Gr een Net wor k I nves t i gat i on i nt oT ypesofUr ban
Cor r i dor sf ort he Redef i ni t i on
and Habi t abi l i t y of St r uct ur alBar r i er si nt heCi t y
Francisco Azagra Parodi
UCL
T he Bar t l et tSchoolofAr chi t ect ur e M Arch Urban Design 10-11 UD 4-Tutors: Anna Rose / Ber nhar d Ret t i g/Dani elRi ngel s t ei n
Almost as a rule, contemporary cities contain structures which have generated large urban barriers dividing the city in several parts. These barriers or corridors, often railway systems, motorways, watercourses or other geographical conditions have been created or manipulated by human action with the purpose of connecting the city at large scale. However, this has often been disastrous for local scale connectivity and pedestrian facilities, and worse, significant environmental damage can be found around these structures in many cases. In the context of rethinking today’s cities fundamentally it becomes clear that those apparently negative attractors have an enormous potential to be regenerated and transformed into a sustainable network of green lines and open spaces interconnected throughout the city. This has been demonstrated through several examples, both completed and under development. Therefore, this essay is investigating the topic of regenerating redundant infrastructure systems into green networks.
2
Contents -
Introduction
4
Urban Green Corridor definition
6
Limits in the City Growth
7
Large Urban Barriers
9
Along the Water Along the Ancient Walls From the Railway Infrastructure to the Motorways
9 10 11
- Why incorporate ecological networks within the city? - Study of Cases -
Rethinking Waterfronts Rethinking Ancient Walls Rethinking Railway Corridors
- Rethinking Cities (Conclusions) - Bibliography - Other references
12 16 16 19 22
24 27 28
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Introduction Considering the invasion of computing around us, full of images, high resolution aerial photos and virtual perspectives where “the user” can visit the streets through a small screen; walking around the city today seems to be the more absurd means to discover the territory in which we live. It is apparently unnecessary to leave the desk to know what is happening somewhere.
However, public space remains for many a commonplace, where we
exchange
ideas
and
experiences,
participation
and
democracy that allows us to feel that our world is broader than our home or workplace, where human beings realize what it means to live in a society and in a specific local environment.
Unfortunately, this place called public space that some texts have described as the “neglected and eroded space”1 has been transformed by history into functional areas, ungrateful to the pedestrian. The dominance of motorised transport, especially the automobile and the related construction of motorways, largely ignores the need for sidewalks and pedestrian corridors. This infrastructure has transformed many cities into a set of iron lines and concrete barriers that have fragmented the urban territory
1
4
Rogers, R. 1997. Cities for a small planet. p.8
into several parts disconnected from each other at pedestrian scale. As a result, squares, parks and other urban open spaces often became small islands immersed in a sea of vehicles. These spaces are being claimed since the process of industrialization which produced the demographic growth and the need of extend cities that up today does not been stopped.
This process which has been present in different cities and in diverse forms has left behind, obsolete territories into the inner cities that generally are linked to redundant infrastructure due to functional changes and new technologies in the industry and transport, leaving thus, a significant number of available territories to propose new uses.
In this scenario where a complex network of rapid circulation on streets, avenues or motorways has removed more and more space from places for recreation, rest and leisure (in many cases connected to the ecological preservation of the soil), it is fair to think of giving back to the city pedestrian spaces through the creation of new green corridors, tree-lined streets and comfortable sidewalks.
The recycling of those obsolete infrastructures in the form of new trails and linear parks, and the use of the edges of rivers, canals and creeks connecting with existing natural corridors, parks and squares, are able to create a second network designed for human beings and their natural environment.
The means to achieve this has consequences and might contradict short term, individual interest. Nevertheless, projecting the cities in the long term, means generating the appropriate habitability
conditions
(physical
and
psychological)
for
all
inhabitants of the territory. Therefore, this would safeguard the conditions of a public realm with a social and environmental perspective - not only economic. This is sustainability.
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Urban Green Corridor definition Finding a clear way to define Green Corridor is not an easy task. Frequently, its definition is associated to natural corridors, which are largely limited to the introduction of vegetation and wildlife in the urban environment, as defined below: “A thin strip of land that provides sufficient habitat to support wildlife, often within an urban environment, thus allowing the movement of wildlife along it. Common green corridors include railway embankments, river banks and roadside grass verges.”2
Similarly, the concept of “Green Belt” is often associated to green corridor in a large scale, sometimes as an outer ring which divide the rural and urban space; sometimes as an inner ring integrated to the urban structure.
