Switzerland Construction Thalwil Tender

The flood relief tunnel between Langnau am Albis and Thalwil is intended to transfer extreme floods from the Sihl into Lake Zurich and thus protect the lower Sihl valley and the city of Zurich from devastating floods and damage amounting to billions. The first preparatory work for the construction of the tunnel will take place in autumn construction will start next March. The structure should be completed in 2025.In the event of an extreme flood of the Sihl the lower Sihl valley and the city of Zurich are at acute risk of flooding. The possible damage is estimated at up to CHF 6.7 billion for the city of Zurich alone. In view of this enormous damage potential the Canton of Zurich is planning a relief tunnel to transfer flood peaks of the Sihl near Langnau am Albis into Lake Zurich near Thalwil. It will also protect the lower Sihl valley and the city of Zurich from the rare extreme flood peaks of the Sihl.In December 2020 the government council set the project for the flood tunnel and the necessary ecological replacement measures i.e. issued the building permit. In May 2021 the Cantonal Council unanimously approved the property loan of 175.5 million francs for the planning and construction of the tunnel and the replacement measures. It is now certain that construction work will start as planned in mid-March 2022. In October and November of this year some preparatory work will be carried out in Rtiboden for the future intake structure of the tunnel on the Sihl. Before construction begins it is necessary to lay utility lines for water electricity and sewage and to carry out forestry work along the river. In good time before the actual start of construction next March the construction department will provide media and public with detailed information about the construction work and its effects. The construction management expects a construction time of around three and a half years so that the flood tunnel should be completed by the end of 2025.