BOB Railway Straightening of Zweilütschinen - Lütschental Section and Construction of New Buechiwald Tunnel

The one track narrow-gauge railway between Zweilütschinen and Grindelwald is electrified. The core part of the track straightening is the one track Buechiwald Tunnel which bypasses a section of the line exposed to natural hazards in the form of a leaning tunnel. The tunnel was mined out of moraine and heavily fissured rock under the protection of a piperoof. The bridge has a double shell. Special conditions existed because of the water catchment near the east portal which defined the approval process as well as the constructional engineering and operational boundary conditions. The limited space at both portals and the only access to the construction site being via the tracks meant that special attention had to be paid to railway operation during implementation.

Main Data

  • Straightened section: 1.4 km
  • Length of tunnel: 708 m
  • Of which cut-and-cover: 45 m
  • Excavation profile: max. 70 m2


Berner Oberland-Bahnen AG


IUB Engineering Ltd. in consortium

Construction period


Construction costs

CHF 38 million

Scope of services

General planning for phases 31 to 53 for construction engineering, railway technology and surveying.