However, for the purposes of this essay we will talk about "Urban Green Corridor", including human activity as a fundamental part in
2 Defined by Planning Portal. UK Government's online planning and building regulations resource for England and Wales. http://www.planningportal.gov.uk/england/professionals/en/1115310689250.html
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linking ecological systems (not necessarily wildlife) within towns and city centres, places of employment and communities. Often follows along a river, this used railway or roadway; promoting paths for running, cycling or skating.
Zooming out to a greater large we find the road network structured as radial or ring pattern. Thus, the concept of Urban Green Network can be generated by rethinking the historical barriers in cities
through
analyzing
the
existing
corridors
and
the
transformation of obsolete infrastructure of urban green corridors.
Limits in the City Growth The context of rapid urbanisation today accounts for 50% of the total global population lives in cities (rural areas 50 years ago accounted around 70%3). Citizens prefer the urban lifestyle over the countryside, despite the perception in the quality of living in cities is quite debatable.
This process has been the subject of extensive discussion with various experiences in different cities. The logic of urban growth
3
United Nations Human Settlements Programme (UN-HABITAT).2008.
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can be described in two main concepts: urban sprawl and compact city4. Although for many urban professionals, the last typology is closer to the sustainable urban model, most societies and planning systems has not yet been able to overcome the free sprawl of the cities.
Throughout history, many towns have sought to limit their territory for defensive purposes as the walled cities of the Middle Ages, or for planning reasons as in the case of post-industrial cities.
Planning, as a discipline in western societies, generated the division of functional areas in many city plans, thereby, different zones were clearly recognized, such as residential, commercial or industrial areas which were connected through main transport routes.
The emphasis on the connectivity of the city was one of the most significant issues in the designed theories for the growing cities. Thus, certain concepts such as radial/rings or organic systems were proposed and articulated by transport corridors, originally were manifested by the railway system as a clear limit that was imposed on the city.
The need to pass these limits to satisfy the urban sprawl, produced the construction of new bridges and elevated motorways to connect them with residential neighbourhoods, shopping centres and new sub-centres that have guided the attention toward new areas of interest and development. Meanwhile, the old sites (transport and industrial corridors) are now shaping urban voids characterized
by
insecurity,
low
standard
habitability
and
deteriorating, under a concept which Ignasi de Sola-Morales has defined as "Terrain Vagues"5
4 5
Benton-Short, L.; Rennie, J. 2008. Cities and Nature. p.86
Ignasi de Solà-Morales defines terrain vague as land in a “potentially exploitable state but already possessing some definition to which we are external,” or “strange places” that “exist outside the city’s effective circuits and productive structures”
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Large Urban Barriers To understand the concept of "TerrainVague" in the contemporary city is necessary to review the typologies of the former boundaries and peripheries that represent a series of clearly recognizable situations in various parts of the territory. This is manifested in the form of lines that have scored the city creating a number of barriers which indisputably, have fragmented the city under topographic or manmade interventions.
In that sense, we observe sites of industries associated to disused rail infrastructure; the old port which later were accompanied for a large urban highway; or ancient walls that once were the city boundaries. Thereby, we can identify a group of situations along the water, along the ancient structures or along the transport development from the railway infrastructure to the motorways.
ALONG THE WATER With a clear awareness of the importance of water in human settlements development, the logic of the settlement of towns was the searching for strategic locations along rivers, canals or
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coastlines which by natural condition determinates one of the most significant limits of the development of cities.
Later, with the growth of the city, these boundaries became barriers industrial and port machinery on major rivers that have kept away for long to the people of their edges, which meant one of the episodes more pollutants in the history of the aquatic environment. 1. The Neolitic city of Catalhoyuk, Turkey. c7000 BCE. Considered one of the first human settlements.
Figure
In recent decades, the moving of the industry toward new centres, the use of air transport, innovation of new technologies and the reduction of space for the port works, produced the release of many areas, because the nature of trade has changed (Banks instead of Ports) bigger ships meant ports moved away from city centres, so sites became available for regeneration.
These sites have now been redefined and transformed into service corridors, recreation and culture, highlighting the potential for tourist attraction that has been a model for rethinking cities and awareness of quality of life.
ALONG THE ANCIENT WALLS Since old age, and perhaps before, walls where built as defensive and control systems of a given area at different times and locations.
