Luz Alicia Cárdenas Jirón.
MSc.
Departamento de Urbanismo,
Facultad de Arquitectura y Urbanismo, Universidad de Chile.
Casilla 3387, Santiago. Chile. Fax: (56 2) 222 9522
Email: lcardena@abello.dic.uchile.cl
Constantino Mawromatis
Padzerka
Departamento de Diseño,
Facultad de Arquitectura y Urbanismo, Universidad de Chile.
Casilla 3387, Santiago. Chile. Fax: (56 2) 222 9522
| Abstract |
|
Metropolitan
Santiago is one of the many Latin American cities which has
been developed according to a spread model of urbanisation.
This pattern has caused at least two types of consequences:
economic and physical ones. The former is shown in the speculation
of land value at the rural fringe of the metropolitan area which
has low prices, these have suddenly increased after the normative
changes in the land use, from rural to urban. The later shows
location of massive low-income housing and commercial malls
regardless connection to the urban fabric and spatial shaping
of the existing city. This results in a chaotic urban form resembling
a "patchwork".
This
paper reviews the scope of a Chilean policy instrument called
"Plan Regulador" used to control physical urban growth,
particularly sprawled on the fringe of the city. It is believed
that as a consequence of this Plan, normative procedures are
not good enough for achieving its objectives. Conversely, urban
form appears to be a result of a profitability plan made by
private developers. Given the weakness of this instrument, some
recommendations related to spatial models are suggested to incorporate
to or complement the "Plan Regulador"
|
Overview
Santiago’s Metropolitan region is the smallest region in Chile.
Of its 791,581Has.only 46,179 Has. have been urbanised, leaving approximately
18,015 for future sprawl. Its 4,676,900 inhabitants represent almost
40% of the national population with a density of 101,3 (Hab./Hà.)
. Santiago is the capital of Chile and it has traditionally hosted
industrial, commercial, financing, administrative, and cultural services.
National GDP reaches 41,5 %. The Metropolitan area is composed by
34 districts from which 16 are located in the central area and the
rest on the periphery (Figure 1).
Santiago has been developed according to a spread model of urbanisation,
which has had an enormous economic, social and physical impact on
the city. Since the 1950´s, the Metropolitan Area has shown a rapid
physical growth using new land in the periphery (Figure 2). Particularly,
since the 1980´s when urban development policy was based on free market
principles, which stated that land was an inexhaustible resource,
private developers started to buy land and build large number of low
income housing at the periphery. Such is the case of Maipú.
Figure 3 and 4 show a comparison of the evolution of the housing and
the land market of Maipú and Santiago. As it can be seen, the growth
rate in terms of surface and land value for both has increased, however
this growth has been accentuated in Maipú. Another important fact
is displayed in Figure 5, which reveals the housing market behaviour
in the 34 districts. This figure shows a classification of districts
according to their location whether in central or peripheral areas.
Policy
and Urban planning instruments in Chile
To understand the context in which this research takes place, the
policy and planning stages in Chile will be outlined briefly. Up to
1974 urban planning was strongly centralised by the state and the
main concern was housing and land for the poor. Is the time of land
invation ("tomas de terreno") for housing purposes. From
1974 up to 1980 urban planning still being restrictive with regulatory
framework but it starts a decentralisation process through "regionalización".
Main concern was infrastructure - particularly transport - and housing,
not only for the poor but also for middles incomes groups as well.
In the 1990´s as many Latin American cities, is less centralised,
more flexible and the state looks for partnership with private sector
and community participation. Planning tends to focus on environmental
issues and empowerment of the local level. "Real State Agencies
are seen as catalistic agents of social change and structural development.
The last three Urban Development Policies (UDP) are quite different
from each other in terms of principles and major concern, as follow:
(MINVU, 1979) (MINVU, 1985)
In 1979, "Política Nacional de Desarrollo Urbano" stated
that land is an exhaustible resource, therefore there is no need to
control land use and to set up limits to physical growth. (Urban Growth
Boundaries)
In 1984, "Política Nacional de Desarrollo Urbano" stated
that land is a scarce resource, and thus land use must be planned
to control urban growth for public good.
