Although a planned development may be built by a single owner who may sell or rent the dwelling units, it is highly probable in the case of a cluster subdivision that the units will be sold individually at some time, if not immediately after construction. If individual lots are not shown on the plat, there should be a plan for subsequent fragmentation of the project, with arrangements for maintenance of the common land and facilities.

In answer to the questions asked by Planning Advisory Service, the respondents were in general agreement that planned development provisions, where they are in existence, would be adequate for the accommodation of the cluster subdivision. They urged caution in regard to the arrangements concerning the common land (a subject that will be taken up in a later section).

Criticism of the planned development provisions as a vehicle for the cluster subdivision can arise in relation to the two fundamental aspects of the enabling ordinances: the review procedure and the standards for development. William L. Weismantel points out that: "St. Louis County experience has shown that the requirement of a hearing and subsequent ratification has proven a substantial deterrent to the cluster subdivision." The developer may regard the review procedure as an additional liability and for this reason favor the conventional subdivision rather than the cluster.

From another quarter, William L. Nelson says that the planned development provisions which would permit cluster subdivisions would not provide the regulations necessary to insure their proper development. It is important to recognize the need for very precise and detailed delineation regulatory standards and controls for such group projects. He says, "... We have already seen studies purporting to be ‘clusters' which reveal an obvious lack of understanding or design competence and are in fact nothing more than poor imitations of some of the facets of cluster design which have been published...." Recognizing that the term "cluster" has no magic within itself (and very little that is precise), he points out that planning boards and governing bodies "in evaluating projects submitted to them must continue to use their good common sense and aesthetic standards in determining the quality of a proposal, no matter what name it is given."

"Cluster Zoning"

It is evident that while the planned development provisions have evolved as a means of introducing flexibility in the zoning regulations, they have not been specifically designed to accommodate cluster subdivisions. There have been, however, some recent innovations in zoning for clusters.

Guilford, Connecticut, has adopted an amendment to the subdivision regulations with the express purpose of permitting cluster development. In an article, "Open Space in Subdivisions" in the Connecticut State Journal, James Frost has explained the purpose and evolution of the new provisions. The regulations maintain the density permitted in the zone while allowing a reduction in individual lot size, which is spelled out. The remaining land, not contained in the building lots, shall be usable for recreation.

To date, perhaps the most carefully worked out provisions allowing cluster development are contained in a proposed amendment to the zoning ordinance for St. Louis County. (The provisions are reprinted in Appendix II.) The section entitled "Density Development Procedure for Single Family Residence Districts" takes the crucial question of lot size into account. Prior to application, the subdivider computes the number of lots he will be permitted to develop. After subtracting certain portions from his tract, such as land within flood plains and that which is not available to him due to easements, he then subtracts a given percentage of the remainder for street right-of-way (whether or not it is actually used for the right-of-way) and divides the area now remaining by the minimum lot area requirement of the district. The result gives the number of lots that may be established on the tract. Individual lot sizes may be reduced below the requirements of the district, provided that the average, including any common open space, does not fall below the district requirements.

There is considerable latitude in the use that may be made of the common open space, so that it may still qualify in computing the average (see Appendix II, Section 5). The amendment specifies the minimum area to which individual house lots may be reduced in any district according to a sliding scale that depends on the original requirements of the district.

PROBLEMS ASSOCIATED WITH COMMON PROPERTY

The cluster subdivision represents a departure from the usual subdivision practice in that it may include land devoted to neighborhood or community use and enjoyment — in addition to the individual lots, streets, and sites for public playgrounds, parks, and schools that are customarily found in conjunction with any subdivision. The presence of the common land gives rise to problems of ownership the use of the land, and its control. There must be a governing body capable of making and carrying out decisions on these matters, and charged with the continuing responsibility for maintenance and police protection. Adequate legal arrangements should be made to guarantee the integrity of the common land.

