preventive conservation of the world heritage site of alberobello

Leuven, March
th
24
–
th
25
2009
Inauguration of UNESCO Chair
on Preventive Conservation, Monitoring and Maintenance of Monuments and Sites
1. Background
Visual integrity of heritage is not only an aesthetic concept, but also an historical composite, the cumulative result of a long history. For this reason, views can play an
essential role in the values appreciation and conservation of the historical environment and of its integrity and authenticity. Starting form these considerations, this
document explains which evaluations have been applied in order to define the guidelines for the strategies included into the management plan of “The Trulli of
Alberobello” (Italy, Puglia region), at present in drafting phase by SiTI (Higher Institute on Territorial Systems for Innovation, founded in 2002 by the Polythecnic of Turin
and Compagnia di Sanpaolo). The property is inscribed into the World Heritage List of Unesco since 1996, on the basis of cultural criteria (iii), (iv) and (v) considering
that the site “is of outstanding universal value being an exceptional example of a form of building construction deriving from prehistoric construction techniques that have
survived intact and functioning into the modern world.” (Committee decision n. 787, Merida, Mexico,1996). The site has been selected to face this topic as considered of
particular significance, for its historic features and for the processes happening at present, in relation to the preservation, together with the heritage in itself, of the visual
perception of its cultural significance, factor that assumes relevance even in relation to the peculiar morphology and shape of the site and of its components.
2. Territorial and project context
At present days the living community is deeply aware on the historic-artistic quality of the Trulli, and of the importance of an adequate policy of protection, preservation
and valorisation. The monumental quarters have to be considered not only has an historic document, but above all they are one of the best preserved examples of
spontaneous architecture within the Italian architecture tradition. Discussions upon the proper use and method of conservation of their cultural and urban heritage are
constantly object of public debate. In particular the huge touristic flows due to the site’s visits are growing and becoming a relevant source of economic development, but
also pose the need to the creation of the right services and interventions in support of it. The first element to make real these operations has to be identified into the
recognition and the assessment of the values characterizing the site. The analysis made on the existing documentation and the surveys on field allowed to put in
evidence a multitude of values characterizing the site. Among these there are urban, architectonic, documentary (particularly referring to the prehistoric building
technologies), testimonial (the site is representative of a disappeared civilization) and social values. Nonetheless, in order to better evaluate the importance of the town
of Trulli for all mankind, this has to be confronted with several built-up areas scattered in the whole planet and namely in the Mediterranean region. Concerning the main
features of the urban area, it is useful to point out that the practically integral conservation of the historical centre through the centuries is mostly due to:
−- the outstanding strength of the urban structure of the monumental neighbourhoods, “Monti” and “Aia Piccola”,
−- the steadiness of the local building tradition and the relative cultural isolation of the district.
The urban renewal and the suburban expansions of the last century, indeed, have neither modified the essence of the urban structure nor affected the extraordinary
architectural heritage of the town of Trulli. Nowadays, Alberobello is advisedly considered to be one of the most significant and better preserved spontaneous urban
settlements in Europe. At present, however, some threats impend on this urban area, caused by the rising trend of housing pressures and the subsequently increasing
needs of facilities. These two emerging facts automatically lead to planning of new buildings, meant as infrastructure for accessibility and leisure, facilities, houses.
In the urban area of Alberobello, with its extent and its orographical features, this depicts two kinds of threats, in particular the loss of visual integrity and the loss of
functional and perceptual continuity between historical centre and countryside.
A third element takes the shape of a potential risk: the restoration of Trulli by using techniques not in keeping with the traditional ones, that at present appear to be
expensive and applicable only by skilled labour, getting scarcer and scarcer due to the fact that here, like elsewhere, the knowledge of mortarless stone building
techniques is being replaced by modern technologies based on machining.
In 2006 the Murgia of Trulli was included in the 100 most endangered sites in the world by the World Monument Fund. An element that testify the need to find an efficient
solution, through an appropriate project, to the ongoing and worsting decay of this precious area of this region. Moreover, the diffusion of this typology on the surrounding
territory, the Itria Valley, allows to define real landscape values on a territorial scale.
UNESCO, in application of the principles written into the 1972 Convention, is concerned to ensure that the Outstanding Universal Value of World Heritage Sites is not
adversely affected by pressure for continuing development, particularly in urban locations.
In this specific case, the urban development that occurred during the last years and the still strong pressures on the development increase the necessity to put in
evidence, while editing the management plan, the definition of an appropriate buffer zone. Zone that, in accordance with the art. 104 of the Operational guidelines for the
implementation of the Convention, “(…) should include (…) important views and other areas or attributes that are functionally important as a support to the property and
its protection (…)”. This issue includes the assessment of the compatibility criteria for the inclusion of new architectural elements dictated by the current needs of the site,
primarily related to the tourists reception. Aspect that needs a a predisposition of specific methodologies for the assessment of the level of interference of the new
projects with the values of the site and their integrity and authenticity.