In 1990, "Política Nacional de Asentamientos Humanos" states
that poverty and environmental degradation are the main issues to
be tackled by the state and society, hence land use should be controlled
according to equity and against pollution.
Chilean town planning instruments are organised in order of a cascade,
as follow : (MINVU, 1998)
Plan Regional de Desarrollo Urbano
Plan Regulador
Intercomunal
Plan Regulador
Comunal
Plan Seccional
All of them differ in terms of the scale in which they are applied,
from regional, to inter-district, to district, to neighbourhood. The
variables used by instruments to control growth are zoning, facilities,
width of road and street system, priority areas to be developed, boundaries,
densities, land use, building standard, site division, etc.
Town planning, Architectural
codes and Urban form
Chilean town planning and architectural codes seem to have little
or no effect at all in shaping the public space of suburban Santiago.
This is quite obvious, if you see the poverty of the metropolitan
periphery of Santiago, especially in low-income areas (Figure 6).
However are those very codes intended to regulate the structure and
morphology of the city? And, in doing so, are they not intended to
shape the physical space of the communities? These are critical questions;
nonetheless, they are not an issue in the written law.
For a better understanding of the suburban sprawl phenomena in present-day
Santiago, it is necessary to identify the historical forces that triggered
the unprecedented horizontal expansion of the metropolitan area. Throughout
the last decade and a half, Chile experienced a dramatic restructure
in its economic system. Historically, during most of the century,
the Chilean State was destined to overtake the responsibility of public
and social enterprises. The shift to an open market economy turned
the lead of urban development to the private sector. Suburban growth
developed as an attractive investment field.
Private developers have been benefiting since, through a very generous
variance to the ordinance, called "DFL-2 de construcción simultánea",
that overrides the municipal codes and the general ordinance of urbanism
and constructions.
As a result, suburban development projects became increasingly standardised,
uniformed and monotonous. Maximising profit and minimising risks has
been the motto shaping the suburban landscape of middle and low-income
communities.
The central issue regarding the ineffectiveness of Chilean Ordinances
in conforming a community, is based on two main points:
Firstly, the municipal codes, as well as the general ordinance of
urbanism and constructions have been conceived as written law. The
urban form as a central issue in the structure of a city, is not considered.
Zoning is the basis in the shaping of suburban development. The urban
space, as a result, is non-existent in terms of form and identity.
Second, the codes and regulations are structured as a restrictive
instrument, which has proven to fail in achieving a good urban form.
The American experience regarding the effects of suburban sprawl allows
anticipating the potential destruction of vernacular urban culture
through zoning criteria in urban policies. Economic growth and access
to a higher standard of living in Chile may accelerate the predominance
of the car in urban planning, favouring therefore, and the American
suburban model. Collector highways, closed developments and even more
restrictive regulations for a mixed used environment can be the consequence.
Mixed-use, hierarchy, urban and architectural typology, is clear and
specific variables that are essential in conforming a neighbourhood,
a town, and a community to identity. These variables can be incorporated
in local codes that prescribe rather than restrict.
In that respect, the new American towns and the alternative codes
that shape them, like the Traditional Neighbourhood Development TND
(Duany and Zyberck, 1991), have proven to become a quite successful
enterprise. Communities and businesses have benefited through a challenging
and intelligent endeavour.
The Missing Point::
The Urban Form
Given this introduction, the Maipú district has been selected as a
case study as it is located in the fringe of Metropolitan Santiago
City and it has shown a great dynamism in the last 15 years. The instrument
known as Plan Regulador Comunal (PRC) has been applied in Maipú since
1965 and urban fabric has been shaped by social, legal, political
and economic factors in different decades. Remarkably, before the
creation of PRC, there were legible physical structures in the old
centre. After this instrument was applied, physical structure of the
city started to blurr, though it appears certain significant elements
that could shape urban form of Maipu in terms of spatial boundaries,
connections and centrality. However, they hardly articulate an urban
design project to develop the city (Figure 7) (Figure 8).