Ownership

The common property in a cluster subdivision may be held in private hands, under any one of a number of arrangements, or it may be dedicated and held by the public. It is important for a community to determine to what extent there is a public interest in any land that can be subdivided. This interest can be determined before subdivision is contemplated and indicated in the comprehensive plan. For example, the community can decide in advance which hilltops, which ravines, which stream valleys, which park sites will be retained as common open space for the various future subdivisions (or for the community). The advantage is that open spaces will be continuous or according to a community-wide pattern, even though they are not in public ownership. However, this procedure involves a great many unanswered questions of method and law which have been most fully explored by William H. Whyte, Jr., and Shirley A. Siegel.

In general, the test of whether the common property should be in public or private hands is whether the area is so located as to benefit more than the contiguous area and the property owners living therein. Even though the com-munity may not have indicated in the comprehensive plan that there is a public interest in a given tract, it may be discovered that the public can benefit from the development that takes place on it, and that the common property should be held by the city. This situation is exemplified by the creation of a playground that will be open to use by the entire community.

There remains an unanswered philosophical and political question, which is to what extent the local government should assume responsibility for environmental amenities in residential areas serving only a few families. In appropriate situations, the virtue of dedication is that the property will be maintained by an impersonal authority, avoiding the necessity for establishing an association of neighboring property owners. The dedication of common open space may also result in maintenance economies, since most cities and towns already have tractors and commercial lawn mowers, and deploy trained operators to handle such equipment.

There are disadvantages in dedication, however. First, it may destroy the exclusiveness of the common open space, as well as the feeling of seclusion. Second, whether or not a special assessment is levied, maintenance is subject to the vicissitudes of municipal budgets, priorities, and administration. Third, it has been suggested that public ownership might be objectionable because it would invite pressure for improvement of land which might better lie idle in its natural state. Finally, unless large or contiguous parcels are dedicated, the municipality may be unable to maintain the land in a satisfactory fashion at reasonable cost.

There are two points of view regarding the restrictions that should be placed on municipally owned land. One is that open space should never be used for anything else. The advocates of this idea believe that the only way to guarantee this result is to include a clause in the deed stating, in effect, that if the dedicated land is ever used for other than the intended purpose, it will revert back to the previous owner. The other viewpoint is that the municipality should not be bound forever in the use that is made of the property, and that it should be held without encumbrance.

The subdivision regulations of Guilford, Connecticut, make explicit the conditions under which the common land may either be deeded to the town or held in corporate ownership. The relevant provisions are reprinted in Appendix III.

Private Tenure

When the entire project is held in a single ownership, the problems associated with the common open space are greatly simplified. As in a high-rise or a garden apartment project, the tenants have certain rights and responsibilities with regard to the common facilities; these are written into the lease. Maintenance costs are a factor in the rents, and the owner is able to assume control over the use and upkeep of the area on the basis of decisions that he himself makes. In small projects, which do not warrant on-site management, difficulties in administration and maintenance of the common area are likely to arise.

The cluster subdivision, as it has been considered in this report, is usually not a rental project, but one in which single lots are held by individual owners, with common property that is held for the benefit of either the community or the project residents. If, according to the previous criteria, the common space is not appropriate for dedication, and is not retained by the developer (and this is highly unlikely unless the developer sells only the structures and retains title to the land), the responsibility must be transferred to some private body.

There are several ways in which the common property can be held. The simplest is merely to extend the individual lot lines to include the common open space. Appropriate restrictions can be placed upon the use of the land through covenants or easements. A second method is for the ownership of the common open space to be vested in all the property owners. With each deed would go a "perpetual, undivided, proportionate interest" in all the common space associated with the project. The owner would not be able to determine which portion of the open space is "his." Both of these methods define and make explicit the relationship between an individual lot and the entire associated common area.

Another method is the creation of a nonprofit community corporation in which the title to the common land is vested. Individual lot owners are given a voice in the affairs of the corporation by means of voting rights, which can be distributed one to a family, on the basis of land area, or on the basis of assessed value. Membership in the corporation can be made a right and a condition of purchase such that interest in the common space is not severable from ownership of the residential parcel.

