The Crocetto (275 m) and Giustizia (64 m) tunnels are located between Biasca and Osogna-Cresciano in the Canton of Ticino (CH). The two-track tunnels were commissioned in 1874, together with the opening of the Gotthard pass tunnel, and have been renovated and refurbished several times.

In regards of the 4-Meter-Corridor project, the tunnels will be expanded to a larger clearance profile and the old structurewill be upgraded according to the concept of "Tunnel maintenance II" for a useful life of 50 years.

The establishment of the profile clearance is implemented by means of a track sinking and profile sawing in the vault and masonry demolitions. As a result of the lowering of the track, the abutments must be undertaken continuously. The renovation measures are carried out by rehabilitating the masonry joints, specific drainage measures and sprayed concrete sealinglining.

The two-track railway tunnels Crocetto and Giustizia were upgraded under running railway operation. The railway tunnels are crossed daily by up to 180 passengers and freight trains, which requires a 100% availability of the railway track.

Vault renovation from rehabilitation train:

• Vault cleaning with HDWE 2’000 m²
• Vaultsawing 500 m²
• Joint repair 500 m²
• Sprayed concrete waterproofing 2’000 m²
• Arch drainage 500 m

Invert sinking down to 1.3 m depth in rock and loose material from the site trail:

• Nail wall 700 m²
• Diamond bladesawing 200 m²
• Invert sinkingby blasting 3’500 m³

(under running train operation)

• Sole lowering in loose material 3500 m³
• Tunnel drainage 1’600 m
• Substructure PSS 2’000 to
• Subbase coating 1’100 to
• Cable channels 1’600 m

• Subbase coating 1’100 to
• Cable channels 1’600 m

Abutment undertakingof the tunnel vault in 340 stages as well as performance of theedge walls in the pre-cuts.

• Arch support by means of rock bolts and

longarines 700 m

• Injections 250 to
• Abutment undertaking in the"pilgrim "

step method 3’000 m³

• Rehabilitation of the edge walls 350 m²

Niche:

• Escape niches 13 units