Since the 1980’s sprawl of the metropolitan Santiago city was
explosive and particularly Maipu district which cross far beyond legal
boundaries of PRC and starts to form conurbation Santiago - Maipu.
A critical issue was how to control spread without architectural codes
and urbanism recommendations derived from PRC. Therefore others urban
planning instruments were applied to land use such as Plan Regulador
Intercomunal, (PRI) and Plan Seccional, (PS) as well as
a legal regulations like Housing DFL-2 "construcción simultánea"
and another one ironically called "conjuntos armónicos".
(Harmonic project) However, none of them consider means to structure
the urban fabric of Maipú as a whole, consequently urban form becomes
chaotic and disconnected to the old city square. At the end, building
the city in Maipu district is a process to add one by one but regardless
of the functional and composition principles.
On the other hand, these instruments considered variables to control
physical growth of buildings, sites, land and streets but it still
not good enough for shaping the urban form. This is due to architectural
codes such as building height, constructibility parameters, as well
as urban regulation like land use, land occupancy percentage, size
of site, densities, distance from neighbourhood site, etc. are applied
to regulate space within private property. While normative to control
streets, water-sewage pumping, communications network, etc - all elements
located on the public space - are applied to protect right function
of the single service but not to regulate public space as a property
of the community and users. Therefore, at the end of the day the design
of public space is not a conscious but a residual task.
To illustrate, there is a technical manual to control street size
according to safety and geometric principles in order to guarantee
that vehicles can easily move on it. The design concept of the street
is platform for mobility instead of space for pedestrian and vehicles
whether staying or moving. Moreover, to link such public space to
architecture and activity within it. For example, a concert hall building
would likely need more public space for staying and waiting people
in a safety manner, so design of the street might be different than
standard street size.
In this case, the question would be how to link activities, architecture
and street (public space)
In an ordinance in which matches all different requirements?
In others words, to conceive public property as a space for living
people rather than a platform to provide services only such as cars
traffic or water supply. In this sense, it seems that a new normative
which considers other elements and dimensions to shape urban form
in the cities is required.
Blending Spacials Models
Going back to the origins of spatial analysis methods, it can be found
that the first attempt to work with such a graphic methods took place
in the sixties. In fact, the Scottish architect and city planner Mc
Harg set up the basis for ecological planning to protect natural environment
from urbanisation projects. In doing so, the author proposed a method
for environmental impact analysis which support EPA (Environmental
Policy Act) in the USA (McHarg, 1967). Moreover some authors have
stated that concepts behind Geographical Information System GIS started
with Mc Harg method of environmental planning method (Sainz, 1992)
(Martin, 1996). However, the first technical example was the Canadian
Geographical Information System applied to land use in 1964 (Bosque,
1992).
In addition to that, technology began to develop, i.e. in 1962, Sutherland
developed the first software package for drawing in Massachusetts
Institute of Technology (MIT) which is considered as the basis for
Computer Aided Design CAD. (Sainz, op. cit.). However, since then,
many graphics software have been created for spatial analysis and
they can be classified under an umbrella term known as Computer-assisted
Cartography which is composed by CAD and CAM Computer -aided Map.
CAD is widely used in architectural and engineering design environments
which when applied to map is known as CAM (Martin, 1996).
After the creation of IBM’s Personal Computer PC, in the nineties
a wide variety of graphic software have been launched to the market.
While CAM was developed, GIS emerged as a mayor tool for spatial analysis.
Nowadays, GIS is considered both a technology and a spatial analysis
method for modelling (Birkin, 1996). Broadly speaking, GIS is a device
for turning data into information for decision making (Hearnshaw,
1996) But it also involves a process that consists of at least four
stages: collection and input data; storage and retrieval; manipulation
and analysis; and finally output a digital map and reporting (Martin,
op. cit.). Geographical Information System, whether technology or
process, is widely used for regional and urban planning purposes and
recently for spatial decisions support system (SDSS) (Birkin, op.
cit.).