No matter what form of private tenure is used, one of the practical problems will be launching the project at the time of its sale to individual lot owners. One of the early experiments in which restrictive covenants were used in con junction with privately held common land was in Radburn. There, arrangements were made for a property owners' association to operate from the beginning.

A section of the Protective Restrictions, published in 1929, states:

Residents Will Control

For the present, until Radburn is a more fully developed community, the members of The Radburn Association are the nine Trustees named in the Certificate of Incorporation and such other persons as they may elect to membership. It is the expectation of City Housing Corporation and of the incorporators of The Radburn Association that as the population of Radburn increases and the residents and owners organize themselves, the right to designate one or more Trustees of The Radburn Association will be given to their representatives, and that eventually the entire administration of and membership in The Radburn Association will be in the hands of the residents and owners or their representatives.

William K. Brussat, in an article in Landscape Architecture (Spring 1960), discusses the problem of establishing an organization for control of common property in group housing developments. Some of his ideas are equally applicable to cluster subdivisions. He suggests that the developer be responsible for setting up the association initially:

The developer can provide the legal framework of rules, restrictions, easements, responsibilities, etc. in the deeds, as noted above. However, these covenants are not self-enforcing, so the developer must also provide the mechanism for their enforcement. He must, prior to selling the houses, form a property owners' association, membership in which is a condition of sale. Moreover, the covenants and declaration of restrictions must be linked to the association as their executor. This association is responsible for levying, collecting, and disbursing funds for maintenance and seeing that restrictions are observed — by recourse to the courts if necessary.

It would be in the interest of the future of the commons for the developer to retain control of the commons until all the properties are sold — or perhaps until some specified time thereafter — say six months or more. This would set an operational precedent for the organization until it had elected its officers and begun learning how to manage the commons efficiently.

Restrictions, Responsibilities, and Communal Authority

Brussat also points out that one basis for the criticism that is leveled at common areas by builders and financing agencies is the possibility that they will be misused or neglected. A facility involving general use must have rules and regulations which provide for maximum enjoyment by all while restricting individual activities that would be detrimental to general enjoyment.

Restrictions on the use of the commons will depend to a large extent for their nature upon the design, but certain injunctions will be desired in any event:

1. Building (by individuals).
2. Fencing (by individuals).
3. Planting (by individuals).
4. Such other activities as may be deemed harmful to the general use and enjoyment such as ball-playing, dining, nudity (as in the rules of one commons visited!), noise-making, pets, littering, etc.

There will be further responsibilities of a financial nature. There are a number of basic expenses connected with the proper care and maintenance of the commons .... the major cost factors will be:

1. Gardener service (mowing, hedge-trimming, tree--pruning, planting, etc.).
2. Repairs to walks, fences, and equipment.
3. Additions and alterations to equipment and facilities.
4. Additions and alterations to gardens and greenery.
5. Policing and clean-up.
6. Administration (bookkeeping, legal, insurance, etc.).

In cases where the locality has a public interest in the common open space and the land has been dedicated, there is of course no need to establish a neighborhood organization to govern and maintain the space.

Where land is privately held, the community corporation or a property owners' association must be given the power to carry out its responsibilities effectively. The executive powers of such organizations can be vested in a board of directors or trustees, with the necessary authority to levy assessment.

This power can be established in the provisions of the deed. In the event of failure of the constituted authority to carry out its responsibilities, two types of safeguards have been suggested by the respondents to the questions sent out by Planning Advisory Service.

The first is to incorporate on the face of the subdivision plat provisions for the construction and maintenance of private facilities. This arrangement has been employed in Milwaukee. It permits the municipality to enter onto the land to construct and maintain the facility and, if the participants fail in their obligations, to charge the cost to participants on the tax rolls. Although experience is limited, this arrangement places an extra burden on the city's department of public works.