The period that recognizes the peak of these constructions is the middle age where castles, villages and feudal cities were built in territories that today can be seen in several examples which have been maintained, rebuilt or restored in some of their pieces for the purpose of tourism and heritage preservation. Within these structures, there is the possibility to incorporate the old bridges and culverts that have been embedded in the city. However, there are also a significant number of structures that have become an obstacle rather than an opportunity, due to the high degree of damage and recovery costs have been. Many of
10
Figure 2. Sforzinda. Middle age city squeme. c1464. Unbuilt.
them have survived war or natural disasters, but have not been able to respond to social and economic dynamics of the contemporary city, become them into barriers without clear use or destination. Figure 3. Walled city of Avila,
Spain.
FROM THE RAILWAY INFRASTRUCTURE TO THE MOTORWAYS Originally associated with the industrial sector, the use of the train brought considerable benefits to the productive activity of the cities, however its implementation represented one of the most obvious physical barriers which have crossed or surrounded the city. Subsequently, functional and technological changes based on the reduction of space in the infrastructure or the introduction of new lines by subterranean systems, have left rendered obsolete some lines that no longer play the role as in the past.
Similar to this, the highway began to appear slowly in the first half of the twentieth century. By reusing traditional streets of the city, which were used by people on foot or on horses, bicycles, carriages, and then on automobiles; the condition of the former pedestrian street was transformed. In the second half of the century, the explosive growth in the number of cars and the need to interconnect cities expanding, produced vast stretches of concrete through the city and the countryside on elevated structures, flush with the floor or under ground, leaving no clear quality in the edges around it.
Under different perspectives, the city has been fragmented by various natural and manmade corridors, which, following the logic of growth have been embedded in key areas of the city. According to Benton & Rennie (2008): Figure 4. Cloverleaf in Seattle,
Washington, US.
“The decline of manufacturing especially in the older inner city areas is creating the brownfields of an industrial legacy with issues of soil contamination and pollution. The trajectory from factories to brownfields to Greenfield sites is not only a social process but also an ecological transformation�6
6
Benton-Short, L.; Rennie, J. 2008. Cities and Nature. p.151
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If in the past, the need to connect the city was one of the main tasks, introducing fossil fuels (coal, oil and gas) in the transport system,
which
have
produced
enormous
damage
to
our
environment.
Today the task is to amend this damage, but not from the creation of new neighborhoods, but also recovery from the existing structure by introducing a suitable and sustainable environment for the design of our cities.
Why incorporate green networks within the city? The perception of today’s modern family is to live on the outskirts of the city. Due to the characteristics that the edge of the town and countryside provide an area physically attractive, with more recreational spaces, green areas and lower density, in other words
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there is a clear relationship between nature-place-habitability which means quality of life.
It is important to understand that vegetation and nature positively influences the climate of a given area, not only in the physical or aesthetic aspect but also in the psychological environment that produces clean air and microclimate. It has also been shown that the presence of mature trees and landscape, influence human behaviour by generating greater peace of mind and reducing stress. In fact, according to colour therapy:
“Green is the neutral colour in the middle of the visible light spectrum (between red/orange and blue/violet). Green is therefore the easiest colour for the eye to see functions like a “tonic” when we are exhausted”. 7
In the physical aspect, it is known that vegetation and landscape brings many benefits, from creating a microclimate generated by the process of photosynthesis and the extraction of CO2 from the air, bind airborne particles thereby reducing dust, reduce noise, absorb rainwater and slow drainage, stabilizes temperature, rises the local humidity and act as a windbreak8.
It could add more features, but for the purposes of this essay is not necessary to address, the important thing is to realize the role that nature plays in our environment and how it can be incorporated in one of the key issues in urban settlements: the connectivity.
As has been mentioned, the need to connect the city has been a natural human urge, generating conditions for moving supplies for our subsistence, and our own movement to different areas.
The problem of this has been the means used to resolve this issue, fundamentally the motorized transport, which has invaded our settlements. The current model of urban development for decades has promoted the use of private car over public transport, which
7
Wauters, A. 1999. Homeopathic Color Remedies. California: Crossing Press.
8
Von Borcke, C. 2009. Landscape and Nature in the City.
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has produced a system collapsed in most towns and cities around the world.
