PPP Notes - Land Analysis

(These notes are compiled from Spreiregen's ARE Exam Review)

CHAPTER NINE - LAND ANALYSIS

INTRODUCTION

Land has always been a precious resource, for the simple reason that it is limited in amount.  Man has bartered his life and soul and waged war for possession of land.  He has sometimes made it more beautiful and productive, through alteration and cultivation.  But he has also damaged it, through poorly planned development.

To assure its proper use, numerous regulations have been adopted.  The result is that we must now deal with a highly complex array of rules and procedures that were nonexistent until relatively recent times.  In addition to complying with zoning ordinances, building codes, and height restrictions, we must also plan for the optimum use of the land.  This requires a thorough knowledge of a site's topography, boundaries, soil, geography, and aesthetic qualities.  The architect must seek ways to establish a relationship between a proposed development on a site and the existing character of the neighborhood around the site.  And he must consider cost.  A conscientious architect must be able to address these issues, considering a building and its site as a unity.

OWNERSHIP

The idea of ownership has ancient origins.  Early man appropriated territory by occupying it.  He chose to occupy areas plentiful in resources, such as water, game, and fertile soil.  His choices were influenced by that which he could successfully defend.

Land was first owned communally, establishing the precedent for sovereign states to own land.  With communal ownership, an individual might possess the right to use land.  In medieval times, land ownership was in the hands of a few.  Under the practice of primogeniture, land passed from father to eldest son, which limited the diffusion of land ownership.  However, some societies divided land up among heirs, thereby creating a multitude of small and often inefficient farms.

In 1066, the Normans conquered England and introduced a system under which ownership of land was vested in the king, who granted parcels of land to nobles in return for loyalty, military support, and financial support.  This feudal system of land tenure was gradually eliminated in England, and evolved into the system of "fee simple" ownership, under which land could be used or transferred by its owner as he pleased.  However, land ownership today also carries the responsibility of payment of taxes, compliance with zoning ordinances, and other restrictions.

Some land in England, however, remains the property of the Crown, or the public, but its use can be obtained by leasing.  Such leasehold property may be held by the lessee for a period of up to 99 years, after which time it reverts to the Crown.

Initially, land in America was controlled by colonizing companies, publicly franchised and privately financed.  After the Revolution, the colonial lands were placed under the authority of the respective states.  Individuals who had owned the lands under the Crown now owned it under the newly established states.  The land gained from the British, and later the French, which had not been under the control of a colony became public domain, under the control of the federal government.  The original public domain consisted of lands given up by several of the eastern states.  This was known as the Northwest Territory, because it was northwest of the Ohio River.  The land of the Louisiana Purchase was purchased from the French during the Napoleonic Wars.  Land was also obtained from Spain and Mexico.  Most of this public land, over 1 billion acres, has since been sold or deeded to individuals; some was transferred to states and municipalities for public use.  Some land was given to veterans for their service, and a large amount of land was granted to universities and other educational institutions.  Land grants were also made for the development of railroads and canals.

A large amount of public land was transferred to private ownership through the Homestead Act, passed by Congress in 1862.  160 acres of land were given, free, to anyone who built a house and lived on the land for five years.  Thousands took advantage of this opportunity.  About a third of a billion acres of land has been granted to homesteaders since the enactment of the Homestead Act.  The only place in this country where homesteading is still practiced to any extent is Alaska.

(The 1787 division system of the U.S.A. incorporated a basic grid layout, 6 miles square, subdivided into one mile squares.  Three were divided into "quarter sections" - each 160 acres, later to become a homestead.)  

About 750 million acres, one third of the nation's area, still remains as public land.  The policy of the federal government today, for the land in the public domain, is a combination of conservation and resource extraction.

As the nation grew in size and population, competition for land ownership intensified.  Large estates, ranches, and land grants were subdivided and sold as parcels of varying sizes.  Owning land and a home of one's own became the common goal of all.  Building and development were synonymous with the 19th and 20th century American experience, at a scale and intensity not hitherto known.

With that eventually grew a consciousness that land is a scarce and easily damaged resource.  And so we have developed a number of methods for the proper and responsible use of land, including planning, resource management, and land use regulation.

CATCHMENT AREAS

The term "catchment" means the geographic area from which the participants in an activity are drawn.  For example, a catchment may comprise the area within which the patrons of a supermarket or shopping center reside.  

