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Ruisseau le Gobé – Micro-tunneling work under the highway – Pregny – Chambésy (Switzerland)

Ruisseau le Gobé – Micro-tunneling work under the highway – Pregny – Chambésy (Switzerland)

Geotechnical engineering

  • Project Owner: DETA/DGEAU Lake, Watercourse Renaturation and Fishing Department
  • Mission: Complete project management (phase 31 to 53, in accordance with SIA 103)
  • Cost of the works: 3’488’400 CHF (ATI) (décembre 2016)
  • Cost of the mission: 149’886 CHF (AIT)
  • Mission date: 2017-2018


The project involves the design and construction of a second Gobé arch (doubling the existing upper arch) to reduce the risk of flooding to the buildings on the Chemin des Tuileries in Bellevue. The proposed variant provides for the creation of:

  1. a 96 m DN1800 arch parallel to the existing DN2000 arch,
  2. two DN1800 arches linking the arch water collection chamber (which will be used as a thrust chamber) to the Vengeron,
  3. a DN1200 arch collecting water from the SETEC at the Vengeron interchange.

The project is characterised by a high level of constraints and interference. The DN1800 arch to be built over 96 m crosses the ground under the N1a motorway lanes, under the Colovrex interchange (engineering structure 330 b) and runs alongside the existing arch located a few metres away. The water collection chamber will be used as a thrust cell for the 4 blasts.

The arches will be built using the micro-tunneling technique.

The characteristics of the project are as follows:

  • Arching DN1800 over 96 m under the motorway lanes and under the engineering structure 330 b;
  • 204 m of DN1200 arching;
  • water collection chamber used as a thrust chamber during the micro-tunneling works, 12 m in diameter and around 10 m deep;
  • 2 arches DN1800 of 36.5 m and 24 m respectively to connect the collection chamber to the Vengeron.


GEOS is in charge of the complete project management on behalf of CERA.

These studies include the following services (in accordance with SIA 103):

Phase 31: Preliminary design ;
Phase 32: Project design;
Phase 33: Permit application procedure;
Phase 41: Call for tenders, comparison of bids, award proposals;
Phase 51: Execution project;
Phase 52: Execution of the work;
Phase 53: Commissioning, completion.


Posted on

27 July 2023