Idrodemolizione e idrolavaggio galleria ferroviaria in esercizio

La galleria ferroviaria della tratta Paradiso–Melide rappresenta un elemento strategico della linea che collega Lugano a Melide, in Svizzera. Si tratta di una struttura a doppio binario, in esercizio sin dal XIX secolo, che attraversa un tratto complesso dal punto di vista geomorfologico e infrastrutturale. Dal punto di vista costruttivo, la galleria è caratterizzata da pareti in calcestruzzo armato nella parte inferiore, mentre la volta e l’intradosso sono realizzati in pietra naturale.

Considering that the rail traffic on the route is continuous, any maintenance work had to be planned in such a way as to guarantee the full operation of the trains, while ensuring the safety of operators and users.

L’intervento ha previsto un idrolavaggio e un’idroscarifica estensiva of the tunnel to a height of approximately 8 metres from the base to the intrados of the vault. In order to operate safely while keeping one track in operation, a barrier was set up in the middle of the tunnel: one track was temporarily excluded while the other remained in operation.

The first activity involved the hydro-washing of the upper part of the tunnel, aimed at removing smog, residues and loose parts of the stone. A rotating nozzle system, consisting of three swivelling discs, known as a Buster, mounted on the arm of an excavator, was used to perform this operation. This tool made it possible to effectively remove the loose material, easily reaching the end of the tunnel vault.

Following the hydro-washing, robotised hydrodemolition of the reinforced concrete walls of the tunnel was carried out. The intervention involved the removal of thicknesses between 10 and 15 cm, for a height of approximately 2.5 m, including the area underneath located approximately 50 cm from the level of the track. At the end of the work, the same operation was carried out on the opposite side of the tunnel, allowing the maintenance to be completed without interfering with normal rail traffic operations.

The ultimate goal of the intervention was the overall redevelopment of the tunnel, improving its durability, safety and functionality for rail traffic.