Certainly, the traffic congestion on the streets creates an imbalance in the estimated time for a particular journey, but it also creates stress on drivers and often noise when the horn is used repeatedly
in
high
traffic
jam
situations
and
obviously,
environmental pollution by the emission carbon dioxide.
On the other hand, increasing travel time can mean delays and reduction of productivity times, which ultimately affects the economy of cities.
Therefore, it is clear that sustainable transportation is far from be motorized, so the recommended ways of moving for small and medium distances are Walking and Cycling. According to a research conducted in London, traveling by car or public transport is slower than cycling on many routes. As an example, a journey to the centre (1.7 mile) takes around 20 minutes or less by cycle, whereas by car or public it takes around 30 minutes.
Walking and Cycling, apart from being a not pollutant way of move, is also an economic and healthy exercise. Bicycles do not consume fuel and today there is more availability since the rental bike system (also known as Bicycle sharing systems) is operating in several European cities. In terms of healthy, they fight obesity, one of the mayor problems in urban societies.
During the last years, many cities have promoted cycling and walking more than a recreational activity. However, just a few have actually created the necessary infrastructure for this, i.e. welldesigned roads, accompanied with vegetation to allow the separation from motorized routes.
These reasons have stopped the increase in the use of these sustainable systems which obviously are consistent with other public transport systems, as the subway, the light train and other
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means of transport of low energy consumption and non-polluting, for long distances journeys. Unfortunately, the perception of citizens regarding the automobile is still social status and comfort, with priority over any other mean of transport. But a way of coping may be through well-structured green corridors that can be attractive for users. The biggest challenge then, is how to introduce these green corridors in the heart of the city, where the percentage of green areas is much lower or is reduced to some disconnected islands of grey environment where operates the city. Faced with the inability to build garden cities everywhere, perhaps as the visionary Ebenezer Howard9 had dreamed, or inability to control private property to the entire population assuring a green space in their homes or places of work, we must act on the existing natural corridor, streets and redundant infrastructure capable of making a city-wide transformation, considering that many of these actions can be taken by the hand of one head: the state or the administrative system which is in charge for public use.
Therefore, we must not understand the redundant infrastructure as a barrier within the city, but as an opportunity to integrate new sustainable uses as have been shown in many individual cases around worldwide.
Figure 5. Garden City Scheme, Ward and Centre by Ebenezer Howard, and a
personal proposal rethinking green structures.
9 Ebenezer Howard is mentioned as the main author of the Garden City theory based in his publication Garden Cities of Tomorrow (1898).
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Study of Cases RETHINKING WATERFRONT
The recovery process of obsolete infrastructure has not been a linear path. The recycling of the edges of river linked to the transformation of the ports and the release of industrial land, it has been developing for several decades, especially in big cities where the touristic interest has turned toward the edges, which have created pedestrian walkways linked with culture, sports, recreation and services in the different sections covered. This new understanding of the waterfront is also often recognized by business world. Docklands development, for instance, illustrate different experience as London Docklands in United Kingdom, Puerto Madero in Buenos Aires, Argentina or Dockland Victoria in
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Melbourne, Australia; which old ports have developed enormous transformations creating new Central Business Districts with high standard conditions.
Nevertheless, the development of many other waterfronts or riverbanks, have been complicated to address, because several managements are in charge of the edges, which has been fragmented and difficult to create a continuous structure along the water.
The case of New York, a city intersected by rivers, has many experiences in their edges, which were developed in isolation in the past and now are looking for connect with each other in Figure 6. Battery Park, Downtown,
integrated projects.
New York City. US.
Battery Park in Manhattan, a recognized riverbank that connect residential and office development in a key site of Downtown, New York, today is connecting with Hudson River Park and East River in a system of bikeways, promenades and green spaces as part of the Manhattan Waterfront Greenway project.
Brooklyn waterfront, was long been a forgotten riverbank in front of Manhattan. In the last decade, new projects started to change the old face of the obsolete industry, by encouraging projects as the recently open Brooklyn Bridge Park which includes commercial and residential development to make the park financially selfsustaining and attractive.
Other
project
under
development
is
Brooklyn
Waterfront
Greenway, a 9 km-long corridor which run along separate paths for bicycles and pedestrians allowing cyclists and walkers to commute exercise, explore, and relax along the route.
All these projects have been developed with community, nonprofit organization and local government participation, as The Brooklyn Heights Association, a neighborhood association who Figure 7. Olympic Sculpture Park,
Seattle Waterfront, Seattle. US.
worked on the Brooklyn Bridge Park project from the beginning; or Brooklyn Greenway Initiative (BGI), at Greenway case.
