Operation and safety
The construction of the second tunnel tube has become a matter of urgency. For one thing, the first tube has been in operation for over 40 years and requires extensive maintenance. Furthermore, there needs to be better safety, as traffic has increased significantly since the existing tunnel was built. Once the first tube has undergone an overhaul and is reopened, traffic will flow in each separate tube in one direction only. Each tube will have just one carriageway, but also an emergency lane to improve safety. There will be no increase in capacity.
Safety precautions during construction of the second tube
The construction site for the second Gotthard tube (2TG) is structurally separated from the tunnel currently in operation (1TG). Traffic in 1TG will therefore not be affected during construction of the main 2TG tunnel. FEDRO continuously checks the first tube, the SIT and other existing structures to ensure they are not affected by the construction work on the second tube. This includes measuring vibration in the existing portal control centres, suspended ceilings, tunnel cladding and utility facilities, and measuring for any deformation in the vault or suspended ceiling. Visual inspections are also carried out e.g. for cracks or spalling in the cladding.
Safety during operation
Once the work has been completed and the second tube is in operation, single-lane traffic will flow through each tunnel tube. A second lane will serve as an emergency lane. Southbound traffic towards Airolo will be routed through the existing, newly renovated tube, while northbound traffic towards Göschenen will be routed through the new tube. Traffic can be diverted into one or other tube across a central reservation in the portal areas, as required.
As is currently the case, two traffic lanes will merge into one at the tunnel portals. Traffic will be routed along the carriageway to the left, the right-hand lane being the emergency lane. This means that, even in the event of a breakdown, traffic can continue to flow, making the important north-south link smoother and more reliable than is currently the case.
Should a tunnel tube have to be closed for any length of time (e.g. for maintenance work), the affected traffic can be diverted into the other tube and a two-way system operated for as long as is necessary.
The current system of restricting the number of vehicles entering the tunnel at any one time, which has been established in law and has been in operation since 2002, will be retained for both cars and lorries for safety reasons. Even with two tubes, there will be a limit of 1,000 cars per hour and direction, and a maximum of 150 lorries per hour and direction. There will be no change to these limits, which ensure that sufficient distance is maintained between individual lorries. This significantly reduces the risk of accidents.
Tunnel utilities
Ventilation
The ventilation duct for extracting the exhaust air is located above traffic lanes, separated by the suspended ceiling. The duct leads to the underground ventilation centres, two of which are located at the portals in Göschenen and Airolo, with four others distributed along the length of the tunnel and connected to the existing ventilation shafts in the first tube. In the event of a fire, the emergency ventilation system is activated: ventilation flaps in the suspended ceiling of the tunnel are selectively opened to extract smoke gases. The people in the tunnel can then be evacuated.
Control centres
New control centres for the central service and infrastructure tunnel are to be installed and integrated into the existing systems. The new control centres will be connected to the existing communication network. The existing video cameras will be moved to new locations.
The lighting requirements in a tunnel the size of the Gotthard road tunnel are huge. Lighting is a central element of the new second tube and is essential to safety during its operation. FEDRO is therefore equipping the second tube with the following installations:
- Continuous lighting incl. emergency lighting
- Adaptive lighting at the entrances, suitable for traffic in either direction
- Optical guidance system with additional emergency lane escape route lighting
- Escape route lighting (shelters, flashing beacon on escape route doors)
- Standard lighting in tunnel and utilities ducting
