slight extension of the line, in the Sagrera train station’s axis. The extension, necessary for such a shunting, indeed more expensive, did not seem like an unmanageable task.
ICOMOS considers that the works that have been undertaken and the forward-looking studies provided, in the perspective of maintaining the underground line in its plan, in the vicinity of the Sagrada Familia and the Casa Milà, provide elements which are in principle in favor of the projects’ upholding : irrelevant subsidence effects compared to those due to the actual weight of the Cathedrals’ structure, reinforcement of the Cathedrals’ foundations with the bored pile wall, irrelevant hydrological effects compared to the natural variations, a ground favorable to the tunnel driving of a relative depth with no surface damage, use of
boring material and use speed for rail convoys, Construction Monitoring
of additional techniques with low vibratory effects, highly limited etc. Furthermore, ICOMOS considers the implementation of a Committee, including independent experts as an element of
warranty. The Committee must provide a monthly report concerning all recorded events related to the effects of the tunnel’s excavation, in any way connected to the conservation of the Cathedrals’ structural integrity. However, ICOMOS emphasizes the following points:
The suggested creation of a Committee in charge of monitoring the construction works must be implemented and its formation must be extended – in comparison to the suggestion made to date. The point of view of the critical experts for the project must absolutely be taken into account. They especially recall the structural fragility of the Sagrada Familia, which cannot tolerate any slight risk-taking. For this reason, it would be necessary to integrate within the Construction Monitoring Committee, for instance, at least a representative of the Ministry of Culture and a representative of the Property Management Authority. This Construction Monitoring Committee must particularly be in charge of:
On a permanent basis, collecting and interpreting results of the supervision related to the process of progress of the train tunnel and existing buildings, taking into account the various ground layers along the path ;
Creating an independent model for the examination of buildings in the vicinity of the Sagrada Familia, on the basis of monitoring outcomes ;
Creating an independent model for the examination of buildings in the vicinity of Casa Milà, adjusting it with the outcomes of the further ground studies report and going by the monitoring results ;
On a permanent basis, adjusting the calculation models according to the measures that have been taken and to the previsions concerning ground movements as the works progress, and take extra measures if necessary;
Undertaking a long-term monitoring of the ground pressure increase on the tunnel, due to further constructions in the Sagrada Familia Cathedral, including a long-term monitoring of the structure originally built by Gaudi;
Keeping the World Heritage Centre regularly updated with the outcomes.
These measures must contribute to create a permanent monitoring instrument, accepted by all members of the Building Monitoring Committee. This Committee must be able to initiate an immediate halt of the tunnel boring works, in the occurrence of proved exceeding of the physical limits, part of the global chosen indicators and examine the reasons. The Committee’s remits must concern the Sagrada Familia and the Casa Milà.
The question of possible vibration transmissions when underground trains pass must constitute a topic for a specific, precise and regular monitoring programme. This must be added to the property’s monitoring in the Management Plan, for the future high-speed train, if this itinerary is finally achieved, as well as for the metro lines 5 and 2, which pass in the immediate vicinity of the Sagrada Familia. A possible reinforcement of the vibration absorption systems inside the tunnel must be envisaged with the rail constructor. The speed of the convoys must be strictly limited.
State of conservation of World Heritage properties inscribed on the World Heritage List
WHC-10/34.COM/7B.Add, p. 178