Teamwork

The 100m building will comprise 152 apartments, a hotel, a medical centre and a restaurant.

The location of the construction site near the Bern-Belp Airport had an impact on the crane concept. The planning team opted for the Wolff flat tops due to the lower assembly heights and maximum overall heights, the manufacturer said. Both the crane assembly and operation had to be reported to the Federal Office of Civil Aviation, and the two highest cranes were equipped with obstruction lights and warning sleeves on the slewing part.

Due to the immediate proximity of the construction site to a rail line, all three cranes were also fitted with a working range limitation to comply with the safety requirements of the railroad.

The highest crane, a 6031.8 Clear, was initially assembled to a hook height of 81m, then climbed and tied to the building twice during the construction process to its final height of 126.5m.

“Due to the design of the facade elements, the tie-ins could not be attached to the floor slabs as is usual but had to pass through window and door openings to be fixed inside the building,” said Johannes Eckert, head of sales at Wolffkran Schweiz. The attachment points of the tie-ins on the building and crane tower had to be precisely determined prior to the crane assembly and the foundation of the 6031.8 Clear calculated accordingly.

The facades are installed in one go as soon as a floor is completed, which is typically every seven days. “The order in which the facade components are installed is thus fixed and a later installation almost impossible,” explained the certified crane expert Beni Buchs. “Door and window frames of the affected facade elements have therefore been modified to allow for an installation around the tie-ins.”

Two of the three Wolff cranes have since been dismantled. The 126.5m 6031.8 Clear is still on site, lifting concrete and facade elements into place. While the last of the 32 floors are still being built, interior work on the lower apartments has already been completed and two-thirds of the 152 units have already been leased.