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On Monday 7 March 2016 at around 7.15 p.m. a landslide occurred on the eastern wall of the Calanca Valley, in the Italian-speaking region of Grigioni. The landslide affected the cantonal road at the level of the village of Buseno, damaging it significantly and also damaging Swisscom’s cable channel and all of the cables it contained.
This road is the only access route and the only telecommunications channel for the Calanca Valley. The valley’s 400 inhabitants were cut-off from the rest of the world, unable to use the road and unable even to communicate. In fact, the damaged fibre optic cable was the only one that linked up with the Selma headquarters, to which all the users to the north of the landslide were connected, as well as all the antennae of the mobile network.
Already by Tuesday morning, employees of cablex’s southern region were on site to assess the damage and get an idea of the work required to restore the damaged connections. They were shocked by what they saw: masses of earth as big as trucks had completely destroyed the road and buried it along a stretch of approximately 200 metres. The only way of restoring the services was to construct a temporary elevated line with a copper cable measuring 20x2 and a fibre optic cable of 48 Fs. It immediately became apparent that the repair work would take at least two days, so Swisscom decided to supply a number of satellite phones to the villages in the valley to allow them to communicate in an emergency while the lines remained down.
In a cable chamber to the north of the landslide, the existing cables that run towards the north were connected to the new temporary cables (48 Fs FO and copper cable 20x2). A temporary tube was installed for the cables running out of the cable chamber.
The landslide affected virtually all of the valley slope, almost down to the river, so in order to prevent the temporary cables from being damaged during the repair work on the road, a decision was taken to place the cables in an elevated position on the opposite bank of the Calancasca River. We made use of existing posts (electricity, street lighting) and set up new temporary telephone masts. We also made use of existing structures, such as bridges and a dam.
After a provisional stretch of 800 metres, from a lamp post the cable is redirected back towards the cantonal road on the south of the landslide, where the temporary cables are reinserted into the existing channel and are connected to the existing transmission cables running towards the south.
Thanks to the quick actions of the 15 cablex employees in the service and grid construction sectors who went on site, communication was restored on Thursday morning. The Swisscom client and the inhabitants of the valley expressed their great satisfaction with the quality and speed with which cablex carried out the work. A big thank you to all the workers involved!