Context and challenges

This client is a major player that provides engineering, consultancy and project services to affiliates of Istanbul Metropolitan Municipality.

Istanbul Metropolitan Municipality manages several infrastructures and construction projects. One of its projects deals with the “Kabataş Üsküdar Bosphorus Pedestrian Tunnel”. It aims at enabling pedestrians to cross thought the Bosphorus undersea, connecting the Asian and European sides.

It integrates the rail transit system at both shores and is to be excavated via tunnel boring machine under the Bosphorus Strait. This tunnel enables a more efficient use of the public transportation network by connecting Kabataş and Üsküdar that are the transportation centres of Istanbul. This client needed to perform the requisite survey studies before starting the construction of the tunnel.

This client called on Assystem to perform geotechnical site surveys required for building the pedestrian tunnel.

Project scope

  • Onshore and offshore drilling works:
    • 14 boreholes at 1104 m offshore
    • 2 boreholes at 202 m onshore
  • Geotechnical tests, measurements related to engineering properties of geological units:
    • CPT (Cone Penetration Test)
    • RPM (Reduced Pressure Meter) tests
    • HPD (High Pressure Dilatometer) tests
    • Packer Permeability tests
  • High resolution acoustic tele viewer (HiRAT) measurements
  • PS Suspension logging
  • Sampling and laboratory tests
  • Preparation of geotechnical reports


  • Geotechnical and geophysical data collection and analysis to identify the underlying soils and rock units along the proposed tunnel route
  • Analysis of the geotechnical and geophysical properties of the different units in order to facilitate engineering analyses associated to the construction of the proposed Bosphorus Pedestrian Tunnel
  • Definition of the necessary specific parameters for the design of the tunnel

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