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Other recent experience, The Olympic Sculpture Park in Seattle Waterfront has transformed an industrial site into open green space destined to art. This project crosses and connects Seattle’s urban fabric, affording a wide range of environmental process of regeneration,
including
“brownfield”
redevelopment,
native
plantings salmon, habitat restoration and sustainable design strategies in only one integral proposal.
On the other hand, the case of the Thames River in London, the major river flowing through the city, presents its edges partially developed for pedestrian use, because a significant number of buildings and infrastructure interrupt this continuity.
The project called “London Promenade”10 running along the Southbank, proposes the extension of the existing promenade at the South Bank Centre to connect with an existing jetty at Butler's Wharf.
This Promenade includes a riverside park to attract new cultural activities and residential areas around; creating a world class waterfront, universal access and river transport. Such ideas are what ultimately may change the image of a city.
Although many of these projects have implicit the concept of ecology considering the water resources that provide the flow, however, they also are introducing green areas connecting with piers, ferry and ship terminals, promenades and public spaces on the banks, trying to change the old image of the waterfronts, decontaminating the aquatic environment to re-unite people with their edges, understanding that this is a space for citizenship and improve quality of life in cities.
In that sense, the cases of Manhattan and Brooklyn waterfronts are developing several projects connected by a Greenway; similarly, 10The London Promenade Urban Integration Study. 2006. Space Syntax presentation. http://www.scribd.com/doc/28046129/London-Promenade-UrbanIntegration-Study
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Figure 8. Thames riverside, London, UK. Narrow pathway at London Bridge area.
Olympic Park in Seattle concentrates culture, infrastructure, and green area in one integral project which can orientate other waterfronts in development, as London riverside, especially in the north bank.
The participation of the community who decide what kind of project they want to development in the public realm is essential for the progress of any initiative.
RETHINKING ANCIENT WALLS As stationary and permanent parts of many cities, the walls, bridges and aqueducts have drawn different shapes, structures and functions in the places where they are located. However, they have the common feature to be linear elements that generate the division of different areas.
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The choice of cases has been based on structures well preserved or demolished, not as a work of architecture itself, but as elements that have generated urban situations over time.
The Walls of Tallinn inserted in the center of Estonia dating since the 13th century and contain a tourist area (commerce, hotels and service), which in the past corresponded to the old city. Figure 9. Walled City of Tallinn,
The exterior of the walls is set up by a green belt and outside this
Estonia.
corridor, there is a ring road where circulate the public transport which does not interfere with the internal structure of the old city.
On the contrary, the fortified town of Naardeen, Netherlands, is inserted in the middle of the water through an artificial surrounding moat. It was built in the fourteenth century as a 5-pointed star, on the tradition of an Old Dutch defensive line (Hollandse Waterlinie).
The perimeter wall of this star was transformed over time into a green corridor, linking parks, water and bridges which connect with the rest of the city, defining a compact territory with a high standard of green area.
The case of Istanbul, the old settlement of Byzantium and Constantinople civilization had two important walls surrounding the city. The particular geography defined by Marmara Sea and the Bosphorus Strait has changed over time the morphology of these walls.
At present, a 6.5 km wall is recognized at the boundary of the ancient Constantinople city. This wall clearly generates the division of two sectors with inefficient connection between its parts; first is located the mixed sector housing, commerce and services, on the other, there are a number of areas with no clear destination, produced by activities that stopped working in the territory, some cemeteries and other industrial sites which have left reduced space for residential activity.
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Figure 10. Situation
at present, Theodosian walls in Istanbul. Turkey. 5th century.
On the other hand, the known case of Berlin Wall, a 140 km line constructed by the German Democratic Republic (GDR, East Germany) on 1961 and demolished on 1989, today it configures several areas destined in green and public scopes, as squares, linear parks and areas of urban renovation as Potzdamer Platz in the core of Berlin.
Reviewing individual cases, both the walls preserved of old towns Figure 11. Former Berlin Wall site.
that retain attractive tourist areas, such as those demolished structures which still retain traces of its past; they open an excellent opportunity to generate green corridors adapted to the urban fabric. The greatest challenge lies in the ability to change the image of the wall as a divisive element into an integrated program, as the Berlin wall that had long been the symbol of the conflicts and divisions, and later it becomes the symbol of unity and integration.
