The “skew sliding” shaft formwork  
It is composed of four corner with slopped cut, lift by a stripping device allowing it to retract and be move by a single crane pick.

The “retractile” Shaft formwork
We take advantage of the flexibility of the metal skin to reduce its size at the stripping time. It automatically resumes the original shape when it is put on place.

The “Vertical half-tunnel”
It can be composed of two or four vertical half-tunnel. Each set of vertical half-tunnel is assembled by key locks. The retraction of the cage is performed by a device composed of strut and cam-action system..