Or, it may be the area within which the employees of an industrial plant reside.  A given parcel of land may be located within numerous catchments simultaneously - some large, some small - each catchment containing a specific class of participants in a particular activity.  Catchment areas may be distinctly defined by physical boundaries, or the boundaries may be indistinct.  The size and shape of a catchment may be drawn with respect to a particular function or population.

Catchment boundaries may be determined by geographic features.  Two neighborhoods, for example, may be separated by a physical feature such as a railroad or a waterway.  A less definite boundary might be the demarcation between two ethnic neighborhoods.  The boundary of two such areas may be set arbitrarily for purposes of analysis.

Catchment areas may also be termed "market areas," "trade areas," or "tributary areas."  The drawing shown in Figure 9.3 represents the employment catchment for a factory, along with the catchment areas for two nearby shopping centers.  Note that some factory employees live in two separate but overlapping market catchments because they trade at both shopping centers.  In this example, the market catchments are larger than the employment catchment areas.  

Catchments may increase or decrease in size.  The employment catchment shown could easily increase if the ZRP Factory were to increase its business activity, or if a major connecting traffic artery were built, thus becoming more accessible to a greater number of workers by car.  Conversely, if ZRP's activities were to decrease substantially, its employment catchment would shrink accordingly.

A catchment area can come into existence, or grow, as a result of population growth in an area or as a result of a municipal development program.  School districts are catchments serving students residing within established boundaries.  Recreation facilities can also form catchment areas.  A catchment area may be local, regional, or national, and it can be all of these simultaneously.  For example, Disneyland, in Anaheim, California, draws its visitors from Los Angeles and Orange Counties, along with visitors from out-of-state.  The latter group constitutes the major catchment area.

Residential catchments are determined by local transportation systems.  Railroads or highways linking an urban center with an undeveloped area may encourage the formation and development of that area, and the establishment of a new catchment.  Under such conditions the commuting time, rather than the mileage, determines the maximum distance between home and place of work.  For most people, a half-hour commute is the acceptable maximum for one-way travel by either automobile or rapid transit, although some people travel for up to one hour.

Zoning ordinances help to create and preserve catchment areas by specifying which land uses are permitted.

Existing catchments are subject to alteration from a number of sources.  As new technologies are developed, their use may alter employment catchments.  Retail stores selling new or innovative products may alter the shopping catchments.

The improvement of underdeveloped land may alter catchments to a great extent.  In Figure 9.5, the residential population of catchment 1 increases.  This causes growth of the commercial area of catchment 2, by intensification or expansion.  Or, commercial development may occur in catchment 3, hitherto undeveloped.

The point is that catchment areas changes as a consequence of their interaction with each other.  Thus, up-to-date information must be used in planning new or expanded uses which depend on their "catchment" or "user" areas.

LAND USE AND LAND VALUE

The use to which a parcel of land may be put depends on its potential role in a catchment area, its location, its topography, and its cost.  Topography, access, zoning, utilities, and nearby uses are among the factors contributing to land value.

Land can be placed into eight basic categories of potential use, which determine value, as follows:

1. Natural resources (e.g., mining, forestry, etc.)

2. Agricultural

3. Residential

4. Commercial

5. Industrial

6. Governmental

7. Institutional

8. Open space / conservation

For the first five categories, there are four methods by which the value of land may be determined.  It should be noted, however, that regional factors will cause variations in valuation.

Whether land is vacant or improved, it is valued in relation to the type of use which will yield the highest return.  That use must, of course, be warranted by prevailing market conditions, and its conformance to legal requirements of zoning and land use ordinances.

Not that the term "improvement" refers to any structure on a parcel of land which has value and "improves" the parcel's usefulness.

COMPARISON METHOD / MARKET DATA APPROACH METHOD

The first method is called the comparison method or market data approach.  This method reflects the market value most closely.  One of the requirements of this method, however, is the availability of sufficient data on comparable land being offered for sale at the time of valuation.  Consequently, if industrial land in a given location, with all necessary access and utility services, sells for $20,000 per acre, a similar plot of ground with similar services in a similar location should also sell for about $20,000 per acre.  Nevertheless, no two parcels of land are identical, and adjustments are often necessary to determine the value of a specific parcel of land.