In the meantime, CAD developed a three-dimension (3D) software which
emerged as a step toward modelling architecture and public space,
in other words, to support urban design. This device is a cornerstone
for architects and city planners to work with architectural and urbanism
concepts that traditional means such as CAD or even GIS cannot convey
to the users or decision-makers. This is due mainly to the fact that
both packages are applied in two dimensions (2D) of reality. In this
sense, it is important to distinguish both capability surfaces modelling
and volume modelling to enable research on the interaction of different
shapes in the realm of public space (GisEurope, 1997) (MicroStation,
1997).
In the nineties, Virtual Reality VR emerges in the zenith of computer
graphic technique and urban modelling concept, because it becomes
a way of developing a virtual urban environment for planning and design
purposes (Batty, 1997). In fact, on web sites it is possible to find
"virtual cities" in different ways such as online guides;
or "flat" which use 2D maps of cities and buildings; or
3D which use virtual reality technology to model the built form of
cities; or "true" virtual cities which are an effective
digital equivalent of real cities. For example, a realistic built
form, a diversity of services, functions and information, is able
to support social interaction with other users (Dodge et al., 1997).
The most popular approach to create virtual cities is the Virtual
Reality Modelling Language, VRML which provides a flexible, powerful,
platform-independent tool to model the urban form of virtual cities.
Given the "state of the art" in spatial modelling, this
paper intend to propose an integration of method to be included as
a regulatory framework in Chilean planning process in order to guide
decision makers in controlling urban form. It is believed that through
visualisation technique private developers, users and decision makers
can more effectively communicate and achieve an understanding of the
spatial impact of its interventions on the built environment.
According to requirements of disciplines is the method to be applied
on; a case in point is the use of GIS traditionally has been applied
to environmental planning, land use planning, regional planning, etc.
While CAD, 3D and recently VR has been applied to architecture, urban
design and urbanism. In the latter, it should be mention a couple
of remarkable examples: the famous architects Duany and Zyberck in
USA (Katz, 1994) with "the new urbanism" and Batty in UK
(Batty, op. cit.) with "the virtual cities" on the nineties.
To implement these experiences in Chilean planning, it is imperative
to provide the local municipal authorities, the private developers,
and the common citizen, with a clear and tangible view of how investing
in better projects can ultimately benefit everyone. Thus it would
be possible to anticipate and to improve the understanding of the
impact and potentials of urban interventions in the city.
As stated previously, the missing point in Chilean town planning is
the urban form, this paper intends to explore the ways to bridge the
gap between 2D and 3D visualisation as a concept to be applied to
planning instruments. It would therefore be possible to display information
of planned and unplanned changes on the urban environment (Bishop,
1994). An integration of both methods is thus proposed: a "cartographic
model" based on GIS and a 3D visualisation, both of them working
in an interactive way as shown in Figure 9 and Figure 10.
As shown in Figure 9, the cartographic model works with 2D based on
base map that overlap to create a new map with new information in
a type of flow chart. The final result is then contrasted with alternatives
of urban design to assess and evaluate spatial changes. Prescriptive
rather than restrictive codes are suggested in order to support town-planning
instrument for shaping an urban form
Prescriptive codes are easier to formulate, if they go together with
clear, simple spatial and volumetric rules. The urban form, as structure
and as public space, is physically defined by the relation between
buildings and the open space. This can be replicated using 3-D software.
3-D modelling allows experimenting in urban space through trial and
error at a low cost (Figure 10).
Urban Planning and Architecture in the metropolitan area and even
in at a neighbourhood scale may result very abstract for the common
citizen. Nevertheless, a community may participate and become involved
with its environment through computer generated simulations. Involvement
creates commitment. Commitment creates identity, which result in better
communities.
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