Second Gotthard tube: segment production for the main tunnel, south section
The project
The second tube of the Gotthard road tunnel is one of the most important infrastructure projects in Switzerland. The new main tunnel runs around 70 meters parallel to the existing tube and stretches over 16.9 kilometers. Two service ducts running under the roadway will accommodate important supply lines for tunnel operation, one of which will be used as a pioneering project for the Swissgrid high-voltage line.
Tunnelling is being carried out simultaneously from the north (Göschenen) and south (Airolo) using two Herrenknecht Single Shield TBMs with segmental lining. Consorzio Gottardo Sud (Marti Tunnel AG, Mancini & Marti SA, Ennio Ferrari Impresa Generale SA) was awarded the contract for construction lot 341, the main south tunnel from Airolo. It comprises the 7.8-kilometre-long excavation of the main tunnel, the excavation of the 290-metre-long southern fault zone around 4.9 kilometers from the south portal as well as three complex ventilation or logistics caverns and several cross-passages.
Challenging segment production
In order to drive construction forward efficiently and avoid unnecessary transportation, the concrete for the excavation support and the tunnel lining is being produced directly at the Airolo construction site. As part of a joint venture, Marti Technik AG is preparing all the gravel for the concrete production at both the north and south portals directly from the tunnel excavations. Two temporary production factories were built near the south portal for the production of the concrete elements, which will be dismantled once the work is complete: One for the tunnel segments and one for the plant ducts (WELK). Since the end of 2024, Marti Tübbingwerk AG has been producing the concrete elements weighing several tons for the consortium to expand the tunnel:
- Ridge and elm segments with a weight of approx. 10.4 tons each
- Invert segments with weighing 13.5 tons each
- Key segments with an individual weight of 7 tons and
- the frontrunners in terms of weight: the so-called WELK elements (for the plant ducts) with 20 tons each
In order to meet the high demands placed on the production of these concrete elements, a powerfu and highly automated production facility has been set up. The precise production of the segments and the complex elements for the plant ducts requires sophisticated process control and state-of-the-art technology.
As this is a newly built plant with partly new personnel, the focus is on ease of operation and high safety standards. The sometimes prevailing winter conditions with snow and ice also require a robust and reliable infrastructure to ensure production under extreme conditions.
Our solutions
The large and heavy components require precise and reliable handling solutions. A specially developed vacuum gripper for the highly eccentrically loaded invert segments allows these demanding concrete elements to be turned and transported safely. In addition, our proven vacuum devices ensure safe stripping, turning and transportation of the 20-ton WELK elements.
Working at an altitude of 1,175 meters above sea level places additional demands on the vacuum technology, as the lower air pressure affects the lifting capacity. To counteract this effect, we have equipped each of our vacuum lifting devices with two powerful vacuum pumps. To prevent malfunctions in cold temperatures, valve heaters have also been installed in all vacuum lifting devices used outdoors.
Scope of supply
Tunnel segments:
- 1 DVL-14.0T-EXT (Retrofit) Device for stripping and turning by 90 degrees (in the segment factory)
- 1 DVL-14.0T-INT (new with rotation and center of gravity adjustment specially developed for the Gotthard project) for storage management (open storage) for ridge and elm segments
- 1 DVL-10.0T-INT (Retrofit) Storage management device (outdoor storage) for two types of invert segments
WELK: Vacuum devices with a payload of 20.0t
- 1 DVL-20.0T 2x90 Stripping and turning device (rotatable by 90° on both sides) for the factory
- 1 DVL-20.0T 2x90 Stripping and turning device (rotatable by 90° on both sides) for outdoor storage
