"Buechi" bypass tunnel project, village of Gündlischwand
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.
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.
at 9200 km - open routeing that covers approx. 600 m
Rüdli area (Buechiwald)
End of project on Baumgarten side:
open routeing that covers approx. 570 m to 11,030 km
703 m single-tracked
Tunnel longitudinal slope:
Total length of project:
approximately 1,830 m
Minimum curve radius:
Power rails 1500 VDC
Rails type EN 46 E1, concrete sleepers in the tunnel
64 or 70 km/h
approximately 9,900 m3 loose
Excavation deposited on site:
approximately 33,300 m3 loose
Excavation for removal:
approximately 62,600 m3 loose
approx. 2.5 years
CHF 36 million
Rail technology share:
CHF 2.0 million
Slope debris/rockfall deposits, blocky
Moraine, blocky, dense to very densely embedded, east of the site is rock
only local water ingress, no groundwater resources, which significantly affects the construction project
Tunnel forecast: Tunnel construction entirely in loose stone, unless the axis is shifted to the south.
The implementation is directly dependent on public financing negotiations with the federal and cantonal authorities