RESIDUAL / INCOME APPROACH METHOD

The second method is the residual method or income approach method.  This is used in highly developed areas with no vacant land, where the appraiser is unable to obtain comparative data for land value.  Value must then be determined by estimating the potential income from site improvements.  The cost of site improvement must, of course, be taken into account when calculating the land value.

In order to make such calculations, the investor hypothesizes improvements which would provide the highest financial returns.  This requires considerable knowledge, since variations in the investment rate of return as well as in the proposed improvements can result in substantial differences in value.

When calculating land value, the improvement must represent the highest and best use of the land.  Highest and best use is defined as "that use which is most likely to produce the greatest net return over a given period of time."

ALLOCATION METHOD

The third method is the allocation method.  It may be used to determine land value of improved properties.  The value of the land can be estimated be deducting the value of the site improvements from the total value of the property.  The reliability and accuracy of the allocation method depends on skill and knowledge.

DEVELOPMENT METHOD

Land that has a potential use for residential or industrial subdivision may be valued by the fourth method, called the development method.  This method depends on estimated development costs.  It should be used when sales prices of similar parcels are not available.  The development method requires: determination of the ultimate selling prices of individual lots, the costs required to develop the subdivision (capital outlays, financing, carrying and sales costs), the period of time necessary to sell the developed lots, and possible discounting of the net sale price.

To summarize the four methods, the comparison method of determining land values is applicable to all classes of land.  If proper data is available, it is the most accurate method.  The residual, allocation, and development methods are used when data for comparable parcels is not available.

OVERIMPROVEMENT AND UNDERIMPROVEMENT

The concept of overimprovement or underimprovement is related to highest and best use.  The term underimprovement refers to a property that is not being used to its highest and best use.  For example, an owner of land might erect a building on his property that produces substantially less income than could be obtained with a better, larger, or different building.  Such an underimprovement will reduce the value of the property, because it is not being put to its "highest and best use."

Conversely, overimprovement means that the cost of the improvement exceeds potential revenue or income: more has been built on the site than is warranted.  For example, someone may buy an old house and rehabilitate it.  The cost of rehabilitation may be far greater than the market value of the house.  This is an overimprovement.

In addition to determining the cost of land, other factors must be analyzed, as follows:

1. SUITABILITY

Is the land suited for the intended purpose?

2. ACCESS

Is the site sufficiently accessible?

3. CIRCULATION

Can people, goods, and services comfortably circulate within the parcel?

4. VARIETY

Is it possible to accommodate a reasonable range of varied uses on the site?

5. COST

Initial cost must be balanced against estimated operational and maintenance costs.

6. ADAPTABILITY

Successful development plans must possess flexibility to allow for modifications in the future, within the general form.  Plans should permit future changes in use.

7. AMENITIES

What are the positive features of the site, such as views, landscaping, orientation, topography?  Can these be utilized to advantage?  Can they be augmented?

8. OPEN SPACE

How can the value of open space and wildlife habitats such as woodlands, prairies, wetlands, and waterways be maintained while considering development opportunities?  Can open space preservation complement sustainable design techniques in the building architecture?

Through the process of analysis, an awareness of the special attributes of each site is revealed - its topography, drainage patterns, and plant life.  Such elements constitute the intrinsic character of a site.

SURVEYS

Surveys describe the location, form, and boundaries of land.  They also describe all the special features of a site that are pertinent to site development and building design.  Surveying for building construction is done at three levels of detail, commensurate with design needs.

These are:

1. PRELIMINARY SURVEY

Which provides basic information to the architect for the preparation of building plans.

2. CONSTRUCTION SURVEY

Which describes the precise condition of the site and adjacent structures, and establishes base lines, offsets, and benchmarks. 

3. POSSESSION SURVEY

Made after the completion of construction to record the completed development, including site improvements and structures.

A land survey provides the following information:

1. Title of survey, property location, and date.

2. Scale and compass orientation

3. Tract boundary lines, courses, and distances

4. Names of owners of adjacent properties

5. Benchmark with reference elevation

6. Names and locations of all existing road rights-of-way, on or near the property

7. Location of all existing structures on the site, including buildings, foundations, bridges, wells, cisterns, walls, fences, and rock outcroppings.

8. Location, type, size and flow of all existing storm and sanitary sewers on or contiguous to the tract; top and invert elevations of all manholes, inlet and invert elevations of other drainage structures.

