^{Layout plan of LK 1:25,000}

The Buechiwald tunnel is on the Zweilütschinen – Grindelwald section of track. This section presently runs through several curves with a radius of less than 100 m and an approximately 60-metre tunnel with built-on gallery requiring renovation. In addition, the profile of the tunnel is too small to comply with today’s specifications (tunnel profile, escape plan, etc.). The railway sections before and after the tunnel are exposed to a concentration of various natural hazards. These include avalanches, landslides, snow slides and rock falls. The steep, forested location also requires periodic removal of wood after storms.

Feasibility Study

The first work began in 2001 with tunnel surveys by civil engineers ILF, Zurich. Geological surveys were carried out in 2004 by Geotest AG, Zollikofen (seismic refraction, rotary core drilling, geotechnical tunnel prognosis). Based on this information, engineers Ingenieur Unternehmung AG, Bern carried out a feasibility study in 2005 with an initial cost estimate of CHF 22 million. This was based on very rough subsoil data as well as a first assumption for line layout.

PGV Application Project

As part of a public tender, Planergemeinschaft Engineering Ltd., Bern, Prona Umwelt, Sicherheit, Biel, Prantl Bauplaner AG, Grindelwald and Geotest AG, Bern were issued the order for further consideration of the project. The application dossier was compiled in close cooperation with landowners, the Federal Office of Transport, environmental experts, internal agencies and other involved groups. This was based on additional soil investigations, which have shown that the pending mountain water is to be expected, and therefore the tunnelling procedures and the type of tunnel profile

are to be adapted. Moreover, the layout of the tunnel lines has been optimised, i.e. shifted to the bedrock in the south, so that a section of 390 is now constructed by drilling and blasting. The remaining portion of the 703 m long tunnel is located in the loose rock. The project requires that an acquisition of approximately 4,400 m2 terrain and temporary use of approximately 27,300 m2 can be arranged. The relevant agreements are already available. The request to the Federal Office of Transport was submitted for review in late March 2012. The work shall begin in the year 2013, in the case of the ideal progress of the application and funding. The construction period is two and a half years.