25 de juny de 2009

UNESCO - informe preliminar (de su organismo el ICOMOS) sobre el paso del AVE cerca de la Sagrada Familia

Possible Impact of the Spanish High-Speed Train (AVE) on the Church of the Sagrada Familia in Barcelona

fuente: ICOMOS - Spain Heritage at Risk 2006/2007 - pag 143 – 144 – 145

In Barcelona the proposed construction of an underground tunnel for passage of the Madrid-Zaragoza-Barcelona-French border line of the Spanish high speed train (AVE) has generated public alarm as a result of cracks already appearing in buildings in the city of El Prat de Llobregat where the tunnel is presently under construction.

There is serious concern about a possible repetition of this phenomenon in the city of Barcelona. At the same time, a heated public debate has arisen about the suitability of the route chosen for the underground passage of the train through the center of Barcelona, because of the possibility that the construction of the new tunnel might damage nearby buildings. This has also caused concern among members of the construction committee of the Church of the Sagrada Familia, i.e. specialists and cultural heritage associations and other concerned groups, because of the potential negative impact of the AVE on the integrity of the monument, mainly owing to the close proximity of the church and the new train line.

In view of this situation, the Spanish Committee of ICOMOS, after examining the assessment made by the construction committee (CC) of the Church of the Sagrada Familia as well as the geological and chemical reports provided by the CC on the potential impact of the high speed train on the church; and after consulting other specialists and analyzing the case in the light of the provisions of the World Heritage Convention, submits the present report to the competent authorities in World Heritage and the institutions involved in its defense for all pertinent purposes:

Preliminary considerations

The projected route of the AVE line Madrid-Zaragoza-Barcelona- French border includes the construction of an underground tunnel for passage of the train at the point where it crosses Mallorca Street in Barcelona. This tunnel will be approximately 12 m in diameter and will be located at a depth of 30 m and at a distance of 3-4 m from the Glory façade (main façade) of the Church of the Sagrada Familia. To prevent potential damage from the tunnel construction and the passage of the high-speed train, the tunnel construction team has proposed to build a reinforced concrete slurry wall 240 m long and 42 m deep, composed of 1.5 m piles separated by 2 m. The distance from this wall to the foundations of the church will be 1.75 m and 0.75 m to the tunnel.

The church is a unique and structurally complex monument of large proportions, volume and weight, and when it is finished it will reach a maximum height of 170 m and have towers 120 m high (Glory façade). The already built central nave reaches a height of 45 m and its roof, now under construction, will rise to 70 m. The columns of the central nave branch at a certain height, forming a light tree-like structure, which, according to the temple construction committee, “is vulnerable due to its fragility to possible differential movements greater than those foreseen in the construction project for the church.” The towers of the Nativity façade, declared World Heritage, reach a height of 110 m and belong to an earlier period of construction. Because of this, they rise on foundations that are shallower and less rigid than the rest of the church.

The Nativity façade and crypt of the Sagrada Familia, direct work by the architect Antoni Gaudí and located in this church, were recognized by UNESCO as works of outstanding universal value and were included on the World Heritage List on July 15, 2005. Although the rest of the church is not included in the work of outstanding universal value, it forms a “whole” with the declared property, i.e. a single architectural unit (from a conceptual, functional, spatial, structural, volumetric viewpoint), and is therefore also subject to protection. The legal figure for its protection is that of a “buffer zone” (or setting) of a World Heritage property.

In the dossier for declaring the Nativity façade and crypt of the Sagrada Familia World Heritage, which was evaluated by the UNESCO World Heritage Committee at the initiative of the Kingdom of Spain, their inclusion on the World Heritage List is justified on the basis of complying with criteria I, II, III and VI

The Spanish State, as a signatory of the World Cultural and Natural Heritage Convention, has the responsibility and the obligation, among others, to ensure the conservation and transmission of the cultural heritage included on the World Heritage List for future generations (Art. 4), because they are unique and irreplaceable properties of exceptional universal value. It also has the obligation Art. 6) not to take any deliberate measures that directly or indirectly damage this cultural heritage.

Reports consulted

With regard to the potential impact of the proposed tunnel on the building elements of the church, the reports consulted underline the following:

  • The monumental nature of the church.

  • For the above reason the need for more careful precautions to be taken than usual in project design and execution of the works.

  • Concern that the works for construction of the tunnel and protective wall do not adversely affect the integrity of the church.

  • Consideration of the structural complexity and unity of the church complex.