Similarly, the case of Tallinn illustrates a green belt which acts as an organizing element between the tourist-urban pedestrian and the urban environment more polluted. In Naardeen, the water appears as a green belt along the border, playing an important role as organizing element for preserving the interior of the city.
These two experiences can serve as an intervention strategy on wall edge in particular cases such as Istanbul, where control of space beyond the walls has been difficult to manage, however, the development potential of these vulnerable areas is still present. The role of local governments in developing and promoting integrated projects for recovery here is fundamental.
To sum up, the enormous tourist capital (economic and social benefit) on these areas must be reinforced by a good preservation and connectivity, well-lit paths, cycling and walking facilities, parking areas not interfering in the landscape (preferably underground) and staff who can work in the security of the sector.
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RETHINKING RAILWAY CORRIDORS One of the trends that have been occurring in cities with significant rail experience is the recycling of railway infrastructure along lines that have fallen into disuse or have reduced their facilities to transform them into linear parks elevated or at grade level, which have revitalized and reformulated the degraded character of industrial areas in the vicinity of dense urban areas.
The case in Paris known as Promenade PlantĂŠe, is an elevated park developed between 1987 and 2000. The Project is a 4.5 km-long corridor constructed on an abandoned railway viaduct which ceased operation on 1969. The parkway runs from the Bastille area connecting the eastern suburbs of Paris.
Similarly, the High Lines Park in New York City is a 2.3 km-long corridor which run along the west side of Manhattan over the former High Line railway at Chelsea. In this particular case, the
22
Figure 12. Promende PlantĂŠe, Paris. France.
neighbours of the obsolete railway line decided to defend the Line's permanence and transform it in a public open space in a project which try to preserve the wild grasses, plants, shrubs, and rugged trees which grew along most of the route on the period Figure 13. Cross section, High Line Park project. New York City, US.
when the train did not work.
The project Pasillo Verde Ferroviario in Madrid is a 7 km-long corridor developed between 1989 and 1996, connecting Atocha and Principe Pio Station. This urban repair project involves the undermining of the existing railway, construction of new stations, a new system of parks and green areas; on a proposal that not only tries to make more efficient the rail system in the city, but also try to reduce its impact and regenerate surrounding areas.
All these cases have the virtue of being located at key sites of the city, effectively reviving areas that were previously degraded and with low interest for the citizens.
The two first examples of elevated parks have generated a second floor habitable, safe and effective to separate the recreation of vehicular pollution, with adequate furniture and lighting to control and maintenance of its facilities.
However, without diminish the importance of Promenade PlantĂŠe which was the first experience of this kind, High Lines Park achieves greater interest in the community with high participation in the Figure 14. Pasillo Verde Ferroviario
site plan. Madrid, Spain.
design process and the rescue of pre-existing values for the construction of the new corridor (preservation of wild vegetation).
This experience is largely icon of other projects in development as The Bloomingdale Trail in Chicago, which has been also worked through the community participation (Friends of the Bloomingdale Trail) and the local government.
Pasillo Verde Ferroviario operates on a larger scale of recovery that will be developed in the long term, following examples such as the Paris Rive Gauche, Paris. The strong emphasis in this case, is given Figure 15. Situation at present,
Bloomingdale Trail in Chicago, US.
by a green area structure as a focus of interest for the renewal of
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other activities and the resurgence of the city's forgotten neighborhoods.
Therefore, for the recovery of large railway structures is not necessary to destine wide corridors of vegetation, only is necessary to provide a continuous well-connected structure which can use the remaining space in the creation of new residential edges.
Rethinking Cities (Conclusions) Although many cities, especially in northern Europe and America, are defined with a high standard of green areas (measured by the ratio of square meters per capita), it is difficult to determine how the green space is divided homogeneously at all sectors and even more difficult is verify if the green space is habitable and plays an active role in the city. That is why we have chosen different cases in different cities that can define the concept of�Urban Green Corridor� trying to build a mental image of what could be called the green network.
It is known that cities will continue to grow in some way, in many places at an exponential equation. It is also known that squares and parks appear statics in the local regulatory plans, so it is
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difficult to improve this percentage of green areas by the high cost to create a and
It is known that private property is not called to develop green structural projects in the city at sufficient levels (although there are interesting examples of local development). Therefore, is the public linear space, railway lines, roadsides, streets, rivers, canals and existing natural corridors, which seems to provide most obvious potential to rethink city.