3. Methodology
As regards the assessment of the visual impact of new interventions near or in relation with the site, SiTI is developing a method to help it assess the historical
significance of views, systematically and consistently. The proposed method draws on the Principles for sustainable management of the historic environment already
remembered by he recent charters on conservation as The Charter of Cracow 2000, Principles for conservation and restoration of built heritage, and on the principles
stated by the Unesco Convention in 1972 and its Operational guidelines. The methodology proposed describes a method of assessing the historical significance of a
view that would be applicable whatever historic assets may be visible in it. To this purpose has been carried out a project aimed at the three-dimensional display of
Alberobello historic centre. This was realized by the simulation of a flight through the trulli and the other buildings of the town, in a Geographical Information System
environment. The project has been carried out using dedicated software, Esri ArcGIS and its extension for 3D environment, ArcScene. In order to accomplish the task,
geo-referred data concerning the elevations of the terrain (such as contour lines and elevation points) have been processed, together with geo-referred building features
and cadastral surveys containing information about the buildings (their typology, dimensions, volumes). Afterwards, each building and land feature has been extruded
and modelled on the basis of its own dimensional attributes, so that the spatial distribution, and mutual positions of the built-up area elements have been highlighted.
After that, with a specific tool of the software, a simulation of a plane flying through the buildings and taking pictures of them has been set and run. Then the data so far
processed have been integrated with more information, not essential fro the scientific point of view but still useful to improve the final result of the job, such as trees,
vehicles in the streets etc. the final step consisted in the projection of aerial pictures (scale 1:2.000 and 1:500) on the rendered solids, so that at the end a realistic 3D
model of all the buildings in the town has been made available. The captured sights furnish both global and detailed views of built-up areas in the town, allowing to
analyze the sights from the two monumental neighbourhoods of the old city centre towards the modern part of the city, and from here to the old town. Thus, the final
outcome of the project is an analysis tool, also able to simulate the placement of new buildings, allowing a preliminary assessment of their visual impact.
4. Implications and potential of implementation
The legislative protection and the plans prepared by the authorities ensure since a long time ago the substantial maintenance of architectural quality of the place.
Therefore, within the city of trulli it is not possible today to demolish, to rebuild nor to elevate buildings, and not even to make any transformations to the urban structure.
Anyway, even before this legislative protection was in force, a traditional management of the architectural heritage of the city has always operated with attention to the
integrity and the respect of the totality and of the single details. The care employed in the restoration operations has thus avoided the production of false buildings, which
is however an unknown possibility because of the strict and universally recognized Italian culture in this field. But this attention cannot be said to be equally rigorous in the
areas adjacent to the site perimeter, where the existing urban instrumentation makes it eligible the construction of new buildings with a strong potential of visual
interference with respect to the consolidated historic core. Such issues are among the many that local planning authorities must consider, and this method of assessment
is intended to help clarify the heritage aspect of the planning process by local authorities. This work provide local planning authorities, developers and the wider public
with a reliable method for assessing both the heritage significance of views, and of the likely impacts of specific development proposals on such views. It does not impose
or dictate judgement as to whether the impact is acceptable or not. That judgement is the responsibility of the local planning authority. This approach should, however,
help all parties involved to evaluate impact based on a common understanding and so reduce the scope for differing judgements, and contribute to establish a baseline
against which to judge the impact of proposals upon heritage significance.
Moreover, the tool developed could have a relevant contribution, through virtual simulations, to address new forms of infrastructure which can profoundly influence the
rural landscapes. These structures can be profoundly visually influential, as they can obscure the significance or interpretation of a view and this need to be given
substantial attention in evaluating their impact on the historically significant elements in a view.
The relevance of this tool could enhance the debate and discussions over the future development of agri-environment schemes in relation to appraising historically
significance elements in view which are directly influenced by agricultural practice. Impact assessment and design development should be part of an iterative process and
it will be important for a developer to show how the results of an assessment have been considered in the design process to avoid harm to heritage significance within the
view. Aspects of design such as scale, mass, silhouette and reflectivity may be particularly relevant to mitigation of impacts on the historic environment. On that issue
there are in the recent past and at present many cases that can be relevant to this discussion, as the bridge building in the Dresden Elbe Valley (Germany), or the Verige
bridge in the Bay of Kotor (Montenegro), the accessibility review to Stonehenge (UK).
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PREVENTIVE CONSERVATION OF THE WORLD HERITAGE SITE
OF ALBEROBELLO
INTERPRETATION AND PROTECTION OF LANDSCAPE VISUAL INTEGRITY
MONDINI Giulio, Italy; DONGIOVANNI Arianna, Italy; RE Alessio, Italy; SOLDANO Silvia, Italy; VALLE Marco, Italy