25. November 2021

Jakob rope work on the Grimselpass

The construction of the new Spitallamm replacement dam is a special project in a high alpine location in the Bernese Oberland. Jakob Rope Systems is supporting this construction project with work in the field of hoisting and lifting technology.

Large dams are rarely built in Switzerland anymore. This makes the construction of the Spitallamm replacement dam on the Grimsel Pass in the Bernese Oberland all the more spectacular. A new 113-metre-high dam will be built here between 2019 and 2025. In future, it will replace the dam wall, which is around 90 years old and in need of renovation. By replacing the dam, Kraftwerke Oberhasli AG (KWO) is ensuring that the water from Lake Grimsel can be used for electricity production in the long term.

Two tower cranes from WOLFFKRAN with a maximum lifting capacity of 60 tonnes are ensuring site supply. The two giant cranes with luffing jibs have free-standing tower heights of 92 and 87 metres. With maximum outreach of 75 and 70 meters, the cranes are each capable of lifting 11 tons at the top. Jakob Rope Systems, in cooperation with its partner Von Rotz & Wiedemar (Kerns) will be allowed to equip these two cranes with ropes four times over the next few years.

Due to the high alpine location, the construction site was shut down for the winter at the beginning of November. The two tower cranes will independently rotate 360 degrees twice a day until spring 2022, when the construction site will come back to life. This will prevent gears, bearings and other moving parts from getting stuck over the winter. Should there be any malfunctions at the cranes during the cold winter months, a rope access system from Jakob Rope Systems will ensure that the two cranes can be reached from the dam wall at a height of 90 meters above ground level, even in snowy conditions and avalanche danger. For this purpose, our engineering team has created supporting calculations that simulate the rope behavior under loads caused by personnel access in advance.

Our two height safety specialists Tobias Singer and Stephan Angst installed the special winter access at dizzy heights at the beginning of November. Next spring, they will dismantle the rope access again. Jakob Rope Systems is allowed to install and dismantle the rope access three more times until 2024.

(Photos: David Birri / Tobias Singer)