As part of the overall renovation of the A8 motorway between Interlaken-Ost and Brienz, the entire operating and safety equipment was completely renewed under the direction of IG Engineering N08 (IUB Engineering, IM Maggia). After the two already renovated tunnels Sengg and Chüe-balm, the longest tunnel, the Giessbach tunnel (3,340 m), was also thoroughly tested.
The preparatory work (project planning, procurement of contractors for realisation) was carried out together with the other tunnels and the entire open section between the Bönigen half-junction and the Brienz junction in the period from 2012 to 2019. As in the two shorter tunnels, temporary equipment was first installed in the Giessbach tunnel to create space for the structural renovation of the tunnels. In particular, the existing suspended ceiling was demolished in the area of the three exhibition bays to make room for the installation of two jet fans each, as the entire ventilation system in the tunnel had to be converted to a combination of smoke extraction and longitudinal ventilation.
This measure was necessary in order to fulfil the greatly increased safety requirements for ventilation since the tunnel was first opened in 1988. The final BSAs were installed and put into operation in spring and summer 2024. The final, integral overall tests were carried out last week. This test was carried out over two nights to check that all systems (emergency telephony + ventilation system + fire alarm system + signalling + lighting, etc.) work together perfectly.
The site management of IG Engineering N08 prepared and successfully completed a detailed test programme for these comprehensive commissioning tests of the Giessbach Tunnel. All systems functioned as desired. The tunnel is now ready for operation.
Over the next two months, the underside of the intermediate ceiling in the tunnel will be cleaned and waterproofed on site. The temporary video cameras will then be replaced by the permanent ones to give the tunnel the finishing touches.