In that sense, the choice of the cases presented, not only reflect the intention to recover the obsolete infrastructure to enhance the surplus value of the properties in their context, or the indiscriminate introduction of nature and wildlife in the city, by being a theme fashion in the urban design; on them it reflects the citizen participation, as demonstrated the High Lines project, a local recovery vision of a degraded space which now it want to be returned to the city. Obviously this could not be achieved in each of the corners of our cities, but as all urban scale projects, it is developed through stages which together generate the entire project along the time.
The question is how to set or recognize an Urban Green Corridors (UGC) and the response can be read from the case studies presented. The UGC, thus: :
favours sustainable transport modes, walking and cycling over any other, through dynamic pedestrian walkways that allow efficient communication;
is often located in key areas(generally around city centre) which is important to create a network of connections well integrated to the urban fabric;
can be associated with other sustainable transport systems, as light train, that allows the extension and linking with existing parks, squares and natural corridors;
looks for obsolete or degraded programs, to improve and renew the entire area around It (specially attractive for new residential areas) ;
integrates the vegetation along the route and takes advantage of water flow, not only as an
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ecological but also psychological, creating a suitable environment for recreation and leisure;
uses and preserves pre-existing values of the city which are attractive for touristic purposes;
can also integrate culture and commerce to do financially self sustaining projects;
recovers waterfronts transforming the image of the city, creating a world class riversides, with efficient access and transport system
often generates a second habitable floor, separated from motorized systems, which introduces street furniture and use programs for different ages;
It must be strengthened with appropriate lighting and security to encourage new users.
If today the focus is on the waterfront or river edges and slowly begin to emerge recovery projects of railways; tomorrow will be the Motorways who will have to be rehabilitated when their functions no longer fulfil the role they now play.
Thus, the city will find again the possibility to recover a lost space for citizens, a space where walking and cycling cannot be interrupted by the horn of a car and where people can cross freely from one extreme to other because the city is the space for everyone.
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Internet Web Pages After High Line’s Success, Other Cities Look Up, By Kate Taylor, Published: July 14, 2010. Available in: http://www.nytimes.com/2010/07/15/arts/design/15highline.html?_r=1&pa gewanted=all
Planning Portal. UK Government's online planning and building regulations resource for England and Wales. Available in: http://www.planningportal.gov.uk/england/professionals/en/11153106892 50.html
Green Network
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London Promenade, Urban Integration Study by Space Syntax. April 2006. Available in: http://www.scribd.com/doc/28046129/London-Promenade-UrbanIntegration-Study
Image references Figure 1. The Neolithic city of Catalhoyuk, Turkey. Available in: http://www.foodandwine.hu/2009/09/22/etyeki-kezes-labosfesztival-2009/ Figure 2. Sforzinda. Middle age city squeme. Available in: Wall, E. and Waterman, T. 2010. Urban Design. Lausanne: AVA publishing SA. P. 27. Figure 3. Walled city of Avila, Spain. Available in: Periodismo Independiente, http://www.periodismoindependiente.es/sabiasque/las-murallas-de-avila/ Figure 4. Cloverleaf in Seattle, Washington, US. Available in: http://www.periodismoindependiente.es/sabias-que/las-murallasde-avila/ Figure 5. Garden City Scheme, Ward and Centre by Ebenezer Howard, and a personal proposal rethinking green structures. Howard, E. 2003. To-Morrow, a peaceful path to real reform. Oxon: Routledge Figure 6. Battery Park, Downtown, New York City. US. Available in: http://en.wikipedia.org/wiki/Battery_Park Figure 7. Olympic Sculpture Park, Seattle Waterfront, Seattle. US. Available in: http://www.gsd.harvard.edu/news/weiss_manfredi_green_prize_4_ 07.html Figure 8. Thames riverside, London, UK. Available in: http://www.scribd.com/doc/28046129/London-Promenade-UrbanIntegration-Study Figure 9. Walled City of Tallinn, Estonia. Available http://travelingboy.com/archive-travel-ed-baltic.html
in:
Figure 10. Theodosian walls in Istanbul. Turkey. Available in: http://www.whereist.com/?p=501 Figure 11. Former Berlin Wall http://www.slate.com/id/2234900/
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Figure 12. Promende PlantĂŠe, Paris. France. Taken by Francisco Azagra. September, 2010.
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