Building a tunnel with a continuously changing cross-section is far from standard practice. In the case of the Carlberg Tunnel (Moss, Norway), the width evolves from 13.80 m to 20.65 m along its length, creating a continuous conical transition. This type of geometry requires rethinking traditional formwork approaches: if the tunnel changes, the formwork must change with it.
For this project, a variable and adjustable formwork system was used, capable of adapting progressively at each stage. The lining was executed in 78 advances, each one different, using modular elements that allowed geometrical continuity and precise shaping throughout the transition.
This approach is especially relevant for projects that involve:
- Non-constant or evolving cross-sections
- The need for tight geometric control of the final lining
- Optimized construction cycles without compromising quality
In other words: when the structure cannot adapt to the formwork, the formwork must adapt to the structure.
If you are planning or designing a tunnel with variable geometry, you may find the full technical description useful. You can access it through the link below.
→ See full project details: Link