9. Location of roads, drives, curbs, getters, steps, walks, and paved areas, indicating types of material or surfacing.

10. Location, type, and size of all water and gas mains, meter boxes, hydrants, and other appurtenances.

11. Location of utility poles, telephone lines, and power lines, with indication of nearest leads either on-site or off-site; pertinent information and ownership of all utilities.

12. Location of all swamps, springs, streams, drainage ditches, lakes, and other bodies of water; elevation of maximum flood plain, if applicable.

13. Outline of wooded areas, location of trees, identification of trees by type, and identification of trees with trunks over eight inches in diameter three feet above ground.

14. Road elevations for all improved roads, on or adjacent to property; improved gutter elevations on property line side.

15. Elevations through the site sufficient to develop a complete and thorough contour map or the topographic contour lines of the site, at an appropriate interval, depending on the steepness of the site.

Land surveys are of two types: geodetic and plane.  Geodetic surveys take into consideration the spherical shape of the earth.  Thus they describe large land areas with great precision.  Plane surveying assumes that the earth is a flat plane, and earth curvature is disregarded.  Geodetic surveys are used for very large land areas, while plane surveying is sufficiently accurate for most site development work.

Among the various kinds of plane surveying are:

LAND SURVEY

This refers to the general measurement and description of land parcels or sites, where building development is contemplated.

TOPOGRAPHIC SURVEY

This refers to a map showing natural and manmade features and elevations, which are normally described by contour lines.  For building projects the contours must be drawn very accurately.

ROUTE SURVEY

This is used by civil engineers when laying out a road or utility line.

HYDROGRAPHIC SURVEY

This describes and maps oceans, lakes, rivers, and other bodies of water for purposes of navigation, water supply, or water-related construction.

CITY SURVEY

This is used to measure areas in and near cities, locate property lines and improvements, and determine the configuration and physical features of the land.  Such surveys are essential to city planning.

AERIAL SURVEY

This is prepared through the use of aerial photography (photogrammetry), augmented with large scale land surveys to maintain accuracy.

CONSTRUCTION SURVEY

This provides a system of markers to determine the precise location of a building on its site.

In all land surveying, distances between points are measured on a horizontal plane.  Vertical distance, or elevation, is expressed with reference to distance above sea level or some other established point of reference.  Such a point may be a U.S. Geological Survey monument, a bronze plate set in stone or concrete which shows the elevation above sea level.

Both horizontal and vertical distances are measured in feet and decimals.

SITE ANALYSIS

GENERAL PURPOSE

Site analysis is the process of investigating basic data that relates to a particular site, such as survey information, topographic data, geological information, zoning ordinances, existing character, microclimate, development patterns, social patterns, etc.  The purpose of site analysis is to determine whether a parcel of land is suitable for a specific proposed use.  It would be undesirable, for example, to situate a school adjacent to a major freeway.  Similarly, a roadside cafe should not be located out of sight of the road, nor should a meat packing plant be placed upwind of dwelling units.  All of these are examples of inappropriate uses for a given site, or perhaps inappropriate sites for a given use.  In theory, almost any site will support almost any use; however, the ideal situation is one that most fully satisfies the project criteria, while requiring the least modification or compromise.

Every site is as unique as an individual person, and even as identical twins have distinct personalities, so too, adjacent parcels of land possess distinguishable characteristics.  Part of this uniqueness is reflected in a site's equilibrium.  The flow of surface water creates a discrete drainage pattern, plant and animal life constitute an ecological system, and human use conforms to a workable social structure.  Site factors such as these are interrelated, and at any given moment they are in balance, even if they are in the process of change.  The recognition of a site's character reveals the practical limits imposed on a planner, as well as the potential damage that may be inflicted by development.

All development implies change, and occasionally this changes produces undesirable effects.  Excavation, for example, may alter drainage patterns, grading may cause erosion, and the construction of new facilities may destroy plants, pollute the air, or create traffic congestion.  Environmental changes, therefore, are an inevitable result of the development process.

RELEVANT DATA

The relevant site data that must be gathered and analyzed comprise those factors that determine the suitability of a site for its proposed use.  Although no single set of factors applies to every situation, the following list includes data that is relevant in most circumstances.