The second and more commonly suggested method is to establish the organizational arrangements and the assessment in the deed indenture. In Missouri, subdivision trustees may be vested with the tax collecting powers of a governmental unit. Alternatively, the raising of funds may be based on the special assessment device. In either case, deed indenture could provide that if the trustees failed in their maintenance obligations, the funds and rights to accomplish the work could be transferred to the city. Due to the legal complexities, an attorney, thoroughly familiar with state and local regulations, should be consulted in handling the problems associated with common property.

Arrangements to Guarantee Integrity of Open Space

Dedicated land may seem to be secure from the speculative desire to resubdivide open space, but there is always the possibility that the municipality may wish to use it for some other purpose than was originally anticipated. A problem can arise if the city is saddled with land which in future years will be restricted to inappropriate uses. It may be advisable to incorporate an escape mechanism whereby improvements could be made if approved by, say, an extraordinary majority of the local legislative body, and perhaps with some form of consent from a high proportion of the lot owners.

There are several ways in which the integrity of privately held common land can be guaranteed. The first is through deed indenture by explicit prohibition of other than the intended uses. Such provisions can be fortified by the exemption of these sections from further amendment. Second, the contractual arrangements and common open space can be noted on the face of the plat. Third, approval of the subdivision may be given on condition that the common area be covered by an open space easement conveyed to the community. The terms of the easement would permit only such development as would be consistent with its permanent use as open space, subject to the approval of the planning commission. Finally, in the case of a planned development, the terms of zoning approval imply that the common land in any cluster subdivision will be kept from further subdivision, for the new zone is tailor-made to fit only the plat as submitted and approved.

Another means to insure the integrity of the common area is through design. The tract may be so subdivided that it cannot be further subdivided, either because the area is too small or because necessary access is barred except to pedestrians. Furthermore, the common property may be so well designed and considered such a boon to the development that no one would think of parting with it. While these design factors may be present, it is advisable to reinforce the intended effect of a cluster subdivision with legal supports.

Some respondents to the questions were concerned with the liability of freezing the use of the common in perpetuity. It would seem that the integrity of the common property need not last any longer than the physical life of the project itself. One planner suggested that none of these devices should run for more than 20 years but should be capable of extension after 20 years if the lot owners so decide.

The course that should be followed in the light of these considerations is, on the one hand, to avoid making the provisions so weak that they are subject to the sway of speculative pressure and, on the other hand, to allow enough flexibility that other appropriate uses can be made and in relation to the life of the subdivision.

CONCLUSIONS

The cluster subdivision has two characteristics that distinguish it from suburban development of the past decades. The first is a design principle in which small groups of houses are set off from one another by intervening space. The second is the common ownership of the space between the groups.

The cluster has recently received a great deal of publicity, but it is not a new idea. Historical precedents are to be found, and elements of the cluster have been used in subdivisions for a great many years. Now it is claimed that the cluster is a means of accomplishing a number of desirable objectives. They are:

Preservation of the rural character of the land;

Economy in construction and maintenance;

Inclusion of special facilities;

Variation in design;

Privacy and sociability;

Individual lot sizes that are practical and desirable.

It has been demonstrated that while these claims are capable of capturing the imagination of a public that has grown accustomed to the monotonous schemes of the postwar period, whether these objectives are actually accomplished is determined largely by the individual design. There is no magic in the cluster itself. At worst, as a label, it may be nothing more than a sales gimmick. On the other hand, it is an opportunity to realize the objectives listed.

The purpose of this report is not to pass judgment on the cluster subdivision, but rather to raise the questions that should be asked when the term is used, or when a cluster scheme is submitted for approval. Since there is no standard form of cluster subdivision, it will have to be determined in each case whether the cluster does in fact accomplish the stated objectives.