  • Concern about “the fragility and structural vulnerability of the church to differential movements greater than those foreseen in the construction project for the church”. These movements could be caused “by possible differential settling of the foundations of its supporting elements caused by probable incidents during tunnel construction or use or during construction of the pile wall for protection of the church”. They could also be caused by “future geological movements, such as washout of sands from increased water flow caused by reduced water passage due to the barrier of the pile wall barrier, or as an effect of the final weight of the building on the Pliocene ground underneath that could damage the structure of the tunnel.”

  • It is also noted as a building experience that “during their construction the Nativity towers experienced a settling of a few centimeters due to their weight and the characteristics of their stone and lime mortar foundations, which caused cracks in the façade and adjacent windows”. It can be inferred from the above that as a consequence of the new shallower and less rigid foundations any damage occurring to the church would be greater than on the previous occasion.

  • The consideration that the predicted maximum movements or displacements cannot be guaranteed, but only estimated, because their calculation is based on the assessment of a very complex and heterogeneous medium such as the subsoil, which may contain hidden features. As a consequence of this and due to the fragility and massiveness of the church, “the damages that may be caused will probably be irreparable”.

  • The consideration that in addition to potential irreparable damage to the structure of the church, there is a risk of physical injuries to persons from possible falling objects.

  • The projected tunnel “must be excavated in Tertiary soil (Pliocene) formed by decarbonated sands and layers of clay and marls below the water table level”. This soil is classified by Dr. Riba as “poorly cohesive and soft”.

  • The consideration that the pile wall does not totally guarantee the protection of the church.

  • The negative impact that could be caused to the church by “possible deterioration over the years in the reinforced concrete structure proposed by ADIF, since it is located partially and permanently below the water table level and very close to the church foundations, which remain above the water table level.

  • ”The lack of consideration in the informative study of “possible natural or intentional accidents that could affect the work of the brilliant architect Gaudí”.

  • Concern about the “impact of the vibrations on the fragile structures of the church caused by the passage of the train”. Once the tunnel has been built, high-speed passage of the trains consisting of several 80-ton cars will produce waves of vibration that will be transmitted to the ground both through the air and directly through the rails. The vibrations will propagate through the ground to the foundations and from there to the building structure. This concern is based, among other reasons, on the fact that in the informative study an evaluation is missing of the dynamic impact that will be caused by the vibrations produced on the fragile structure and foundations of the church and on the pile wall. In addition, there is no study on how these vibrations may affect the durability of the church, the vaults and the rest of the building structures. The pile wall as currently proposed is not considered to be a sufficient protective measure against this type of impacts.

  • Therefore, the proposal to avoid potential damage to the monument by moving the tunnel away from it.


Due to the high cultural value of the Church of the Sagrada Familia in Barcelona the conservation of its integrity is imperative, especially if one considers that the UNESCO included the Nativity façade and crypt on the World Heritage List for their outstanding universal value. For this reason, in accordance with the World
Cultural and Natural Heritage Convention, the responsible bodies must use all the means and measures at their disposal to guarantee the monument’s integrity and avoid any possible damage.

It is noted that the current project for the tunnel and protective wall for the church calls for their construction within a few centimeters of the monument, which, due to its structural fragility and the nature of the underlying ground, could affect the foundations and cause differential settling, which might damage the structure of the church. The predicted maximum displacement cannot be guaranteed, but only estimated, because its calculation is based on an assessment of a very complex and heterogeneous medium such as the subsoil. High-speed passage of the train may also produce vibrations that could affect the foundations and structure of the church. To our knowledge, no study on the dynamic impact on the foundations and structure has been made, and we consider that a pile wall is not an effective protective measure against this type of impact. In summary, the project submitted does not offer sufficient guarantees for a conservation of the integrity of the built work or the work pending construction, and may cause irreparable damage to the monument and possible accidents.

A new project needs to be developed in which extraordinarily complex and detailed tests, analyses and studies are performed in an attempt to minimize the risk, which would then be used as the basis for designing new protective and safety measures if they are feasible. Even so, and in spite of the quality of the possible studies and projects, there would be no absolute guarantee, given the complexity of the ground and the monument.

In view of this, it would be recommendable to choose another route further away from the monument so that the high-speed train will not pose any risk to the integrity of such an irreplaceable heritage property as this work by Gaudí. At the same time, the competent competent State authorities in World Heritage protection are reminded that under the World Heritage Convention they have the obligation to take appropriate measures to prevent possible irreparable damage to the monument and the loss of its integrity.

ICOMOS Spain Madrid, 1 February 2007

informe procedente de la web del ICOMOS: http://www.international.icomos.org/risk/world_report/2006-2007/pdf/H@R_2006-2007_40_National_Report_Spain.pdf