2010 and a consultation meeting held at the World Heritage Centre on 16 April 2010, the State Party confirms the essence of the technical options described in the previous point.
They are currently being carried out.
The tunnel boring machine is working since the month of March, from the north-east junction of the Sagrada Familia and the Casa Milà’s. It should reach the vicinity of the Sagrada Familia at the beginning of autumn and later on, the Casa Milà. It is a specific tunnel boring machine with a permanent pressure compensation mechanism, whose results have been successfully tested. A series of measures and supervision are being carried while this machine is being used, for its entire route.
Three independent mathematical studies, known as « with finished elements » can predict the dynamic behavior of the grounds and anticipate the subsidence’s effects or the hydrological behavior of the bored pile wall. For the project promoters, studies show the following in a categorical way: on one hand, the effects of subsidence linked to the building itself, due to its weight and on the other hand, the bored pile wall having a positive impact on the stability of the building, induced by the buttressing of its south-east side. With this existing situation, the subsidence induced by the train tunnel excavating would be insignificant; However, less optimistic conclusions to these studies are brought forward by independent experts. They comparatively consider the results of these studies and relativize their impact in regard to the specificity and structural fragility of the Sagrada Familia and to a lesser extent that of the Casa Milà, a residential building with smaller proportions.
The concrete piles are practically all in place (April 2010). However, various trustworthy sources have mentioned unexpected secondary effects. At the beginning of March, during the construction works, an 80 centimeters deep breakdown in the paving in front of the cathedral was noticed; in the immediate vicinity of the bored pile wall. Furthermore, following a storm, rainwater would not have been evacuated, making the ground abnormally soft in front of the Cathedral’s south-east porch. These anomalies are considered to be surface ones and purely isolated, unrelated to implantation of the piles;
The hydro geological effects have been carefully compared to natural movements of the water table and its seasonal flow variations. The effects of the bored pile wall remain very much below natural variations and neither do affect the flows nor the water table's seasonal level changes;
A technical network for the monitoring of the static and dynamic behavior of the grounds in vicinity of the Sagrada Familia and the Casa Milà has been put in place. Four automatic stations in charge of controlling the structural shape changes of the Cathedral also guarantee its supervision. It appears that the subsidence effects linked to the building, to its construction being carried out , or to the wind, must be followed- up carefully, as well as the recording of wall cracks.
The State Party suggests establishing a monitoring Committee, in order to ensure the quality and supervison of construction works, including independent experts;
The European precautionary norms and construction supervision norms in urban zones have been respected; and beyond.
In conclusion, the World Heritage Center and ICOMOS deeply regret that a re-routing solution of the underground plan in the vicinity of the Sagrada Familia and the Casa Milà has never been seriously examined. The technical arguments of the viary network and its angles which would be to sharp in case of a re-routing seem to be denied by a simple examination of the city’s planning structure. The two streets parallel to the Mallorca street, in the south- east, the Valencia and Arago streets, offer the same angular characteristics, at the price of a
State of conservation of World Heritage properties inscribed on the World Heritage List
WHC-10/34.COM/7B.Add, p. 177