The cluster subdivision is ordinarily not permitted under zoning regulations based on the "single-lot envelope." Therefore special provision must be made to accommodate the characteristic layout of the true cluster. More advanced zoning ordinances include "planned development provisions" as an exception, a practice which appears to permit the construction of these developments. There is a feeling in some quarters that under the planned development provisions, the cluster must unjustly be subject to closer examination than conventional schemes when, at the same time, the cluster may represent a vast improvement. Where clusters are making their appearance, efforts are being made to develop regulations which will permit these new developments without cumbersome and uncertain review procedures.

One danger of the cluster is that the concept and the enabling provisions may be subverted. It is readily apparent that where the groups of houses stand, the net density of the individual lots is increased above what is anticipated under single-lot zoning. If this is allowed, it should be demonstrated that there are advantages to be gained in allowing this "local" increase in density.

The neighborhood density may be effectively increased in cluster developments if:

1. The common land is used for a purpose which would ordinarily not be an accessory use on an individual residential lot, such as a school site.
2. Additional residential structures are eventually built on the common land.

The other problems of the cluster subdivision are those peculiar to the common land. These include ownership, the use of the common area, its control, and maintenance. Of particular importance are the arrangements guaranteeing the integrity of the common land, for it is easily seen that the whole idea of the cluster is corrupted if this land is not used for its intended purpose.

We have tried to point out the factors which should be considered by anyone concerned with the cluster subdivision. Definitive answers are not possible, for experience with the cluster has been limited. Through careful guidance and control at this time, the cluster shows every promise of bringing a delightful new form of development to the suburban scene.

ENDNOTES

1 For complete information on the references given in the text, see the list at the end of this report.

2 See General City Law, Chapter 21 of the Consolidated Laws, Article 3, Section 37, excerpts of which are published in Appendix I. Section 179-p is applicable to villages, and Section 281 is applicable to towns.

ACKNOWLEDGMENTS

Planning Advisory Service wishes to thank the following people for their opinions and timely comments about their experiences with cluster subdivisions, and for supplying some of the material which has been reprinted in this report.

Robert Catlin, Planning Consultant, Bagby & Catlin, Denville, New Jersey.

Carroll J. Donohue, Lawyer, St. Louis, Missouri.

Roland B. Greeley, Associate Professor of Regional Planning, Massachusetts Institute of Technology, Cambridge, Massachusetts.

Alfred W. Jarchow, Director, Appraisal and Mortgage Risk Division, Federal Housing Administration, Washington, D. C.

Alfred Kahn, Assistant Planning Director, St. Louis County Planning Commission, Clayton, Missouri.

Roger Montgomery, Assistant Professor, School of Architecture, Washington University, St. Louis, Missouri.

William L. Nelson, Planning Consultant, Nelson-Ball & Associates, Milwaukee, Wisconsin.

Bernard H. Scheftell, Chief, Current Work Section, Board of Public Land Commissioners, Milwaukee, Wisconsin.

Stephen Sussna, Planning Consultant, Stephen Sussna Associates, Trenton, New Jersey.

Irving Wasserman, Chief, Division of Land Planning, City Planning Commission, Philadelphia, Pennsylvania.

William L. Weismantel, City Planner, Harland Bartholomew and Associates, St. Louis, Missouri.

REFERENCES

Brussat, William K. "The 'Commons' in New Residential Squares," Landscape Architecture, Spring 1960.

Catlin, Robert. "Density Control Zoning," The American City, September 1959.

"Cluster Plans at Project Give Houses Open Land-and Privacy," New York Times, January 3, 1960.

Crabtree, G. H., Jr. "Developing Golf Course Subdivisions," Urban Land, September 1958.

Curtis, M. Hover. "Livability Planning ... A Double Frontage System of Neighborhood Design." Reprinted from National Real Estate and Building Journal, December 1953 through March 1954.

Feld, Myron X. "Cluster Garden Subdivision," The American City, July 1959.

Frost, James. "Open Space in Subdivisions," Connecticut State Journal, August 1960.

