Restoring a major power connection over the Swiss Alps
Completion of repairs and commissioning of the storm damaged 380 kV Pradella–Sils transmission lines in Switzerland
In the night of 29th to 30th October, 2018, extremely high winds from the storm front Vaia toppled four pylons of the 380 kV line Filisur–La Punt in Switzerland, near the top of the alpine pass. Due to this incident the monthly net transmission capacity to Italy was reduced by 900 MW until the line was back in operation on 29th July, 2019.
Soon after the damaging event, ÅF was commissioned by the national grid operator Swissgrid with the planning engineering work for the replacement of the defective line and with the dimensioning of the new structures. These included the tower statics, dimensioning of the foundations, civil engineering site management and the construction management for the assembly work.
Already in the middle of April 2019, before the official opening of the Albula Pass road, the repair measures could be started. However, heavy snowfalls, extremely low temperatures and snow drifts, especially in the month of May, made work in this high alpine zone difficult. Thanks to the snow removal work carried out by the Civil Engineering Office of Grisons and a special avalanche control system for avalanches, the activities nevertheless continued on.
To begin with, the existing foundations had to be removed and new ones constructed. The towers were then erected and the conductors installed. The new pylons have the same geometry as the old ones, but have been built to withstand stronger winds and conditions thanks to reinforced foundations and structures. Additional avalanche protection has been installed for the foundations of two masts.
Since 29th July, 2019 – nine months after the pylons were downed – electricity is flowing again.