A pattern language - читать бесплатно онлайн полную версию книги автора Christopher alexander (122 BUILDING FRONTS*) #24

122 BUILDING FRONTS*

. . . this pattern helps to shape the paths and buildings simultaneously; and so completes building complex (95), wings of

LIGHT (107), POSITIVE OUTDOOR SPACE (l06), ARCADES (I 19), path shape (I 21), and also ACTIVITY POCKETS ( I 24).

Building set-backs from the street, originally invented to protect the public welfare by giving every building light and air, have actually helped greatly to destroy the street as a social space.

In positive outdoor space (106) we have described the fact that buildings are not merely placed into the outdoors, but that they actually shape the outdoors. Since streets and squares have such enormous social importance, it is natural to pay close attention to the way that they are shaped by building fronts.

The early twentieth-century urge for “cleanliness” at all costs, and the social efforts to clean up slums, led social reformers to pass laws which make it necessary to place buildings several feet back from the street edge, to make sure that buildings cannot crowd the street and cut off sunshine, light, and air.

But, the set backs have destroyed the streets. Since it is possible to guarantee plenty of air and sun in buildings and streets in other ways—see, for example, four-story limit (21) and wings of light (107)—it is essential to build the front of buildings on the street, so that the streets which they create are usable.

Finally, note that the positive shape of the street cannot be achieved by merely staggering building fronts. If the building fronts are adjusted to the shape of the outdoors, they will almost always take on a variety of slightly uneven angles.

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Slight angles in the building fronts.

Therefore:

On no account allow set-backs between streets or paths or public open land and the buildings which front on them. The set-backs do nothing valuable and almost always destroy the value of the open areas between the buildings. Build right up to the paths; change the laws in all communities where obsolete by-laws make this impossible. And let the building fronts take on slightly uneven angles as they accommodate to the shape of the street.

no setbacks
slight angles

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Detail the fronts of buildings, indeed the whole building perimeter, according to the pattern building edge (160). If some outdoor space is needed at the front of the building, make it part of the street life by making it a private terrace on the street (140) or gallery surround (166) j and give the building many openings onto the street—stair seats (125), OPEN STAIRS (158), STREET WINDOWS (164), OPENING TO THE STREET (165), FRONT DOOR BENCH (242) . ... ¹

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TOWNS

This process can be implemented by regional zoning policies, land grants, and incentives which encourage industries to locate according to the dictates of the distribution.

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towns of 1,000,000-250 miles apart towns of 100,000 - 80 miles apart towns of 10,000 - 25 miles apart towns of 1,000- 8 miles apart

As the distribution evolves, protect the prime agricultural land for farming—agricultural valleys (4); protect the smaller outlying towns, by establishing belts of countryside around them and by decentralizing industry, so that the towns are economically stable—country towns (6). In the larger more central urban areas work toward land policies which maintain open belts of countryside between the belts of city—city country fingers

(3). • •

123 PEDESTRIAN density*

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. . . in various places there are pedestrian areas, paved so that people will congregate there or walk up and down—promenade

(31), SMALL PUBLIC SQUARES (6l), PEDESTRIAN STREET (lOO),

building thoroughfare (ioi), path shape (121). It is essential to limit the sizes of these places very strictly, especially the size of areas which are paved, so that they stay alive.

Many of our modern public squares, though intended as lively plazas, are in fact deserted and dead.

In this pattern, we call attention to the relationship between the number of people in a pedestrian area, the size of the area, and a subjective estimate of the extent to which the area is alive.

We do not say categorically that the number of people per square foot controls the apparent liveliness of a pedestrian area. Other factors—the nature of the land around the edge, the grouping of people, what the people are doing—obviously contribute greatly. People who are running, especially if they are making noise, add to the liveliness. A small group attracted to a couple of folk singers in a plaza give much more life to the place than the same number sunning on the grass.

However, the number of square feet per person does give a reasonably crude estimate of the liveliness of a space. Christie Coffin’s observations show the following figures for various public places in and around San Francisco. Her estimate of the liveliness of the places is given in the right-hand column.

Sq. ft. per person

Golden Gate Plaza, noon: 1000 Dead

Fresno Mall: 100 Alive

Sproul Plaza, daytime: 150 Alive

Sproul Plaza, evening: 2000 Dead

Union Square, central part: 600 Half-dead

Although these subjective estimates are clearly open to question, they suggest the following rule of thumb: At 150 square feet per person, an area is lively. If there are more than 500 square feet per person, the area begins to be dead.

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BUILDINGS

Even if these figures are only correct to within an order of magnitude, we can use them to shape public pedestrian areas—• squares, indoor streets, shopping streets, promenades.

To use the pattern it is essential to make a rough estimate of the number of people that are typically found in a given space at any moment of its use. In the front area of a market, for example, we might find that typically there are three people lingering and walking. Then we shall want the front of this market to form a little square, no larger than 450 square feet. If we estimate a pedestrian street will typically contain 35 people window shopping and walking, we shall want the street to form an enclosure of roughly 5000 square feet. (For an example of this calculation in a more complicated case—the case of a square in a public building that has yet to be built—see A Pattern Language Which Generates Multi-Service Centers, Alexander, Ishikawa, Silver-stein, Center for Environmental Structure, 1968, p. 148.)