Goldston, Eli, and Scheuer, James H. "Zoning of Planned Residential Developments," Harvard Law Review, December 1959.

"Good Land Design Vital, Planner Says," Milwaukee Journal, January 31, 1960.

Greeley, Roland B. "The Case for Low-Density," The American City, February 1, 1958.

"Is Archaic Zoning the Real Cause of Monotony in Subdivisions?" House and Home, June 1960.

"Is This New Idea for Subdivision Layouts a Good Answer to 'Big Lot' Zoning?'' House and Home, September 1959.

Keats, John. The Crack in the Picture Window. Cambridge, Mass.: The Riverside Press. 1957.

Local Planning and Zoning. Albany: New York Department of Commerce, rev. ed., 1958.

McNamara, Miles. "New Idea in Subdividing — Clustering — Planned Here," Milwaukee Journal, January 31, 1960.

Miller, Richard A. "The Slumberous State of Subdivision Planning," Architectural Forum, February 1959.

Radburn — Protective Restrictions and Community Administration. Fair Lawn, New Jersey: City Housing Corporation, 1929.

Siegel, Shirley Adelson. The Law of Open Space. New York: Regional Plan Association, Inc., 1960.

Stein, Clarence S. Toward New Towns for America. New York: Reinhold Publishing Corp., 1957.

Suburbia Reshaped: The Case for Flexible Zoning Controls. Philadelphia: Philadelphia Housing Authority, April 1960.

"This Cluster Plan Puts Only 283 Houses on 530 Acres," House and Home, May 1960.

Tuemmler, Fred W. "Zoning for the Planned Community," Urban Land, April 1954.

Whyte, William H., Jr. Securing Open Space for Urban America: Conservation Easements. Washington, D. C.: Urban Land Institute, Technical Bulletin 36, December 1959.

Zoning for Group Housing Developments. Chicago: ASPO, Planning Advisory Service Information Report Number 27, June 1951.

APPENDIX I

Extract from New York General City Law, Chapter 21 of the Consolidated Laws, Article 3.

Section 37. Planning board, changes in zoning regulations. The body creating said planning board is hereby authorized by ordinances or resolution applicable to the zoning regulations of such city or any portion of such zoning regulations, to empower it, simultaneously with the approval of any such plat either to confirm the zoning regulations of the land so platted as shown on the official zoning maps of the city or to make any reasonable change therein, and such board is hereby empowered to make such change. The owner of the land shown on the plat may submit with the plat a proposed building plan indicating lots where group houses for residences or apartment houses or local stores and shops are proposed to be built. Such building shall indicate for each lot or proposed building unit the maximum density of population that may exist thereon and the minimum yard requirements. Such plan, if approved by the planning board, shall modify, change or supplement the zoning regulations of the land shown on the plat within the limitations prescribed by such legislative body in said ordinance or resolution. Provided that for such land so shown there shall not be a greater average density of population or cover of the land with buildings than is permitted in the district wherein such land lies as shown on the official zoning map. Such building plan shall not be approved by the planning board unless in its judgment the appropriate use of adjoining land is reasonably safeguarded and such plan is consistent with the public welfare. Before the board shall make any change in the zoning regulations there shall be a public hearing preceded by the same notice as in the case of the approval of the plat itself.... On the filing of the plat in the office of the county clerk or registrar such changes, subject, however, to review by court as hereinafter provided, shall be and become part of the zoning regulations of the city, shall take the place of any regulations established by the board of estimate or other legislative authority of the city, shall be enforced in the same manner and shall be similarly subject to change.

APPENDIX II

Proposed Amendment Zoning Ordinance

Density Development Procedure for Single Family Residential Districts

(St. Louis County)

1. The purpose of this Article is to provide for variation in lot sizes in single family residential districts so that permitted density of dwelling units contemplated by the minimum lot size requirements is maintained on an overall basis and desirable open space, tree cover, recreation areas or scenic vistas are preserved.