CLIMATE

Every site is affected by regional climate patterns, as well as the microclimate that applies to a small area.  Climate is related to topography, slope orientation, vegetation, and the presence of water; and it is important because it bears directly on human comfort.  Climatological data may be obtained from the National Weather Service, through talks with local inhabitants, and by personal observation of weathered structures and existing plant material.  The following features may be analyzed:

1. Temperature averages and extremes

2. Precipitation averages and extremes

3. Snowfall averages and extremes

4. Wind intensity and directions

5. Humidity patterns

6. Solar angles

7. Days of sunlight

8. Frost data

TOPOGRAPHY

Topography is the form of a site's surface features, and it is a factor that strongly influences land development.  The gradient of roads, disposition of structures, and visual aspects of a site are all influenced by the character of the landform.  Topographic data is available from the U.S. Geological Survey aerial photographs, or on-site surveys, and the features that may be analyzed are:

1. Elevations

2. Slope amount and direction

3. Unique landforms

4. Natural drainage patterns

SOILS

Knowledge of the soil conditions on a site is important to determine the soil's capacity to support buildings and roads, as well as its ability to sustain plant material.  Soils data is obtained from the U.S. Department of Agriculture Soil Conservation Service, test borings, visual inspection, and the experience of neighboring developers.  The following features may be analyzed:

1. Soil types

2. Moisture content

3. Depth of organic topsoil

4. Depth to water table

5. Depth to bedrock

6. Drainage characteristics

7. Susceptibility to compaction

8. Soil fertility

9. Rock outcroppings

HYDROLOGY

Hydrology refers to the occurrence, movement, and quality of water on a site.  Surface water and drainage patterns affect vegetation, climate, and potential development, and this data is available from the U.S. Geological Survey, local hydrological studies, and on-site inspections.  Hydrological considerations include:

1. The form of surface water (streams, lakes, etc.)

2. Drainage patterns

3. Runoff rates

4. Subsurface water characteristics

5. Aquifer (water-bearing) zones

VEGETATION

Plant types and patterns represent a major site resource, and they contribute significantly to the unique character of an area.  Native landscaping is closely related to climate, hydrology, and topography, and it often determines the form of development.

Data on vegetation is available from U.S. Geological Survey maps, aerial photos, and on-site observation.  The factors that may be analyzed are:

1. Types and extent of vegetation

2. Density of vegetation

3. Heights of vegetation

4. Health of vegetation

EXISTING LAND USE

As a site is developed, manmade features become more important than natural features.  Structures, circulation systems, and activity patterns must be considered.  Such data is obtained from land use maps, state highway maps, historical preservation societies, and personal inspections, and some of the factors that may be analyzed are:

1. Existing roads and paths

2. Existing utility lines

3. Existing air and rail facilities

4. Type and number of structures

5. Uses of open space

6. Human behavior patterns

7. Historical sites, structures, and trails

SENSORY QUALITIES

The sensory qualities of a site are those intangible elements that affect people through the sense of sight, smell, touch, and hearing.  The uniqueness of a site may be its view or its geometry, the smell of wildflowers or of the ocean, the feel of heat or of wind, or the sound of traffic, church bells, or singing birds.  The perception of sensory qualities is as important to site analysis as any other relevant factor, and pertinent data of this sort is almost always obtained through first-hand on-site observation.  The features to be analyzed may include:

1. Scenic vistas

2. Spatial illusions

3. Quality of light

4. Characteristic smells

5. Characteristic sounds (noises, echoes, etc.)

6. Sensation of natural forces

7. Perception of textures

NATURAL HAZARDS

There are several natural elements that are potentially hazardous to certain types of development, and others, such as earthquake faults, that may restrict almost all construction.  Information on hazards is generally available from a variety of government agencies, local inhabitants, and sometimes (unfortunately) through personal experience.  Analysis may include:

1. Earthquake fault zones

2. Hurricane zones

3. Tornado zones

4. Flood plains

5. Tidal inundation areas

6. Wet zones (peat bogs, quicksand, etc.)

7. Areas of poisonous plants

8. Areas of poisonous snakes or reptiles

9. Areas of annoying insects

The actual site analysis begins when all of the pertinent information is collected.  At this point, a base map is prepared showing legal boundaries, contours, roads, buildings, utilities, and other natural or manmade key features.  The base map is used as a background on which various overlays are produced, generally one for each area of concern.  For example, a soils overlay may classify soils by type and depth, with locations and logs of known test borings.  A visual survey overlay may consist of personal notes and observations regarding scenic views or unsightly features in need of modification or removal.  When environmental concerns are explored, the resulting overlay may serve as a checklist for an environmental impact assessment.