Therefore:

For public squares, courts, pedestrian streets, any place where crowds are drawn together, estimate the mean number of people in the place at any given moment (P), and make the area of the place between 150P and 300P square feet.

average number of people, P

area of 150P to i , /■ .•300P square feet ■ S

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Embellish the density and feeling of life with areas at the edge which are especially crowded—street cafe (8 8), activity

POCKETS (124), STAIR SEATS (I 2 5), PRIVATE TERRACE ON THE STREET (14O), BUILDING EDGE (l6o), STREET WINDOWS (164), OPENING TO THE STREET ( 165), GALLERY SURROUND (l66). . . .

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124 ACTIVITY pockets**

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. . . in many large scale patterns which define public space, the edge is critical: promenade (31), small public squares (61),

PUBLIC OUTDOOR ROOM (69), PEDESTRIAN STREET (lOO), BUILDING thoroughfare (101), path shape (121). This pattern helps complete the edge of all these larger patterns.

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The life of a public square forms naturally around its edge. If the edge fails, then the space never becomes lively.

In more detail: people gravitate naturally toward the edge of public spaces. They do not linger out in the open. If the edge does not provide them with places where it is natural to linger, the space becomes a place to walk through, not a place to stop. It is therefore clear that a public square should be surrounded by pockets of activity: shops, stands, benches, displays, rails, courts, gardens, news racks. In effect, the edge must be scalloped.

Further, the process of lingering is a gradual one; it happens; people do not make up their minds to stay; they stay or go, according to a process of gradual involvement. This means that the various pockets of activity around the edge should all be next to paths and entrances so that people pass right by them as they pass through. The goal-oriented activity of coming and going then has a chance to turn gradually into something rrtore relaxed. And once many small groups form around the edge, it is likely that they will begin to overlap and spill in toward the center of the square. We therefore specify that pockets of activity must alternate with access points.

A conceptual diagram.

600 124 activity pockets

The scalloped edge must surround the space entirely. We may see this clearly as follows: draw a circle to represent the space, and darken some part of its perimeter to stand for the scalloped edge. Now draw chords which join different points along this darkened perimeter. As the length of the darkened edge gets smaller, the area of the space covered by these chords wanes drastically. This shows how quickly the life in the space will drop when the length of the scalloped edge gets shorter. To make the space lively, the scalloped edge must surround the space completely.

As the activities grow around the space, it beco?nes more lively.

When we say that the edge must be scalloped with activity, we mean this conceptually—not literally. In fact, to build this pattern, you must build the activity pockets forward into the square: first rough out the major paths that cross the space and the spaces left over between these paths; then build the activity pockets into these “in-between” spaces, bringing them forward, into the square.

A pocket of activity which bulges into the square.

Therefore:

Surround public gathering places with pockets of activity —small, partly enclosed areas at the edges, which jut for-

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BUILDINGS

ward into the open space between the paths, and contain activities which make it natural for people to pause and get involved.

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Lead paths between the pockets of activity—paths and goals (i 20)—and shape the pockets themselves with arcades and seats, and sitting walls, and columns and trellises—arcades (119),

OUTDOOR ROOM (163), TRELLISED WALK ( I 74) , SEAT SPOTS

(241), sitting wall (243); above all shape them with the fronts of buildings—building fronts (122); and include, within the pockets, newsstands—bus stops (92), food stands (93), gardens, games, small shops, street cafes (88), and a

PLACE TO WAIT (150). . . .

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125 STAIR SEATS*

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. . . we know that paths and larger public gathering places need a definite shape and a degree of enclosure, with people looking into them, not out of them—small public squares (6i), POSITIVE OUTDOOR SPACE (l06), PATH SHAPE (l2l). Stairs around the edge do it just perfectly; and they also help embellish

FAMILY OF ENTRANCES (l02), MAIN ENTRANCES ( I I o) , and OPEN STAIRS (158).

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Wherever there is action in a place, the spots which are the most inviting, are those high enough to give people a vantage point, and low enough to put them in action.

On the one hand, people seek a vantage point from which they can take in the action as a whole. On the other hand, they still want to be part of the action; they do not want to be mere onlookers. Unless a public space provides for both these tendencies, a lot of people simply will not stay there.

For a person looking at the horizon, the visual field is far larger below the horizon than above it. It is therefore clear that anybody who is “people-watching” will naturally try to take up a position a few feet above the action.

The trouble is that this position will usually have the effect of removing a person from the action. Yet most people want to be able to take the action in and to be part of it at the same time. This means that any places which are slightly elevated must also be within easy reach of passers-by, hence on circulation paths, and directly accessible from below.

The bottom few steps of stairs, and the balusters and rails along stairs, are precisely the kinds of places which resolve these tendencies. People sit on the edges of the lower steps, if they are wide enough and inviting, and they lean against the rails.

There is a simple kind of evidence, both for the reality of the forces described here and for the value of the pattern. When there are areas in public places which are both slightly raised and very accessible, people naturally gravitate toward them.

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125 STAIR SEATS

Stepped cafe terraces, steps surrounding public plazas, stepped porches, stepped statues and seats, are all examples.

Therefore:

In any public place where people loiter, add a few steps at the edge where stairs come down or where there is a change of level. Make these raised areas immediately accessible from below, so that people may congregate and sit to watch the goings-on.

public place

Give the stair seats the same orientation as seat spots (24.1). Make the steps out of wood or tile or brick so that they wear with time, and show the marks of feet, and are soft to the touch for people sitting on them—soft tile and brick (24.8) ; and make the steps connect directly to surrounding buildings—connection TO THE EARTH ( 168) . . . .

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