2. The developer of a subdivision in a single family district, except the "E" 6,000 sq. ft. Single Family District, may vary the lot sizes within the subdivision by use of the procedures contained in this Article. The maximum number of lots that may be created under this procedure shall be computed by subtracting 20 per cent of the total area being subdivided for street right--of-way and dividing the remaining area by the minimum lot area requirement of the single family district or districts in which the subdivision is to be located. This method shall apply regardless of the amount of land actually required for street right-of-way. Land utilized by utilities for easement for major facilities such as electric transmission lines and water mains, where such land is not available to the owner for development because of the easements, shall not be considered as part of the gross acreage in computing the maximum number of lots that may be created under this procedure. Land within the flood plains of the Mississippi, Missouri and Meramec Rivers or within the normal banks of other watercourses shall not be considered as part of the gross acreage in computing the maximum number of lots that may be created under this procedure.

3. Under this procedure, lots may be reduced in area below the minimum lot size required in the district in which the subdivision is located provided that the average lot size of the lots created in the subdivision is not below the minimum lot size required in the district. In subdivisions containing ten or more lots, common land for open space or recreational use may be set aside for use by the owners of residential lots and such common land may be included in determining the average lot size of the lots created in the subdivision.

4. Under this procedure no lot in single family residential district shall be reduced in area below the following minimum standards nor shall such reduced lots contain a frontage less than the applicable frontage required in the Subdivision Regulations:

The location, extent, and purpose of common land proposed to be set aside for open space or for recreational use within any subdivision must be reviewed and approved by the Planning Commission before the provisions of this Section shall apply. A private recreational use such as a golf course or a swimming pool, whose use is limited to the owners or occupants of lots located within the subdivision, may be approved as common land. Other uses or sites which may qualify as common land include historic buildings or sites, parks and parkway areas, ornamental parks, extensive areas with tree cover, and low land along streams or areas of rough terrain where such areas are extensive and have natural features worthy of preservation.

The maintenance of common land for open space or recreational use shall be guaranteed by trust indenture approved by the Planning Commission and shall be filed with the Recorder of Deeds of St. Louis County simultaneously with the recording of the final plat of the subdivision. Such common land shall be set aside by deed restrictions for a minimum period of thirty years.

Editorial Note: This proposed amendment to the zoning ordinance of St. Louis County, Missouri, has not yet been adopted and may still be subject to modification. Planning Advisory Service is reprinting the provisions of the proposed amendment, not as a recommendation, but as a sample of density control zoning which will accommodate a cluster subdivision.

APPENDIX III

Town of Guilford, Conn.

Amendment to the Subdivision Regulations

Section 9 — CLUSTER DEVELOPMENT

C. The balance of the land not contained in the building lots shall be of such condition, size and shape as to be usable for recreation. This land shall be either:

(1) Deeded to the Town of Guilford (subject to paragraphs C-3 and 4 below) or

(2) Held in corporate ownership by the owners of lots within the development and such other nearby landowners who may wish to become members of the corporation, (in which case the Open Land may be restricted to members of said corporation as said corporation may itself decide). In the case of a corporation the developer shall include in the deed to the owners of the building lots a beneficial right in the use of the Open Land.

No structure save that related to recreation shall be permitted thereon. Open Land shall not be sold for any use other than recreation.

(3) The land deeded to the town shall be a minimum of 6 acres; and owned corporately shall be a minimum of 4 acres. If held in corporate ownership the Open Land shall be subject to taxation.

(4) In the case of a subdivision containing 30 lots or more and laid out in conformity with this Section, the developer may petition the Planning and Zoning Commission that the Open Land be deeded to the town to be used as public Open Space.

(5) Resale by the town of Open Land for any other use than for recreation shall require the written consent of 75% of all householders within 2,500 feet of the said Open Land.

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Prepared by Jon Rosenthal

Copyright © 1960 American Society of Planning Officials