A map on which all the overlaid information has been superimposed is known as a site analysis map, an example of which is shown in Figure 9.11.  This map indicates the degree to which a site is suitable for a proposed function.  At this point, the planner may discover that compromises may be necessary.  For example, a site that appears optimum for a shopping center, based on population growth studies, topography, suitable soil, etc., may be located too far from freeway access.  For the shopping center and freeway access to be closer together, one may be forced to accept a lower quality site.  Therefore, when a site is judged to be suitable for a proposed use, it is almost always a matter of striking a balance between what is ideal and what is reasonably possible.

NATURAL LANDFORMS

Landform refers to the shape of the earth's surface, which may include everything from mountain ranges to furrows in a field.  Landform is important because it affects the aesthetic character of an area, as well as one's perception of space.  Level land, for example, unifies the landscape, while hilly land tends to divide it.  Landform types also have a direct impact on the development with which they are visually compatible.  The natural shape of land, therefore, affects how it is perceived, modified, and used.

Landform may be classified by character, steepness, geology, etc., but where visual, functional, and perceptual qualities are concerned, the most significant factor is form.  The landscape is a continuous composition of varying earth forms that blend into and reinforce one another.  Where a level stretch of desert ends, the concave slope of a mountain begins, but that precise point may be difficult to detect.  Similarly, the merger of a slope and a valley may be nearly imperceptible.  Following is a discussion of the most common landform configurations with some implications of their potential for site design.

LEVEL LANDFORMS

A level landform is any area that appears visually parallel to the horizon.  Of course, there is no such thing as a perfectly level piece of land, because all ground has some amount of slope.  Nevertheless, land perceived to be level is stable, static, and in equilibrium.  Level land is comfortable because it requires little effort to stand, walk, or rest on a surface that is in balance with the earth's gravitational forces.  For these same reasons, level areas are the most sought-after sites for buildings.  In fact, when level sites are not available, they are often created by remodeling sloping terrain into flat pads.

Level landforms lack spatial definition; other than the horizon, no elements appear to enclose space.  On the other hand, this openness permits extensive, uninterrupted views, which establishes a unifying force on the landscape.  Level land induces a feeling of exposure; there is no protection against sun or wind, there is no defense against objectionable noises or views, and there is no privacy.  In other words, there is no place to hide.

Development of level land is relatively unrestricted; structures may be built upward, outward, and in almost any direction.  Horizontal forms appear harmonious when set on the level landscape, because they reflect the horizon and emphasize the earth's stability.  Vertical elements, on the other hand, attract attention and tend to dominate the landform.  Even the modest height of a farm silo on the Midwestern plain is clearly visible for miles.

Level ground offers little indication of the correct orientation for development.  With no restriction imposed by landform, all directions appear equally valid, and this has occasionally led to multidirectional developments that sprawl repetitiously across the landscape.  A level landform provides a neutral, sometimes uninteresting setting that can be characterized as peaceful, calm, and quiet, although in reality it may be none of these.  Nevertheless, level topography is flexible, practical, and highly desirable for the majority of human uses.

SITE DESIGN CHARACTERISTICS

We have stated that site design is the conscious rearrangement of the environment for human use.  The environment comprises a number of components, or characteristics, including space, scale, mass, proportion, etc., all of which contribute to that elusive and subjective element known as aesthetics.  The aim of all site design, therefore, is to produce a functional solution that is perceived as a visual whole, that is aesthetically.  And aesthetics is the consequence of a harmonious blend of design characteristics.

SPACE

Space is defined as the three-dimensional expanse that surrounds one, and it is perceived through all our senses.  While architectural space is circumscribed by roof, walls, and floor, outdoor space is defined by the variety of elements found in the open and urban landscape.  This may include, for example, a group of university buildings around a quad, a narrow street lined with uniform structures, or an open park surrounded by trees.  Some outdoor space is vast and limited only by sky, earth and distant horizon.

