Bodio & Faido sections, Alptransit Gotthard Base Tunnel

Construction of two parallel single-track railway tunnels with a Gripper TBM and of a multi-function station using blasting

Context: The Gotthard Base Tunnel (GBT; German: Gotthard-Basistunnel, Italian: Galleria di base del San Gottardo, Romansh: Tunnel da basa dal Son Gottard) is a railway tunnel through the Alps in Switzerland. It opened on 1 June 2016, and full service began on 11 December 2016. With a route length of 57.09 km (35.5 mi), it is the world's longest railway and deepest traffic tunnel and the first flat, low-level route through the Alps.
Bodio: Railway tunnel with two parallel single-track tunnel tubes, each 30 km in length (57 km in total), cross-passages every 300 m. Shell construction: excavation, securing and interior construction.
Faido: Excavation, securing and interior construction of the 2.5-kilometre-long multi-function station (MFS) at Faido (with track changeover for the eastern/western tunnel tubes, emergency stop stations with exhaust air systems and escape tunnels, caverns for technical equipment).

Bodio: The two single-track tunnels were excavated using tunnel boring machines (Gripper TBM). The section from the Bodio portal to the multi-function station (MFS) in Faido is approx. 15.5 km long and is situated in the Pennine gneiss zone. The section from the Faido MFS to the Sedrun sub-section is approx. 11 km long and traverses the Piora syncline and the Gotthard massif.
Faido: The multi-function station at Faido (9.6 km of tunnels in total, including 2 track changeovers) was excavated using blasting. The interior is constructed from in-situ concrete and shotcrete.
Shell equipment: Equipment of ancillary structures of the Gotthard Base Tunnel. This includes planning, manufacture, delivery, installation, commissioning and start-up of tunnel and railway technology.

Bodio:

Gripper TBM (an open tunnel boring machine for hard rock) with track-mounted material removal system.
TBM used for boring in areas with convergences, unstable working face, seismic disturbances, and rock fall, with injections and boring in the opposite direction from the neighbouring tunnel tube.
Exploratory boring with preventers for protection, cooling of underground workspaces.
Interior construction (tunnel lining) in parallel with TBM operation –> use of special equipment (worm gear).

Faido:

6 parallel tunnelling sites (blasting).
Various disturbance zones, squeezing rock zones, radial convergences of up to 1 m, seismic disturbances.
Use of flexible steel structures due to squeezing rock.
Use of emulsion explosives (pumped).
Access via a 2700-metre-long tunnel with a gradient of 13%.
Crushing plant in MFS, material removal via access tunnel.
In-situ concrete tunnel lining in tunnel branch caverns (continuous profile expansion) with special formwork (lining with waterproofing & reinforcement).
Methane gas levels, including deflagration, were measured in the crystalline rock during the excavation work.

Shell construction equipment:

Installation of electrical systems 50 Hz and earthing.
Installation of the control technology and the head computer.
Planning and construction of the operational and event ventilation.
Various steel construction measures for the interior fittings such as railings, crane systems, doors and gates.
Installation of the fire protection bulkheads.