The base plane is closely related to the arrangement of use areas, for it is on this volumetric floor that we are most concerned with use. What we see when we look at a project plan is what will be laid out on the base plane. It will establish not only the kinds of use but also the plan rela-tionship of each use to all others.
The base plane surface is often the natural surface of the earth. With its topsoil strata, ranging from thin to deep, its soil moisture and fertility, and its cover of plants, this plane is veritably the base of all life. The wise planner will never disturb or modify the natural ground surface without reason. Any modifications made will be those that implement the pro-posed use while protecting the quality of the project site.
The general composition of the earth plane is mineral, ranging in hard-ness from granite, limestone, and shale to the clays, loam, and sand. The supporting strength and stability of the soil strata depend not only on the nature of each but also on its angle of inclination, the presence of water, and its relation to the other strata and the surface. Appearances are deceptive; deceptions are often disastrous. When the degree of sup-port and stability are of consequence, the soil types and load-bearing capacities are to be determined by test pits or core borings.
Soils and the moisture and frost they retain are powerful eroders and corroders. From the structural point of view, extreme care must be taken in the selection of materials that are placed on or make contact with the earth. In considering outdoor spaces, we associate with the ground plane such natural construction materials as rock, gravel, and sand and such constructed materials as brick, concrete, asphalt, and ceramic tile. These seem compatible. Most other materials, including untreated wood or uncoated metals, are subject to rapid decay or rust.
170 LANDSCAPE ARCHITECTURE
The Base Plane
Where flows are light, absorption by lawn, planting, or mulches may be sufficient.
Drives, walks, and bicycle paths are often used as drainageways.
If flows are to be heavy, the paving is made concave in section.
Or better, where width permits, the paving is crowned with drainage to a swale or gutter at the side.
In recreation courts, as elsewhere, the drainage planes are related to the overall design.
Site Volumes 171
Within a given area surface materials, patterns, and colors define the appropriate use.
Uses suggested by differentiation of surface materials.
Uses defined by delineation.
THE BASE PLANE IS THE PLANE OF USE.
Base surfaces range from fluid to rigid.
The size, shape, and texture of the base are designed to express the use.
The base plane establishes the volumetricarea.
It is on the base plane that we establish our trafficways. They are best aligned in compliance with the earth’s natural conformation. To violate the land is to incur expensive cuts and fills and require costly drainage structures. Moreover, on the disturbed surface areas a tight-knit cover must be reestablished for the sake of appearance and to preclude devastat-ing erosion. The most stable and beautiful drives and highways of the world are those that follow the ridges and valley floors and rise or fall across the side slopes where the cross gradient is most suitable. Perhaps such drives are pleasant because they are basically lines of dynamic force flowing in harmony with the natural forms and forces of the earth. Our friend Plato, if we could question him on this point, would nod in sage agreement.
Every object existing on the base plane has plan significance. If the object is to be preserved, its relation to other elements of the plan must be thoughtfully considered. If the object is to be moved, the ease and means of moving warrant study. If the object is to be modified, the degree and type of modification must be analyzed.
The base plane, in a world governed by the law of gravity, gets the most use and wear. It requires the most care and maintenance. The planner must recognize, as does the caretaker, that all materials and textures applied to this plane should be selected with concern for their perma-nence and appearance during all phases of their projected use.
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Base Plane Surface Drainage Stair Characteristics Tread-Riser Relationships
Site activities are generally associated with level planes.
Except when porous, these must be tilted or shaped to provide for surface drainage.
In site usage the warped plane most often connotes passive areas or buffer zones.
Narrow steps increase the apparent height and separation of levels. Broad steps unite the planes visually.
In natural sites or naturalized embankments, steps need not be of uniform size, shape, height, or depth.
Ramps, perrons, or steps are used to provide transition from level to level.
Terraces are designed to fit level use areas to sloping ground and to separate site functions.
THE BASE PLANE MAY BE LEVEL, WARPED, RAMPED, STEPPED, OR TERRACED.
As a connector of base planes, the ramp has several advantages over steps. A ramp is:
• Easier to ascend/descend
• Less formidable for wheeled vehicles
• More of a unifier than divider
• More economical to construct
THE RAMP (An inclined path or plane)
Never use a single riser except at a building platform.
In flights of six or more risers a handrail is recommended.
In an informal architectural setting steps need not be arranged in rigid flights.
Often they can be turned loose to find their way.
Where areas are drained to a central inlet, the fall is computed from the farthest warped or tilted to conduct runoff to a gutter or outfall at one or more sides.
In modular areas a coffered grid can relate
The earth plane—level, warped, sloped, or terraced—is the base for all construction. This is the plane on which, in which, and around which all things are placed. On this plane are established the primary plan forms of the project. The treatment of the ground plane is important to the accomplishment of proper transitions. The shapes and patterns of the base, if well handled, may subtly or powerfully relate a structural ele-ment to the site and to all other components. Through the sensitive design treatment of the ground surface we may coordinate, accentuate, and integrate all elements placed thereon.
The art of manipulating levels is a large part of the art of townscape.
Gordon Cullen Sidewalks and pavings traversed each day can be transformed into a hard-surface mural or community quilt—a participatory and collective artifact engaging people in making their turf.
Karen Bergmann
Site Volumes 173
Various functions of the base plane.
Edward D. Stone Associates (EDSA)Floor & Associates, Kristina Floor, Christopher Brown
Gustafson Guhrie Nichol Ltd.© D. A. Horchner/Design Workshop