Compared to architectural space, site space is generally larger in extent, more irregular, less geometric, and invariably perceived as being wider than it is high.  People relate to exterior space differently from the way they relate to interior space.  In a vast, open plain, some will feel threatened or overwhelmed, while others will experience a sense of freedom or a need for action.  Large areas often encourage mass action, such as on a football field or a ski slope.  Any tall object set on a large, unobstructed surface becomes an important element on which attention is focused, such as a solitary tree in a field or the Washington Monument.

Space is further defined by light, color, texture, and the scale of its elements, although perceptions may be modified through spatial illusions.  It is difficult, for example, to accurately estimate outdoor distances, and actual gradients may be considerably different from what they appear to be.  And outdoor light is not constant, since the sun varies with the hour, the season, and the weather, all of which affect the form, color, and texture of the landscape.

ENCLOSURE

People are aware when they are inside a building, regardless of how open it may be, but outdoor enclosure is perceived by widely spaced trees, rolling foothills, or a change in ground texture.  In other words, the definition of outdoor space may be a visual suggestion, rather than a visual obstruction.  Even a low railing or a line of bollards defines outdoor space as effectively as a wall.  In general, the amount of enclosure necessary to create a definable outdoor space is just enough so that one's attention is focused on the space, rather than beyond it.

Urban spaces are enclosed by the building masses of a city; they are the voids formed by the absence of solids.  An urban square surrounded by tall buildings is easy to visualize, but the linear arrangement of houses is no less an enclosure for the corridor-like space it creates along the street.  Unlike indoor spaces, outdoor volumes may be infinite in scope, limited perhaps only by the horizon.  Site designers, therefore, are not nearly as restricted as building designers.  Because outdoor space is loosely defined, the site designer has greater freedom, as well as responsibility, to create a clear, comprehensible volume.

SCALE

Scale is a system of relative measurement based on anthropometric dimensions.  For example, because that is the height that people raise their feet comfortably when climbing steps.  We say, therefore, that a seven-inch riser is in scale.  The 20-inch risers of the Parthenon's stylobate, on the other hand, while in harmonious proportions to the structure, are clearly out of scale with human beings:  people do not normally climb 20-inch high steps.

Interior scale and exterior scale are quite different from each other.  In general, outdoor spaces must be considerably larger, relative to interior spaces, in order to feel comfortable.  A three-foot wide hallway in a house, for example, feels adequate, whereas a three-foot wide sidewalk will feel narrow.  Similarly, a 10 by 12 foot bedroom is comfortable, while the same size patio will be undersized.  This variation in perception inside and outside scale is caused by differences in the fields of vision, as well as the physical behavior that is appropriate in each circumstance.  One can run, shout, or throw a ball outside, while these same activities inside are considered inappropriate.

Outside activities can be visually distinguished up to about 450 feet, outdoor spaces appear intimate if they are between 40 to 80 feet in size, and people who stand three to ten feet away are considered to be in direct relationship.  It is clear, therefore, that site planning requires an entirely different perception of scale than planning interior spaces.

Exterior scale is more than a matter of dimensions, however; it may also relate to speed, context, and custom.  Walking speed, for example, which averages about 2-1/2 miles per hour, determines the size and scale of a city's elements.  The willingness of people to walk only 10 to 15 minutes in performing routine tasks affects the arrangement of parking lots, shopping centers, commercial zones, and the size of neighborhoods.  The relationship of scale to context means that neighboring spaces and buildings must be in scale with each other.  A towering building in the midst of a community of single-family dwellings, for example, is out of context with the neighborhood, and consequently out of scale.  All buildings in an area need not be the same mass or height, but when a structure changes one's perception of the local scale, the structure is likely to be disorienting.

Finally, scale is perceived in accordance with the customary way things have always been.  If a coherent neighborhood has always consisted of 500 families who support a shopping center, recreational facilities, and an elementary school, then doubling the number of families would probably overwhelm the neighborhood and destroy the established scale.  Similarly, a person who has spent his life on a farm will experience a dramatic disorientation in spatial scale if he were to move to a large metropolitan area.

MASS

The perception of mass is largely controlled by the way we see, as well as the prevailing light conditions.  From a viewing distance equal to the building height, that is, a 45-degree angle from the eye to the roof line, one notices the details of the facade more than the entire building mass.  From twice the viewing distance to the same roof line, that is, a 1 to 2 relationship, one can perceive the entire building mass together with its details.  At a 1 to 3 relationship, the building mass is observed in relation to surrounding objects, and at 1 to 4, or a viewing distance of four times the building height, one sees the mass as an edge that frames a distant view.

Light conditions affect one's perception of mass: in bright sunlight, individual elements stand out, while on cloudy days, the mass is perceived in its entirety.  Dark objects seen against a light background recede, such as a tree clump viewed against the sky.  However, light objects seen against a dark background, such as a highway billboard set against dark hills, tend to advance visually.  Depth perception is also affected by light conditions: distances are more difficult to discern on a dull, grey day.

AESTHETICS

Aesthetics refers to what is beautiful, and beauty, as we all know, can be quite subjective.

Most natural landscapes are beautiful, because the many factors of which they are composed have achieved an equilibrium.  Beauty, therefore, must include a concept of order.  A natural site may have existed for thousands of years, but it only exists in relation to people through some positive development that establishes a permanent connection between people and site.  Even a natural wilderness area has no relation to people unless there is access to the area, or at least vantage points from which the area can be observed.  A structure introduced on a site will exist visually and spatially in relation to that site and the surrounding landscape.  Building and site become one indivisible experience.  Unity, therefore, is a goal of the design process and an essential element of beauty, because it confirms our idea of what is right, proper, and fit for human use.

SITE DESIGN PROCESS

The site design process is an exploration of possible solutions to a specific problem.  This exploration involves a number of essential steps, generally performed in sequence, which ultimately leads to a solution of the project's objectives.  In the usual case, a client intends to develop a piece of land for some purpose.  The designer may be contacted by the client either before or after the site has been selected.  Either way, the designer must become familiar with the client's goals, the intended land use, and the parcel of land itself.  From that point on, the sequence of activities includes the following steps:

1. PROJECT PROPOSAL

A. SCOPE OF SERVICES

B. COST OF SERVICES

C. TIME OF PERFORMANCE

2. RESEARCH AND ANALYSIS

A. SITE INVENTORY

B. DATA ANALYSIS

C. CLIENT OBJECTIVES

D. PROGRAM PREPARATION

3. DESIGN PHASE

A. CIRCULATION PATTERN

B. FUNCTIONAL PATTERN

C. FORM COMPOSITION

D. DIAGRAMMATIC PLAN

E. SCHEMATIC PLAN

F. PRELIMINARY PLAN

G. MASTER PLAN

4. CONSTRUCTION PHASE

A. TECHNICAL PLAN

B. GRADING PLAN

C. LANDSCAPING PLAN

D. CONSTRUCTION DETAILS

E. CONTRACT DOCUMENTS

5. POST CONSTRUCTION

A. EVALUATION

B. MAINTENANCE

While these various steps occur in sequence, some may overlap or occur simultaneously.  Moreover, no step occurs independently of the others.  The design process outline above does not guarantee a beautiful or even functional solution; it is merely a framework of activities that one must perform to achieve an answer to a specific puzzle.  The answer may result in a masterpiece, a disaster, or more than likely, something in between.

Design success relies on a designer's knowledge, inspiration, experience, intuition, talent, ability, and creativity, and these qualities vary with the individual.  In this course we have addressed one of the most important factors for successful design: knowledge.  We hope, however, that this knowledge will lead to more inspired, creative, and responsible solutions to site problems.

SUMMARY

Site analysis must be undertaken with regard for the site's intended use.  But the range of possible uses must be based on the site's intrinsic potential.  While land should be used according to its suitability, its value is a function of its economic usefulness.

To be usable, the cost of a site must be commensurate with its potential uses.  Determination of cost requires an appraisal of its value in relation to potential use, and an estimate of its operational costs.

Surveys describe location, form, and boundaries of the land.  Topography describes the land's surface features.  Slopes must be suitable for circulation, utilities, and special uses.  Slopes should not be altered so as to cause water drainage problems or erosion.  Other physical problems may derive from surface and subsurface soil, rock, and water.

Sites should be chosen, and their uses determined, according to the ease with which they can be developed, so that development costs will be commensurate with expected benefits.  The role of landscaping is to achieve an artistic relationship between earth, rock, water, plants, and manmade details.  It may also modulate climatic extremes, to assume comfort for the users.